CN109134425B - Method for preparing high-purity ethylene sulfide - Google Patents
Method for preparing high-purity ethylene sulfide Download PDFInfo
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Abstract
The invention provides a method for preparing high-purity ethylene sulfide, which comprises the following steps: (1) firstly, feeding a part of ethylene carbonate preheated to be liquefied according to 0.2-0.7 time of the total feeding amount of the ethylene carbonate, stirring, controlling the temperature to be 40-70 ℃, then adding thiocyanate, and rapidly heating to 75-105 ℃; (2) collecting the ethylene sulfide generated by the reaction by adopting a condensing system in combination with a gas-liquid separator, simultaneously beginning to dropwise add the residual ethylene carbonate with the temperature of 45-85 ℃, controlling the temperature in the dropwise adding process to be 80-110 ℃, continuously heating to 130-140 ℃ after finishing dropwise adding, and ending the reaction until no fraction is distilled out. The method avoids the risk of material flushing, has short reaction time and produces few impurities; the yield of the obtained product of the ethylene sulfide is up to more than 97%, and the gas phase detection purity of the product is up to more than 99%.
Description
Technical Field
The invention relates to the technical field of production of medical intermediates, in particular to a preparation method of high-purity episulfide ethane.
Background
Diethylaminoethanethiol is an important intermediate for synthesizing veterinary drug tiamulin, and many methods for synthesizing diethylaminoethanethiol are reported in the literature, but at present, two main industrial production processes exist: the first is that the diethylaminoethanol is chloridized and then reacts with thiourea to generate S-substituted isothiourea salt, and then the diethylaminoethanethiol is prepared after alkaline hydrolysis by strong base; the second method is that ethylene carbonate reacts with thiocyanate to generate ethylene sulfide, and then diethylamine reacts with ethylene sulfide to generate diethylamino ethanethiol. The first process has high cost, long route, heavy pollution and poor operation condition, and is gradually eliminated; the second process is simple to operate and short in period, and is a mainstream production process at the present stage. However, the second process also has certain problems, such as for the reaction of the first step, the operation mode of slowly raising the temperature has to be adopted in the prior art to avoid the material flushing problem caused by the rapid temperature rise. The slow temperature rise operation leads to the reaction time of the first step to be as long as 6-8 hours, and the generated ethylene sulfide can be retained in the reactor due to the long reaction time to generate polymerization reaction, so that the yield of the obtained ethylene sulfide is low, and the impurities are more. The research of the invention finds that the slow temperature rise is mainly used for controlling the reaction rate, so that the generated ethylene sulfide is not beneficial to fast evaporation and is retained in a reaction system, the ethylene sulfide can generate self-polymerization reaction or generate other impurities under the action of nucleophilic reagents such as thiocyanide and hydroxyl in the reaction system, the yield is influenced when the polymer and other impurities are not evaporated, and the purity of the ethylene sulfide is influenced when the polymer and other impurities are evaporated, so the ethylene sulfide generated by the reaction needs to be separated as fast as possible, and the damage of the ethylene sulfide is reduced. If the temperature rises rapidly, the risk of flushing materials is high, the episulfide is difficult to be condensed and recycled effectively, and safety accidents are easy to happen.
Therefore, there is a need to optimize existing processes for the production of ethylene sulfide.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a novel method for preparing ethylene sulfide. The step-by-step dripping operation adopted by the invention can realize rapid temperature rise in the early stage, avoid the ethylene sulfide from being retained in a tank, and drip at high temperature in the later stage, so that the ethylene sulfide can be rapidly gasified, and can be subjected to gas-liquid separation and condensation to generate fraction, and the fraction can be stably dripped at constant speed to condense at constant speed, so that the prepared ethylene sulfide has high purity and high yield. Thereby providing high-quality production raw materials for synthesizing the diethylaminoethanethiol, correspondingly effectively reducing the generation of impurities and improving the purity of products.
