Method for preparing chloroester from γ-butyrolactone and its application

Abstract

The invention provides a method for preparing chloroester from γ-butyrolactone and its application, and relates to the technical field of organic synthesis, comprising the following steps: (a) acylation reaction of γ-butyrolactone and methyl acetate mixed solution in the presence of sodium methoxide to obtain acetobutyrolactone sodium salt; (b) chlorine is passed through and acetobutyrolactone sodium salt is added to water for chlorination reaction to obtain chloroester. The invention solves the technical problems of cumbersome acetobutyrolactone process, high yield loss, large raw material consumption, and high energy consumption caused by distillation and rectification in the prior art, and achieves the technical effects of directly synthesizing chloroester from acetobutyrolactone sodium salt, shortening the synthesis steps, reducing chlorine consumption, saving raw materials and avoiding yield loss.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, in particular to a method for preparing chloroester from gamma-butyrolactone and application thereof. Background Art

[0002] In the prior art, the acetyl butyrolactone process is to use solid sodium methoxide or metallic sodium as a catalyst, and γ-butyrolactone and methyl acetate as the main raw materials are acylated in a third-party inert solvent (toluene or xylene) under normal pressure conditions. After the acylation is completed, the solvent is first distilled to remove the solvent, and then neutralized with aqueous phosphoric acid or aqueous sulfuric acid, and finally extracted with a solvent (toluene or xylene), the extract is concentrated, and then vacuum distilled to obtain pure acetyl butyrolactone; the process operation is relatively cumbersome, and there is a certain yield loss in the extraction, and the energy consumption of the distillation of the solvent and the distillation of acetyl butyrolactone is also high; at the same time, the acetyl butyrolactone sodium salt is completely neutralized and extracted, resulting in a large consumption of neutralized sulfuric acid, and a large amount of by-product sodium sulfate aqueous solution needs to be evaporated and discharged, the energy consumption is high, and the cost of sodium sulfate outsourcing is also high. In addition, the acetyl butyrolactone obtained by distillation needs to use baking soda in the subsequent synthesis of chloroesters, and the consumption of subsequent synthetic raw materials is also high; at the same time, chloroesters will produce a large amount of carbon dioxide during the synthesis process, which is easy to carry chlorine gas to escape, resulting in an increase in the consumption of chlorine gas.

[0003] In view of this, the present invention is proposed. Summary of the invention

[0004] One of the purposes of the present invention is to provide a method for preparing chloroester from gamma-butyrolactone, which can shorten the process synthesis steps, completely eliminate the yield loss in the neutralization, extraction and distillation processes, reduce steam energy consumption, and at the same time reduce the raw material consumption of the synthesized chloroester, and effectively reduce the chlorine consumption.

[0005] The second object of the present invention is to provide an application of a method for preparing chloroester from γ-butyrolactone, which can achieve outstanding application effects.

[0006] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0007] In the first aspect, a method for preparing chloroester from γ-butyrolactone comprises the following steps:

[0008] (a) acylation reaction of a mixture of γ-butyrolactone and methyl acetate in the presence of sodium methoxide to obtain acetylbutyrolactone sodium salt;

[0009] (b) adding the sodium salt of acetylbutyrolactone into water while passing chlorine gas to carry out chlorination reaction to obtain the chloroester.

[0010] Furthermore, the temperature of the acylation reaction is 80-90° C., and the time of the acylation reaction is 3-5 hours.

[0011] Furthermore, after the acylation reaction, the process further comprises cooling the material to below 0°C.

[0012] Furthermore, the material cooled to below 0°C is subjected to solid-liquid separation to obtain the acetylbutyrolactone sodium salt.

[0013] Furthermore, the solid-liquid separation method includes filtration.

[0014] Furthermore, after the filtration, the process further comprises a step of washing the product with methyl acetate.

[0015] Furthermore, the temperature of the chlorination reaction is 5-10°C.

[0016] Furthermore, the pH condition of the chlorination reaction is 3.5-5.

