CN101328125A - Method for preparing diethyl carbonate by two-step coupling reaction - Google Patents
Method for preparing diethyl carbonate by two-step coupling reaction Download PDFInfo
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- CN101328125A CN101328125A CNA2008101504109A CN200810150410A CN101328125A CN 101328125 A CN101328125 A CN 101328125A CN A2008101504109 A CNA2008101504109 A CN A2008101504109A CN 200810150410 A CN200810150410 A CN 200810150410A CN 101328125 A CN101328125 A CN 101328125A
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Abstract
The invention discloses a method for preparing diethyl carbonate by two steps of coupling reaction. The method takes carbamide, ethanol and glycol as raw materials and takes an appropriate metal oxide as a catalyst. The catalyst, the carbamide, the ethanol and the glycol are added into a reaction kettle according to a certain proportion; the carbamide and the glycol have alcoholysis reaction at a temperature of between 160 and 180 DEG C and a pressure of between 2.2 and 3.5MPa to produce an intermediate product of ethylene carbonate, and the ethylene carbonate and the ethanol have ester exchange reaction to produce diethyl carbonate. Compared with the sole carbamide alcoholysis method, the two steps of the coupling reaction effectively reduce gibbs free energy of the reaction. The produced target product of diethyl carbonate has a yield coefficient up to 78 percent. Meanwhile, the process does not produce water, thereby bringing convenience to the subsequent separation and the glycol can be recycled.
Description
Technical field
The present invention relates to a kind of preparation method of diethyl carbonate, is raw material by urea, ethanol and ethylene glycol particularly, the method for preparing diethyl carbonate by two-step coupling reaction.
Background technology
Diethyl carbonate (diethyl carbonate) vehicle economy C is a kind of important very low environmental friendliness organic carbonate of toxicity.Its molecular formula is C
5H
10O
3, relative molecular weight 118.13, structural formula is:
Because of containing ethyl, oxyethyl group, carbonyl and carbonyl oxyethyl group in its molecular structure, therefore diethyl carbonate can carry out ethylation reaction, ethoxylation, carbonylation reaction and carbonyl ethoxylation, can also carry out condensation reaction, condensation and cyclization reaction etc. with multiple organic compound.Can react with the compound of the compound that contains active hydrogen group as diethyl carbonate, generate polycarbonate with dibasic alcohol or dihydric phenol reaction as alcohol, phenol, amine, ester.It has the general character of ester, can carry out all reactions of ester, is important organic synthesis intermediate.According to rough Statistics, diethyl carbonate can be produced 35 big classes, hundreds of derived product.Be widely used in agricultural chemicals, medicine intermediate production at present.Along with whole world environment protection and more and more strictness of Occupational safety hygienic requirements, the market of products such as the only just alternative phosgene of diethyl carbonate, methyl-sulfate, methyl chloride, methyl-chloroformate is just considerable.Diethyl carbonate or with the mixture of other compounds, also can be used as the electrolytic solution of lithium ion battery, also can be used as the softening agent of polymer gel electrolyte, be used for increasing electroconductibility and stability.DEC can be used as the oxygenated additive of fuel also because of its higher oxygen level (40.6%) and octane value (RON114, MON 101), to improve the octane value of fuel, reduces the tail gas smoke content, and this is its maximum potential use.
Diethyl carbonate traditional synthetic method mainly comprise phosgenation etc., be raw material because of it adopts phosgene and ethanol, poor stability, " three wastes " amount is big, eliminates gradually.At present, ethanol liquid-phase oxidative carbonylation method is the most a kind of production method of domestic and international application.At first found by Fenton in 1966, and adopted carbon monoxide and pure catalytic gas phase oxidation coupling to make carbonic ether and barkite, after this research day animando of this respect.This kind method Atom economy reach 86.18%, by product is harmless water, meets the principle of Green Chemistry.Can etching apparatus but the employed CuCl catalyzer of this method produces HCl in reaction process, and catalyst life shortens, and has water to generate simultaneously in the product, increased separation purification difficulty, also has hidden peril of explosion.
From the synthetic difficult ester of producing of a kind of ester that is easy to get is method commonly used the organic synthesis, i.e. ester-interchange method.According to the raw material difference that it adopted, its production technique mainly contains transesterify and the carbonate and the alcoholic acid transesterification reaction of ethyl sulfate and carbonate.Though ester-interchange method reaction conditions gentleness, productive rate is higher, and this route expensive raw material price influences the investment and the cost of suitability for industrialized production.