The reaction scheme in the process of the invention is as follows:
wherein A ═ Na+、K+Or NH4 +。
Specifically, the method for preparing the ethylene sulfide comprises the following steps:
(1) stirring the first part to be preheated to liquefied ethylene carbonate, then adding thiocyanate, and rapidly heating to 75-105 ℃;
(2) and collecting fractions generated by the reaction by combining a condensing system with a gas-liquid separator, simultaneously dropwise adding the rest second part of ethylene carbonate which is preheated to be liquefied, continuously heating until no fractions appear after dropwise adding, and finishing the reaction.
Preferably, in step (1) of the process of the present invention, the first portion of ethylene carbonate is 0.2 to 0.7 times, preferably 0.4 to 0.6 times the total charge of ethylene carbonate.
Preferably, in step (1) of the method of the present invention, the temperature is controlled to be between 40 and 70 ℃, preferably between 50 and 55 ℃ during the stirring.
Preferably, in step (1) of the process of the present invention, the thiocyanate is sodium thiocyanate, potassium thiocyanate or ammonium thiocyanate; the molar ratio of the thiocyanate to the ethylene carbonate is 1: 0.8-1.4. .
Preferably, in step (1) of the method of the present invention, the gas-liquid separator is a cyclone separator, a gravity settling separator, a baffling separator, a centrifugal separator, a packing separator, a wire mesh separator, a microfiltration separator or the like, which can achieve gas-liquid separation.
Preferably, in step (2) of the process of the present invention, the temperature of the second portion of ethylene carbonate is 45 to 85 ℃, preferably 65 to 75 ℃.
Preferably, in the step (2) of the method of the present invention, the temperature of the dropping process is controlled to be between 80 ℃ and 110 ℃, preferably between 100 ℃ and 110 ℃.
In step (2) of the method of the present invention, after the second portion of ethylene carbonate is dripped, the temperature is preferably further raised to 130-140 ℃.
In the method, the ethylene carbonate is fed in two steps, and the first feeding is 0.2-0.7 times of the total feeding amount. The inventors of the present application have found experimentally that this operation is on the one hand convenient for stirring, since the other starting material thiocyanate is solid; on the other hand, a part of ethylene carbonate is added firstly, so that bumping and flushing caused by temperature rise can be effectively controlled. When the feeding amount of the first part of ethylene carbonate is too much, the reaction cannot be well controlled after the temperature rise, the material is easy to flush, and the temperature rise cannot be carried out by quickly introducing steam; when the feeding amount of the first part of ethylene carbonate is too small, most of materials are solid after the thiocyanate is added, so that stirring is difficult to promote mass transfer.
For the dropwise adding operation adopted by the invention, the inventor of the invention finds in practical work that if the dropwise adding feeding mode is not adopted, a temperature rising mode of rapid temperature rise cannot be adopted, otherwise the materials are flushed by bumping, and only the reaction rate can be controlled by slow temperature rise. The slow temperature rise is controlled, the reaction rate is not favorable for the generated ethylene sulfide to be quickly evaporated, the ethylene sulfide remained in the reaction system can generate self-polymerization reaction or react with other nucleophilic reagents (such as thiocyanate, hydroxide and the like in the reaction system) to generate impurities, so the generated ethylene sulfide needs to be separated as quickly as possible, and the damage of the ethylene sulfide is reduced. Therefore, the stepwise dripping operation adopted by the invention can realize rapid temperature rise in the early stage, overcomes the prejudice of the prior art, avoids the ethylene sulfide from being retained in the tank, and can ensure that the ethylene sulfide is rapidly generated by dripping at high temperature in the later stage. Then, a mode of combining a condenser with a gas-liquid separator is adopted to transfer the generated ethylene sulfide fraction in time, so that the reaction operation is stable at a constant speed, and the polymerization reaction caused by the fact that the ethylene sulfide is retained in the reactor for a long time can be avoided; meanwhile, the method of the invention also accelerates the reaction process, shortens the production period and reduces the production cost.
In the process of the invention, the rapid temperature increase is limited to the ability to heat the distillate in the shortest amount of time and with the most aggressive heating regime without bumping the batch.