[0017] Furthermore, the added acetyl butyrolactone sodium salt is a dry product of acetyl butyrolactone sodium salt.

[0018] A second aspect is an application of any of the methods described above in chemical production.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects:

[0020] The method for preparing chloroester from gamma-butyrolactone provided by the present invention directly synthesizes chloroester by extracting acetylbutyrolactone sodium salt through an acetylbutyrolactone synthesis process, which can not only shorten the process synthesis steps and completely eliminate the yield loss in the neutralization, extraction and rectification processes, but also reduce the amount of acid used for neutralization and the steam energy consumption in the distillation, rectification, evaporation of salt water and salt removal, etc., and in the subsequent process of directly synthesizing chloroester from acetylbutyrolactone sodium salt, it is not necessary to add sodium bicarbonate, thereby reducing the consumption of reaction raw materials, and no large amount of carbon dioxide is produced during chlorination, so the carrying of chlorine by carbon dioxide in the chlorination process can be effectively avoided, thereby effectively reducing the consumption of chlorine.

[0021] The application of the method for preparing chloroester from gamma-butyrolactone provided by the present invention can achieve outstanding application effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 A schematic diagram of a reaction for synthesizing chloroester from γ-butyrolactone is provided in accordance with one embodiment of the present invention. DETAILED DESCRIPTION

[0024] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] According to a first aspect of the present invention, there is provided a method for preparing a chloroester from γ-butyrolactone, comprising the following steps:

[0026] (a) acylation reaction of a mixture of γ-butyrolactone and methyl acetate in the presence of sodium methoxide to obtain acetylbutyrolactone sodium salt;

[0027] (b) While passing chlorine gas, sodium acetobutyrolactone is added to water to carry out chlorination reaction to obtain chloroester.

[0028] The method for preparing chloroester from gamma-butyrolactone provided by the present invention directly synthesizes chloroester by extracting acetylbutyrolactone sodium salt through an acetylbutyrolactone synthesis process, which can not only shorten the process synthesis steps and completely eliminate the yield loss in the neutralization, extraction and rectification processes, but also reduce the amount of acid used for neutralization and the steam energy consumption in the distillation, rectification, evaporation of salt water and salt removal, etc., and in the subsequent process of directly synthesizing chloroester from acetylbutyrolactone sodium salt, it is not necessary to add sodium bicarbonate, thereby reducing the consumption of reaction raw materials, and no large amount of carbon dioxide is produced during chlorination, so the carrying of chlorine by carbon dioxide in the chlorination process can be effectively avoided, thereby effectively reducing the consumption of chlorine.

[0029] In a preferred embodiment, the temperature of the acylation reaction can be 80-90°C, and typical but non-limiting temperatures are, for example, 80°C, 82°C, 84°C, 86°C, 88°C, and 90°C; the time of the acylation reaction can be 3-5 hours, and typical but non-limiting times are, for example, 3 hours, 4 hours, and 5 hours.

[0030] The acylation reaction and its time of the present invention are more conducive to further improving the acylation reaction effect of gamma-butyrolactone and methyl acetate, making the acylation reaction more complete.

[0031] In a preferred embodiment, the present invention further comprises a step of cooling the material to below 0°C after the acylation reaction.

[0032] In the present invention, the material cooled to below 0°C can be separated into solid and liquid to obtain acetyl butyrolactone sodium salt; wherein the solid-liquid separation method includes but is not limited to filtration, and acetyl butyrolactone sodium salt can be preferably separated by centrifugal filtration, which is not only simple and easy to operate, but also more conducive to further improving the yield of acetyl butyrolactone sodium salt.

[0033] After the acylation reaction is completed, the material in the autoclave can be cooled to below 0°C using chilled water, and then the material is removed from the autoclave. The removed material is then centrifuged in a centrifuge to filter out acetyl butyrolactone sodium salt.

