CA1172649A - Production of alkyl silicates - Google Patents
Production of alkyl silicatesInfo
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- CA1172649A CA1172649A CA000376490A CA376490A CA1172649A CA 1172649 A CA1172649 A CA 1172649A CA 000376490 A CA000376490 A CA 000376490A CA 376490 A CA376490 A CA 376490A CA 1172649 A CA1172649 A CA 1172649A
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Abstract
ABSTRACT
An alkoxysilane of the general formula (RO)nSi(OA)4-n where R is C1 - C6 alkyl A is - C2H4CH3; -C2H4OC2H5; -C2H4OC6H5;
-C2H4OC2H4OCH3; -C2H4OC2H4OC2H?; -C2H4NR1R2 where R1 and R2 are C1 - C4 alkyl and n is 1, 2, 3 or 4, is made by the reaction of the mixture of ROH and AOH and a silicon or a silicide in a large volume of a solution containing as catalyst the metal alkoxide corresponding to the alcohol AOE.
An alkoxysilane of the general formula (RO)nSi(OA)4-n where R is C1 - C6 alkyl A is - C2H4CH3; -C2H4OC2H5; -C2H4OC6H5;
-C2H4OC2H4OCH3; -C2H4OC2H4OC2H?; -C2H4NR1R2 where R1 and R2 are C1 - C4 alkyl and n is 1, 2, 3 or 4, is made by the reaction of the mixture of ROH and AOH and a silicon or a silicide in a large volume of a solution containing as catalyst the metal alkoxide corresponding to the alcohol AOE.
Description
- ~ ~726~g DESCE~IPTI ON
This invention relates to the manufacture of alkyl silicates by the catalysed reaction of silicon or silicides with an alcohol and is a develop-ment o~ the invention, hereinafter called the previous : invention, set out in EPC Application No, 79 300 542 published under the number 0,004,418 on 17th October 1979. This published specification is primarily concerned with the production of ethyl silicate, We have discovered that, when a metal alkoxide correspondiny to the alcohol AOH is used as a catalytic agent, substituted alkoxysilanes containing the group _ SioA are produced. The present invention proposes a method of increasing the yield of the substituted alkoxysilanes which products have industrial applica-tions, ~`
: Thus according to the present invention :~ ~ there is provided a method of manufacturing alkoxy-~ silanes of the type (Ro)nsi(oA)4 n where R is Cl - C6 :
: 20 alkyl, preferably ethyl, A is -C2H4OCH3, -C2H4OC2H5;
C H OC6H5, -C2H4oc2H4ocH3; -C2H~Oc2H4oc2Hs- 2 4 1 2 where Rl and R2 are Cl - C4 alkyl and n is 1, 2, 3 or 4, ~: ~ by reacting together the alcohol ROH and silicon or a silicide in a catalytic solution containing a ~;
~ 1726 metal alkoxide corresponding to ~he alco~ol AOH,there be-ing preferably at least 500 ml of catalytic solution for each mole of silicon or silicide, thereby having sufficient thermal capacity effecti~ely to maintain a temperature to catalyse the rsaction and to dis-char~e as a product a'~oxysilanes as vapour to-Oether ~ith the alcohol vapour and hydro5en gas.
~he method of the invention is charac-; terised by ~he step of mixing with the alcohol ROH a quæntity of the alcohol AOX~ This mixinO
step si$nificantly increases the yield o~ the s~bstituted alkoxysilane in the product which also co~ta~ns the u~s~x~ituted~tra~o~ysi~LQ ~C~. It should be noted that the use of 10~o AOH as the starting ; 15 alcohol would not proàuce a 10~/o yield o~ the alkox~si-lane Si(OA)4 but a mixed product. In fact approxi-. ~ .
matel~ 5% AOH, 95% (molar ratios) ROH provides a ! ~
notably increased yield of substituted product as compared to a 100% ROH starting material. Up to about 50/c AOH can in certain circumstances be used.
.~ .
~ i 7~649 The reaction between the alcohol and sili-con or a silicide is carried out at high tempera-ture in a catalytic solution which has su~ficient thermal capacity t~ maintain the reaction tem~er-ature and to catalyse the reactio~ and to dischargethe alko~ysilæne products as a vapour to$ether, with the alcohol va~ou~ and hydrogen ~as. The ; thermal capacity o~ ~he catalytic solution can ~e ; . maintained and indeed increased by stepwise additions of the alcohol æ~d silicon or 2 silicide, ~ ~ then the alko~silæ~e ~ro.ucts are re~oved as ;~ vapour ænd the secuence ~epeated.
he term silicide is intended to cover aàditionally to the ~e~allic silicides , carbon silicide more usually called silicon carbide~
The necessary thermal capacity is achieved by :
(a) :carrying out the reaction at as high , ~
~ .
~ .
.
' , ~726~9 . .
a temperatuxe as is practicable~ .
(b) maintaining a relatively large volume of catalytic solution, that is metal al~oxide in a sol~ent, a~ least 500 ml per mole of silicon, (c) selecting an appropriQ~e solvent.
F-eferred solvents are linear oligomeTs ; of the followin~ general formula I:
.
:: I _ _ I where n lS 1 or ~ - Si - O - Si - O - Si - ~ a whole number : ; 1 o L ~ n l greater than 1 :~ :
~0~ ~ A I
or cyclic compounds of the general formula II :
_ .
: A where n is 3 or ::~ _ O - Si- - a whole number ~; 15 ~ ~~ n greater than 3 FORMUI~ II
:
.. .
.
~ 11 72`B~l~
A is CE3; OR where R is C1 - C4 alkyl preferably eth~l; O(G~2CX20)mD where D is meth~l, ethyl or phen~l and m is 1 or 2. Preferably all the A
groups ære the sa~e in-each compound~ 3 is t~e s~e as h and when ~ s C~3, 3 can also be C6E5 when ~ is OR or O(CF2CH20)~D, the solvent m~y also contain Sih~ and/or ~3Si-O-Si~3 s~ecies, provided that the-e lS not mo-e than 20Yo by we~ght of SiA4 and 4~/o by ~eight of A~Si-O-Si~3.
~en A is C~3, the sol~-ent may also contain not more than 20% by weight of Si(OR)4 and/or Si [O(C-~.2CE20) ~;~ species. When ~ is C~3 and 3 is C6H5 the solvent may also contain no~ mc~e than 6~/o of Si(OR)4 ; species, R belng preferably ethyl~
:
~he sol~et m~- also com~rise a mixture of components having differen~ h ~roups and it may also ~ ~ be a mixture of cyclic and linear polymers.
; ~ Examples of suitable solvents are the methyl polysiloxanes and the methyl phenyl poly-siloxanes, which may be linear or cyclic, also the ;~ ethoxypolysiloxanes~ ~etraethoxysilane and technical ethyl silicate are other suitable solvents, one exa~ple of the latter being described in ~ritish .
~ ' .
~ ~ 7~4~
Pa~ent No. 67~,137. Another suitable solvent is the alkoxysilane reaction product.
The catalyst comprises at least one metal alkoxide corresponding to the alcohol 4C~
in solution in a solvent defined as abo-~e. ~he pre-ferred meval alkoxides are the alkali metal alkoxides. A mi}~vure of the sodium alkoxide a~d the ?otassium alkoxide is advantageous. We have now disco~rered ~hzt the metal alko~:ide, preferred in vhe pre-~-ious inveltion, is essent-al to pro-;~ duce the substituted al~oxysila~es. It ~ill be appreciated that the ~lkoxide has a reacvion func-tion 2S We11 aS a catalytic and is consumed to a certain extent~
15The reaction ma~ be carried out using batches of reagents or ay be 5! arted with batches of reagents and then ~aintained by ccntinuous addi-tions of the alcohol ~nd silicon or silicide to a relatively large volume of the catal~tic solution~
: ~
A pre~erred expedlent 1S to introduce the reagents below the surface of the solution preferably near the bottom OL the reaction vesselO When the reagents are not preheated, on ent~y they i~itiall~ lower the ~temperavure of the solution and then commence their :
.
~ ' .
~ ,726~g catalysed reaction As the reagents rise through the catalytic solution the reaction proceeds until the mixture of alcohol and products is vapourised with a considerable loss of heat. The large thermal capacity of the volume of the catalytic solution at elevated temperature readily provides that heat. The rate of reaction can be monitored by measuring the rate of evolution of hydrogen. Alternatively, the - alcohol (or mixture of alcohols) can be introduced as a vapour The product of the process is an alkoxy-silane (a silicon ester) of the formula (Ro)nSi(oA)4 n where n is 1, 2, 3 or 4. The unsubstituted tetra alkoxysilane Si(oR)4 which inevitably forms part of the reaction product is, of course, the case when ~; n = ~ The present invention also proposes converting the product to a mixture of alkoxypolysiloxanes by con--trolled hydrolysis and condensation-pol~merisation, thereby increasing the silica equivalent~ Thus when the product is tetraethoxysilane it can be converted by controlled hydrolysis and condensation-polymerisation to technical ethyl silicate, which is a mixture of tetraethoxysilane and ethoxypoly-; siloxane oligomers. The preferred technical ethyl ~ ~72049 silicate contains silicon equivalent to approxi-mately 4~o by weight SiO2o The substituted alkoxysilane products which characterise the present inventlon can be used in the binding of refractory powders and paint pig-ments. On hydrolysis, the p-oducts form a hydrolysate whivh gels, usually with the aid of a catalyst, to provide a rigid and coherent gel. Slurries of re-fractory powder and a gellable hydrolysate can thus be formed to the recuired shape either by cavity or pattern ~oulding and 'hereafter set in this shape by gelllng of the hydroIysateO A paint for anti-corrosion applications can be made by dispersing zinc dust in the hyàrolysate. ~or this use the hydrolysate is preferably prepared from an alko~-silane pro~uct rich in the (RO)n Si(Oh)4 n species according to the in~Tenvion ~Jhere n is 1, :
This invention relates to the manufacture of alkyl silicates by the catalysed reaction of silicon or silicides with an alcohol and is a develop-ment o~ the invention, hereinafter called the previous : invention, set out in EPC Application No, 79 300 542 published under the number 0,004,418 on 17th October 1979. This published specification is primarily concerned with the production of ethyl silicate, We have discovered that, when a metal alkoxide correspondiny to the alcohol AOH is used as a catalytic agent, substituted alkoxysilanes containing the group _ SioA are produced. The present invention proposes a method of increasing the yield of the substituted alkoxysilanes which products have industrial applica-tions, ~`
: Thus according to the present invention :~ ~ there is provided a method of manufacturing alkoxy-~ silanes of the type (Ro)nsi(oA)4 n where R is Cl - C6 :
: 20 alkyl, preferably ethyl, A is -C2H4OCH3, -C2H4OC2H5;
C H OC6H5, -C2H4oc2H4ocH3; -C2H~Oc2H4oc2Hs- 2 4 1 2 where Rl and R2 are Cl - C4 alkyl and n is 1, 2, 3 or 4, ~: ~ by reacting together the alcohol ROH and silicon or a silicide in a catalytic solution containing a ~;
~ 1726 metal alkoxide corresponding to ~he alco~ol AOH,there be-ing preferably at least 500 ml of catalytic solution for each mole of silicon or silicide, thereby having sufficient thermal capacity effecti~ely to maintain a temperature to catalyse the rsaction and to dis-char~e as a product a'~oxysilanes as vapour to-Oether ~ith the alcohol vapour and hydro5en gas.
~he method of the invention is charac-; terised by ~he step of mixing with the alcohol ROH a quæntity of the alcohol AOX~ This mixinO
step si$nificantly increases the yield o~ the s~bstituted alkoxysilane in the product which also co~ta~ns the u~s~x~ituted~tra~o~ysi~LQ ~C~. It should be noted that the use of 10~o AOH as the starting ; 15 alcohol would not proàuce a 10~/o yield o~ the alkox~si-lane Si(OA)4 but a mixed product. In fact approxi-. ~ .
matel~ 5% AOH, 95% (molar ratios) ROH provides a ! ~
notably increased yield of substituted product as compared to a 100% ROH starting material. Up to about 50/c AOH can in certain circumstances be used.
.~ .
~ i 7~649 The reaction between the alcohol and sili-con or a silicide is carried out at high tempera-ture in a catalytic solution which has su~ficient thermal capacity t~ maintain the reaction tem~er-ature and to catalyse the reactio~ and to dischargethe alko~ysilæne products as a vapour to$ether, with the alcohol va~ou~ and hydrogen ~as. The ; thermal capacity o~ ~he catalytic solution can ~e ; . maintained and indeed increased by stepwise additions of the alcohol æ~d silicon or 2 silicide, ~ ~ then the alko~silæ~e ~ro.ucts are re~oved as ;~ vapour ænd the secuence ~epeated.
he term silicide is intended to cover aàditionally to the ~e~allic silicides , carbon silicide more usually called silicon carbide~
The necessary thermal capacity is achieved by :
(a) :carrying out the reaction at as high , ~
~ .
~ .
.
' , ~726~9 . .
a temperatuxe as is practicable~ .
(b) maintaining a relatively large volume of catalytic solution, that is metal al~oxide in a sol~ent, a~ least 500 ml per mole of silicon, (c) selecting an appropriQ~e solvent.
