CN112608234A - Method for producing high-content ethylene glycol diacetate and coproducing diethylene glycol diacetate - Google Patents
Method for producing high-content ethylene glycol diacetate and coproducing diethylene glycol diacetate Download PDFInfo
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- JTXMVXSTHSMVQF-UHFFFAOYSA-N 2-acetyloxyethyl acetate Chemical compound CC(=O)OCCOC(C)=O JTXMVXSTHSMVQF-UHFFFAOYSA-N 0.000 title claims abstract description 59
- UBPGILLNMDGSDS-UHFFFAOYSA-N diethylene glycol diacetate Chemical compound CC(=O)OCCOCCOC(C)=O UBPGILLNMDGSDS-UHFFFAOYSA-N 0.000 title claims abstract description 43
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 8
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims abstract description 132
- 238000006243 chemical reaction Methods 0.000 claims abstract description 124
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims abstract description 89
- HXDLWJWIAHWIKI-UHFFFAOYSA-N 2-hydroxyethyl acetate Chemical compound CC(=O)OCCO HXDLWJWIAHWIKI-UHFFFAOYSA-N 0.000 claims abstract description 50
- DCKVNWZUADLDEH-UHFFFAOYSA-N sec-butyl acetate Chemical compound CCC(C)OC(C)=O DCKVNWZUADLDEH-UHFFFAOYSA-N 0.000 claims abstract description 35
- 239000000203 mixture Substances 0.000 claims abstract description 32
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 29
- 239000003054 catalyst Substances 0.000 claims abstract description 24
- 238000000034 method Methods 0.000 claims abstract description 12
- 238000005886 esterification reaction Methods 0.000 claims abstract description 6
- 238000002156 mixing Methods 0.000 claims abstract description 6
- 238000003756 stirring Methods 0.000 claims abstract description 6
- 238000010438 heat treatment Methods 0.000 claims abstract description 3
- 239000011541 reaction mixture Substances 0.000 claims abstract description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 37
- 239000000047 product Substances 0.000 claims description 25
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 24
- 238000000066 reactive distillation Methods 0.000 claims description 8
- 239000012043 crude product Substances 0.000 claims description 6
- 239000000376 reactant Substances 0.000 claims description 6
- JOXIMZWYDAKGHI-UHFFFAOYSA-N toluene-4-sulfonic acid Chemical compound CC1=CC=C(S(O)(=O)=O)C=C1 JOXIMZWYDAKGHI-UHFFFAOYSA-N 0.000 claims description 6
- 230000035484 reaction time Effects 0.000 claims description 4
- IYDGMDWEHDFVQI-UHFFFAOYSA-N phosphoric acid;trioxotungsten Chemical compound O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.OP(O)(O)=O IYDGMDWEHDFVQI-UHFFFAOYSA-N 0.000 claims description 3
- 239000002994 raw material Substances 0.000 abstract description 26
- 239000006227 byproduct Substances 0.000 abstract description 7
- 230000015572 biosynthetic process Effects 0.000 abstract description 2
- 150000002894 organic compounds Chemical class 0.000 abstract description 2
- 238000003786 synthesis reaction Methods 0.000 abstract description 2
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 12
- 239000012295 chemical reaction liquid Substances 0.000 description 7
- 238000001816 cooling Methods 0.000 description 7
- 238000006297 dehydration reaction Methods 0.000 description 7
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 6
- OAIYNRAQCIOEBD-UHFFFAOYSA-N butyl acetate;hydrate Chemical compound O.CCCCOC(C)=O OAIYNRAQCIOEBD-UHFFFAOYSA-N 0.000 description 6
- 230000018044 dehydration Effects 0.000 description 6
- 238000004821 distillation Methods 0.000 description 6
- 238000004817 gas chromatography Methods 0.000 description 6
- 239000012535 impurity Substances 0.000 description 5
- 239000002699 waste material Substances 0.000 description 5
- 238000010533 azeotropic distillation Methods 0.000 description 4
- 238000000926 separation method Methods 0.000 description 4
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 3
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 description 2
- 230000000711 cancerogenic effect Effects 0.000 description 2
- 231100000315 carcinogenic Toxicity 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 230000032050 esterification Effects 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 231100000419 toxicity Toxicity 0.000 description 2
- 230000001988 toxicity Effects 0.000 description 2
- 239000008096 xylene Substances 0.000 description 2
- HBVWZQCLPFPSCF-UHFFFAOYSA-N 2-hydroxyethyl 3-oxobutanoate Chemical compound CC(=O)CC(=O)OCCO HBVWZQCLPFPSCF-UHFFFAOYSA-N 0.000 description 1
- 206010007269 Carcinogenicity Diseases 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 231100000260 carcinogenicity Toxicity 0.000 description 1
- 230000007670 carcinogenicity Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
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- 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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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/30—Preparation of carboxylic acid esters by modifying the acid moiety of the ester, such modification not being an introduction of an ester group