[0034] In a preferred embodiment, the filtered acetobutyrolactone sodium salt can be washed with methyl acetate (for example, the product can be washed twice with methyl acetate, but not limited thereto), which can effectively remove impurities, improve product purity, and is more conducive to improving the chloroester synthesis effect of the subsequent chlorination reaction.

[0035] In a preferred embodiment, the temperature of the chlorination reaction can be 5-10°C, and typical but non-limiting temperatures are, for example, 5°C, 6°C, 7°C, 8°C, 9°C, and 10°C, which are more conducive to further improving the effect of synthesizing chloroesters by chlorination reaction and making the chlorination reaction more complete.

[0036] In a preferred embodiment, the pH condition of the chlorination reaction can be 3.5-5, and its typical but non-limiting pH conditions are, for example, 3.5, 4, 4.5, and 5, which are more conducive to further improving the effect of synthesizing chloroesters by the chlorination reaction and making the chlorination reaction more complete.

[0037] In a preferred embodiment, during the chlorination reaction, the added acetyl butyrolactone sodium salt can be a dry product of acetyl butyrolactone sodium salt, which is more conducive to further improving the effect of synthesizing chloroesters by the chlorination reaction, and is more conducive to further improving the reaction yield and product purity.

[0038] A typical method for synthesizing chloroesters from γ-butyrolactone is shown in Figure 1 , including the following steps:

[0039] (a) Acylation: solid sodium methoxide is added to a high-pressure reactor, and a mixture of γ-butyrolactone and methyl acetate (the mixture is mixed uniformly in advance) is added using a pressure balance tank, and the material is heated to 80-90° C. under stirring, and the temperature is kept for 3-5 hours to carry out the acylation reaction;

[0040] Cooling and filtering sodium salt: After the insulation is completed, the material in the autoclave is cooled to below 0°C using chilled water, and then the material is removed from the autoclave, and then acetyl butyrolactone sodium salt is centrifuged and filtered out by a centrifuge. The obtained acetyl butyrolactone sodium salt is washed twice with methyl acetate;

[0041] Drying the sodium salt; drying the washed acetobutyrolactone sodium salt under negative pressure to obtain a dry product of acetobutyrolactone sodium salt;

[0042] (b) Chlorination: first add water into the chlorination kettle, then control the temperature to 5-10°C under stirring, while passing chlorine gas, add the above-obtained acetobutyrolactone sodium salt dry product, and monitor the pH value in the kettle online to 3.5-5;

[0043] After the chlorine is passed, the temperature is kept high, and then the chlorine is removed by vacuum. The obtained material is allowed to stand for more than 3 hours, and the lower oil phase is separated to obtain chloroester.

[0044] It can be seen that the method for preparing chloroester from γ-butyrolactone provided by the present invention directly cools down and filters to extract acetylbutyrolactone sodium salt after acylation is completed, and the obtained acetylbutyrolactone sodium salt can be directly used for synthesizing chloroester after washing and drying with a solvent (methyl acetate), which effectively shortens the synthesis steps, reduces the yield loss and energy consumption in the neutralization, extraction and distillation processes of acetylbutyrolactone, and also reduces the sodium bicarbonate consumption and chlorine consumption in the chloroester synthesis process.

[0045] According to a second aspect of the present invention, there is provided an application of any of the above methods in chemical production.

[0046] The application of the method for preparing chloroester from gamma-butyrolactone provided by the present invention can achieve outstanding application effects.

[0047] The present invention is further described below by way of examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or directly purchased from the market.

