CA1045636A - Process for the production of dipropylene glycol dibenzoate - Google Patents
Process for the production of dipropylene glycol dibenzoateInfo
- Publication number
- CA1045636A CA1045636A CA209,353A CA209353A CA1045636A CA 1045636 A CA1045636 A CA 1045636A CA 209353 A CA209353 A CA 209353A CA 1045636 A CA1045636 A CA 1045636A
- Authority
- CA
- Canada
- Prior art keywords
- process according
- dipropylene glycol
- aluminium
- methylbenzoate
- catalyst
- Prior art date
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C69/00—Esters of carboxylic acids; Esters of carbonic or haloformic acids
- C07C69/76—Esters of carboxylic acids having a carboxyl group bound to a carbon atom of a six-membered aromatic ring
- C07C69/78—Benzoic acid esters
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/08—Preparation of carboxylic acid esters by reacting carboxylic acids or symmetrical anhydrides with the hydroxy or O-metal group of organic compounds
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE:
The present invention is concerned with a process for the preparation of dipropylene glycol dibenzoate, which comprises transesterifying methylbenzoate with dipropylene glycol, at a tem-perature above 150°C and in the presence of an aluminium alkoxide or an aluminium-silicon alkoxide, or both, as catalyst. The pro-cess according to the invention enables to obtain light-coloured dipropylene glycol dibenzoate starting from commercial grade me-thylbenzoate and dipropylene glycol.
The present invention is concerned with a process for the preparation of dipropylene glycol dibenzoate, which comprises transesterifying methylbenzoate with dipropylene glycol, at a tem-perature above 150°C and in the presence of an aluminium alkoxide or an aluminium-silicon alkoxide, or both, as catalyst. The pro-cess according to the invention enables to obtain light-coloured dipropylene glycol dibenzoate starting from commercial grade me-thylbenzoate and dipropylene glycol.
Description
The present invention relates to a process for the production of dipropylene glycol dibenzoate.
Dimethyl terephthalate can be produced commercially by catalytically oxidizing _-xylene and methyl-_-tolate with air, by esterifying the products of oxidation with methanol, and by separating the methyl esters obtained. The esters (mainly methyl-_-tolate, dimethyl terephthalate and methyl esters of other mono-functional and polyfunctional acids) are separated from one another by distillation or recrystallisation or by a combination of these two processes. Dimethyl terephthalate is recovered, valuable intermediate products are recycled, and secondary products are - removed. Some of the secondary products consist of impure methyl-benzoate containing a number of compounds with substantially the ~same boilingpoint as methylbenzoate. Unless these compounds are removed beforehand, for example by pretreatment under oxidising conditions in accordance with Applicant's German Auslegeschrift No. 1,927,554 of May 17, 1973, pure methylbenzoate cannot be obtained, even with considerable technical outlay on distillation.
The impure methylbenzoate obtained in industrial plants for the ; 20 manufacture of dimethyl terephthalate generally contains more than 80% of pure methylbenzoate.
Attempts to transesterify such impure methylbenzoate with dipropylene glycol (also known as ~,~'-di-hydroxy-di-_-propyl ether) in the presence of conventional transesterification cata-lysts have shown that some of these catalysts, for example anti-mony -trioxide and boron trioxide, are unexpectedly totally inactive whilst others, for example sodium methylate, catalyse the reaction to a very limited extent only. This is indicative of the formation of inhibiting substances from the impurities in the methylbenzoate.
Although a number of other transesterification catalysts, such as tetrabutyl titanate, zinc compounds and magnesium compounds, are sufficiently active, the esters obtained are brown to brown-black in colour with iodine colour numbers of up ~ - 1 - ~
to t50. In many cases, the es-ters are so dark brown to black in colour that their iodine colour numbers cannot be mea~ured. A few examples are set out in Table 1, which shows the iodine colour numbers o~ the transesterifiaation products of commercial grade methylbenzoate and dipropylene glycol, measured in identical standard batches and under comparable conditions using different catalysts. The examples are selected in such a way that products with substantially the same degree of transesterification, charac-terised by hydroxyl numbers in the range from 10 to 30, were ob-tianed.