- C07C67/31—Preparation of carboxylic acid esters by modifying the acid moiety of the ester, such modification not being an introduction of an ester group by introduction of functional groups containing oxygen only in singly bound form
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
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- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention provides a method for producing high-content ethylene glycol diacetate and simultaneously producing diethylene glycol diacetate as a byproduct, belonging to the field of synthesis of organic compounds. The specific method comprises the following steps: adding acetic acid and ethylene glycol into a reaction kettle, stirring and mixing, then adding a catalyst and a water-carrying agent sec-butyl acetate, stirring again, gradually heating after completely mixing, carrying out a first-stage esterification reaction, and finally reacting to obtain a mixture 1; adjusting the temperature of the obtained reaction mixture 1, carrying out the second stage reaction, and finally separating the mixture 2 to obtain ethylene glycol diacetate and diethylene glycol diacetate. The invention can reduce the content of ethylene glycol monoacetate by controlling the proportion of raw materials and the reaction temperature of different stages, thereby obtaining the high-content ethylene glycol diacetate, and the invention has simple operation and low equipment requirement and can simultaneously obtain the byproduct diethylene glycol diacetate.
Description
Technical Field
The invention belongs to the field of synthesis of organic compounds, and particularly relates to a method for producing high-content ethylene glycol diacetate and coproducing diethylene glycol diacetate.
Background
At present, the content of most of ethylene glycol diacetate produced in China is between 80 and 95 percent, because ethylene glycol monoacetate is often generated in the process of preparing the ethylene glycol diacetate, and the ethylene glycol monoacetate is difficult to separate from a system. It has been reported that ethylene glycol monoacetate and ethylene glycol diacetate produced in the reaction are separated by azeotropic distillation after extraction, but the extractants used therein are benzene, toluene and xylene, all of which have a certain toxicity and benzene is strongly carcinogenic. An azeotropic distillation tower is required to be added while an extracting agent is adopted, the operation is complex, and the practicability is low. The existence of hydroxyl in ethylene glycol monoacetate influences the stability of the product and also influences the product performance. It is desirable to minimize the ethylene glycol diacetate content of ethylene glycol monoacetate. Meanwhile, a small amount of diethylene glycol diacetate is produced during the production of ethylene glycol diacetate, and the diethylene glycol diacetate is basically discharged as waste liquid, thereby causing waste and pollution.
In the prior art, the ethylene glycol monoacetate generated by the reaction can only exist in a product system due to difficult separation. Therefore, most of ethylene glycol diacetate in the market has more ethylene glycol monoacetate, and the stability of the product is seriously influenced by the existence of hydroxyl. It has been reported that ethylene glycol monoacetate and ethylene glycol diacetate produced in the reaction are separated by azeotropic distillation after extraction, but the extractants used therein are benzene, toluene and xylene, all of which have a certain toxicity and benzene is strongly carcinogenic. An azeotropic distillation tower is required to be added while an extracting agent is adopted, the operation is complex, and the practicability is low. And a small amount of diethylene glycol diacetate generated in the reaction is separated in a rectifying tower to be used as impurities and cannot be utilized.
At present, the preparation of ethylene glycol diacetate adopts a direct esterification method, and acetic acid and ethylene glycol are used as raw materials, and the acetic acid is slightly excessive. During the reaction, more ethylene glycol monoacetate and a small amount of diethylene glycol diacetate are produced. For the ethylene glycol monoacetate to enter the product, the diethylene glycol diacetate is separated as an impurity in the rectification column. After ethylene glycol monoacetate enters a product, the water absorption of the product is enhanced due to exposed hydroxyl, the water content is easy to exceed the standard, and the instability exists. And the impurity diethylene glycol diacetate is waste because the amount is small and most of the impurity diethylene glycol diacetate is treated as waste liquid.