Preparing diethyl carbonate by urea alcoholysis method is a kind of new production technique of developing in recent years, all is in the laboratory study stage both at home and abroad at present.This technology with wide material sources, cheap urea and ethanol as basic raw material, thereby make the purposes of urea expand to the chemical industry field by traditional agriculture field.Reacting used catalyzer mainly comprises: alkali metal compound, transition metal simple substance and compound, organic tin compound and quaternary ammonium compounds etc.Because anhydrous generation in this art production process is purified later separation and is oversimplified.But the required severe reaction conditions of this technology, and yield is lower.This results of laboratory shows: though ZnO is best to the catalytic effect of this reaction, the yield of DEC also only is 14.2%
[11]
Summary of the invention
The objective of the invention is a kind of novel process of attempting developing, promptly solve the low problem of alcoholysis of urea yield and solve the expensive less economical problem of ester-interchange method raw material again for the yield that improves diethyl carbonate.
For reaching above purpose, the present invention adopts following technical scheme to be achieved: a kind of method of preparing diethyl carbonate by two-step coupling reaction comprises the steps:
(1) by urea: ethanol: ethylene glycol is 1: the mol ratio of 3-7: 6-10 adds in the reactor, and adds the catalyzer of described quality of material 5-10%, seals, and described catalyzer is the oxide compound of transition metal or the oxide compound of alkaline-earth metal;
(2) with the nitrogen purging reactor and replace air in the still, and the still internal pressure is prefabricated to 0.6～0.8Mpa, be heated to 160 ℃-180 ℃ of temperature of reaction, and make the still internal pressure remain on 2.2～3.5Mpa;
(3) turn on agitator, stirring velocity are 600～800rpm, react at least 4 hours;
(4) after reaction is finished,, obtain diethyl carbonate, ethylene glycol and excessive unreacted alcohol mixture with the reactor cool to room temperature.Remove solid catalyst by centrifugation, the ethylene glycol that redistillation separates is wherein prepared against secondary response use down, and the liquid that obtains at last mainly contains ethanol and final product diethyl carbonate.
In the aforesaid method, in step (3) reaction process, can regularly carry out the same processing of same step (4) to the about 1ml still liquid of reaction solution sampling, form to determine the yield of product with the gas chromatograph analysis of mixtures then by sampling valve.The oxide compound of described transition metal is a zinc oxide, and titanium oxide is zirconic a kind of, and the oxide compound of alkaline-earth metal is a calcium oxide, magnesian a kind of.
The present invention is a raw material by selecting urea, ethanol for use, adds ethylene glycol simultaneously as couplant.By choosing appropriate catalyst, and processing condition such as suitable reaction temperature, reaction pressure, in a reactor, realized that urea and glycol reaction generate NSC 11801, NSC 11801 is further carried out two reaction couplings that transesterify generates diethyl carbonate and ethylene glycol with ethanol.That is:
NH
2CONH
2+HOCH
2CH
2OH→C
3H
4O
3+2NH
3
C
3H
4O
3+2CH
3CH
2OH→HOCH
2CH
2OH+CO(OCH
2CH
3)
2
Though Gibbs (gibbs) free energy of two reactions under standard state is respectively 4.16kJ/mol and 28.52kJ/mol, the above Gibbs free energy of 418K all becomes negative value.And the Gibbs free energy change of alcoholysis of urea under standard state turns to 31.61kJ/mol.Therefore, two-step approach has more advantage on thermodynamics.By the technological design of two-step approach, make the total Gibbs free energy in reaction coupling back reduce greatly, thereby the diethyl carbonate yield improve a lot with respect to the Gibbs free energy of urea alcoholysis single reaction, can reach 78%.The ethylene glycol that participates in coupling reaction in addition consumes in first reaction, generates second reaction again, and therefore, it can be recycled, and has embodied better economic.Simultaneously, the ethylene glycol boiling point is 198 ℃, differs greatly for 126 ℃ with the boiling point of diethyl carbonate, thereby makes later separation more convenient.
In sum, the used reaction raw materials of the present invention is cheap and easy to get; Coupling reaction has more advantage from thermodynamics analysis than alcoholysis of urea; Later separation is convenient, and couplant ethylene glycol can be recycled.