Table 1 . . . . . . .
Catalyst Quantity of Transesteri- OH- iodine catalyst fication ti- number colour ~`
me (hours) number .
Sodium methylate 0.2 11 24100 Magnesium acetate 0.2 5 3080 Magnesium methylate 0.2 3 19130 Zinc stearate 0.2 7 13100 Zinc dust 0.2 3 1830 Dibutyl tin ~ilaurate0.2 4 1770 Tin (IV) butylate 0.2 4 black-brown Titanium silicon 0.2 4 black_brown alkoxide lycerol titanate 0.2 8 1780 etrabutyl titanate 0.2 2760 etrabutyl titanate 0.1 4 3060 Tetrabutyl titanate 0.5 20 70 The deep colour of the esters cannot be lightened to any appreciable extent by bleaches such a~ active carbon or fuller's i~45636 earths. Similarly, oxidising agents, such as hydrogen peroxide or ozone, do not have any significant effect. ~istillation in vacuo produces deep-yellow distillates. r~he eolour quality is inadequate for commercial application. ln addidition, the ~ster undergoes thermolysis at the high temperatures used accompanied by the libe-ration of benzoic acid, leaving the distillates with acid contents, reducing yield and giving rise to considerable teclmical difficul-ties through the accumulation of sublima-tes in the apparatus used.
Accordingly, it has not higherto been possible to use the methylbenzoate obtained in considerable quantities as a commer-cial se~ondary product for the production of light-coloured trans-esterification products.
Accordingtothe present invention, there is provided a process for the preparation of dipropylene glycol dibenzoate, which eomprises transesterifying methylbenzoate with dipropylene glycol in the presence o~ an aluminium alkoxide and/or an aluminium-sili-con alkoxide as a catalyst at a temperature above 150C.
Surprisingly, it has been found that the process of the invention can be used for the preparation of light-coloured dipro-pylene glycol dibenzoate from impure methylbenzoate containing atleast 80~ by weight of methylbenzoate, for example that obtained as a secondary produet in the manufacture of dimethyl terephthala-te from P-xylene and/or methyl-~-tolate as deseribed above, for instance, in aecordance with German ~atent No. 1,041,945 of May 27, 1959 to Chemisehe Werke Witten. The compounds bolling at lower temperatures than dipropylene glyeol dibenzoate are distilled, off, preferably in Yacuo, on eompletion of the liberation of methanol, and the product of transesterification~ cooled to below 150C, is, if neeessary, ozonised to improved its colour and optionally refined in a known manner, The alkoxy groups of the aluminium alkoxides and the alu-minium-silieon alkoxides (the latter of which eontain the group ,.~ ' AlOSi in the nucleus) are identical or different and preferably contain from 1 to 4 carbon atoms. ~xample,~, of such catalysts aie Al-ethylate, Al-n-propylate, Al-sec-butylate and (C2H50-)3SiOAl (-0-sec C4Hg)2.
Transesterification is preferably effected under an inert atmosphere. The inert atmosphere is established by displa-cing the air with gases contai.ni.ng little or no oxygen, such as nitrogen, helium or, optio.nally, hydrogen.
'rhe methyl benzoate is preferably used in a quantity of at least 2 mol~ based on its methylbenzoate conte.nt in the case of ~
impure methylbenzoate, per mol of dipropylene glycol. A slight ,.
excess of up to 25 mol % of methyl benzoate can be useful i.n rapid- ~:
. ly completing the reaotio.n.
If impure methyl benzoate containing less than 80~ by weight of methylbenæoate is to be used, it may be e~riched to at least 80% by weight by simplé distillation.
The concentration o~ catalyst should not exceed 0.8%.