From the synthetic process route, the process reaction of the invention not only produces gaseous ethylene sulfide products, but also generates a large amount of carbon dioxide, the carbon dioxide is not needed, the conventional condensation can not be condensed into liquid, and finally the liquid still escapes from tail gas, so the condensed ethylene sulfide can be entrained, especially the condensed ethylene sulfide liquid is impacted, the gasification of the liquid is carried out by carbon dioxide gas flow, the yield is low, the tail gas treatment cost is increased, the three wastes are increased, and other negative effects are caused. The invention reduces the negative effect brought by carbon dioxide by using a gas-liquid separation means, directly improves the yield, reduces the requirement on a condenser, saves the cost and indirectly reduces the generation of three wastes.
According to the novel preparation method of the episulfide ethane, the episulfide reaction time is only about 2 hours, the episulfide ethane with high yield and high quality can be prepared and used for synthesizing the diethylaminoethanethiol, the two steps are carried out integrally, the total time of the two steps of reaction is shortened to about 3 hours, and the obtained diethylaminoethanethiol has high yield, short time and good product quality. The preparation of the episulfide ethane effectively controls the reaction process by dripping the ethylene carbonate, shortens the reaction time, avoids the risk of flushing materials, reduces the generation of impurities, and ensures that the gas-phase detection purity of the prepared episulfide ethane reaches more than 99 percent. The produced ethylene sulfide can be recovered to the maximum extent by a gas-liquid separation means, the yield is improved, and the yield is over 97 percent. The subsequent synthesis of diethylaminoethanethiol adopts the high-purity episulfide ethane prepared by the method, so that the reaction temperature is increased, the reaction time is shortened, the yield is up to more than 98%, the quality is good, and the purity of gas-phase detection is more than 99%. Meanwhile, the method saves the production cost of artificial water and electricity and the like, and improves the utilization rate of equipment. The production process effectively reduces the discharge of three wastes, improves the production efficiency, reduces the risk of material punching, and is a green and environment-friendly process with low production cost and easy industrial operation.
The process of the invention is suitable for synthesizing the raw material of the ethylene sulfide for preparing the diethylaminoethanethiol, and other similar products can also be applied. The method can be well applied to industrial production in the future, and reactions with similar properties and similar products can also be used for reference.
Drawings
Embodiments of the invention are described in detail below with reference to the attached drawing figures, wherein:
FIG. 1 shows a schematic diagram of an apparatus for producing ethylene sulfide by the process of the present invention; in the figure, the first fraction receiving flask can receive the liquid fraction, and the gas no longer impinges on the received fraction, but enters the secondary condensation system.
Detailed Description
Example 1
Adding 220kg of ethylene carbonate (0.52 time of the total input amount of the ethylene carbonate) into a reaction tank, heating to 55 ℃ for melting, stirring, adding 375kg of sodium thiocyanate, directly heating to 85 ℃ by starting steam, separating and collecting fractions by a coil condenser and a cyclone separator after fractions are obtained, simultaneously dropwise adding 200kg of the remaining ethylene carbonate with the temperature of 75 ℃, and controlling the temperature in the dropwise adding process at 100 ℃. After the ethylene sulfide is dripped, the temperature is continuously raised to 138 ℃, and the reaction is ended until no fraction is distilled out. The chemical reaction and the operation in the step are stable, the duration is 2 hours, 270.8kg of the episulfide ethane is obtained, the purity of the gas phase detection is 99.6 percent, and the yield is 97.5 percent.
Transferring 270.8kg of the ethylene sulfide fraction to a 1000L autoclave, adding 330kg of diethylamine, stirring in a sealed condition, heating to 125 ℃, keeping the pressure at 0.5MPa for 1 hour, and ending the reaction to obtain 590.9kg of diethylaminoethanethiol, wherein the purity is 99.3% by gas phase detection, and the yield is 98.4%.
In the industrial production stage, the two-step charging and condensation combined gas-liquid separation operation of the invention is adopted for the production of the episulfide, thereby not only avoiding the risk of material flushing, but also having high yield and good purity of the episulfide. Meanwhile, the diethylaminoethanethiol is prepared from the episulfide ethane obtained by the method, so that high yield and purity are obtained.