In the prior art, the generated ethylene glycol monoacetate is difficult to separate and basically remains in the ethylene glycol diacetate, thereby causing the instability of the product quality. The separation technology reported in the patent has the defects of complex operation and complicated equipment, and is difficult to realize industrially by using an extractant containing strong carcinogenicity. The ethylene glycol monoacetate and the ethylene glycol diacetate are difficult to separate, the separation cost is high, and the process is complicated.
Disclosure of Invention
In view of the above problems in the prior art, the applicant of the present invention provides a method for producing high content of ethylene glycol diacetate with the coproduction of diethylene glycol diacetate. The invention can reduce the content of ethylene glycol monoacetate by controlling the proportion of raw materials and the reaction temperature of different stages, thereby obtaining the high-content ethylene glycol diacetate, and the invention has simple operation and low equipment requirement and can simultaneously obtain the byproduct diethylene glycol diacetate.
The technical scheme of the invention is as follows:
a method for producing high-content ethylene glycol diacetate and coproducing diethylene glycol diacetate comprises the following specific steps:
(1) adding acetic acid and ethylene glycol into a reaction kettle, stirring and mixing, then adding a catalyst and a water-carrying agent sec-butyl acetate, stirring again, gradually heating after completely mixing, carrying out a first-stage esterification reaction, and finally reacting to obtain a mixture 1;
(2) and (2) adjusting the temperature of the reaction mixture 1 obtained in the step (1), carrying out second-stage reaction, and finally separating the mixture 2 to obtain ethylene glycol diacetate and diethylene glycol diacetate.
The reaction temperature in the step (1) is 140 ℃ and 170 ℃, and the reaction time is 4-8 h.
The molar ratio of the ethylene glycol to the acetic acid in the step (1) is 1: 1.1-1.6; the dosage of the catalyst is 0.5-3% of the total mass of the reactants, and the dosage of the sec-butyl acetate reactant is 15-25% of the total mass of the reactants.
In the step (1), the catalyst is at least one of p-toluenesulfonic acid, sulfuric acid or phosphotungstic acid.
And (2) taking out water generated in the step (1) and sec-butyl acetate as a water-carrying agent from the top of the reactive distillation tower in an azeotropic way, returning acetic acid to the reaction kettle for continuous reaction, and reacting to generate ethylene glycol diacetate and ethylene glycol monoacetate.
The reaction temperature in the step (2) is 100-140 ℃, and the reaction time is 2-4 h.
The specific steps for separating the mixture 2 in the step (2) are as follows:
the mixture 2 passes through a light component removal tower, wherein the sec-butyl acetate with the water carrying agent and the residual acetic acid in the reaction are separated from the top of the tower, a crude product is extracted from a side line, and the catalyst enters a tower kettle to be collected; adding the obtained crude product into a finished product rectifying tower, collecting ethylene glycol diacetate at the tower top, and collecting diethylene glycol diacetate at the tower bottom.
The beneficial technical effects of the invention are as follows:
the first stage reaction is that raw materials acetic acid and ethylene glycol are subjected to esterification reaction under the action of acidic catalysts such as catalysts of p-toluenesulfonic acid, sulfuric acid, phosphotungstic acid and the like and water-carrying agent sec-butyl acetate, the reaction temperature is gradually increased to 140-170 ℃, the temperature is at the appropriate esterification temperature, the acetic acid and the ethylene glycol react rapidly, water generated by the reaction and the water-carrying agent sec-butyl acetate are subjected to azeotropy and are extracted from the top of a reaction rectifying tower, the acetic acid returns to a reaction kettle to continue the reaction, and ethylene glycol diacetate and ethylene glycol monoacetate are generated by the reaction. After the reaction is finished, ethylene glycol diacetate and ethylene glycol monoacetate exist in the system. At the moment, the second stage reaction is carried out, the cooling inner coil pipe of the reaction kettle is opened, the reaction temperature is reduced to 100-140 ℃, the ethylene glycol monoacetate generated in large quantity can carry out intermolecular dehydration, and the ethylene glycol monoacetate of two molecules reacts to generate the diethylene glycol diacetate of one molecule. After reacting for 2-4 hours, most of the ethylene glycol monoacetoacetate in the system is reacted into ethylene glycol diacetate, and the content of the residual ethylene glycol monoacetate in the system is less than 1 percent. The reaction liquid passes through a light component removal tower, a water-carrying agent and trace acetic acid are separated from the top of the tower, a crude product is extracted from a side line, and a catalyst enters a tower kettle to be collected. And the crude product enters a finished product rectifying tower from the tower, ethylene glycol diacetate with the content of more than 99 percent is extracted from the tower top, and diethylene glycol diacetate is extracted from the tower bottom.