Preferably, amounts of from 0.02 to 0.5%, more preferably from 0.05 to 0.2%, based on the sum of the weights of methylbenzoate and di-propylene glycol, are used. `~
Whe.n the transesterification mixtures are heated, sm~
quantities of low-boiling compounds and water i.nitially distil off.
~he liberation of methanol begins at a vessel temperature of around 150C. During transesterificatio.n, the reactio.n temperature rises steadily up to æound 270C. ~ra~sesterification is best c æ ried out in an inert gas, for example nitrogen. -When the catalysts used in accordance with the inventio~
are employed and impure methyl.benzoate is used, the reactive impu-rities i.n the impure methylbenzoate (which impurities otherwise readily change into deep-coloured products duri.ng transesterifica-tio.n as can be seen from '~able 1) surprisingly remain substantiallY
unchanged, which accounts for the light colour of the transesteri-ficatio.n products. ~y virtue of the considerable differe.nce in the boilin~ points of the impurities and the dipropylene ~lycol dibenzoate, the impurities can readily be removed by distilla-tion, preferably in vacuo, o.n completion of transesterificatio.n.
If an excess of methyl be.nzoate has been used, it is also distil-led off. ~he methylbenzoate-co.ntaining distillate can be used in accordance with the inventio.n in a subsequent batch without in any way adversely affecting the colour quality of the end product. I
Removal of the low-boiling co.nstituents by di~tillation leaves light-coloured dipropyleLe glycol dibenzoate If desired, the co-lour can be further lightened by treatment with an ozone-contai.n-ing gas stream, in complete contrast-to the aforeme.ntioned disco- ~
very that the deep colour of the esters produced with conventio.nal L
catalysts is.not significantly impro~ed by treatment with oxidisi.ng agents. . I
If the methylbenzoate used contains small quantities of 1.
free acids, the end product has corresponding acid .numbers. In such a case, it is possible to carry out a simple de-acidifying refiDing operatio.n of the kind.normally applied in the production of plasticisers, for example by treatme.nt with aqueo.us alkal~e - so.lutions. ~inally, small quantities of readily volatile substan-ce~ can be removed by passing air or steam through the product.
. Dipropylene glycol dibe.nzoate is a high-grade, quick-gelling plasticiser for polymers, for example for polyvinyl chlori-de.
~he process according to the invention will now be bet-ter illustrated with refere.nce to the following non-restrictive ~xamples.
2144 parts by weight of dipropylene glycol (t6 mols) and 5227 parts by weight of commercial-grade methylbenzoate with a `, content of 93.6% by weight (36 mols of pure ester) were heated in -- 5 -- .
~ 45636 the presence of 7.4 parts by weight oP aluminium-sec.-butylate as Catalyst (0.1% by weight, based on the total sum of the startlng materials) i.n a 10-litre flask equipped with an electrical heater, a stirrer, a fractionating column co.ntaining glass Raschig ri.ngs and a nitrogen inlet. Readily volatile compounds and water ini- ..
tially distilled off from the mixture at temperatures in the reac-tion flask of up to 160C. ~he liberation of methanol began at 160C. The temperature of the flask rose steadily to 240C over a period of 5 hours, after which the liberation of methanol was over.
The methanol-containing distillate had a methanol content of 95%, .
as determined by gas chromatography. The balance consisted of im-purities in the commercial-~rade methylbe.nzoate used as starti.ng material. ~ow-boiling constituents and the excess of methylbenzoa-te were subsequently distilled off o.n a ~acuum of 20 Torr after cooling to temperatures of 200C. ~he dipropylene glycol dibenzoa-te, obtained in a yield of 98~o of the theoretical yield based o.n the dipropylene glycol used, had an acid number of 1.6, a hydroly-sis .number of 326.5 (calculated 328) and an iodine colour number of 10. After cooling to 150C, the product was ozonised for 30 miDutes using a Type S2 ozoniser supplied by Argentox, Hamburg, Germany, having an output of 1.5 g of 03 per hour at 12 KV/90 W.