Example 2
This example is a bench test conducted in the laboratory, the main purpose being to test the technical effect of a two-step addition.
200g of ethylene carbonate (0.49 time of the total dosage of the ethylene carbonate) is added into a four-mouth bottle, the mixture is heated to 50 ℃ to melt, stirred, 375g of sodium thiocyanate is added, the oil bath is heated to 95 ℃, 208g of ethylene carbonate with the residual temperature of 65 ℃ is dripped after fraction discharge, and the temperature in the dripping process is controlled at 110 ℃. After the ethylene sulfide is dripped, the temperature is continuously raised to 136 ℃, and the reaction is ended until no fraction is distilled out. The reaction time of the step is 1 hour, 270.1g of the episulfide ethane is obtained, the purity by gas phase detection is 99.3 percent, and the yield is 97.2 percent.
Transferring 270g of the ethylene sulfide fraction to a 1L autoclave, adding 329g of diethylamine, stirring in a sealed condition, heating to 128 ℃, keeping the pressure at 0.4MPa for 1 hour, and finishing the reaction to obtain 590.9g of diethylaminoethanethiol, wherein the purity is 99.4% by gas phase detection, and the yield is 98.7%.
Example 3
This example is a bench test conducted in the laboratory, the main purpose being to verify the reliability of the technical effect of the two-step feeding.
Adding 260g of ethylene carbonate into a four-mouth bottle, heating to 55 ℃ for melting, stirring, adding 443g of potassium thiocyanate, heating in an oil bath to 100 ℃, beginning to dropwise add 160g of the remaining ethylene carbonate with the temperature of 75 ℃ after fraction discharge, and controlling the temperature in the dropwise adding process at 105 ℃. After the dripping of the ethylene sulfide, the temperature is continuously raised to 129 ℃, and the reaction is ended until no fraction is distilled out. The reaction time of the step is 1.2 hours, 267.2g of episulfide ethane is obtained, the purity by gas phase detection is 99.2%, and the yield is 97.5%.
Transferring 267.1g of ethylene sulfide fraction to a 1L autoclave, adding 325g of diethylamine, stirring in a sealed condition, heating to 120 ℃ under the pressure of 0.5MPa, keeping for 1 hour, and ending the reaction to obtain 583.2g of diethylaminoethanethiol, wherein the purity is 99.3% by gas phase detection, and the yield is 98.5%.
Example 4
This example is a bench test conducted in the laboratory, the main purpose being to verify the problems of the "one-shot" operation.
Adding 420g of ethylene carbonate into a four-mouth bottle, heating to 55 ℃ for melting, stirring, adding 443g of potassium thiocyanate, and slowly heating in an oil bath. After the epithioethane fraction comes out, the epithioethane is condensed and collected, and meanwhile, the temperature is slowly increased, so that the situation that the materials are flushed due to quick temperature rise is prevented. Along with the continuous distillation of the ethylene sulfide, the temperature of the reaction system is gradually increased to 129 ℃, and the reaction is finished until no fraction is distilled. The reaction time of the step is 1.5 hours, and the episulfide ethane of 248.1g is obtained, the purity by gas phase detection is 94.0 percent, and the yield is 90.5 percent.
Transferring 248g of the ethylene sulfide fraction to a 1L autoclave, adding 305g of diethylamine, stirring in a sealed condition, heating to 120 ℃ under the pressure of 0.5MPa, keeping the temperature for 1 hour, and ending the reaction to obtain 495.8g of diethylaminoethanethiol, wherein the purity of the gas phase detection is 94.3%, and the yield is 90.2%.
In the gas-mass spectrometry detection of the final product (the compound shown in the formula A), the impurities are mainly a compound shown in the formula (B) to a compound shown in the formula (E), and the structures are as follows:
from a structural point of view, most of the impurities are associated with the polymerization of ethylene sulfide. These enter the second reaction step, new impurities are formed, which affect the purity and yield of the product.
Example 5
This example is a pilot test, in which the effect of gas-liquid separation on the yield of ethylene sulfide was tested without increasing the gas-liquid separation operation.