Therefore, the process designs two different reaction stages, wherein the first stage mainly takes acetic acid and ethylene glycol as raw materials to generate ethylene glycol diacetate and ethylene glycol monoacetate, and the content of the ethylene glycol monoacetate is higher at the moment. By changing the reaction temperature, the reaction temperature is adjusted to a temperature suitable for the dehydration reaction of ethylene glycol monoacetate into diethylene glycol diacetate, and the ethylene glycol monoacetate in the system is consumed, so that the ethylene glycol diacetate with high content and the byproduct diethylene glycol diacetate are obtained.
The invention changes the excess of acetic acid into the excess of glycol in the traditional process for producing glycol diacetate in the aspect of raw material proportion, can effectively improve the conversion rate of acetic acid, reduce the pressure of light component removal, and reduce the recycling and waste of acetic acid. The two-stage reaction is adopted in the simultaneous reaction, and the reaction temperature of the two stages is changed by adding a cooling inner coil in the reaction kettle, so that the optimum reaction temperature for different chemical reactions in the two reaction stages is reached. The impurity ethylene glycol monoacetate generated in the reaction is used as the raw material of the second reaction stage to be consumed, so that the content of the ethylene glycol monoacetate is reduced. The invention reduces the content of the ethylene glycol monoacetate in the reaction, avoids the complicated separation of the ethylene glycol monoacetate, has simple equipment and is easy for industrialized operation. The high-content ethylene glycol diacetate can be obtained, and the diethylene glycol diacetate can be byproduct, so that the high utilization rate of raw materials is realized. Due to the reduction of the content of the ethylene glycol monoacetate, the product content of the ethylene glycol diacetate is more than 99 percent, and the quality and the stability are obviously improved. Because the ethylene glycol monoacetate is not basically present in the product, the stability and the performance of the product are more excellent. Meanwhile, the diethylene glycol diacetate is obtained as a byproduct, so that the resources are utilized to the maximum extent.
Drawings
FIG. 1 is a schematic view of the apparatus of the present invention.
Detailed Description
The present invention will be described in detail with reference to the accompanying drawings and examples.
Example 1
Raw materials of ethylene glycol and acetic acid are added into a 5L reaction kettle, the feeding amount is 1:1.2 according to the mol ratio, 1370g of ethylene glycol and 1590g of acetic acid are added, the feeding amount of concentrated sulfuric acid serving as a catalyst accounts for 1% of the total mass of the raw materials, and 740g of sec-butyl acetate serving as a water-carrying agent accounts for 25% of the total mass of the raw materials. In the first stage reaction, the reaction temperature is rapidly raised to 176 ℃, and the water-carrying agent, the acetic acid and the generated water are subjected to reactive distillation through a distillation tower on the reaction kettle. The residual acetic acid in the reaction is returned to the kettle from the rectifying tower for continuous reaction, water and sec-butyl acetate generate azeotropy and are extracted from the tower top, and the water-carrying agent is forced to flow back from the tower top of the rectifying tower through a pump and is returned to the system for continuous water carrying. The sec-butyl acetate continuously takes away water generated by the reaction, so that the reaction is carried out in the forward direction to generate ethylene glycol diacetate and ethylene glycol monoacetate. And when the reaction is carried out for 8 hours and the top temperature is almost unchanged, opening the cooling coil pipe in the reaction kettle to reduce the temperature of the reaction kettle to 140 ℃ for carrying out the second-stage reaction. At this stage, the ethylene glycol monoacetate undergoes intermolecular dehydration to form diethylene glycol diacetate. After four hours of reaction, the reaction liquid enters a lightness-removing tower from the tower, 665g of sec-butyl acetate is collected from the tower top, a mixture of ethylene glycol diacetate and diethylene glycol diacetate is collected from the side line, and the catalyst sulfuric acid falls into the tower kettle for collection. The mixture enters a finished product rectifying tower from the tower, 875.9g of a mixture of ethylene glycol diacetate and ethylene glycol monoacetate is extracted from the tower top, and the composition of a product at the tower top is analyzed by gas chromatography, wherein the content of the ethylene glycol diacetate is 99.1 percent. 2760g of diethylene glycol diacetate and 96g of ethylene glycol are collected from the bottom of the column.