F-eferred solvents are linear oligomeTs ; of the followin~ general formula I:
.
:: I _ _ I where n lS 1 or ~ - Si - O - Si - O - Si - ~ a whole number : ; 1 o L ~ n l greater than 1 :~ :
~0~ ~ A I
or cyclic compounds of the general formula II :
_ .
: A where n is 3 or ::~ _ O - Si- - a whole number ~; 15 ~ ~~ n greater than 3 FORMUI~ II
:
.. .
.
~ 11 72`B~l~
A is CE3; OR where R is C1 - C4 alkyl preferably eth~l; O(G~2CX20)mD where D is meth~l, ethyl or phen~l and m is 1 or 2. Preferably all the A
groups ære the sa~e in-each compound~ 3 is t~e s~e as h and when ~ s C~3, 3 can also be C6E5 when ~ is OR or O(CF2CH20)~D, the solvent m~y also contain Sih~ and/or ~3Si-O-Si~3 s~ecies, provided that the-e lS not mo-e than 20Yo by we~ght of SiA4 and 4~/o by ~eight of A~Si-O-Si~3.
~en A is C~3, the sol~-ent may also contain not more than 20% by weight of Si(OR)4 and/or Si [O(C-~.2CE20) ~;~ species. When ~ is C~3 and 3 is C6H5 the solvent may also contain no~ mc~e than 6~/o of Si(OR)4 ; species, R belng preferably ethyl~
:
~he sol~et m~- also com~rise a mixture of components having differen~ h ~roups and it may also ~ ~ be a mixture of cyclic and linear polymers.
; ~ Examples of suitable solvents are the methyl polysiloxanes and the methyl phenyl poly-siloxanes, which may be linear or cyclic, also the ;~ ethoxypolysiloxanes~ ~etraethoxysilane and technical ethyl silicate are other suitable solvents, one exa~ple of the latter being described in ~ritish .
~ ' .
~ ~ 7~4~
Pa~ent No. 67~,137. Another suitable solvent is the alkoxysilane reaction product.
The catalyst comprises at least one metal alkoxide corresponding to the alcohol 4C~
in solution in a solvent defined as abo-~e. ~he pre-ferred meval alkoxides are the alkali metal alkoxides. A mi}~vure of the sodium alkoxide a~d the ?otassium alkoxide is advantageous. We have now disco~rered ~hzt the metal alko~:ide, preferred in vhe pre-~-ious inveltion, is essent-al to pro-;~ duce the substituted al~oxysila~es. It ~ill be appreciated that the ~lkoxide has a reacvion func-tion 2S We11 aS a catalytic and is consumed to a certain extent~
15The reaction ma~ be carried out using batches of reagents or ay be 5! arted with batches of reagents and then ~aintained by ccntinuous addi-tions of the alcohol ~nd silicon or silicide to a relatively large volume of the catal~tic solution~
: ~
A pre~erred expedlent 1S to introduce the reagents below the surface of the solution preferably near the bottom OL the reaction vesselO When the reagents are not preheated, on ent~y they i~itiall~ lower the ~temperavure of the solution and then commence their :
.
~ ' .
~ ,726~g catalysed reaction As the reagents rise through the catalytic solution the reaction proceeds until the mixture of alcohol and products is vapourised with a considerable loss of heat. The large thermal capacity of the volume of the catalytic solution at elevated temperature readily provides that heat. The rate of reaction can be monitored by measuring the rate of evolution of hydrogen. Alternatively, the - alcohol (or mixture of alcohols) can be introduced as a vapour The product of the process is an alkoxy-silane (a silicon ester) of the formula (Ro)nSi(oA)4 n where n is 1, 2, 3 or 4. The unsubstituted tetra alkoxysilane Si(oR)4 which inevitably forms part of the reaction product is, of course, the case when ~; n = ~ The present invention also proposes converting the product to a mixture of alkoxypolysiloxanes by con--trolled hydrolysis and condensation-pol~merisation, thereby increasing the silica equivalent~ Thus when the product is tetraethoxysilane it can be converted by controlled hydrolysis and condensation-polymerisation to technical ethyl silicate, which is a mixture of tetraethoxysilane and ethoxypoly-; siloxane oligomers. The preferred technical ethyl ~ ~72049 silicate contains silicon equivalent to approxi-mately 4~o by weight SiO2o The substituted alkoxysilane products which characterise the present inventlon can be used in the binding of refractory powders and paint pig-ments. On hydrolysis, the p-oducts form a hydrolysate whivh gels, usually with the aid of a catalyst, to provide a rigid and coherent gel. Slurries of re-fractory powder and a gellable hydrolysate can thus be formed to the recuired shape either by cavity or pattern ~oulding and 'hereafter set in this shape by gelllng of the hydroIysateO A paint for anti-corrosion applications can be made by dispersing zinc dust in the hyàrolysate. ~or this use the hydrolysate is preferably prepared from an alko~-silane pro~uct rich in the (RO)n Si(Oh)4 n species according to the in~Tenvion ~Jhere n is 1, :
2 or 3, ~he reason for this is that the hydrol~sis products are less volatile due to their higher molecular weight.
The invention will now be described by way of the following speci~ic examples:-~; .
~' ' . .
, .
~ r, i i~2649 General Notes to Examples Moisture must be rigorously excluded.
Reactions are commenced in an atmosphere of dry nitrogen. Dry alcohol must be used, the procedures for drying are given in Example 1. The rate of reaction may be followed by measuring the rate of hydrogen evolution, This is used to control the rate of addition of reactants to maintain optimum reaction rate, Usually silicon (or silicide) is added in batches and alcohol added dropwise, or a silicon/alcohol slurry added, when the observed rate of hydrogen evolution diminishes to a low value, The reaction temperature is maintained as constant as possible, A - Metal alkoxide preparation 2-Ethoxyethanol (290 ml, 2.9~ mole) was introduced into a flask fitted with a reflux conden-: ser and nitrogen inlet. The vessel was flushed with nitrogen and potassium (19g, 0.5 mole) was slowlyadded over a 3 hour period, followed by sodiu~
(11.5g, 0.5 mole). The mixture was refluxed for 4 ::
-,~
:
'~
` g ~ 7~4g _ 11 .
hours until hydrogen evolution ceased. ~he initial solution was pale yellow but turned deep red after 2 hours~
Using the apparatus and proceaure of Method 1, to 2-etho~ethænol (180 ~l, 1.75 mole) sodium (5.58g, 0.254 mole) was slowly added, fol-lowed by potassium (9.42g, 0.242 mole) and the re-sulting mixture refluxed for two hours.
.
,: 10 rrF~mHOD 3 ~
Sodium (7.4g, 0.311 mole) was slowly added to 2 ethoxyeth~nol (170 ml, 1.75 mole) and ~: :
the resulti~g mixture reflu~ed for 1 hour. In a separate vessel, potassiu~ (13g, 0.33 mole) was slowly added to 2-ethoxyethanol (160 ml, 1.65 mole) ard the resulting mixture ref1uxed for 1 hour. The two solut1ons ma~ be combi~ed for use, or used individuall~.
Toluene (40-50 ml) was placed in a flask fitted with a reflux condenser, nitrogen inlet and dropping funnel, whose lower end was under the toluene. The flask was flushed with dry nitrogen which was passed through the flask -throughout the course of the reaction. Potassium (19g, 0.5 mole) was added, then 2-ethoxyethanol (160 ml, 1~7 mole) was slowly added dropwise When the potassium had reacted, sodium (11,5g, 0 5 mole) was added, then further 2-ethoxyethanol added dropwise until a total volume of 300 ml was added. The solution was warmed and toluene distilled off at 121C, ~he remaining solution was refluxed for 4 hours. The 2-ethoxyethanol can also be added to sodium and potassium metals concurrently.
~ 15 METHOD 5 - Using the apparatus and procedure of Method 1, dry ethanol (100 ml, 1.77 mole) was :
~used to dissolve sodium (4.75g, 0.207 mole) and ;~ potassium (9,29g, 0,238 mole) which were slowly ~; 20 added in the order given. The mixture was refluxed for two hours, then used immediately, Sodium and potassium may be dieeolved in ethanol individually.
;
~ 37~6~
: ME~OD 6 A 2 litre, 5 necked flas~, fitted with a partial take-off head, mechanieal stirrer, dropping funnel, the~mometer and nitrogen inlet was ~lushed ~ th nitrogen after introducing a solutio~ comprising technical eth~l silicate (4~b SiO2 w/w - 110 ~l) ~nà dry ethanol (46g - 1 ~ole).
To this solution was added ~otass um(5.5g, 0.14 ~; mole), then sodiu~ (,.2g, G~16 ~ole). ~he mixture ~0 was war~ed fcr 3 hours to give the ca..alytic solution.
ME~HOD 7 : . ~ Using ~he procedure of Method 1, methyl-digol (200 ml, 1.70 mole) was used as solvent for sodium (5~67g, 0.247 mole), then for po~assiu~
(9.65g, 0.247 mole)~
ME~HOD 8 ~: Using the procedure Or Method 1~ 2-phenoxy- -~ ethanol (250 ml, 1.99 mole) was used as sol~rent for :~: 20 sodium (5~66g, 0.246 mole) and for potassium ~ (9.82g, 0.252 mole).
~ ', , .
~, .
.
~ ! 726~9 Using a flask fitted with a reflux con-denser and dropping funnel, sodium ethoxide solid (NaOEt . 2EtOH, 83~6g 0.54 mole) was dissolved in 2-ethoxyethanol t250 ml, 2.58 mole), which was added dropwise over a period of 2 hours.
There was a very exothermic reaction, giving a liquid mixtureO The dropping funnel and reflux condenser were removed and replaced by a distillation head and condenser. The mixture was heated under reduced pressure (100 mm Hg) and 102 grams distillate collected over 2 hours. This distillate comprised ethanol 41 parts and 2-ethoxyethanol 59 parts. The residue was used in the preparation of mixed alkoxy-15 silanes (Eto)nSi(OCM2CH2OEt)4 n~; n = 4, 3, 2, 1.
Using the procedure of Method 2, ethyldigol(190 ml, 1~4 mole) was used as solvent for sodium (5,80g, 0.252 mole) and for potassium (9.83g, 0.252 -20 mole).
.~
~ l 72~9 ME~HOD 11 Using the procedure of Me~hod 2, 2-di-methylaminoethanol (125 ml, 1.21 mole) was used as solvent for sodium (4.84g, 0.21 mole) and for potas-sium (9.70g~ 0.25 mole).
~ - Production oD Alkoxysilanes -- .
.
~ EX~lPLE 1 ... .. ~
A 2 litre~ 5 nec~ed flask fit~ed witn a partial take-off heaà, mechanical stirrer, ~ropping funnel and nitrogen gas inlet was flushed with ni-trogen. Then 170 ml of meual alkoxide solution prepared as described in Method 2 was adàed, to-ge'her with 340 ml of tetraethoxysil~ne to form the catalytic solution. 14g of siliccn powder, average 15 particle size 50 - 80 microns, composition 9~/o Si,
The invention will now be described by way of the following speci~ic examples:-~; .
~' ' . .
, .
~ r, i i~2649 General Notes to Examples Moisture must be rigorously excluded.
Reactions are commenced in an atmosphere of dry nitrogen. Dry alcohol must be used, the procedures for drying are given in Example 1. The rate of reaction may be followed by measuring the rate of hydrogen evolution, This is used to control the rate of addition of reactants to maintain optimum reaction rate, Usually silicon (or silicide) is added in batches and alcohol added dropwise, or a silicon/alcohol slurry added, when the observed rate of hydrogen evolution diminishes to a low value, The reaction temperature is maintained as constant as possible, A - Metal alkoxide preparation 2-Ethoxyethanol (290 ml, 2.9~ mole) was introduced into a flask fitted with a reflux conden-: ser and nitrogen inlet. The vessel was flushed with nitrogen and potassium (19g, 0.5 mole) was slowlyadded over a 3 hour period, followed by sodiu~
(11.5g, 0.5 mole). The mixture was refluxed for 4 ::
-,~
:
'~
` g ~ 7~4g _ 11 .
hours until hydrogen evolution ceased. ~he initial solution was pale yellow but turned deep red after 2 hours~
Using the apparatus and proceaure of Method 1, to 2-etho~ethænol (180 ~l, 1.75 mole) sodium (5.58g, 0.254 mole) was slowly added, fol-lowed by potassium (9.42g, 0.242 mole) and the re-sulting mixture refluxed for two hours.
.
,: 10 rrF~mHOD 3 ~
Sodium (7.4g, 0.311 mole) was slowly added to 2 ethoxyeth~nol (170 ml, 1.75 mole) and ~: :
the resulti~g mixture reflu~ed for 1 hour. In a separate vessel, potassiu~ (13g, 0.33 mole) was slowly added to 2-ethoxyethanol (160 ml, 1.65 mole) ard the resulting mixture ref1uxed for 1 hour. The two solut1ons ma~ be combi~ed for use, or used individuall~.