[0048] Example 1

[0049] A method for preparing chloroester from gamma-butyrolactone comprises the following steps:

[0050] (a) Acylation: First, add 115 kg of solid sodium methoxide into an autoclave, then use a pressure balance tank to balance and add a mixture of 135 kg of γ-butyrolactone and 350 kg of methyl acetate (mixed in advance), raise the temperature of the materials to 80-90° C. under stirring, and keep the temperature for 3-5 hours to carry out the acylation reaction. The pressure in the autoclave is 0.2 MPa;

[0051] Cooling and filtering sodium salt: After the insulation is completed, the material in the autoclave is cooled to below 0°C using chilled water, and then the material is removed from the autoclave, and acetyl butyrolactone sodium salt is centrifuged and filtered out using a centrifuge. The obtained acetyl butyrolactone sodium salt is washed twice using 50 kg of methyl acetate;

[0052] Sodium salt drying; the washed acetobutyrolactone sodium salt is dried under negative pressure to obtain 231.5 kg of acetobutyrolactone sodium salt dry product, with a sodium butyrolactone content of 95% (equivalent to 187.6 kg of pure acetobutyrolactone by conversion, with a butyrolactone yield of 93.4%);

[0053] (b) Chlorination: First, add 250 kg of water into the chlorination kettle, then control the temperature at 5-10° C. under stirring, while passing chlorine gas, add the above-obtained acetobutyrolactone sodium salt dry product, and monitor the pH value in the kettle online at 3.5-5. The amount of chlorine passed is about 120 kg;

[0054] After the chlorine is passed, the temperature is kept for 30 minutes, and the chlorine is removed by vacuum for 1 hour. The resulting material is allowed to stand for more than 3 hours, and 235.6 kg (content 98%) of chlorinated ester in the lower oil phase is separated, and the chlorination yield is 97%.

[0055] The product chloroester obtained in this example is 235.6 kg, with a content of 98%; the combined yield of the two steps from γ-butyrolactone to chloroester is 90.59%.

[0056] In this embodiment, water is added to the chlorination kettle as a base, chlorine gas is passed, and acetobutyrolactone sodium salt dry product is added, and the pH value in the chlorination kettle is controlled to be 3.5-5. The chlorinated ester content obtained by this process is 98%, the chlorination yield is 97%, and the combined yield of γ-butyrolactone to chlorinated ester is 90.6%, which shows that the yield is relatively high; the process of this embodiment effectively reduces and avoids the damage to acetobutyrolactone caused by the strong alkalinity during the dissolution process of acetobutyrolactone sodium salt, and effectively reduces the consumption of raw and auxiliary materials, and also reduces energy consumption.

[0057] Example 2

[0058] A method for preparing chloroester from gamma-butyrolactone comprises the following steps:

[0059] (a) Acylation: First, add 115 kg of solid sodium methoxide into an autoclave, and then use a pressure balance tank to balance and add a mixture of 135 kg of γ-butyrolactone and 350 kg of methyl acetate (mixed in advance), and heat the materials to 80-90° C. under stirring, and keep the temperature for 3-5 hours to carry out acylation reaction. The pressure in the autoclave is 0.2 MPa;

[0060] Cooling and filtering sodium salt: After the insulation is completed, the material in the autoclave is cooled to below 0°C using chilled water, and then the material is removed from the autoclave, and acetyl butyrolactone sodium salt is centrifuged and filtered out using a centrifuge. The obtained acetyl butyrolactone sodium salt is washed twice using 50 kg of methyl acetate;

[0061] The sodium salt is dried; the washed acetobutyrolactone sodium salt is dried under negative pressure to obtain 230.5 kg of acetobutyrolactone sodium salt dry product, with a sodium butyrolactone content of 95% (equivalent to 186.9 kg of pure acetobutyrolactone by conversion, with a butyrolactone yield of 93%);

[0062] (b) Chlorination: The obtained acetylbutyrolactone sodium salt dry product was dissolved in 250kg water, transferred to a dropping tank, and then 50kg of water was added to the chlorination kettle as a base. Under stirring and temperature control at 5-10°C, chlorine was introduced while acetylbutyrolactone sodium salt aqueous solution was added dropwise. The pH value in the kettle was monitored at 3.5-5 by an online pH meter, and the chlorine flow rate was about 120kg;

[0063] After the chlorine is passed, the temperature is kept for 30 minutes, and the chlorine is removed by vacuum for 1 hour. The resulting material is allowed to stand for more than 3 hours, and 232.5 kg (content 97%) of chlorinated ester in the lower oil phase is separated, and the chlorination yield is 95%.