Example 2
Raw materials of ethylene glycol and acetic acid are added into a 5L reaction kettle, the feeding amount is 1:1.4 according to the mol ratio, 1240g of ethylene glycol and 1680g of acetic acid are added, the feeding amount of concentrated sulfuric acid serving as a catalyst accounts for 1% of the total mass of the raw materials, and 584g of sec-butyl acetate as a water-carrying agent accounts for 20% of the total mass of the raw materials. In the first stage reaction, the reaction temperature is rapidly raised to 158 ℃, and the water carrying agent, the acetic acid and the generated water are subjected to reactive distillation through a distillation tower on the reaction kettle. The residual acetic acid in the reaction is returned to the kettle from the rectifying tower for continuous reaction, water and sec-butyl acetate generate azeotropy and are extracted from the tower top, and the water-carrying agent is forced to flow back from the tower top of the rectifying tower through a pump and is returned to the system for continuous water carrying. The sec-butyl acetate continuously takes away water generated by the reaction, so that the reaction is carried out in the forward direction to generate ethylene glycol diacetate and ethylene glycol monoacetate. And when the reaction is carried out for 8 hours and the top temperature is almost unchanged, opening the cooling coil pipe in the reaction kettle to reduce the temperature of the reaction kettle to 140 ℃ for carrying out the second-stage reaction. At this stage, the ethylene glycol monoacetate undergoes intermolecular dehydration to form diethylene glycol diacetate. After four hours of reaction, the reaction liquid enters a lightness-removing tower from the tower, 555g of sec-butyl acetate is collected from the tower top, the mixture of ethylene glycol diacetate and diethylene glycol diacetate is collected from the side line, and the catalyst sulfuric acid falls into the tower kettle for collection. The mixture enters a finished product rectifying tower from the tower, 1232.9g of a mixture of ethylene glycol diacetate and ethylene glycol monoacetate is extracted from the tower top, and the composition of a product at the tower top is analyzed by gas chromatography, wherein the content of the ethylene glycol diacetate is 99.6 percent. 2130g of diethylene glycol diacetate and 23.9g of ethylene glycol were collected from the bottom of the column.
Example 3
Raw materials of ethylene glycol and acetic acid are added into a 5L reaction kettle, the feeding amount is 1:1.6 according to the mol ratio, 1180g of ethylene glycol and 1830g of acetic acid are added, the feeding amount of concentrated sulfuric acid serving as a catalyst accounts for 1% of the total mass of the raw materials, and the amount of sec-butyl acetate with a water carrier accounts for 452g and 15% of the total mass of the raw materials. In the first stage reaction, the reaction temperature is rapidly raised to 143 ℃, and the water carrying agent, the acetic acid and the generated water are subjected to reactive distillation through a distillation tower on the reaction kettle. The residual acetic acid in the reaction is returned to the kettle from the rectifying tower for continuous reaction, water and sec-butyl acetate generate azeotropy and are extracted from the tower top, and the water-carrying agent is forced to flow back from the tower top of the rectifying tower through a pump and is returned to the system for continuous water carrying. The sec-butyl acetate continuously takes away water generated by the reaction, so that the reaction is carried out in the forward direction to generate ethylene glycol diacetate and ethylene glycol monoacetate. And when the reaction is carried out for 7 hours and the top temperature is almost unchanged, opening the cooling coil pipe in the reaction kettle to reduce the temperature of the reaction kettle to 140 ℃ for carrying out the second-stage reaction. At this stage, the ethylene glycol monoacetate undergoes intermolecular dehydration to form diethylene glycol diacetate. After four hours of reaction, the reaction liquid enters a lightness-removing tower from the tower, 441g of sec-butyl acetate is collected from the tower top, the mixture of ethylene glycol diacetate and diethylene glycol diacetate is collected from the side line, and the catalyst sulfuric acid falls into the tower kettle for collection. The mixture enters a finished product rectifying tower from the tower, 1699.1g of a mixture of ethylene glycol diacetate and ethylene glycol monoacetate is extracted from the tower top, and the composition of a product at the tower top is analyzed by gas chromatography, wherein the content of the ethylene glycol diacetate is 99.7 percent. 1373g of diethylene glycol diacetate and 10.8g of ethylene glycol were recovered from the bottom of the column.