After ozonisation, the iodine colour number wa~ 3, and, after aqueous-alkaline refining, was 2. The end product had an acid ~um-ber of 0.3 and a hydrolysis.number of ~29.5.
EXA~P~E 2 ~ he same procedure as in Example 1, was carried out, ex-cept that 5818 parts by weight (40 mols of pure ester) of commer-cial-grade methylbenzoate (methylbe.nzoate conte.nt 93.6% by weight) f were used instead of 522~ part~ by weight. Under otherwise the sa-me co.nditions, transesterification was complete after 4 hours.
The procedure of Example 1, was repeated using the cata-.
- 6 - ` I
~45636 lysts given in Table 2. The reaction times and iodine colour numbers of the products are given in the Table, '~able 2 . .____ Catalyst Quantity Reaction Iodi~e colour - (~ by weight) time number of the end _ _ product Al-ethylate O.05 5,5 hours 1 - 2 Al-ethylate 0.1 . 4 " 1 - 2 Al-ethylate O.2 3.5 " 1 - 2 Al-n-propylate 0.1 4.5 " 1 - 2 Al-i-propylate 0.1 4 " 1 - 2 .
1ate ¦ 0 1 ¦ 5 .
' - . I
- 7 - ~
Dimethyl terephthalate can be produced commercially by catalytically oxidizing _-xylene and methyl-_-tolate with air, by esterifying the products of oxidation with methanol, and by separating the methyl esters obtained. The esters (mainly methyl-_-tolate, dimethyl terephthalate and methyl esters of other mono-functional and polyfunctional acids) are separated from one another by distillation or recrystallisation or by a combination of these two processes. Dimethyl terephthalate is recovered, valuable intermediate products are recycled, and secondary products are - removed. Some of the secondary products consist of impure methyl-benzoate containing a number of compounds with substantially the ~same boilingpoint as methylbenzoate. Unless these compounds are removed beforehand, for example by pretreatment under oxidising conditions in accordance with Applicant's German Auslegeschrift No. 1,927,554 of May 17, 1973, pure methylbenzoate cannot be obtained, even with considerable technical outlay on distillation.
The impure methylbenzoate obtained in industrial plants for the ; 20 manufacture of dimethyl terephthalate generally contains more than 80% of pure methylbenzoate.
Attempts to transesterify such impure methylbenzoate with dipropylene glycol (also known as ~,~'-di-hydroxy-di-_-propyl ether) in the presence of conventional transesterification cata-lysts have shown that some of these catalysts, for example anti-mony -trioxide and boron trioxide, are unexpectedly totally inactive whilst others, for example sodium methylate, catalyse the reaction to a very limited extent only. This is indicative of the formation of inhibiting substances from the impurities in the methylbenzoate.
Although a number of other transesterification catalysts, such as tetrabutyl titanate, zinc compounds and magnesium compounds, are sufficiently active, the esters obtained are brown to brown-black in colour with iodine colour numbers of up ~ - 1 - ~
to t50. In many cases, the es-ters are so dark brown to black in colour that their iodine colour numbers cannot be mea~ured. A few examples are set out in Table 1, which shows the iodine colour numbers o~ the transesterifiaation products of commercial grade methylbenzoate and dipropylene glycol, measured in identical standard batches and under comparable conditions using different catalysts. The examples are selected in such a way that products with substantially the same degree of transesterification, charac-terised by hydroxyl numbers in the range from 10 to 30, were ob-tianed.
Table 1 . . . . . . .
Catalyst Quantity of Transesteri- OH- iodine catalyst fication ti- number colour ~`
me (hours) number .