Adding 11kg of ethylene carbonate (0.52 time of the total feeding amount of the ethylene carbonate) into a reaction tank, heating to 55 ℃ for melting, stirring, adding 18.8kg of sodium thiocyanate, directly heating to 85 ℃ by starting steam, separating and collecting fractions by a coil heat exchanger after the fractions are discharged, simultaneously dropwise adding 10kg of the remaining ethylene carbonate with the temperature of 75 ℃, and controlling the temperature in the dropwise adding process at 100 ℃. After the ethylene sulfide is dripped, the temperature is continuously raised to 135 ℃, and the reaction is ended until no fraction is distilled out. The reaction time was 1.2 hours, 10.8kg of ethylene sulfide was obtained, the purity by gas phase detection was 99.5%, and the yield was 77.5%.
Transferring 10.8kg of the ethylene sulfide fraction to a 50L autoclave, adding 16.5kg of diethylamine, stirring in a sealed condition, heating to 125 ℃, keeping the pressure at 0.5MPa for 1.5 hours, and finishing the reaction to obtain 29.3kg of diethylaminoethanethiol, wherein the purity is 99.3% by gas phase detection, and the yield is 97.8%.
Claims (5)
1. A process for the preparation of high purity ethylene sulfide, said process comprising the steps of:
(1) stirring the first part to be preheated to liquefied ethylene carbonate, then adding thiocyanate, and rapidly heating to 75-105 ℃;
(2) collecting fractions generated by the reaction by adopting a condensing system in combination with a gas-liquid separator, simultaneously dropwise adding the rest second part of ethylene carbonate which is preheated to be liquefied, continuously heating until no fractions appear after the dropwise adding is finished, and finishing the reaction;
in the step (1), the first part of ethylene carbonate accounts for 0.4-0.7 time of the total dosage of the ethylene carbonate;
in the step (1), the temperature is controlled to be 50-55 ℃ in the stirring process;
in the step (2), the temperature of the second part of ethylene carbonate is 65-75 ℃;
in the step (2), the temperature in the dripping process is controlled to be between 100 and 110 ℃;
in the step (2), after the second part of ethylene carbonate is dripped, the temperature is continuously increased to 130-140 ℃.
2. The method of claim 1, wherein in step (1), the first portion of ethylene carbonate is 0.4 to 0.6 times the total dosage of ethylene carbonate.
3. A process according to claim 1, wherein the thiocyanate is sodium thiocyanate, potassium thiocyanate or ammonium thiocyanate.
4. The method according to claim 1, wherein the molar ratio of thiocyanate to ethylene carbonate is 1: 0.8-1.4.
5. The process of claim 1, wherein in step (1), the gas-liquid separator is one or more of a cyclone separator, a gravity separator, a baffled separator, a centrifugal separator, a packed separator, a wire mesh separator, or a microfiltration separator.
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| CN110711537A (en) * | 2019-09-26 | 2020-01-21 | 保定加合精细化工有限公司 | Method for continuously producing ethylene sulfide |
| CN110665449A (en) * | 2019-09-26 | 2020-01-10 | 保定加合精细化工有限公司 | Equipment for continuously producing ethylene sulfide |
| CN113387922A (en) * | 2020-03-11 | 2021-09-14 | 新疆上昵生物科技有限公司 | Preparation process for synthesizing ethylene sulfide by using sodium thiocyanate and ethylene carbonate |
| CN113735819B (en) * | 2020-05-29 | 2024-01-12 | 新疆上昵生物科技有限公司 | Preparation process of ethylene sulfide |
| CN113372248A (en) * | 2021-06-11 | 2021-09-10 | 保定北瑞甾体生物有限公司 | Process for preparing thiols |
| CN114315665A (en) * | 2021-12-16 | 2022-04-12 | 保定加合精细化工有限公司 | Preparation method of 2-diethylaminoethanethiol and application of impurities thereof |
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| JPH01278529A (en) * | 1988-04-30 | 1989-11-08 | Cemedine Co Ltd | Ring-opening of heterocyclic compound and polymerization thereof |
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