Embodiment
The present invention is described in further detail below in conjunction with drawings and Examples.
Referring to Fig. 1, realize that the device of the inventive method comprises autoclave 1, nitrogengas cylinder 2, nitrogen charge valve 3, mass flow rate controller 4, agitator 5, temperature and stirring velocity controller 6, sampling valve 7, thermopair 8.
The inventive method may further comprise the steps, and with urea, ethanol, the ethylene glycol of certain mol proportion, and in a certain amount of catalyzer adding reactor 1, seals then.Utilize the nitrogen purging reactor and replace the interior air of still, and first pressing in the still is prefabricated to 0.6～0.8Mpa.After being heated to required temperature of reaction, the still internal pressure remains on 2.2～3.5Mpa, be higher than decide alcoholic acid saturated vapor pressure under the temperature of reaction, guarantee to be reflected under the liquid phase to carry out.And while turn on agitator 5, stirring velocity is 600～800rpm.In reaction process, regularly take out about 1ml still liquid by sampling valve 7, isolate wherein contained solid catalyst by centrifuge separator, after weighing, distills the clarified liq that obtains, and the liquid that steams mainly contains ethanol and diethyl carbonate.Because the boiling point of these two kinds of liquid in system is minimum.With gas chromatograph the liquid that steams is analyzed then.Gas chromatograph is the GC102 that Shanghai analytical instrument factory produces, adopt the TCD thermal conductance to detect, chromatogram column length 4m, in fill carrier (Gaschropack) 54, column temperature is 195 ℃, the vaporizer temperature is 210 ℃, pure hydrogen is adopted in carrier gas, carrier gas flux is 60ml/min, and sample size is 10ul, adopts the external standard method analysis.
With 0.25 mole in urea, 0.75 mole of ethanol, 2.5 moles of ethylene glycol, Zinc oxide catalytic 20.45 grams join in the reactor 1, and inflated with nitrogen pressure is to 0.6MPa.Turn on agitator 5 after mixed solution heated to 170 ℃, timing begin reaction, and the pressure in the control reactor is 2.2Mpa.After reaction is finished, with the reactor cool to room temperature, and adopt the interior mixture of gas chromatographic analysis reactor to form to determine the yield of product, reacted 5 hours, the diethyl carbonate yield reaches and is 78% to the maximum.
With 0.25 mole in urea, 0.75 mole of ethanol, 1.5 moles of ethylene glycol, Zinc oxide catalytic 22.75 grams join in the reactor 1, initial nitrogen pressure 0.7MPa, 170 ℃ of temperature of reaction, mixing speed is 700rpm, pressure in the reactor remains on 2.5Mpa, and reacting 4 hours diethyl carbonate yields is 53.7%, and all the other conditions are with embodiment 1.
With 0.25 mole in urea, 1.75 moles of ethanol, 2.1 moles of ethylene glycol, zirconia catalyst 20.95g joins in the reactor, initial nitrogen pressure 0.8MPa, mixed solution heated to 180 ℃ after, be to react under the effect of 600rpm at mixing speed.Pressure in the reactor remains on 3.0Mpa, reacts after 4 hours, and the yield of DEC is 49.13%, and all the other conditions are with embodiment 1.
Embodiment 4
With 0.25 mole in urea,, 1.25 moles of ethanol, 2.5 moles of ethylene glycol, calcium oxide catalyst 22.75g joins in the reactor, initial nitrogen pressure 0.6MPa, after mixed solution heated to 170 ℃, be to react under the effect of 800rpm at mixing speed, the pressure in the reactor remains on 3.5Mpa, reacts after 4 hours, the yield of DEC is 17.24%, and all the other conditions are with embodiment 1.
With 0.25 mole in urea, 0.75 mole of ethanol, 1.5 moles of ethylene glycol, magnesia catalyst 14.25g, join in the reactor, initial nitrogen pressure 0.8MPa, after mixed solution heated to 160 ℃, be to react under the effect of 600rpm at mixing speed, the pressure in the reactor remains on 2.8Mpa, reacts after 4 hours, the yield of DEC is 13.4%, and all the other conditions are with embodiment 1.