Toluene (40-50 ml) was placed in a flask fitted with a reflux condenser, nitrogen inlet and dropping funnel, whose lower end was under the toluene. The flask was flushed with dry nitrogen which was passed through the flask -throughout the course of the reaction. Potassium (19g, 0.5 mole) was added, then 2-ethoxyethanol (160 ml, 1~7 mole) was slowly added dropwise When the potassium had reacted, sodium (11,5g, 0 5 mole) was added, then further 2-ethoxyethanol added dropwise until a total volume of 300 ml was added. The solution was warmed and toluene distilled off at 121C, ~he remaining solution was refluxed for 4 hours. The 2-ethoxyethanol can also be added to sodium and potassium metals concurrently.
~ 15 METHOD 5 - Using the apparatus and procedure of Method 1, dry ethanol (100 ml, 1.77 mole) was :
~used to dissolve sodium (4.75g, 0.207 mole) and ;~ potassium (9,29g, 0,238 mole) which were slowly ~; 20 added in the order given. The mixture was refluxed for two hours, then used immediately, Sodium and potassium may be dieeolved in ethanol individually.
;
~ 37~6~
: ME~OD 6 A 2 litre, 5 necked flas~, fitted with a partial take-off head, mechanieal stirrer, dropping funnel, the~mometer and nitrogen inlet was ~lushed ~ th nitrogen after introducing a solutio~ comprising technical eth~l silicate (4~b SiO2 w/w - 110 ~l) ~nà dry ethanol (46g - 1 ~ole).
To this solution was added ~otass um(5.5g, 0.14 ~; mole), then sodiu~ (,.2g, G~16 ~ole). ~he mixture ~0 was war~ed fcr 3 hours to give the ca..alytic solution.
ME~HOD 7 : . ~ Using ~he procedure of Method 1, methyl-digol (200 ml, 1.70 mole) was used as solvent for sodium (5~67g, 0.247 mole), then for po~assiu~
(9.65g, 0.247 mole)~
ME~HOD 8 ~: Using the procedure Or Method 1~ 2-phenoxy- -~ ethanol (250 ml, 1.99 mole) was used as sol~rent for :~: 20 sodium (5~66g, 0.246 mole) and for potassium ~ (9.82g, 0.252 mole).
~ ', , .
~, .
.
~ ! 726~9 Using a flask fitted with a reflux con-denser and dropping funnel, sodium ethoxide solid (NaOEt . 2EtOH, 83~6g 0.54 mole) was dissolved in 2-ethoxyethanol t250 ml, 2.58 mole), which was added dropwise over a period of 2 hours.
There was a very exothermic reaction, giving a liquid mixtureO The dropping funnel and reflux condenser were removed and replaced by a distillation head and condenser. The mixture was heated under reduced pressure (100 mm Hg) and 102 grams distillate collected over 2 hours. This distillate comprised ethanol 41 parts and 2-ethoxyethanol 59 parts. The residue was used in the preparation of mixed alkoxy-15 silanes (Eto)nSi(OCM2CH2OEt)4 n~; n = 4, 3, 2, 1.
Using the procedure of Method 2, ethyldigol(190 ml, 1~4 mole) was used as solvent for sodium (5,80g, 0.252 mole) and for potassium (9.83g, 0.252 -20 mole).
.~
~ l 72~9 ME~HOD 11 Using the procedure of Me~hod 2, 2-di-methylaminoethanol (125 ml, 1.21 mole) was used as solvent for sodium (4.84g, 0.21 mole) and for potas-sium (9.70g~ 0.25 mole).
~ - Production oD Alkoxysilanes -- .
.
~ EX~lPLE 1 ... .. ~
A 2 litre~ 5 nec~ed flask fit~ed witn a partial take-off heaà, mechanical stirrer, ~ropping funnel and nitrogen gas inlet was flushed with ni-trogen. Then 170 ml of meual alkoxide solution prepared as described in Method 2 was adàed, to-ge'her with 340 ml of tetraethoxysil~ne to form the catalytic solution. 14g of siliccn powder, average 15 particle size 50 - 80 microns, composition 9~/o Si,
3% ~e, were added, i.e. 51Q ml catalytic solution/
~ mole silicon. Then 30 ml dry ethanol were added.
;~ The ethanol mus~ be dried prior to use either by treatment with a molecular sieve (eOg. ~inde type 3~) or by distillation o~er sodium or magnesium. ~he mixture was heated by an electric heating mantle.
;,': .
~ .
.
~ . .
::
~ ~ 7~
When the reactor temperature reached 120C, the distillation head temperature rose to 90C. ~fter 80 ml distllla-te (mixture of ethanol and alkoxy-silane) was collected, the distillation head tem-perature fell to ambient and the reactor tempera-ture rose to 150C, at which temperature it was maintained for the remalnder of the reaction period.
~he reaction was monitored b~ measuring the rate of hydrogen evolution. Fu~ther reactants were added ;lO when the rate fell to less ~han 30 ml/min. Silicon was added in batches of 7 or 14 grams, ethanol (dr~) belng added dropwise at a rate such that the reactor temperature remained at 150C. The reaction was run in this way for 26 hours. A total of 70~2~14 mole) silicon was added, 93% belng converted to alkoxy-` sil~e. The average rate of production of alkoxy-silane was 18g/hour. The final reaction mixture was distilled at atmospheric pressure to recover pure alkoxysilane.
EX~MPLE 2 180 ml of metal alkoxide solution prepared b~ Method 1 was added to 500 ml of technical ethyl , ~ ~ 7 ~
' silicate to form the catalytic solution. To this was added 12 grams of silicon (i.e. 1587 ml cat~
alytic solution/mole silicon) and 303O5 gr~ms (6.6 mole) dry ethanol. ~he mixture was heated for 3 houh~s at 70 - 80C then the temperature was raised to 120C~ 580 ml of distillate (b~82-90C) being collected. ~he temperature W2S raised to 145C
and a 4: 1 molar ra~io slurry of ethanol : silicon addeà. The reaction ~e~perature rose ar.d vJas main-10 tained in the temperature r~nge 165 190C by ad-justing the rate of addition of the slurry. Distil-~' late (b.115-130C) was collected at the rate of about 90 ml/hour during the 40 hours which the reaction was run, a total of 3500 ml being collected. Frac-tionation at atmospheric ~ressure gave 750g pure tetra ethoxysilane b. 168 - 170C. ~he purity was con-firmed by the IR spectrum.
:
EXAMP~E 3 o the catal~tic solution prepared in ` 20 ~lethod 6, silicon (6~, 0.21 mole, i.e. 798 ml catalvtic solution/mole silicon) was added. Distilla~e was re-moved u~til the reactor temperature reached .
~ 172~9 145C, then a slurry of ethanol/silicon (molar ratio 4 : 1) was added. The reactor temperature rose to 165C and was maintained in the range 165 -190C by adjusting the rate of addition of the ethanol/silicon slurry. The reaction was carried out for 5 hours, during which time 225 ml of dis-tillate (b, 130 - 156C) was collected. Fractiona-tion of this mixture gave 125g pure tetraethoxysilane, The purity was confirmed by the IR spectrum, To the metal alkoxide solution prepared as in Method 5 was added 450 ml of the alkoxysilane product of Example 2 to give the catalytic solution, Then 14g silicon powder, average particle size 50 -15 60 microns were added, i.e. 1100 ml cataIytic solution~mole silicon. Following the procedure of Example 1, 56g ~2.0 mole) silicon and 425 ml (7.5 mole) dry ethanol were added over a period of 22 1/2 hours, the reactor temperature being maintained ' 20 between 150 - 160C. The percentage conversion of silicon to product was greater than 95% and the production rate was 20.5 grams/hour. The product ~ ~728~9 was purified as described in Example 1 EYI~IP~ 5 ~ o 170 ~l o~ the metal alkoxide solution prepared as described in l~e~hod 7, 3~0 ml of tetra-ethox~s lane were added to prepare the catalyticsolution. ~o this was added 1~ grams of sili^on powder, average particle size 50 - 50 microns, i.e. 893 ml catalytic solu~ion/mole silicon, t;~en 30 ml d~y ethanol. The mix~ure W2S heated to 150C
and maintained in the tem?erature range 150 ~ 160C
during 231 hours, in which time 44g (1.7 mole) silicon a d 330 ml (5.85 mole) dry ethanol were added. The percentage conversion of silicon to product was greater than 95% and the production rate -was 16.1 grams/hour.
EX~iPLE 6 `
:
To 250 ml of the metal alkoxide solutio~
prepared as described in Method 8, 340 ml of tetra-ethox~silane were added to prepare the catalytic solu~
tion. To this was added 16 grams of silicon powder, average particle size 50 - 60 microns, i.e. 1033 ~l .
~ ~ 72~
catalytic solution/mole silicon, then 30 ml dry ethanol. The mixture was heated as described in Example 1 and maintained at a temperature of 150 -190C during 13~ hours. In this time 18g (0.64 mola) of silicon and 130 ml (2.3 mole) dry ethanol we~e added. Tha pe~centage converslon of silicon to product was 66% and the production rate was 6.~ grams/hour.
. , .
~X~L~ 7 To 350 ml of metal alkoYide solution preparad as described in Method 1 was added 500 ml technical etnyl silicate to prepa~e the catalytic solution. ~hen 21g of ferrosilicon powder, average particle size 50 - 60 microns was added, i.e. 850 ml catalytic solution/mole silicon, together with 50 ml dry ethanol. ~ollowing ~he procedure of rxample 1, a further 72.5g ferrosilicon (2.5 mole~ and 46~2 ml dry ethanol (1206 mole) were added over 50 hours, the temperature being maintained at 160-180C~
The percentage conversion of silicon to product was greater than 95% and the production rate was 10 grams/
hour.
,' -~ ~ .
, ~ 1 7~
~ 21 -To 290 ml of metal alkoxide solution pre-pared as described in Method 1 was added 700 ml tetraalkoxysilane prepared as described in Example 1, to give the catalytic solution 21 grams of ferrosilicon (1 mole Si), average particle size 50 - 60 microns, were added i e, 990 ml catalytic solution/mole silicon, together with 50 ml dry ethanol. Following the procedure of Example 1, the reaction was carried out for 34 hours at an average temperature of 148C. The percentage conversion of silicon to product was greater than 95% and the production rate was 34 grams/hour, _ _ A catalytic solution was prepared by mixing 150 ml of a metal alkoxide solution prepared according to Method 1 with 250 ml of a polymethyl-phenyl siloxane (Dow Corning 550 fluid)o 7 grams (0,25 mole) of silicon, average particlP size 50 -60 microns, were added, i.e. 1600 ml catalytic solution/mole silicon, Dry ethanol (S0 ml) was added and the mixture was gently warmed, being maintained ~ ~7~6~
_ 22 between 90C and 130C during the reaction (10 hours). Alkoxysilane product was produced at rates between 11 and 56 gram/hour, depending on the reaction temperature.
,~
A catalytic solution was prepared by mixing 150 ml of a metal alkoxide solution prepared according to Method 1 with 125 ml of a polymethyl-phenyl siloxane (Dow Corning 550 fluid) and with 125 ml tetraethoxysilaneO 7 grams (0 2S mole) of silicon, average particle size 50 - 60 microns, were added, i.e. 1600 ml catalytic solution/mole silicon. Dry ethanol (50 ml) was added and the mixture was gently warmed, being maintained between 90C and 130C during the reaction (10 hours).
Alkoxysilane was produced at rates between 11 and 112 gram5/hour, depending on the reaction tempera-; ture, In the preceding Examples, the volume ratio of solvent to metal alkoxide solution, giving the ~ 11 726~9 _ 23 -catalytic solution is 2 : 1 or greater. In this Example, the catalytic solution used has a volume ratio of solvent to metal alkoxide solution of 1 : 2.
The procedure followed is as described in Example 1, The metal alkoxide solution is prepared as described in Method 1. The catalytic solution is made by adding to 350 ml of metal alkoxide solution, prepared as described in Method 1, 170 ml of alkoxysilane prepared as described in Example 1.
To this catalytic solution is added 14g (0.5 mole) silicon powder, average particle size 50 - 60 microns, i.e. 1040 ml catalytic solution/mole silico~, together with 30 ml dry ethanol. The mixture was heated to 15 150C and the reaction was carried out for 14 1/4 ~; hours. During this time 43.75 grams (1.75 mole) silicon and 410 ml (7.27 mole) dry ethanol were ~; added. The percentage conversion of silicon to product was greater than 95% and the production rate was 34 grams/hour, A catalytic solution was prepared by adding 350 ml of tetraethoxysilane to 175 ml of metal .
~: ~
alkoxide solution prepared as described in Method 1. To this catalytic solution is added 14g (0.5 mole) silicon powder, particle size 5 microns or less, i.e. 1050 ml catalytic solution/mole 5 silicon, together with 30 ml dry ethanol. The reaction was carried out as described in Example 1, ; except that the dry ethanol used contained 2% v/v ; toluene. During 19 1/2 hours 61g ~2.1 mole~ silicon and 450 ml (9.27 mole~ ethanol were added. The per-centage conversion of silicon was greater than 95%
and the production rate was 44 grams/hour.
AlkoxysilaneS were prepared following the - procedure of Example 1, except that ethanol was lS introduced into the reactor as a 70 : 30 mixture by - volume of ethanol and alkoxysilane.