Sodium methylate 0.2 11 24100 Magnesium acetate 0.2 5 3080 Magnesium methylate 0.2 3 19130 Zinc stearate 0.2 7 13100 Zinc dust 0.2 3 1830 Dibutyl tin ~ilaurate0.2 4 1770 Tin (IV) butylate 0.2 4 black-brown Titanium silicon 0.2 4 black_brown alkoxide lycerol titanate 0.2 8 1780 etrabutyl titanate 0.2 2760 etrabutyl titanate 0.1 4 3060 Tetrabutyl titanate 0.5 20 70 The deep colour of the esters cannot be lightened to any appreciable extent by bleaches such a~ active carbon or fuller's i~45636 earths. Similarly, oxidising agents, such as hydrogen peroxide or ozone, do not have any significant effect. ~istillation in vacuo produces deep-yellow distillates. r~he eolour quality is inadequate for commercial application. ln addidition, the ~ster undergoes thermolysis at the high temperatures used accompanied by the libe-ration of benzoic acid, leaving the distillates with acid contents, reducing yield and giving rise to considerable teclmical difficul-ties through the accumulation of sublima-tes in the apparatus used.
Accordingly, it has not higherto been possible to use the methylbenzoate obtained in considerable quantities as a commer-cial se~ondary product for the production of light-coloured trans-esterification products.
Accordingtothe present invention, there is provided a process for the preparation of dipropylene glycol dibenzoate, which eomprises transesterifying methylbenzoate with dipropylene glycol in the presence o~ an aluminium alkoxide and/or an aluminium-sili-con alkoxide as a catalyst at a temperature above 150C.
Surprisingly, it has been found that the process of the invention can be used for the preparation of light-coloured dipro-pylene glycol dibenzoate from impure methylbenzoate containing atleast 80~ by weight of methylbenzoate, for example that obtained as a secondary produet in the manufacture of dimethyl terephthala-te from P-xylene and/or methyl-~-tolate as deseribed above, for instance, in aecordance with German ~atent No. 1,041,945 of May 27, 1959 to Chemisehe Werke Witten. The compounds bolling at lower temperatures than dipropylene glyeol dibenzoate are distilled, off, preferably in Yacuo, on eompletion of the liberation of methanol, and the product of transesterification~ cooled to below 150C, is, if neeessary, ozonised to improved its colour and optionally refined in a known manner, The alkoxy groups of the aluminium alkoxides and the alu-minium-silieon alkoxides (the latter of which eontain the group ,.~ ' AlOSi in the nucleus) are identical or different and preferably contain from 1 to 4 carbon atoms. ~xample,~, of such catalysts aie Al-ethylate, Al-n-propylate, Al-sec-butylate and (C2H50-)3SiOAl (-0-sec C4Hg)2.
Transesterification is preferably effected under an inert atmosphere. The inert atmosphere is established by displa-cing the air with gases contai.ni.ng little or no oxygen, such as nitrogen, helium or, optio.nally, hydrogen.
'rhe methyl benzoate is preferably used in a quantity of at least 2 mol~ based on its methylbenzoate conte.nt in the case of ~
impure methylbenzoate, per mol of dipropylene glycol. A slight ,.
excess of up to 25 mol % of methyl benzoate can be useful i.n rapid- ~:
. ly completing the reaotio.n.
If impure methyl benzoate containing less than 80~ by weight of methylbenæoate is to be used, it may be e~riched to at least 80% by weight by simplé distillation.
The concentration o~ catalyst should not exceed 0.8%.
Preferably, amounts of from 0.02 to 0.5%, more preferably from 0.05 to 0.2%, based on the sum of the weights of methylbenzoate and di-propylene glycol, are used. `~
Whe.n the transesterification mixtures are heated, sm~
quantities of low-boiling compounds and water i.nitially distil off.