With 0.25 mole in urea, 0.75 mole of ethanol, 2.5 moles of ethylene glycol, titanium oxide catalyst 20.45g, join in the reactor, initial nitrogen pressure 0.6MPa, after mixed solution heated to 170 ℃, be to react under the effect of 600rpm at mixing speed, the pressure in the reactor remains on 2.4Mpa, reacts after 4 hours, the yield of DEC is 11.9%, and all the other conditions are with embodiment 1.
Claims (4)
1, a kind of method of preparing diethyl carbonate by two-step coupling reaction is characterized in that, comprises the steps:
(1) by urea: ethanol: ethylene glycol is 1: the mol ratio of 3-7: 6-10 adds in the reactor, and adds the catalyzer of described quality of material 5-10%, seals, and described catalyzer is the oxide compound of transition metal or the oxide compound of alkaline-earth metal;
(2) with the nitrogen purging reactor and replace air in the still, and first pressing in the still is prefabricated to 0.6～0.8Mpa, be heated to 160 ℃-180 ℃ of temperature of reaction, and make the still internal pressure remain on 2.2～3.5Mpa;
(3) turn on agitator, stirring velocity are 600～800rpm, react at least 4 hours;
(4) after reaction is finished,, obtain diethyl carbonate, ethylene glycol and excessive unreacted alcohol mixture with the reactor cool to room temperature; Remove solid catalyst by centrifugation, the ethylene glycol that redistillation separates is wherein prepared against secondary response use down, and the liquid that obtains at last mainly contains ethanol and final product diethyl carbonate.
2, according to the method for the described preparing diethyl carbonate by two-step coupling reaction of claim 1, it is characterized in that, in step (3) reaction process, can regularly carry out the same processing of reaction product of same step (4) to the about 1ml of reactor liquid sampling, form to determine the yield of product with the gas chromatograph analysis of mixtures then by sampling valve.
According to the method for the described preparing diethyl carbonate by two-step coupling reaction of claim 1, it is characterized in that 3, the oxide compound of described transition metal is a zinc oxide, titanium oxide is zirconic a kind of.
According to the method for the described preparing diethyl carbonate by two-step coupling reaction of claim 1, it is characterized in that 4, the oxide compound of described alkaline-earth metal is a calcium oxide, magnesian a kind of.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2011013880A2 (en) * | 2009-07-31 | 2011-02-03 | Korea Research Institute Of Chemical Technology | Method for preparing dialkyl carbonate |
| CN102304048A (en) * | 2011-04-27 | 2012-01-04 | 铜陵金泰化工实业有限责任公司 | Method and equipment for refining high-purity diethyl carbonate |
| CN101544627B (en) * | 2009-04-28 | 2012-05-09 | 武汉工程大学 | Method for synthesizing cyclic carbonate ester |
| CN102794189A (en) * | 2011-05-23 | 2012-11-28 | 华中科技大学 | Catalyst for synthesizing glycerol carbonate by urea method |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1298696C (en) * | 2004-05-08 | 2007-02-07 | 河北工业大学 | Process for synthesizing methyl carbonate by alcoholysis of urea with aliphatic diol as cyclic agent |
-
2008
- 2008-07-22 CN CN2008101504109A patent/CN101328125B/en not_active Expired - Fee Related
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101544627B (en) * | 2009-04-28 | 2012-05-09 | 武汉工程大学 | Method for synthesizing cyclic carbonate ester |
| WO2011013880A2 (en) * | 2009-07-31 | 2011-02-03 | Korea Research Institute Of Chemical Technology | Method for preparing dialkyl carbonate |
| WO2011013880A3 (en) * | 2009-07-31 | 2011-09-29 | Korea Research Institute Of Chemical Technology | Method for preparing dialkyl carbonate |
| US8629295B2 (en) | 2009-07-31 | 2014-01-14 | Research Institute Of Industrial Science & Technology | Method for preparing dialkyl carbonate |
| CN102304048A (en) * | 2011-04-27 | 2012-01-04 | 铜陵金泰化工实业有限责任公司 | Method and equipment for refining high-purity diethyl carbonate |
| CN102304048B (en) * | 2011-04-27 | 2012-07-04 | 铜陵金泰化工实业有限责任公司 | Method and equipment for refining high-purity diethyl carbonate |
| CN102794189A (en) * | 2011-05-23 | 2012-11-28 | 华中科技大学 | Catalyst for synthesizing glycerol carbonate by urea method |
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