` The catalytic solution was prepared by adding 350 ml of alkoxysilane prepared as described in Example 1 to 190 ml of metal alkoxide solution prepared as described in Method 1. To this catalytic solution was added 14 grams (0.5 mole) silicon powder, particle size 5 microns or less, i e. 1080 ml catalytic ~:
:;
..~
",~,.~, ~ 172~
solution/mole silicon, together with 30 ml dry ethanol. The average reaction temperature w~s 137C over a 15 hour reaction period. 43,5g (1.5 mole) silicon and 275 ml (5.88 mole) dry ethanol (as the ethanol-alkoxysilane rnixture) were added. The percentage conversion of silicon was greater than 95% and the production rate was 23.6 grams/hour.
:
A catalytic solution was prepared by adding to 500 ml tetraethoxysilane, 290 ml of metal alkoxide solution prepared as described in Method 1.
To this catalytic solution was added 15 grams (0,5 mole) silicon powder (95% Si : 5% Fe + Mn, particle size 50 - 60 microns), i.e, 1580 ml catalytic solution/mole silicon, together with 60 ml dry ethanol. The procedure of Example 1 was followed, giving a percentage conversion of silicon greater than 95% and a production rate of 35.7 grams/hour.
EXAM_ LE 15 Following the procedure of Example 1, ; silicon powder containing 0.5 - 1.5% Fe, 0.2 - 0.75%
-.
g ~726~
_ 26 -Ca and 0 5 - 1 5% Al was used The catalytic solution was prepared by adding to 400 ml tetra-ethoxysilane, 200 ml of metal alkoxide solution prepared as described in Method 1, To this catalytic solution was added 16 grams ~0.5 mole~
of the silicon powder particle size 50 - 60 microns, i.e. 1200 ml catalytic solution/mole silicon, together with 30 ml dry ethanol. The average temperature of the reactor was 133C. The reaction was carried out for 12 hours, 28.5 grams of the silicon and 360 ml dry ethanol being added. The percentage conversion of silicon to alkoxysilane was 66% and the production rate was 22 grams/hour.
EXA~LE 16 _ ~ catalytic solution was prepared by adding 1000 ml tetraethoxysilane to 400 ml of metal alkoxide solution prepared according to Method 1, To this catalytic solution was added 28g (1 mole~
silicon, particle size 50 - 60 microns, i.e. 1400 ml catalytic solution/mole silicon, together with 70 ml dry ethanol. Following the procedure of Example ;; 1, 156~25 grams of silicon, particle size 5 microns , j~
, ~, .
- - ~ 17264~
_ 27 -or less were added together with 1920 rnl dry ethanol in the course of 45 1/2 hours. The reactor temperature was maintained at an average of 148C. The percentage conversion of silicon was greater than 95% and the production rate was 53,5 grams/hour.
A catalytic solution was prepared by adding 600 ml tetraethoxysilane to 300 ml of metal alkoxide solution prepared according to Method 1.
To this catalytic solution was added 28 grams ~1 mole) silicon, particle size 50 60 microns, i,e, 900 ml catalytic solution/mole silicon together with 50 ml dry ethanol, Following the procedure of Example 16, silicon of 74 micron particle size was used.
The percentage conversion of silicon was greater ;~ than 95% and the production rate was 34 grams/hour, A catalytic solution was prepared by adding 300 ml of alkoxysilane prepared as described in Example 1 to 175 ml o~ the metal alkoxide product of Method 8. To this catalytic solution was added ~1 î 1 726~19 14 grams (0,5 mole) silicon, particle size 50 60 microns, i.e~ 950 ml catalytic solution/mole silicon together with 30 ml dry ethanol. Follow-ing the procedure of Example 1, the reaction was carried out for 20 1/2 hours, the mean reaction temperature being 158C. 28 grams silicon and 230 ml dry ethanol were added. The percentage conver-sion of silicon was greater than 95% and the production rate was 10,2 grams/hour.
A catalytic solution was prepared by adding 340 ml of alkoxysilane prepared as described in Example 1 to 170 ml of sodium 2-ethoxyethoxide solu-tion prepared as described in Method 3. To this catalytic solution was added 14 grams (0,5 mole~
silicon powder, particle size 50 - 60 microns, i,e.
1020 ml catalytic solution/mole silicon, together with 40 ml dry ethanol, Following the procedure of Example 1, the reaction was carried out for 22 1/2 20 hours, the mean reaction temperature being 148C, 49 grams silicon and 290 ml ethanol were added, The percen-; tage conversion of silicon to product was greater :
,S' :
~7 than 95% and the production ra~e was 15 grams/hour.
P~ 20 The procedure of ~xample 19 was followed~
except that the catal~t~c sGlu~ion was ~repared usinO 170 ~l of potassium 2-ethoxyethoxide made as describ~d in Method 3. ~he ~ercentage conversion of silicon to alkoxysilans was greater th~ 9,%
anà the ~roduc~ion rate was 22 grams/hour.
: ' .
hXk~PL~ 21 h catalytic solution was prepared by addin ~; 675 ml Or tetraethoxysilane to 290 ml metal alkoxide solution prepared as described in Ms~hod 1. In this catalytic solution the volums ratio of solvent to me-tal alkoxide solution is 2.25 : 1. To the catalytic solution is added 14g (0.5 mole) silicon, i.e. 1930 ml catalytic solution/mole silicon, together with 60 ml dry ethanol. The mixture was warmed to 145C
.
and ethanol slowly added dropwise so as to maintain tbe reaction temperature in the range 165 - 170C~
The alkoxysilane produced was removed from the re-action system by distillation as a mixture of ethanol ~ ~72649 and producv. At 145C the production rate of alkoxysilane was 24 grams/hour~ ht the end of the reaction the production rave of alkoxysilane was 14.6 gr2ms/hour~
~X~'~.L~ 22 n ~nis ~xa~le, the thernal capacity of the cataly~ic solution is first increased by stepwise adaitions o^ ethanol and silicon~ then alkoxysilane and ethanol were r-mo~ed as V&pOU~ and the seauence repeated.
Startin~ ~oceau~e A clean and oLry reaction vessel is purged , .
. with dry nitrogen for a;~out 15 minutes~ The catalytic solution is made by charging the reaction vessel with 204 li~res of tetraethoxysilane, followed by 204 litres of metal alkoxide solutio~ prepared according to Method 4 and then by a further 136 litres of tetraethoxysilane~ To this catalytic solution 5 kg silicon powder was added, i~e. 3046 ml catalytic solution/mole silicon, followed by 10 litres ~rJ
ethanol. The mixture was heated until the reactor temperature was 140C. At this stage the distillation ;: ' ' ~ : ,:, ,: . , 11 117~49 head temperature (head te,perature) was the a~bient temperature~
Dry and preheated ethanol was added at a rate such that the reactor temperature did not drop below 140C. ~thanol was added at this reouired rate until evolution Of hydrogen ceased. Then a further 5 kg silicon was added and more ethanol was added at the r-quired rate u~til evolution of hydrogen ceased.
No ~istillate was collected in ~hi~ cycle, i.e. ~he reactior ~as do~e u~--er total reflux condition.
; It is necessary to mainta n a ~inimum reac-tor temperature of 140C~ Althou~h a minimum reactor ~` ~ temperature of 1'~0C is require~, t:~e te~perature is ~5 preferably in the ræ~ge 155-165C~ The ethanol addition can be replaced by a ~ixture of ethanol and tetraethoxysilane.
he separation of alkoxysilane from the reacticn mi~ture was carried out by the following , ~
procedure.
(i) The preferred reactor temperature is 150C.
- 32 _ ~
(ii~ Dry ethanol was added to the reaction mixture at a rate such that a constant head tempera-ture is maintained.
(iii) It is preferable to remove the product as a mixture of alkoxysilane and ethanol. The product should be removed at a high head temperature (140C
or over~ to ensure that the distillate is rich in alkoxysilane. It is important that only the amount ; of alkoxysilane produced is removed.
The ethanol-alkoxysilane mixture collected is distilled to separate the ethanol and the alkoxy-silane, The ethanol recovered can be re-used.
After the alkoxysilane produced has been removed, the sequence of stepwise additions of silicon and ethanol is repeated to continue the production of , alkoxysilane. This in its turn is removed then the sequence of stepwise additions of silicon and ethanol is continued.
Preparation of polysilicat_ Alkoxysilane - 259 volumes ~i Anhydrous ethanol - 82.2 volumes Water - 16.4 volumes - must be distilled or de-ionised ~ ~ Acid solution - 1,3 volumes ::
.
~ 1726~
- 33 ~
The acid solution is 1% v/v of concentrated sulphuric acid (9~/0 ~ S04 by weight) in anhydrous ethanol.
The mixture of alkoxysilane, anhydrous ethanol and acid solution is heated to reflux temperature and water added dropwise with stirring over a period of 30 minutes. Refluxing is carried out for 60 minutes when the addition is completed.
The ethanol is recovered from the product by dis-tillation under gradual lowering of pressure.
Distillation was finished when a pot temperature of 140C at 100 mm Hg pressure was reached, The . amount of ethanol recovered was 180 volumes, This -: can be used again in the preparation.
Product characterisation , ~ Density at 20C - 1.06 gm/ml Silica content = 36,1% w/w Acidity = 0.013% wv H2S04 - ' .
- :
~ ~ 7~49 A catalytic solution was prepared by mixing 125 ml of the metal alkoxide solution prepared as in Method 11 with 395 ml of tetraethoxysilane. To this solution was added 14g (0.5 mole) silicon powder average particle size 50 - 60 microns and 30 ml dry ethanol, i,e. 1040 ml catalytic solution per mole silicon. The procedure followed was according to Example 1 and over 29 1i2 hours at an average reaction temperature of 155C, the average production rate of alkoxysilane was 18.9 grams/hour with a yield of 86~o based on the weight of silicon used.
A catalytic solution was prepared by mixing 190 ml of the metal alkoxide solution prepared accord-ing to Method 10 with 360 ml of tetraethoxysilane.
To this solution was added 14g (0.5 mole)of silicon powder, average particle size 50 - 60 microns and 30 ml dry ethanol, i.e, 1100 ml catalytic solution per mole silicon, Following the procedure of Example 1 ~7~
the reaction was run for 30 hours at an average temperature o 148C yielding 72~/o of alko~ysilane based on the weight of silicon used, at an average production rate of 19.2 grams/hour.
150 ml of metal alkoxide solution prepared according to Method 2 was added to 300 ml of alkoxy-silane prepared according to Example 1 and to it was added 14g (0.5 mole) of silicon powder, average particle size S0 - 60 microns, and 30 ml dry ethanol (i.e, 900 ml catalytic solution per mole silicon).
The procedure followed was similar to that of Example 1 except that the ethanol was added in the vapour state, being boiled in a 100 ml 3-necked round-bottomed flask fitted with a glass delivery tube to transfer ethanol vapour to the reaction vessel~ below the liquid surface and a 50 ml dropping funnel to add cold ethanol dropwise to the boiling ethanol in the flask. ~he delivery tube was wrapped in trace heating wire in order to prevent condensa-tion of the ethanol between the flasks. The reaction was run for 29.8 hours under these conditions and the average production rate of the product was ~ î7264~
18.9 grams/hour at an average reaction temperature of 152Co The yield of product based on the weight of silicon used was 86~3%~
A catalytic solution was prepared by mixing 300 ml of tetraethoxysilane with 150 ml of metal alkoxide solution made according to Method 2. To this was added 14g (0.5 mole) silicon powder, average particle size 5 microns and 30 ml dry ethanol, i,e, 900 ml catalytic solution per mole silicon. The procedure of Example 1 was followed and the reaction run for 37~8 hours at an average temperature of 153C~ AlkoxySilane was produced at an average rate of 29,1 grams/hour in 94,2% yield based on the weight of silicon used.
.
300 ml tetraethoxysilane were added to 150 ml of metal alkoxide solution made following Method 1 but using only sodium 111,58g, 0.504 mole), to make ' ~ 20 the catalytic solution. To this was added 14g (0~5 mole) of silicon powder, average particle size 5 microns, and 30 ml dry ethanol, to give 900 ml :
~ 1l726~
solution was added 3~0 ml tetraethoxysilane, producing 480 ml of catalytic solution. To this was added l~g (0.5 mole) of silicon powder, average particle size 5 microns, i.e. 960 ml catalytic solution per mole silicon. Following the procedure of Example 1, the reaction was run for 32.8 hours at an average temperature of 149C with an average ester production rate of 19 grams/hour and in 94 1%
yield based on the weight of silicon consumed.
Following the procedure of Method 5, but using only potassium metal (19.47g, 0 499 mole3 a metal alkoxide solution was made up (110 ml) and added to 370 ml tetraethoxysilane to produce the catalytic solution. Silicon powder (14g 0.5 mole) of average particle size 5 microns was added to it, producing a system with 960 ml catalytic solution per mold silicon The reaction was carried out according to Example 1 and over 37 75 hours at an average temperature of 151C produced ester at an average rate of 22.6 grams/hour in ~6 6% yield based ~ ~ 72~19 - 37 ~
catalytic solution per mole silicon. ~ollowing the procedure of Example 1, the reaction was run for 2&.5 hours at an a~erage temperature of 158C
giving a 97.6~o yield Or alkox~sil~ne based on the weight of silicon used, av an average ?roductlon rate of 27.7 ~ra s/hour~
- EK~IPL~ 28 ~ o 300ml tetraethoxysilane were added 150ml of met21 alko~ide solution m~ce following Method 1 bui USl~g only po'vassium metal ( 19.5g, ~.5 mol~ to produce 450ml catalytic solution. Silicon powder g 0.5mole) was added together with 30~1 dr,y ethanol to the catal~tic solution, producing 900ml catal~tic solution per mole silicon. ~ollol.~ing the procedure of ~xample 1 the reaction was run for 3~75 hours at an average te~pera'ure o~ 152C.
he ~ield Or ~x~uct based on the weight of silicon used was~94.1% and the ave-age production rate 28.4 grams/hour.