Example 4
Raw materials of ethylene glycol and acetic acid are added into a 5L reaction kettle, the feeding amount is 1:1.4 according to the mol ratio, 1240g of ethylene glycol and 1680g of acetic acid are added, the feeding amount of concentrated sulfuric acid serving as a catalyst accounts for 0.5 percent of the total mass of the raw materials, and the quantity of sec-butyl acetate as a water-carrying agent accounts for 20 percent of the total mass of 584g of the raw materials. In the first stage reaction, the reaction temperature is rapidly raised to 155 ℃, and the water carrying agent, the acetic acid and the generated water are subjected to reactive distillation through a distillation tower on the reaction kettle. The residual acetic acid in the reaction is returned to the kettle from the rectifying tower for continuous reaction, water and sec-butyl acetate generate azeotropy and are extracted from the tower top, and the water-carrying agent is forced to flow back from the tower top of the rectifying tower through a pump and is returned to the system for continuous water carrying. The sec-butyl acetate continuously takes away water generated by the reaction, so that the reaction is carried out in the forward direction to generate ethylene glycol diacetate and ethylene glycol monoacetate. And when the reaction is carried out for 8 hours and the top temperature is almost unchanged, opening the cooling coil pipe in the reaction kettle to reduce the temperature of the reaction kettle to 140 ℃ for carrying out the second-stage reaction. At this stage, the ethylene glycol monoacetate undergoes intermolecular dehydration to form diethylene glycol diacetate. After four hours of reaction, the reaction liquid enters a lightness-removing tower from the tower, 562g of sec-butyl acetate is collected from the tower top, a mixture of ethylene glycol diacetate and diethylene glycol diacetate is collected from the side line, and the catalyst sulfuric acid falls into the tower kettle for collection. The mixture enters a finished product rectifying tower from the tower, 1173.5g of a mixture of ethylene glycol diacetate and ethylene glycol monoacetate is extracted from the tower top, and the composition of a product at the tower top is analyzed by gas chromatography, wherein the content of the ethylene glycol diacetate is 99.7 percent. 2016g of diethylene glycol diacetate and 86.6g of ethylene glycol were collected from the bottom of the column.
Example 5
Raw materials of ethylene glycol and acetic acid are added into a 5L reaction kettle, the feeding amount is 1:1.4 according to the mol ratio, 1240g of ethylene glycol and 1680g of acetic acid are added, the feeding amount of concentrated sulfuric acid serving as a catalyst accounts for 3% of the total mass of the raw materials, and 584g of sec-butyl acetate as a water-carrying agent accounts for 20% of the total mass of the raw materials. In the first stage reaction, the reaction temperature is rapidly raised to 163 ℃, and the water carrying agent, the acetic acid and the generated water are subjected to reactive distillation through a distillation tower on the reaction kettle. The residual acetic acid in the reaction is returned to the kettle from the rectifying tower for continuous reaction, water and sec-butyl acetate generate azeotropy and are extracted from the tower top, and the water-carrying agent is forced to flow back from the tower top of the rectifying tower through a pump and is returned to the system for continuous water carrying. The sec-butyl acetate continuously takes away water generated by the reaction, so that the reaction is carried out in the forward direction to generate ethylene glycol diacetate and ethylene glycol monoacetate. And when the reaction is carried out for 7 hours and the top temperature is almost unchanged, opening the cooling coil pipe in the reaction kettle to reduce the temperature of the reaction kettle to 140 ℃ for carrying out the second-stage reaction. At this stage, the ethylene glycol monoacetate undergoes intermolecular dehydration to form diethylene glycol diacetate. After four hours of reaction, the reaction liquid enters a lightness-removing tower from the tower, 532g of sec-butyl acetate is collected from the tower top, the mixture of ethylene glycol diacetate and diethylene glycol diacetate is collected from the side line, and the catalyst sulfuric acid falls into the tower kettle for collection. The mixture enters a finished product rectifying tower from the tower, 1218.7g of a mixture of ethylene glycol diacetate and ethylene glycol monoacetate is extracted from the tower top, and the composition of a product at the tower top is analyzed by gas chromatography, wherein the content of the ethylene glycol diacetate is 99.7 percent. 2146g of diethylene glycol diacetate and 17.9g of ethylene glycol were recovered at the bottom of the column.