~he liberation of methanol begins at a vessel temperature of around 150C. During transesterificatio.n, the reactio.n temperature rises steadily up to æound 270C. ~ra~sesterification is best c æ ried out in an inert gas, for example nitrogen. -When the catalysts used in accordance with the inventio~
are employed and impure methyl.benzoate is used, the reactive impu-rities i.n the impure methylbenzoate (which impurities otherwise readily change into deep-coloured products duri.ng transesterifica-tio.n as can be seen from '~able 1) surprisingly remain substantiallY
unchanged, which accounts for the light colour of the transesteri-ficatio.n products. ~y virtue of the considerable differe.nce in the boilin~ points of the impurities and the dipropylene ~lycol dibenzoate, the impurities can readily be removed by distilla-tion, preferably in vacuo, o.n completion of transesterificatio.n.
If an excess of methyl be.nzoate has been used, it is also distil-led off. ~he methylbenzoate-co.ntaining distillate can be used in accordance with the inventio.n in a subsequent batch without in any way adversely affecting the colour quality of the end product. I
Removal of the low-boiling co.nstituents by di~tillation leaves light-coloured dipropyleLe glycol dibenzoate If desired, the co-lour can be further lightened by treatment with an ozone-contai.n-ing gas stream, in complete contrast-to the aforeme.ntioned disco- ~
very that the deep colour of the esters produced with conventio.nal L
catalysts is.not significantly impro~ed by treatment with oxidisi.ng agents. . I
If the methylbenzoate used contains small quantities of 1.
free acids, the end product has corresponding acid .numbers. In such a case, it is possible to carry out a simple de-acidifying refiDing operatio.n of the kind.normally applied in the production of plasticisers, for example by treatme.nt with aqueo.us alkal~e - so.lutions. ~inally, small quantities of readily volatile substan-ce~ can be removed by passing air or steam through the product.
. Dipropylene glycol dibe.nzoate is a high-grade, quick-gelling plasticiser for polymers, for example for polyvinyl chlori-de.
~he process according to the invention will now be bet-ter illustrated with refere.nce to the following non-restrictive ~xamples.
2144 parts by weight of dipropylene glycol (t6 mols) and 5227 parts by weight of commercial-grade methylbenzoate with a `, content of 93.6% by weight (36 mols of pure ester) were heated in -- 5 -- .
~ 45636 the presence of 7.4 parts by weight oP aluminium-sec.-butylate as Catalyst (0.1% by weight, based on the total sum of the startlng materials) i.n a 10-litre flask equipped with an electrical heater, a stirrer, a fractionating column co.ntaining glass Raschig ri.ngs and a nitrogen inlet. Readily volatile compounds and water ini- ..
tially distilled off from the mixture at temperatures in the reac-tion flask of up to 160C. ~he liberation of methanol began at 160C. The temperature of the flask rose steadily to 240C over a period of 5 hours, after which the liberation of methanol was over.
The methanol-containing distillate had a methanol content of 95%, .
as determined by gas chromatography. The balance consisted of im-purities in the commercial-~rade methylbe.nzoate used as starti.ng material. ~ow-boiling constituents and the excess of methylbenzoa-te were subsequently distilled off o.n a ~acuum of 20 Torr after cooling to temperatures of 200C. ~he dipropylene glycol dibenzoa-te, obtained in a yield of 98~o of the theoretical yield based o.n the dipropylene glycol used, had an acid number of 1.6, a hydroly-sis .number of 326.5 (calculated 328) and an iodine colour number of 10. After cooling to 150C, the product was ozonised for 30 miDutes using a Type S2 ozoniser supplied by Argentox, Hamburg, Germany, having an output of 1.5 g of 03 per hour at 12 KV/90 W.
After ozonisation, the iodine colour number wa~ 3, and, after aqueous-alkaline refining, was 2. The end product had an acid ~um-ber of 0.3 and a hydrolysis.number of ~29.5.
EXA~P~E 2 ~ he same procedure as in Example 1, was carried out, ex-cept that 5818 parts by weight (40 mols of pure ester) of commer-cial-grade methylbenzoate (methylbe.nzoate conte.nt 93.6% by weight) f were used instead of 522~ part~ by weight. Under otherwise the sa-me co.nditions, transesterification was complete after 4 hours.