~X~MP~ 29 A metal alkoxide solution was made following the procedure oI Method 5 ard to 100ml o:[ this ~ ::
.
`. ~172~;4~ :
- ~8 -solution :as added 380ml tetraethox~silane, pro-ducing 480ml of catalytic solution. ~o this was added 14g (0.5 mole) of silicon powder, average ~ particle slze 5 microns, i.e~ 960 ml catal~tic ; 5 solution per mole silicon. ~ollowing the proced-ure ol Exa~ple 1, the reaction was run for 32.8 hours at a~- averG_e ~e-~erat~are of 149C wlth a~
avera~e es~er production rate o~ 19 ~ a~ns~ ~& in 9!'.13~ ield based o~ ~ne weight Or silicon 1C co~sumed.
.
~ E~LE 33 . .
~ ollo~.~n~ the procedure of Method ~, but .
: using onl~ potassium metal (19.~7~,0.49~ole) a metal alkoxide solution was ~ade up (110 ml) and ~: ~15 adaed to 370 ~l tetraethox~silane to produce the catalytic solutio~O Silicon powder (1~g 0.5 mole) o~ average particle size 5 microns was added to it, producing a s~stem with 960ml catal~tic solu-tio~ per mole silicon~ The reaction was carried out ~ 20 according to E~smple 1 and o~er 37.75 hours at an : ~ ~ . average tem~eratu~e o~ 151C produced ester at an ~ ~ average rate of 22.6 ~rGms/hour in 86.~5' yield based ': ' ' , , .
~ . .
~ ~7~164 - 3~
.: ,., on the weight of sllicon used.
~h~PL~
A metal alkoxide solution was made up according to Method 7 (145 ml ) ~nd mixed with 290ml tetraethox~s~lane and 14g silicon powder (005mole~
of aver~e particle size 5 microns and 30 ml of dr~ ethanol~ i.e. 870ml catalj~ic solution per mole silicon. ~ollo~ing the procedure of Example 1 the reaction was ru~ for 43.1 hours at an ave~age te~perature of 150C, giving a yield of 95.~/0 pro-duct based on the weight of silicon used at an average production rate of 28.1 ~ra~s/hour.
.
ollowing Method 10 195ml of metal alkoxide solution was made and mixed with 285ml tetraethoxy-silane, 14g (005mole)silicon po~der of average particle size 5 microns and 30 ml of dry ethanol, e. 960 ml catal~tic solution per mole silicon.
he reaction was run for 41.3 hours at an average ~; 20 temperature of 155C according to ~xample 1 and pro-duced a product yield of 97.2/o based on the weight of .
,~, '`.
, ~ ~726~1 silicon used at an average production rate of 27,3 grams/hour, 170 ml of metal alkoxide solution was prepared according to Method 1, but using only sodium metal (15,48g, 0,673 mole), To this was added 340 ml alkoxysilane produced according to Example 1 and 40 ml dry ethanol and 14g (0.5 mole) silicon powder of average particle size 50 - 60 microns, i.e. 1020 ml catalytic solution per mole silicon, Following Example 1 the reaction was run for 22,5 hours at an average temperature of 148C yielding alkoxysilane at an average rate of 15,0 grams/hour in 78,~/o yield based on the weight of silicon used, 175 ml of metal alkoxide solution was :~:
prepared according to Method 1 but using only potassium metal ~26.6g, 0.68 mole). To this was added 350 ml alkoxysilane produced according to Example 1, 30 ml dry ethanol and 14g (0.5 mole) silicon powder of ~! average particle size 50 - 60 microns, i~e, 1050 ml catalytic solution per mold silicon, Following ~ 172~49 Example 1 the reaction was run for 21,8 hours at an average temperature of 155C, producing alkoxysilane at an average rate of 22.7 grams/hour in 84.4% yield based on the weight of silicon used~
130 ml of metal alkoxide solution was pre-pared according to Method 5, but using only sodium metal 511.61g, 0,528 mole), To this was added 420 ml alkoxysilane produced according to Example 1, and 14g (0.5 mole) silicon powder of average particle size 50 - 60 microns, i.e, 1100 ml catalytic solution per mole silicon. Following Example 1 the reaction was run for 23.2 hours at an average temperature of 149C, alkoxysilane was produced at an average rate of 13 grams/hour, -.-100 ml of metal alkoxide solution was pre-; pared according to Method 5, but using only potassium metal (19.50g, 0,50 mole~. To this was added 450 ml alkoxysilane produced according to Example 1 and 14g (0.5 mole) silicon powder of average particle .... ..
_,, ~ ~7~6~9 _ 42 -size, 50-60 microns, i.e. 1100 ml catalytic solu-tion per mole silicon. Following Fxample 1 the reaction was run for 23.2 hours at an average tem-; perature of 152C. Alkoxysilane was produced at an average rate of 16.2 grams/hour in 75.1~ yield based on ~he weicht of silicon used.
X~ 37 - i catalytic solu~ion was ?repared by dis-solvin~ so~iu (4.8g, 0.21 mo1~)in 75 ml 2-dimethyl-~minoeth~nol over a two hour period. It was r.eces-sary to h~at the mixture gently to ~acili~ate solu-tion of the sodium when about half the quantity was added. Potassium (9.70g, 0~25 mole) was now d~ssolved in the mixture over a six hour period, with tne addition of two 25 ml portions of 2-di ethyl~minoeth~nol. ~he mixture was heated for two hours after all the metal dissolved. To this solution was added : :
~ 395 ml alkox~sila~e produced according to xample ; ~
1, then 14 grams silicon powder, avera~e p~rticle size .
53 microns were added (i~e. 1040 ml catalytic solution per molesilicon~. Then 30 ml of dry eth~nol were ~ added. The reaction was run ~or 29~ hours, the avera~e :;:
~: :
!1 ~7~9 reaction temperature being 155C. The average rate of production of alkoxysilane was 18.9 grams/hour, the yield of alkoxysilane, based on the weight of silicon used, was 86.0%.
Identiflcation of Components of the Reaction Product Ester The product collected from the various re-actions detailed in the Examples was analysed by Gas Liquid Chromat`ography (G.L.C.) using a Pye model 204 GCD chromatograph and with SE 30 and OV17 columns, The carrier gas used was nitrogen, at a flow rate of 40 ml per minute and the oven temperature of the chromatograph was 200C.
Peaks other than ethanol, alkali metal solvent and tetraethoxysilane were found, in quantities between 1 and 20 area % depending upon the circumstances under which the product was collected, These peaks have been identified as mixed esters of the type (EtO)nSi(OA)~ n where n = 1, 2, 3 by chemically equilibrating mixtures involving AOH and Si(oEt)4 also EtOH and Si(oA)4 (A=EtOOEI2C~ , _ a~4 _ EtOEI2CH2OCH2CH2) and analysing them by G.L,C.
Major peaks in these mixtures, whose proportion varies systematically with the molar ratio of equilibrants, have similar retention times to 5 the minor product components~
EXAMPLE 3_ Tetraethoxysilane (58 66g, 0~282 mole) and 2-ethoxyethanol (25 69g, 0.285 mole) were refluxed together in a three-necked, 100 ml round-bottomed flask 10 fitted with thermometer and reflux condenser, for 6 hours, the temperature of the mixture fell from 132C to 110C during this time. Similarly mixtures of tetraethoxysilane and 2-ethoxyethanol ~69 75g, 0.335 mole and 85.14g, 0.409 mole with 10~06g, 0.112 mole and 102.10g, 1 138 mole respectively) of mole ratios 3: 1 and 1: 3 were refluxed for 6 hours, the temperatures of the mixtures falling as in the first case.
G.L.C, analysis of these mixtures showed 20 peaks corresponding to ethanol, 2-ethoxyethanol and tetraethoxysilane together with the three mixed esters (EtO)nSi(oCH2CH2oEt)4 n~ n = 1, 2, 3. Samples of ~ ~ 7~6~9 product from Examples 26, 27, 28 showed peaks with similar retention times as the mixed esters Using the procedure of Example 38 two 5 mixtures of ethyldigol and tetraethoxysilane were refluxed and analysed by G.L C In the :Eirst case tetraethoxysilane (43.12g, 0.205 mole) and ethyl-digol (27.98g! 0 209 mole) were refluxed for 7 1/2 hours during which time the temperature of the 10 mixture fell from 164C to 104C In the second case tetraethoxysilane (26.83g, 0.128 mole) and ethyldigol (51.51g, 0.38 mole) were refluxed for 8 hours during which time the temperature of the mixture fell from 170 to 127C.
G.L.C. analysis of these two mixtures after reflux showed the presence of five components, ethanol, ethyldigol, tetraethoxysilane and two mixed esters (EtO~3SioCH2CH2oCH2 CH2OEt and (Eto)2Si(oCH2cH2ocH2cH2oEt)2. Samples of product 20 from Examples 24 and 32 which were also analysed contained components with similar retent:ion times as the mixed esters , , 1 ~ 7~649 Following Example 38 two mixtures of 2-dimethylaminoalcohol and tetraethoxysilane were refluxed and analysed by G,L.C. In the first case tetraethoxysilane (42.70g, 0.205 mole) and 2-dimethylaminoethanol (18.27g, 0.205 mole) were reEluxed for 7 1/3 hours after which the mixture had reached a constant temperature of 105C.
Secondly tetraethoxysilane (29 81g, 0.143 mole) and 2-dimethylaminoethanol (38.39g, 0.431 mole) were refluxed for 6 1/2 hours a Einal, constant tempera-ture oE 107.5~C being reached.
G.L.C. analysis of the two mixtures showed the presence of ethanol, 2-dimethylaminoethanol, and tetraethoxysilane together with the mixed esters (EtO)nSi(OCH2CH2NMe2)4 n; n -- 1, 2, 3, Samples of product from Example 23 were analysed under similar conditions and were :eound to have peaks corresponding to the three mixed esters, 20 ~ EXAMPLE 41 Following Example 38 two mixtures of met~yl digol and tetraethoxysilane were refluxed and analysed by G.L.C. ~etraethoxysilane (34,70g, 0~167 mole) and :
methyl digol (20.01g, 0.167 mole) were refluxed for ' 1 ~72~9 15 1/3 hours attaining a final temperature of 115C.
A second mixture of tetraethoxysilane (20,92g, 0 100 mole) and methyl digol (36 05g, 0 300 mole) was refluxed for 14 3¦4 hours reaching a final, constant, temperature of 116C~
G.L.C, analysis of tne two mixtures showed the presence of ethanol, methyl digol and tetra-ethoxysilane plus two mixed esters (EtO)n Si(ocH2cH2ocH2cH2oMe)4 n; n = 2, 3~ Samples of product from Examples 5 and 31 were analysed under similar conditions and found to contain peaks corresponding to the two mixed esters.
Following Example 38 two mixtures of 15 tetraethoxysilane (20.83g, 0.100 mole and 10.42g, :: 0.050 mole) and 2-phenoxyethanol (14 04g, 00102 mole and 20.23g, 0.146 mole) were refluxed and analysed - by G.L.C. The first mixture was refluxed for 14 1/2 hours reaching a final, constant, temperature of 20 115C and the second for 13 1/4 hours reaching 18C.
G.L,C. analysis of both mixtures showed the presence of ethanol, tetraethoxysilane, ~; 2-phenoxyethanol and PhOC~ CH2OSi~OEt)3 Samples ,~
~ .
6~9 of pro~uct from Example 6 were analysed under the sa e conditions ~nd found to contain PhOCH2CH20Si(O~t) ~XAMPL~ 43 -invention with prc~ortio~ of an zlcohol ~0.~ in t~ ]c~hol.
A catal~,,ic solution W2S prepareà by mixing 300 ml of tetraethox~silane with 150 ml of metal alkoxide solution ?repa~ed according to ~e~hod 2, i.e. the catalyst was the reaction product of otassium and 2-ethoxyethanol~ ~o this solution was acGed 14g (0.~ ~oL~)of silicon powder of average pzrticle size:five~micro~s znd 30 ml dry e~hanol, i.e. 900 ~l catalytic solution per mole of silicon. mhe procedure followed was according to xample 1 wlth the exceptlon that the alcohol added was not pu~e etha~ol but 95% etha~ol b~ volume and /o 2-ethoxyethanol by volume, During a 33.5 hour period at an average reaction te~perature of 158C
the average production rate of product was 30.5gr~ms/hour with a ~ield of 98~o based on the weight of silicon .
used.