[0064] The product chloroester obtained in this example is 232.5 kg, with a content of 97%; the combined yield of the two steps from γ-butyrolactone to chloroester is 88.35%.

[0065] In this embodiment, after acetylbutyrolactone sodium salt is dissolved in water, a small amount of feed water is added as a base, and chlorine gas is passed while acetylbutyrolactone sodium salt aqueous solution is added dropwise to control the pH value in the chlorination reaction kettle to be 3.5-5. The chloroester content obtained by this process is 97%, the chlorination yield is 95%, and the two-step combined yield of γ-butyrolactone to chloroester is 88.35%; the advantage of this process is that the double-dropping process is adopted, which effectively controls the pH value after the dissolution of acetylbutyrolactone sodium salt to be too high, avoids the occurrence of side reactions of chloroesters under alkaline conditions during the chlorination process, and effectively reduces the neutralizing acid consumption of acetylbutyrolactone sodium salt and the sodium bicarbonate consumption in the chlorination process; at the same time, this process does not produce carbon dioxide during the chlorination process, and effectively avoids the escape of chlorine gas carried by carbon dioxide during the chlorination process.

[0066] However, in this embodiment, the alkalinity of acetyl butyrolactone sodium salt after being dissolved in water is too strong, which causes certain damage to acetyl butyrolactone, so the reaction effect obtained is not as good as the process method of Example 1.

[0067] Comparative Example 1

[0068] A method for preparing chloroester from gamma-butyrolactone comprises the following steps:

[0069] (a) Acylation: First, add 288 kg of xylene and 115 kg of solid sodium methoxide into a reaction kettle, heat it to 55° C., quickly add 1 / 3 of a mixture of 135 kg of γ-butyrolactone and 350 kg of methyl acetate (mixed evenly in advance), wait for the reaction material to heat up to 80-90° C. (about 10-15 minutes), start to control the temperature of the reaction material to 80-90° C., slowly add the remaining 2 / 3 (the mixture of γ-butyrolactone and methyl acetate) dropwise, and add dropwise for 3-5 hours. During the dropwise addition, bring the distillation tower back to flow, and distill out the methanol generated by the reaction while dropping. After the dropwise addition is completed, add 100 kg of methyl acetate, and continue to distill to carry out the methanol generated by the reaction;

[0070] Desolventization: Using the distillation tower on the reactor, control the gas temperature at the top of the tower below 55°C under the reflux state of xylene, and distill the methanol and methyl acetate in the flask to concentrate until the bottom temperature of the material reaches about 115-135°C;

[0071] Neutralization: Cool the desolventized material to below 15-20°C, neutralize with 670kg of 15% dilute sulfuric acid to a pH of 6.5-7, and control the neutralization temperature to ≤30°C (the dilute sulfuric acid needs to be pre-cooled to about 5°C in advance);

[0072] Extraction: After neutralization, the neutralized material was allowed to stand for more than 1 hour, and then the upper oil phase (acetyl butyrolactone and xylene mixture) was separated, and the lower sodium sulfate aqueous solution was extracted three times with xylene (30 kg each time);

[0073] Distillation: The extracted oil phase is concentrated and distilled under negative pressure until the solvent is removed, and 200 kg of crude acetobutyrolactone with a content of 90% is obtained (crude product yield 90%);

[0074] Distillation: After vacuum distillation, the crude acetylbutyrolactone product was distilled to obtain 172 kg of pure acetylbutyrolactone with a content of 99.2% (finished product yield 85%);

[0075] (b) Chlorination: 172 kg of pure acetylbutyrolactone obtained by distillation was mixed with 113 kg of sodium bicarbonate and 226 kg of purified water, the temperature was controlled at 5-10°C, and 112 kg of chlorine gas was introduced under stirring;

[0076] After the chlorine is passed, the temperature is kept for 30 minutes, and the chlorine is removed by vacuum for 1 hour. The resulting material is allowed to stand for more than 3 hours, and 216 kg (content 98%) of chlorinated ester in the lower oil phase is separated, and the chlorination yield is 97%.