The procedure of Example 1, was repeated using the cata-.
- 6 - ` I
~45636 lysts given in Table 2. The reaction times and iodine colour numbers of the products are given in the Table, '~able 2 . .____ Catalyst Quantity Reaction Iodi~e colour - (~ by weight) time number of the end _ _ product Al-ethylate O.05 5,5 hours 1 - 2 Al-ethylate 0.1 . 4 " 1 - 2 Al-ethylate O.2 3.5 " 1 - 2 Al-n-propylate 0.1 4.5 " 1 - 2 Al-i-propylate 0.1 4 " 1 - 2 .
1ate ¦ 0 1 ¦ 5 .
' - . I
- 7 - ~
Claims (17)
1. A process for the preparation of dipropylene glycol dibenzoate, which comprises transesterifying methylbenzoate with dipropylene glycol, at a temperature above 150°C and in the pre-sence of an aluminium alkoxide or an aluminium-silicon alkoxide, or both, as catalyst.
2. Process according to claim 1, wherein the catalyst is present in an amount of up to 0.8% by weight, based on the total weight of methylbenzoate and dipropylene glycol.
3. Process according to claim 2, wherein the catalyst is present in an amount of from 0.05 to 0.2% by weight, based on the total weight of methylbenzoate and dipropylene glycol.
4. Process according to claim 1, wherein the transeste-rification is effected in the presence of an aluminium alkoxide or an aluminium-silicon alkoxide or both, which contain identical or different alkoxy groups having from 1 to 4 carbon atoms.
5. Process according to claim 4, wherein the catalyst used is aluminium ethylate, aluminium n-propylate or aluminium sec-butylate.
6. Process according to claim 4, wherein the catalyst used is a compound having the formula:
(C2H5O)3 SiOAl (O-sec.C4H9)2.
(C2H5O)3 SiOAl (O-sec.C4H9)2.
7. Process according to claim4, wherein the catalyst used is aluminiumethylate, aluminium n-propylate or aluminium sec-butylate, alone or with a compound having the formula:
(C2H5O)3 SiOAl (O-sec. C4H9)2.
(C2H5O)3 SiOAl (O-sec. C4H9)2.
8. Process according to claim 1, wherein transesterifi-cation is effected under an inert atmosphere.
9. Process according to claim 8, wherein the inert atmosphere is nitrogen, helium or hydrogen.
10. Process according to claim 9, wherein the inert atmosphere is nitrogen.
11. Process according to claim 1, wherein methylbenzoa-te is used in a quantity of at least 2 mols per mol of dipropy-lene glycol.
12. Process according to claim 1, wherein use is made of impure methylbenzoate containing at least 80% by weight of pure methylbenzoate and the transesterification is effected until libe-ration of methanol is complete, the product obtained being subject-ed to distillation to remove the compounds having a boiling point lower than that of dipropylene glycol.
13. Process according to claim 9, wherein the impure methylbenzoate is a product obtained by catalytically oxidising p-xylene and/or methyl-p-tolate with air, by esterifying the product with methanol and by separating the resulting methyl esters.
14. Process according to claims 12 or 13, wherein dis-tillation is effected in vacuo.
15. Process according to claims 1, 12 or 13, which com-prises the further step of subjecting the dipropylene glycol diben-zoate obtained to ozonisation.
16. Process according to claims 1, 12 or 13, which com-prises the further step of subjecting the dipropylene glycol diben-zoate obtained to a de-acidifying refining treatment.