.: ' :~
' ! 7 7264 ~
~9 _ G,L,C. analysis of the product collected showed that there was an increased yield of the substituted alkoxysilanes (Eto)nSi(oCH2CH2oEt)4 n~
n = 3, 2, 1 compared with product collected from ~ 5 a reaction carried out under the same conditions : but with only ethanol added. The content of such substituted product was increased, Specifically the content of (Eto)3SioCH2CH2oEt was increased from 12 to 2C%~ of (Eto)2Si(oCH2CH20Et)2 from 1.5%
to 3/O and of (Eto)Si(oCH2CH2oEt33 from 0 to 1%.
,~
.
:
::
~ mole silicon. Then 30 ml dry ethanol were added.
;~ The ethanol mus~ be dried prior to use either by treatment with a molecular sieve (eOg. ~inde type 3~) or by distillation o~er sodium or magnesium. ~he mixture was heated by an electric heating mantle.
;,': .
~ .
.
~ . .
::
~ ~ 7~
When the reactor temperature reached 120C, the distillation head temperature rose to 90C. ~fter 80 ml distllla-te (mixture of ethanol and alkoxy-silane) was collected, the distillation head tem-perature fell to ambient and the reactor tempera-ture rose to 150C, at which temperature it was maintained for the remalnder of the reaction period.
~he reaction was monitored b~ measuring the rate of hydrogen evolution. Fu~ther reactants were added ;lO when the rate fell to less ~han 30 ml/min. Silicon was added in batches of 7 or 14 grams, ethanol (dr~) belng added dropwise at a rate such that the reactor temperature remained at 150C. The reaction was run in this way for 26 hours. A total of 70~2~14 mole) silicon was added, 93% belng converted to alkoxy-` sil~e. The average rate of production of alkoxy-silane was 18g/hour. The final reaction mixture was distilled at atmospheric pressure to recover pure alkoxysilane.
EX~MPLE 2 180 ml of metal alkoxide solution prepared b~ Method 1 was added to 500 ml of technical ethyl , ~ ~ 7 ~
' silicate to form the catalytic solution. To this was added 12 grams of silicon (i.e. 1587 ml cat~
alytic solution/mole silicon) and 303O5 gr~ms (6.6 mole) dry ethanol. ~he mixture was heated for 3 houh~s at 70 - 80C then the temperature was raised to 120C~ 580 ml of distillate (b~82-90C) being collected. ~he temperature W2S raised to 145C
and a 4: 1 molar ra~io slurry of ethanol : silicon addeà. The reaction ~e~perature rose ar.d vJas main-10 tained in the temperature r~nge 165 190C by ad-justing the rate of addition of the slurry. Distil-~' late (b.115-130C) was collected at the rate of about 90 ml/hour during the 40 hours which the reaction was run, a total of 3500 ml being collected. Frac-tionation at atmospheric ~ressure gave 750g pure tetra ethoxysilane b. 168 - 170C. ~he purity was con-firmed by the IR spectrum.
:
EXAMP~E 3 o the catal~tic solution prepared in ` 20 ~lethod 6, silicon (6~, 0.21 mole, i.e. 798 ml catalvtic solution/mole silicon) was added. Distilla~e was re-moved u~til the reactor temperature reached .
~ 172~9 145C, then a slurry of ethanol/silicon (molar ratio 4 : 1) was added. The reactor temperature rose to 165C and was maintained in the range 165 -190C by adjusting the rate of addition of the ethanol/silicon slurry. The reaction was carried out for 5 hours, during which time 225 ml of dis-tillate (b, 130 - 156C) was collected. Fractiona-tion of this mixture gave 125g pure tetraethoxysilane, The purity was confirmed by the IR spectrum, To the metal alkoxide solution prepared as in Method 5 was added 450 ml of the alkoxysilane product of Example 2 to give the catalytic solution, Then 14g silicon powder, average particle size 50 -15 60 microns were added, i.e. 1100 ml cataIytic solution~mole silicon. Following the procedure of Example 1, 56g ~2.0 mole) silicon and 425 ml (7.5 mole) dry ethanol were added over a period of 22 1/2 hours, the reactor temperature being maintained ' 20 between 150 - 160C. The percentage conversion of silicon to product was greater than 95% and the production rate was 20.5 grams/hour. The product ~ ~728~9 was purified as described in Example 1 EYI~IP~ 5 ~ o 170 ~l o~ the metal alkoxide solution prepared as described in l~e~hod 7, 3~0 ml of tetra-ethox~s lane were added to prepare the catalyticsolution. ~o this was added 1~ grams of sili^on powder, average particle size 50 - 50 microns, i.e. 893 ml catalytic solu~ion/mole silicon, t;~en 30 ml d~y ethanol. The mix~ure W2S heated to 150C
and maintained in the tem?erature range 150 ~ 160C
during 231 hours, in which time 44g (1.7 mole) silicon a d 330 ml (5.85 mole) dry ethanol were added. The percentage conversion of silicon to product was greater than 95% and the production rate -was 16.1 grams/hour.
EX~iPLE 6 `
:
To 250 ml of the metal alkoxide solutio~
prepared as described in Method 8, 340 ml of tetra-ethox~silane were added to prepare the catalytic solu~
tion. To this was added 16 grams of silicon powder, average particle size 50 - 60 microns, i.e. 1033 ~l .
~ ~ 72~
catalytic solution/mole silicon, then 30 ml dry ethanol. The mixture was heated as described in Example 1 and maintained at a temperature of 150 -190C during 13~ hours. In this time 18g (0.64 mola) of silicon and 130 ml (2.3 mole) dry ethanol we~e added. Tha pe~centage converslon of silicon to product was 66% and the production rate was 6.~ grams/hour.
. , .
~X~L~ 7 To 350 ml of metal alkoYide solution preparad as described in Method 1 was added 500 ml technical etnyl silicate to prepa~e the catalytic solution. ~hen 21g of ferrosilicon powder, average particle size 50 - 60 microns was added, i.e. 850 ml catalytic solution/mole silicon, together with 50 ml dry ethanol. ~ollowing ~he procedure of rxample 1, a further 72.5g ferrosilicon (2.5 mole~ and 46~2 ml dry ethanol (1206 mole) were added over 50 hours, the temperature being maintained at 160-180C~
The percentage conversion of silicon to product was greater than 95% and the production rate was 10 grams/
hour.
,' -~ ~ .
, ~ 1 7~
~ 21 -To 290 ml of metal alkoxide solution pre-pared as described in Method 1 was added 700 ml tetraalkoxysilane prepared as described in Example 1, to give the catalytic solution 21 grams of ferrosilicon (1 mole Si), average particle size 50 - 60 microns, were added i e, 990 ml catalytic solution/mole silicon, together with 50 ml dry ethanol. Following the procedure of Example 1, the reaction was carried out for 34 hours at an average temperature of 148C. The percentage conversion of silicon to product was greater than 95% and the production rate was 34 grams/hour, _ _ A catalytic solution was prepared by mixing 150 ml of a metal alkoxide solution prepared according to Method 1 with 250 ml of a polymethyl-phenyl siloxane (Dow Corning 550 fluid)o 7 grams (0,25 mole) of silicon, average particlP size 50 -60 microns, were added, i.e. 1600 ml catalytic solution/mole silicon, Dry ethanol (S0 ml) was added and the mixture was gently warmed, being maintained ~ ~7~6~
_ 22 between 90C and 130C during the reaction (10 hours). Alkoxysilane product was produced at rates between 11 and 56 gram/hour, depending on the reaction temperature.
,~
A catalytic solution was prepared by mixing 150 ml of a metal alkoxide solution prepared according to Method 1 with 125 ml of a polymethyl-phenyl siloxane (Dow Corning 550 fluid) and with 125 ml tetraethoxysilaneO 7 grams (0 2S mole) of silicon, average particle size 50 - 60 microns, were added, i.e. 1600 ml catalytic solution/mole silicon. Dry ethanol (50 ml) was added and the mixture was gently warmed, being maintained between 90C and 130C during the reaction (10 hours).
Alkoxysilane was produced at rates between 11 and 112 gram5/hour, depending on the reaction tempera-; ture, In the preceding Examples, the volume ratio of solvent to metal alkoxide solution, giving the ~ 11 726~9 _ 23 -catalytic solution is 2 : 1 or greater. In this Example, the catalytic solution used has a volume ratio of solvent to metal alkoxide solution of 1 : 2.
The procedure followed is as described in Example 1, The metal alkoxide solution is prepared as described in Method 1. The catalytic solution is made by adding to 350 ml of metal alkoxide solution, prepared as described in Method 1, 170 ml of alkoxysilane prepared as described in Example 1.
To this catalytic solution is added 14g (0.5 mole) silicon powder, average particle size 50 - 60 microns, i.e. 1040 ml catalytic solution/mole silico~, together with 30 ml dry ethanol. The mixture was heated to 15 150C and the reaction was carried out for 14 1/4 ~; hours. During this time 43.75 grams (1.75 mole) silicon and 410 ml (7.27 mole) dry ethanol were ~; added. The percentage conversion of silicon to product was greater than 95% and the production rate was 34 grams/hour, A catalytic solution was prepared by adding 350 ml of tetraethoxysilane to 175 ml of metal .
~: ~
alkoxide solution prepared as described in Method 1. To this catalytic solution is added 14g (0.5 mole) silicon powder, particle size 5 microns or less, i.e. 1050 ml catalytic solution/mole 5 silicon, together with 30 ml dry ethanol. The reaction was carried out as described in Example 1, ; except that the dry ethanol used contained 2% v/v ; toluene. During 19 1/2 hours 61g ~2.1 mole~ silicon and 450 ml (9.27 mole~ ethanol were added. The per-centage conversion of silicon was greater than 95%
and the production rate was 44 grams/hour.
AlkoxysilaneS were prepared following the - procedure of Example 1, except that ethanol was lS introduced into the reactor as a 70 : 30 mixture by - volume of ethanol and alkoxysilane.
` The catalytic solution was prepared by adding 350 ml of alkoxysilane prepared as described in Example 1 to 190 ml of metal alkoxide solution prepared as described in Method 1. To this catalytic solution was added 14 grams (0.5 mole) silicon powder, particle size 5 microns or less, i e. 1080 ml catalytic ~:
:;
..~
",~,.~, ~ 172~
solution/mole silicon, together with 30 ml dry ethanol. The average reaction temperature w~s 137C over a 15 hour reaction period. 43,5g (1.5 mole) silicon and 275 ml (5.88 mole) dry ethanol (as the ethanol-alkoxysilane rnixture) were added. The percentage conversion of silicon was greater than 95% and the production rate was 23.6 grams/hour.
:
A catalytic solution was prepared by adding to 500 ml tetraethoxysilane, 290 ml of metal alkoxide solution prepared as described in Method 1.
To this catalytic solution was added 15 grams (0,5 mole) silicon powder (95% Si : 5% Fe + Mn, particle size 50 - 60 microns), i.e, 1580 ml catalytic solution/mole silicon, together with 60 ml dry ethanol. The procedure of Example 1 was followed, giving a percentage conversion of silicon greater than 95% and a production rate of 35.7 grams/hour.
EXAM_ LE 15 Following the procedure of Example 1, ; silicon powder containing 0.5 - 1.5% Fe, 0.2 - 0.75%
-.
g ~726~
_ 26 -Ca and 0 5 - 1 5% Al was used The catalytic solution was prepared by adding to 400 ml tetra-ethoxysilane, 200 ml of metal alkoxide solution prepared as described in Method 1, To this catalytic solution was added 16 grams ~0.5 mole~
of the silicon powder particle size 50 - 60 microns, i.e. 1200 ml catalytic solution/mole silicon, together with 30 ml dry ethanol. The average temperature of the reactor was 133C. The reaction was carried out for 12 hours, 28.5 grams of the silicon and 360 ml dry ethanol being added. The percentage conversion of silicon to alkoxysilane was 66% and the production rate was 22 grams/hour.
EXA~LE 16 _ ~ catalytic solution was prepared by adding 1000 ml tetraethoxysilane to 400 ml of metal alkoxide solution prepared according to Method 1, To this catalytic solution was added 28g (1 mole~
silicon, particle size 50 - 60 microns, i.e. 1400 ml catalytic solution/mole silicon, together with 70 ml dry ethanol. Following the procedure of Example ;; 1, 156~25 grams of silicon, particle size 5 microns , j~
, ~, .
- - ~ 17264~
_ 27 -or less were added together with 1920 rnl dry ethanol in the course of 45 1/2 hours. The reactor temperature was maintained at an average of 148C. The percentage conversion of silicon was greater than 95% and the production rate was 53,5 grams/hour.
A catalytic solution was prepared by adding 600 ml tetraethoxysilane to 300 ml of metal alkoxide solution prepared according to Method 1.
To this catalytic solution was added 28 grams ~1 mole) silicon, particle size 50 60 microns, i,e, 900 ml catalytic solution/mole silicon together with 50 ml dry ethanol, Following the procedure of Example 16, silicon of 74 micron particle size was used.