Comparative example 1
Scaling by equal ratio of industrial production examples, raw materials of ethylene glycol and acetic acid are added into a 5L reaction kettle, the feeding amount of the ethylene glycol and the acetic acid is 1:2 according to the molar ratio, 1012g of the ethylene glycol and 1958g of the acetic acid are added, the feeding amount of concentrated sulfuric acid as a catalyst accounts for 1 percent of the total mass of the raw materials, and 742.5g of sec-butyl acetate as a water-carrying agent accounts for 25 percent of the total mass of the raw materials. In the reaction stage, the reaction temperature is slowly raised to 142 ℃, and the water carrying agent, the acetic acid and the generated water are subjected to reactive distillation through a distillation tower on the reaction kettle. The residual acetic acid in the reaction is returned to the kettle from the rectifying tower for continuous reaction, water and sec-butyl acetate generate azeotropy and are extracted from the tower top, and the water-carrying agent is forced to flow back from the tower top of the rectifying tower through a pump and is returned to the system for continuous water carrying. The sec-butyl acetate continuously takes away water generated by the reaction, so that the reaction is carried out in the forward direction to generate ethylene glycol diacetate and ethylene glycol monoacetate. After the reaction is carried out for 11 hours, the top temperature is almost unchanged, the reaction liquid enters a rectifying tower from a reaction kettle, 728g of sec-butyl acetate is collected from the top of the tower, 1892.3g of a mixture of ethylene glycol diacetate and ethylene glycol monoacetate is collected from the side line, and byproducts such as catalyst sulfuric acid, ethylene glycol, diethylene glycol diacetate and the like fall into the tower kettle for collection. The composition of the overhead product was analyzed by gas chromatography, with the ethylene glycol diacetate content being 68.6% and the ethylene glycol monoacetate content being 31.3%.
TABLE 1
| The result of the detection | Conversion of ethylene glycol (%) | Ethylene glycol diacetate content (%) |
| Example 1 | 93.0％ | 99.1％ |
| Example 2 | 98.1％ | 99.6％ |
| Example 3 | 99.1％ | 99.7％ |
| Example 4 | 93.0％ | 99.7％ |
| Example 5 | 99.2％ | 99.7％ |
| Comparative example 1 | 89.1％ | 68.6％ |
Claims (7)
1. A method for producing high-content ethylene glycol diacetate and coproducing diethylene glycol diacetate is characterized by comprising the following specific steps:
(1) adding acetic acid and ethylene glycol into a reaction kettle, stirring and mixing, then adding a catalyst and a water-carrying agent sec-butyl acetate, stirring again, gradually heating after completely mixing, carrying out a first-stage esterification reaction, and finally reacting to obtain a mixture 1;
(2) and (2) adjusting the temperature of the reaction mixture 1 obtained in the step (1), carrying out second-stage reaction, and finally separating the mixture 2 to obtain ethylene glycol diacetate and diethylene glycol diacetate.
2. The method as claimed in claim 1, wherein the reaction temperature in step (1) is 140 ℃ and 170 ℃ and the reaction time is 4-8 h.
3. The method according to claim 1, wherein the molar ratio of the ethylene glycol to the acetic acid in the step (1) is 1: 1.1-1.6; the dosage of the catalyst is 0.5-3% of the total mass of the reactants, and the dosage of the sec-butyl acetate reactant is 15-25% of the total mass of the reactants.
4. The process of claim 1, wherein the catalyst in step (1) is at least one of p-toluenesulfonic acid, sulfuric acid, or phosphotungstic acid.
5. The method as claimed in claim 1, wherein the water produced in the step (1) and the sec-butyl acetate as a water-carrying agent are taken out from the top of the reactive distillation tower in an azeotropic manner, and the acetic acid returns to the reaction kettle to continue the reaction to produce ethylene glycol diacetate and ethylene glycol monoacetate.
6. The method as claimed in claim 1, wherein the reaction temperature in step (2) is 100 ℃ and 140 ℃ and the reaction time is 2-4 h.
7. The method according to claim 1, wherein the mixture 2 in step (2) is separated by the following steps:
the mixture 2 passes through a light component removal tower, wherein the sec-butyl acetate with the water carrying agent and the residual acetic acid in the reaction are separated from the top of the tower, a crude product is extracted from a side line, and the catalyst enters a tower kettle to be collected; adding the obtained crude product into a finished product rectifying tower, collecting ethylene glycol diacetate at the tower top, and collecting diethylene glycol diacetate at the tower bottom.
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