17. Process according to claims 1, 12 or 13, which com-prises the further steps of subjecting the dipropylene glycol di-benzoate obtained to an ozonisation and then to a de-acidifying re-fining treatment.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19732346560 DE2346560A1 (en) | 1973-09-15 | 1973-09-15 | METHOD FOR PRODUCING LIGHT COLORED DIPROPYLENE GLYCOL DIBENZOATE |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1045636A true CA1045636A (en) | 1979-01-02 |
Family
ID=5892694
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA209,353A Expired CA1045636A (en) | 1973-09-15 | 1974-09-13 | Process for the production of dipropylene glycol dibenzoate |
Country Status (18)
| Country | Link |
|---|---|
| JP (1) | JPS5053343A (en) |
| AR (1) | AR199755A1 (en) |
| AU (1) | AU7092074A (en) |
| BE (1) | BE819881A (en) |
| CA (1) | CA1045636A (en) |
| DD (1) | DD113524A5 (en) |
| DE (1) | DE2346560A1 (en) |
| ES (1) | ES430048A1 (en) |
| FR (1) | FR2243929B1 (en) |
| GB (1) | GB1428099A (en) |
| IT (1) | IT1019272B (en) |
| NL (1) | NL7412189A (en) |
| PL (1) | PL95926B1 (en) |
| RO (1) | RO63506A (en) |
| SE (1) | SE7407626L (en) |
| SU (1) | SU583740A3 (en) |
| TR (1) | TR18156A (en) |
| ZA (1) | ZA745845B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102009048774A1 (en) * | 2009-10-08 | 2011-04-28 | Oxea Deutschland Gmbh | Process for the color lightening of polyol esters |
| DE102010027458A1 (en) * | 2010-07-17 | 2012-01-19 | Oxea Gmbh | Process for the post-treatment of polyol esters |
-
1973
- 1973-09-15 DE DE19732346560 patent/DE2346560A1/en active Pending
-
1974
- 1974-06-04 TR TR18156A patent/TR18156A/en unknown
- 1974-06-10 SE SE7407626A patent/SE7407626L/xx unknown
- 1974-07-05 AU AU70920/74A patent/AU7092074A/en not_active Expired
- 1974-07-25 AR AR254894A patent/AR199755A1/en active
- 1974-09-09 SU SU7402057770A patent/SU583740A3/en active
- 1974-09-11 GB GB3970674A patent/GB1428099A/en not_active Expired
- 1974-09-12 DD DD181062A patent/DD113524A5/xx unknown
- 1974-09-12 FR FR7430947A patent/FR2243929B1/fr not_active Expired
- 1974-09-13 JP JP49105941A patent/JPS5053343A/ja active Pending
- 1974-09-13 IT IT53016/74A patent/IT1019272B/en active
- 1974-09-13 BE BE148490A patent/BE819881A/en unknown
- 1974-09-13 RO RO7400079987A patent/RO63506A/en unknown
- 1974-09-13 NL NL7412189A patent/NL7412189A/en not_active Application Discontinuation
- 1974-09-13 PL PL1974174092A patent/PL95926B1/en unknown
- 1974-09-13 ZA ZA00745845A patent/ZA745845B/en unknown
- 1974-09-13 CA CA209,353A patent/CA1045636A/en not_active Expired
- 1974-09-14 ES ES430048A patent/ES430048A1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| TR18156A (en) | 1976-10-11 |
| FR2243929B1 (en) | 1978-03-31 |
| FR2243929A1 (en) | 1975-04-11 |
| SE7407626L (en) | 1975-03-17 |
| NL7412189A (en) | 1975-03-18 |
| ZA745845B (en) | 1975-11-26 |
| GB1428099A (en) | 1976-03-17 |
| ES430048A1 (en) | 1976-10-01 |
| AR199755A1 (en) | 1974-09-23 |
| DE2346560A1 (en) | 1975-04-03 |
| IT1019272B (en) | 1977-11-10 |
| JPS5053343A (en) | 1975-05-12 |
| SU583740A3 (en) | 1977-12-05 |
| PL95926B1 (en) | 1977-11-30 |
| DD113524A5 (en) | 1975-06-12 |
| RO63506A (en) | 1978-08-15 |
| BE819881A (en) | 1974-12-31 |
| AU7092074A (en) | 1976-01-08 |
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