The percentage conversion of silicon was greater ;~ than 95% and the production rate was 34 grams/hour, A catalytic solution was prepared by adding 300 ml of alkoxysilane prepared as described in Example 1 to 175 ml o~ the metal alkoxide product of Method 8. To this catalytic solution was added ~1 î 1 726~19 14 grams (0,5 mole) silicon, particle size 50 60 microns, i.e~ 950 ml catalytic solution/mole silicon together with 30 ml dry ethanol. Follow-ing the procedure of Example 1, the reaction was carried out for 20 1/2 hours, the mean reaction temperature being 158C. 28 grams silicon and 230 ml dry ethanol were added. The percentage conver-sion of silicon was greater than 95% and the production rate was 10,2 grams/hour.
A catalytic solution was prepared by adding 340 ml of alkoxysilane prepared as described in Example 1 to 170 ml of sodium 2-ethoxyethoxide solu-tion prepared as described in Method 3. To this catalytic solution was added 14 grams (0,5 mole~
silicon powder, particle size 50 - 60 microns, i,e.
1020 ml catalytic solution/mole silicon, together with 40 ml dry ethanol, Following the procedure of Example 1, the reaction was carried out for 22 1/2 20 hours, the mean reaction temperature being 148C, 49 grams silicon and 290 ml ethanol were added, The percen-; tage conversion of silicon to product was greater :
,S' :
~7 than 95% and the production ra~e was 15 grams/hour.
P~ 20 The procedure of ~xample 19 was followed~
except that the catal~t~c sGlu~ion was ~repared usinO 170 ~l of potassium 2-ethoxyethoxide made as describ~d in Method 3. ~he ~ercentage conversion of silicon to alkoxysilans was greater th~ 9,%
anà the ~roduc~ion rate was 22 grams/hour.
: ' .
hXk~PL~ 21 h catalytic solution was prepared by addin ~; 675 ml Or tetraethoxysilane to 290 ml metal alkoxide solution prepared as described in Ms~hod 1. In this catalytic solution the volums ratio of solvent to me-tal alkoxide solution is 2.25 : 1. To the catalytic solution is added 14g (0.5 mole) silicon, i.e. 1930 ml catalytic solution/mole silicon, together with 60 ml dry ethanol. The mixture was warmed to 145C
.
and ethanol slowly added dropwise so as to maintain tbe reaction temperature in the range 165 - 170C~
The alkoxysilane produced was removed from the re-action system by distillation as a mixture of ethanol ~ ~72649 and producv. At 145C the production rate of alkoxysilane was 24 grams/hour~ ht the end of the reaction the production rave of alkoxysilane was 14.6 gr2ms/hour~
~X~'~.L~ 22 n ~nis ~xa~le, the thernal capacity of the cataly~ic solution is first increased by stepwise adaitions o^ ethanol and silicon~ then alkoxysilane and ethanol were r-mo~ed as V&pOU~ and the seauence repeated.
Startin~ ~oceau~e A clean and oLry reaction vessel is purged , .
. with dry nitrogen for a;~out 15 minutes~ The catalytic solution is made by charging the reaction vessel with 204 li~res of tetraethoxysilane, followed by 204 litres of metal alkoxide solutio~ prepared according to Method 4 and then by a further 136 litres of tetraethoxysilane~ To this catalytic solution 5 kg silicon powder was added, i~e. 3046 ml catalytic solution/mole silicon, followed by 10 litres ~rJ
ethanol. The mixture was heated until the reactor temperature was 140C. At this stage the distillation ;: ' ' ~ : ,:, ,: . , 11 117~49 head temperature (head te,perature) was the a~bient temperature~
Dry and preheated ethanol was added at a rate such that the reactor temperature did not drop below 140C. ~thanol was added at this reouired rate until evolution Of hydrogen ceased. Then a further 5 kg silicon was added and more ethanol was added at the r-quired rate u~til evolution of hydrogen ceased.
No ~istillate was collected in ~hi~ cycle, i.e. ~he reactior ~as do~e u~--er total reflux condition.
; It is necessary to mainta n a ~inimum reac-tor temperature of 140C~ Althou~h a minimum reactor ~` ~ temperature of 1'~0C is require~, t:~e te~perature is ~5 preferably in the ræ~ge 155-165C~ The ethanol addition can be replaced by a ~ixture of ethanol and tetraethoxysilane.
he separation of alkoxysilane from the reacticn mi~ture was carried out by the following , ~
procedure.
(i) The preferred reactor temperature is 150C.
- 32 _ ~
(ii~ Dry ethanol was added to the reaction mixture at a rate such that a constant head tempera-ture is maintained.
(iii) It is preferable to remove the product as a mixture of alkoxysilane and ethanol. The product should be removed at a high head temperature (140C
or over~ to ensure that the distillate is rich in alkoxysilane. It is important that only the amount ; of alkoxysilane produced is removed.
The ethanol-alkoxysilane mixture collected is distilled to separate the ethanol and the alkoxy-silane, The ethanol recovered can be re-used.
After the alkoxysilane produced has been removed, the sequence of stepwise additions of silicon and ethanol is repeated to continue the production of , alkoxysilane. This in its turn is removed then the sequence of stepwise additions of silicon and ethanol is continued.
Preparation of polysilicat_ Alkoxysilane - 259 volumes ~i Anhydrous ethanol - 82.2 volumes Water - 16.4 volumes - must be distilled or de-ionised ~ ~ Acid solution - 1,3 volumes ::
.
~ 1726~
- 33 ~
The acid solution is 1% v/v of concentrated sulphuric acid (9~/0 ~ S04 by weight) in anhydrous ethanol.
The mixture of alkoxysilane, anhydrous ethanol and acid solution is heated to reflux temperature and water added dropwise with stirring over a period of 30 minutes. Refluxing is carried out for 60 minutes when the addition is completed.
The ethanol is recovered from the product by dis-tillation under gradual lowering of pressure.
Distillation was finished when a pot temperature of 140C at 100 mm Hg pressure was reached, The . amount of ethanol recovered was 180 volumes, This -: can be used again in the preparation.
Product characterisation , ~ Density at 20C - 1.06 gm/ml Silica content = 36,1% w/w Acidity = 0.013% wv H2S04 - ' .
- :
~ ~ 7~49 A catalytic solution was prepared by mixing 125 ml of the metal alkoxide solution prepared as in Method 11 with 395 ml of tetraethoxysilane. To this solution was added 14g (0.5 mole) silicon powder average particle size 50 - 60 microns and 30 ml dry ethanol, i,e. 1040 ml catalytic solution per mole silicon. The procedure followed was according to Example 1 and over 29 1i2 hours at an average reaction temperature of 155C, the average production rate of alkoxysilane was 18.9 grams/hour with a yield of 86~o based on the weight of silicon used.
A catalytic solution was prepared by mixing 190 ml of the metal alkoxide solution prepared accord-ing to Method 10 with 360 ml of tetraethoxysilane.
To this solution was added 14g (0.5 mole)of silicon powder, average particle size 50 - 60 microns and 30 ml dry ethanol, i.e, 1100 ml catalytic solution per mole silicon, Following the procedure of Example 1 ~7~
the reaction was run for 30 hours at an average temperature o 148C yielding 72~/o of alko~ysilane based on the weight of silicon used, at an average production rate of 19.2 grams/hour.
150 ml of metal alkoxide solution prepared according to Method 2 was added to 300 ml of alkoxy-silane prepared according to Example 1 and to it was added 14g (0.5 mole) of silicon powder, average particle size S0 - 60 microns, and 30 ml dry ethanol (i.e, 900 ml catalytic solution per mole silicon).
The procedure followed was similar to that of Example 1 except that the ethanol was added in the vapour state, being boiled in a 100 ml 3-necked round-bottomed flask fitted with a glass delivery tube to transfer ethanol vapour to the reaction vessel~ below the liquid surface and a 50 ml dropping funnel to add cold ethanol dropwise to the boiling ethanol in the flask. ~he delivery tube was wrapped in trace heating wire in order to prevent condensa-tion of the ethanol between the flasks. The reaction was run for 29.8 hours under these conditions and the average production rate of the product was ~ î7264~
18.9 grams/hour at an average reaction temperature of 152Co The yield of product based on the weight of silicon used was 86~3%~
A catalytic solution was prepared by mixing 300 ml of tetraethoxysilane with 150 ml of metal alkoxide solution made according to Method 2. To this was added 14g (0.5 mole) silicon powder, average particle size 5 microns and 30 ml dry ethanol, i,e, 900 ml catalytic solution per mole silicon. The procedure of Example 1 was followed and the reaction run for 37~8 hours at an average temperature of 153C~ AlkoxySilane was produced at an average rate of 29,1 grams/hour in 94,2% yield based on the weight of silicon used.
.
300 ml tetraethoxysilane were added to 150 ml of metal alkoxide solution made following Method 1 but using only sodium 111,58g, 0.504 mole), to make ' ~ 20 the catalytic solution. To this was added 14g (0~5 mole) of silicon powder, average particle size 5 microns, and 30 ml dry ethanol, to give 900 ml :
~ 1l726~
solution was added 3~0 ml tetraethoxysilane, producing 480 ml of catalytic solution. To this was added l~g (0.5 mole) of silicon powder, average particle size 5 microns, i.e. 960 ml catalytic solution per mole silicon. Following the procedure of Example 1, the reaction was run for 32.8 hours at an average temperature of 149C with an average ester production rate of 19 grams/hour and in 94 1%
yield based on the weight of silicon consumed.
Following the procedure of Method 5, but using only potassium metal (19.47g, 0 499 mole3 a metal alkoxide solution was made up (110 ml) and added to 370 ml tetraethoxysilane to produce the catalytic solution. Silicon powder (14g 0.5 mole) of average particle size 5 microns was added to it, producing a system with 960 ml catalytic solution per mold silicon The reaction was carried out according to Example 1 and over 37 75 hours at an average temperature of 151C produced ester at an average rate of 22.6 grams/hour in ~6 6% yield based ~ ~ 72~19 - 37 ~
catalytic solution per mole silicon. ~ollowing the procedure of Example 1, the reaction was run for 2&.5 hours at an a~erage temperature of 158C
giving a 97.6~o yield Or alkox~sil~ne based on the weight of silicon used, av an average ?roductlon rate of 27.7 ~ra s/hour~
- EK~IPL~ 28 ~ o 300ml tetraethoxysilane were added 150ml of met21 alko~ide solution m~ce following Method 1 bui USl~g only po'vassium metal ( 19.5g, ~.5 mol~ to produce 450ml catalytic solution. Silicon powder g 0.5mole) was added together with 30~1 dr,y ethanol to the catal~tic solution, producing 900ml catal~tic solution per mole silicon. ~ollol.~ing the procedure of ~xample 1 the reaction was run for 3~75 hours at an average te~pera'ure o~ 152C.
he ~ield Or ~x~uct based on the weight of silicon used was~94.1% and the ave-age production rate 28.4 grams/hour.
~X~MP~ 29 A metal alkoxide solution was made following the procedure oI Method 5 ard to 100ml o:[ this ~ ::
.
`. ~172~;4~ :
- ~8 -solution :as added 380ml tetraethox~silane, pro-ducing 480ml of catalytic solution. ~o this was added 14g (0.5 mole) of silicon powder, average ~ particle slze 5 microns, i.e~ 960 ml catal~tic ; 5 solution per mole silicon. ~ollowing the proced-ure ol Exa~ple 1, the reaction was run for 32.8 hours at a~- averG_e ~e-~erat~are of 149C wlth a~
avera~e es~er production rate o~ 19 ~ a~ns~ ~& in 9!'.13~ ield based o~ ~ne weight Or silicon 1C co~sumed.
.
~ E~LE 33 . .
~ ollo~.~n~ the procedure of Method ~, but .
: using onl~ potassium metal (19.~7~,0.49~ole) a metal alkoxide solution was ~ade up (110 ml) and ~: ~15 adaed to 370 ~l tetraethox~silane to produce the catalytic solutio~O Silicon powder (1~g 0.5 mole) o~ average particle size 5 microns was added to it, producing a s~stem with 960ml catal~tic solu-tio~ per mole silicon~ The reaction was carried out ~ 20 according to E~smple 1 and o~er 37.75 hours at an : ~ ~ . average tem~eratu~e o~ 151C produced ester at an ~ ~ average rate of 22.6 ~rGms/hour in 86.~5' yield based ': ' ' , , .
~ . .
~ ~7~164 - 3~
.: ,., on the weight of sllicon used.
~h~PL~
A metal alkoxide solution was made up according to Method 7 (145 ml ) ~nd mixed with 290ml tetraethox~s~lane and 14g silicon powder (005mole~
of aver~e particle size 5 microns and 30 ml of dr~ ethanol~ i.e. 870ml catalj~ic solution per mole silicon. ~ollo~ing the procedure of Example 1 the reaction was ru~ for 43.1 hours at an ave~age te~perature of 150C, giving a yield of 95.~/0 pro-duct based on the weight of silicon used at an average production rate of 28.1 ~ra~s/hour.
.
ollowing Method 10 195ml of metal alkoxide solution was made and mixed with 285ml tetraethoxy-silane, 14g (005mole)silicon po~der of average particle size 5 microns and 30 ml of dry ethanol, e. 960 ml catal~tic solution per mole silicon.
he reaction was run for 41.3 hours at an average ~; 20 temperature of 155C according to ~xample 1 and pro-duced a product yield of 97.2/o based on the weight of .
,~, '`.
, ~ ~726~1 silicon used at an average production rate of 27,3 grams/hour, 170 ml of metal alkoxide solution was prepared according to Method 1, but using only sodium metal (15,48g, 0,673 mole), To this was added 340 ml alkoxysilane produced according to Example 1 and 40 ml dry ethanol and 14g (0.5 mole) silicon powder of average particle size 50 - 60 microns, i.e. 1020 ml catalytic solution per mole silicon, Following Example 1 the reaction was run for 22,5 hours at an average temperature of 148C yielding alkoxysilane at an average rate of 15,0 grams/hour in 78,~/o yield based on the weight of silicon used, 175 ml of metal alkoxide solution was :~:
prepared according to Method 1 but using only potassium metal ~26.6g, 0.68 mole). To this was added 350 ml alkoxysilane produced according to Example 1, 30 ml dry ethanol and 14g (0.5 mole) silicon powder of ~! average particle size 50 - 60 microns, i~e, 1050 ml catalytic solution per mold silicon, Following ~ 172~49 Example 1 the reaction was run for 21,8 hours at an average temperature of 155C, producing alkoxysilane at an average rate of 22.7 grams/hour in 84.4% yield based on the weight of silicon used~
130 ml of metal alkoxide solution was pre-pared according to Method 5, but using only sodium metal 511.61g, 0,528 mole), To this was added 420 ml alkoxysilane produced according to Example 1, and 14g (0.5 mole) silicon powder of average particle size 50 - 60 microns, i.e, 1100 ml catalytic solution per mole silicon. Following Example 1 the reaction was run for 23.2 hours at an average temperature of 149C, alkoxysilane was produced at an average rate of 13 grams/hour, -.-100 ml of metal alkoxide solution was pre-; pared according to Method 5, but using only potassium metal (19.50g, 0,50 mole~. To this was added 450 ml alkoxysilane produced according to Example 1 and 14g (0.5 mole) silicon powder of average particle .... ..
_,, ~ ~7~6~9 _ 42 -size, 50-60 microns, i.e. 1100 ml catalytic solu-tion per mole silicon. Following Fxample 1 the reaction was run for 23.2 hours at an average tem-; perature of 152C. Alkoxysilane was produced at an average rate of 16.2 grams/hour in 75.1~ yield based on ~he weicht of silicon used.
X~ 37 - i catalytic solu~ion was ?repared by dis-solvin~ so~iu (4.8g, 0.21 mo1~)in 75 ml 2-dimethyl-~minoeth~nol over a two hour period. It was r.eces-sary to h~at the mixture gently to ~acili~ate solu-tion of the sodium when about half the quantity was added. Potassium (9.70g, 0~25 mole) was now d~ssolved in the mixture over a six hour period, with tne addition of two 25 ml portions of 2-di ethyl~minoeth~nol. ~he mixture was heated for two hours after all the metal dissolved. To this solution was added : :
~ 395 ml alkox~sila~e produced according to xample ; ~
1, then 14 grams silicon powder, avera~e p~rticle size .
53 microns were added (i~e. 1040 ml catalytic solution per molesilicon~. Then 30 ml of dry eth~nol were ~ added. The reaction was run ~or 29~ hours, the avera~e :;:
~: :
!1 ~7~9 reaction temperature being 155C. The average rate of production of alkoxysilane was 18.9 grams/hour, the yield of alkoxysilane, based on the weight of silicon used, was 86.0%.
Identiflcation of Components of the Reaction Product Ester The product collected from the various re-actions detailed in the Examples was analysed by Gas Liquid Chromat`ography (G.L.C.) using a Pye model 204 GCD chromatograph and with SE 30 and OV17 columns, The carrier gas used was nitrogen, at a flow rate of 40 ml per minute and the oven temperature of the chromatograph was 200C.
Peaks other than ethanol, alkali metal solvent and tetraethoxysilane were found, in quantities between 1 and 20 area % depending upon the circumstances under which the product was collected, These peaks have been identified as mixed esters of the type (EtO)nSi(OA)~ n where n = 1, 2, 3 by chemically equilibrating mixtures involving AOH and Si(oEt)4 also EtOH and Si(oA)4 (A=EtOOEI2C~ , _ a~4 _ EtOEI2CH2OCH2CH2) and analysing them by G.L,C.
Major peaks in these mixtures, whose proportion varies systematically with the molar ratio of equilibrants, have similar retention times to 5 the minor product components~
EXAMPLE 3_ Tetraethoxysilane (58 66g, 0~282 mole) and 2-ethoxyethanol (25 69g, 0.285 mole) were refluxed together in a three-necked, 100 ml round-bottomed flask 10 fitted with thermometer and reflux condenser, for 6 hours, the temperature of the mixture fell from 132C to 110C during this time. Similarly mixtures of tetraethoxysilane and 2-ethoxyethanol ~69 75g, 0.335 mole and 85.14g, 0.409 mole with 10~06g, 0.112 mole and 102.10g, 1 138 mole respectively) of mole ratios 3: 1 and 1: 3 were refluxed for 6 hours, the temperatures of the mixtures falling as in the first case.
G.L.C, analysis of these mixtures showed 20 peaks corresponding to ethanol, 2-ethoxyethanol and tetraethoxysilane together with the three mixed esters (EtO)nSi(oCH2CH2oEt)4 n~ n = 1, 2, 3. Samples of ~ ~ 7~6~9 product from Examples 26, 27, 28 showed peaks with similar retention times as the mixed esters Using the procedure of Example 38 two 5 mixtures of ethyldigol and tetraethoxysilane were refluxed and analysed by G.L C In the :Eirst case tetraethoxysilane (43.12g, 0.205 mole) and ethyl-digol (27.98g! 0 209 mole) were refluxed for 7 1/2 hours during which time the temperature of the 10 mixture fell from 164C to 104C In the second case tetraethoxysilane (26.83g, 0.128 mole) and ethyldigol (51.51g, 0.38 mole) were refluxed for 8 hours during which time the temperature of the mixture fell from 170 to 127C.
G.L.C. analysis of these two mixtures after reflux showed the presence of five components, ethanol, ethyldigol, tetraethoxysilane and two mixed esters (EtO~3SioCH2CH2oCH2 CH2OEt and (Eto)2Si(oCH2cH2ocH2cH2oEt)2. Samples of product 20 from Examples 24 and 32 which were also analysed contained components with similar retent:ion times as the mixed esters , , 1 ~ 7~649 Following Example 38 two mixtures of 2-dimethylaminoalcohol and tetraethoxysilane were refluxed and analysed by G,L.C. In the first case tetraethoxysilane (42.70g, 0.205 mole) and 2-dimethylaminoethanol (18.27g, 0.205 mole) were reEluxed for 7 1/3 hours after which the mixture had reached a constant temperature of 105C.
Secondly tetraethoxysilane (29 81g, 0.143 mole) and 2-dimethylaminoethanol (38.39g, 0.431 mole) were refluxed for 6 1/2 hours a Einal, constant tempera-ture oE 107.5~C being reached.
G.L.C. analysis of the two mixtures showed the presence of ethanol, 2-dimethylaminoethanol, and tetraethoxysilane together with the mixed esters (EtO)nSi(OCH2CH2NMe2)4 n; n -- 1, 2, 3, Samples of product from Example 23 were analysed under similar conditions and were :eound to have peaks corresponding to the three mixed esters, 20 ~ EXAMPLE 41 Following Example 38 two mixtures of met~yl digol and tetraethoxysilane were refluxed and analysed by G.L.C. ~etraethoxysilane (34,70g, 0~167 mole) and :
methyl digol (20.01g, 0.167 mole) were refluxed for ' 1 ~72~9 15 1/3 hours attaining a final temperature of 115C.
A second mixture of tetraethoxysilane (20,92g, 0 100 mole) and methyl digol (36 05g, 0 300 mole) was refluxed for 14 3¦4 hours reaching a final, constant, temperature of 116C~
G.L.C, analysis of tne two mixtures showed the presence of ethanol, methyl digol and tetra-ethoxysilane plus two mixed esters (EtO)n Si(ocH2cH2ocH2cH2oMe)4 n; n = 2, 3~ Samples of product from Examples 5 and 31 were analysed under similar conditions and found to contain peaks corresponding to the two mixed esters.
Following Example 38 two mixtures of 15 tetraethoxysilane (20.83g, 0.100 mole and 10.42g, :: 0.050 mole) and 2-phenoxyethanol (14 04g, 00102 mole and 20.23g, 0.146 mole) were refluxed and analysed - by G.L.C. The first mixture was refluxed for 14 1/2 hours reaching a final, constant, temperature of 20 115C and the second for 13 1/4 hours reaching 18C.
G.L,C. analysis of both mixtures showed the presence of ethanol, tetraethoxysilane, ~; 2-phenoxyethanol and PhOC~ CH2OSi~OEt)3 Samples ,~
~ .
6~9 of pro~uct from Example 6 were analysed under the sa e conditions ~nd found to contain PhOCH2CH20Si(O~t) ~XAMPL~ 43 -invention with prc~ortio~ of an zlcohol ~0.~ in t~ ]c~hol.
A catal~,,ic solution W2S prepareà by mixing 300 ml of tetraethox~silane with 150 ml of metal alkoxide solution ?repa~ed according to ~e~hod 2, i.e. the catalyst was the reaction product of otassium and 2-ethoxyethanol~ ~o this solution was acGed 14g (0.~ ~oL~)of silicon powder of average pzrticle size:five~micro~s znd 30 ml dry e~hanol, i.e. 900 ~l catalytic solution per mole of silicon. mhe procedure followed was according to xample 1 wlth the exceptlon that the alcohol added was not pu~e etha~ol but 95% etha~ol b~ volume and /o 2-ethoxyethanol by volume, During a 33.5 hour period at an average reaction te~perature of 158C
the average production rate of product was 30.5gr~ms/hour with a ~ield of 98~o based on the weight of silicon .
used.
.: ' :~
' ! 7 7264 ~
~9 _ G,L,C. analysis of the product collected showed that there was an increased yield of the substituted alkoxysilanes (Eto)nSi(oCH2CH2oEt)4 n~
n = 3, 2, 1 compared with product collected from ~ 5 a reaction carried out under the same conditions : but with only ethanol added. The content of such substituted product was increased, Specifically the content of (Eto)3SioCH2CH2oEt was increased from 12 to 2C%~ of (Eto)2Si(oCH2CH20Et)2 from 1.5%
to 3/O and of (Eto)Si(oCH2CH2oEt33 from 0 to 1%.
,~
.
:
::
Claims (4)
1. A method of manufacturing an alkoxysilane containing the compound (RO)nSi(OA)4-n where R is C1-C6 alkyl, A is -C2H4OCH3, -C2H4OC2H5, -C2H4OC6H5, -C2H4OC2H4OCH3, -C2H4OC2H4OC2H5, -C2H4NR1R2 where R1 and R2 are C1 - C4 alkyl and n is 1, 2 or 3 comprising the preliminary step of preparing a mixture of the alcohol ROH and the alcohol AOH
and thereafter reacting the mixture at an elevated tempera-ture with silicon or a silicide in a solution containing as a catalyst an alkali metal alkoxide corresponding to the alcohol AOH and having sufficient thermal capacity effec-tively to convert the major part of the silicon to alkoxy-silanes and to discharge as vapours alcohol and the reaction products hydrogen gas and the alkoxysilane, said thermal capacity being achieved by having at least 500 ml of cata-lytic solution for each mole of silicon or silicide.
and thereafter reacting the mixture at an elevated tempera-ture with silicon or a silicide in a solution containing as a catalyst an alkali metal alkoxide corresponding to the alcohol AOH and having sufficient thermal capacity effec-tively to convert the major part of the silicon to alkoxy-silanes and to discharge as vapours alcohol and the reaction products hydrogen gas and the alkoxysilane, said thermal capacity being achieved by having at least 500 ml of cata-lytic solution for each mole of silicon or silicide.
2. A method as claimed in claim 1 wherein R is C2H5.
3. A method as claimed in claim 1 wherein there is 10% or less of the alcohol AOH in the said mixture.
4. A method as claimed in claim 1, 2 or 3 in which molar ratio of alkali metal ion to silicon is between 0.50 to 1 and 1.80 to 1.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8023100A GB2059429A (en) | 1979-10-02 | 1980-07-15 | Improvements in the Production of Alkyl Silicates |
| GB8023100 | 1980-07-15 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1172649A true CA1172649A (en) | 1984-08-14 |
Family
ID=10514780
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000376490A Expired CA1172649A (en) | 1980-07-15 | 1981-04-29 | Production of alkyl silicates |
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| Country | Link |
|---|---|
| CA (1) | CA1172649A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4810441A (en) * | 1985-04-02 | 1989-03-07 | Clinotherm Limited | Process for the preparation of a ceramic fiber |
| US4897232A (en) * | 1986-11-28 | 1990-01-30 | Clinotherm Limited | Preparation of fibres from a liquid precursor |
-
1981
- 1981-04-29 CA CA000376490A patent/CA1172649A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4810441A (en) * | 1985-04-02 | 1989-03-07 | Clinotherm Limited | Process for the preparation of a ceramic fiber |
| US4897232A (en) * | 1986-11-28 | 1990-01-30 | Clinotherm Limited | Preparation of fibres from a liquid precursor |
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