[0077] The product chloroester obtained in this comparative example is 216 kg, with a content of 98%; the combined yield of the two steps from γ-butyrolactone to chloroester is 82.45%.

[0078] In this comparative example, dilute sulfuric acid is used to neutralize and extract acetyl butyrolactone, and the loss in the extraction process is about 3%, and the loss in the distillation is about 5%. The process flow is relatively complicated and energy-intensive. The obtained acetyl butyrolactone also needs to be added with sodium bicarbonate in the subsequent synthesis of chloroester, and a large amount of carbon dioxide is generated during the chlorination process, resulting in a certain amount of chlorine carryover. The combined yield of the two steps of γ-butyrolactone to chloroester in this process is about 82.45%.

[0079] Comparative Example 2

[0080] A method for preparing chloroester from gamma-butyrolactone comprises the following steps:

[0081] (a) Acylation: First, add 115 kg of solid sodium methoxide into an autoclave, and then use a pressure balance tank to balance and add a mixture of 135 kg of γ-butyrolactone and 350 kg of methyl acetate (mixed in advance), and heat the materials to 80-90° C. under stirring, and keep the temperature for 3-5 hours to carry out acylation reaction. The pressure in the autoclave is 0.2 MPa;

[0082] Cooling and filtering sodium salt: After the insulation is completed, the material in the autoclave is cooled to below 0°C using chilled water, and then the material is removed from the autoclave, and acetyl butyrolactone sodium salt is centrifuged and filtered out using a centrifuge. The obtained acetyl butyrolactone sodium salt is washed twice using 50 kg of methyl acetate;

[0083] The washed sodium acetobutyrolactone sodium salt is dried under negative pressure to obtain 230 kg of dry acetobutyrolactone sodium salt, with a sodium acetobutyrolactone content of 95% (equivalent to 186.5 kg of pure acetobutyrolactone by conversion, with a acetobutyrolactone yield of 92.8%).

[0084] (b) Chlorination: Dissolve the obtained acetobutyrolactone sodium salt dry product in 250 kg of water, then control the temperature at 5-10°C and introduce 120 kg of chlorine gas under stirring;

[0085] After the chlorine is passed, the temperature is kept for 30 minutes, and the chlorine is removed by vacuum for 1 hour. The resulting material is allowed to stand for more than 3 hours, and 212 kg (content 81%) of chlorinated ester in the lower oil phase is separated, and the chlorination yield is 72.57%.

[0086] The product chloroester obtained in this comparative example is 212 kg, with a content of 81%; the combined yield of the two steps from γ-butyrolactone to chloroester is 67.34%.

[0087] In this comparative example, no inert solvent is added to participate in the reaction. Due to the boiling point of methyl acetate, the process is a pressure reaction with a reaction pressure of about 0.2 MPa. After the acylation is completed, the acylation solution is cooled to below 0°C to filter out the acetyl butyrolactone sodium salt, and after rinsing twice with methyl acetate, the acetyl butyrolactone sodium salt with a content of about 95% can be obtained by drying; the acetyl butyrolactone sodium salt is directly dissolved in water, and then chlorine is passed through for chlorination reaction. The obtained chloroester content is 81%, the chlorination yield is only 72.57%, and the two-step combined yield of γ-butyrolactone to chloroester is 67.34%.

[0088] In this comparative example, although acetylbutyrolactone sodium salt with a relatively high purity was obtained, since the pH of acetylbutyrolactone sodium salt when dissolved in water was relatively high, about 11 to 12, the synthesized chloroester under alkaline conditions underwent side reactions, resulting in a low chlorination yield.

[0089] Comparative Example 3

[0090] A method for preparing chloroester from gamma-butyrolactone comprises the following steps:

[0091] (a) Acylation: First, add 115 kg of solid sodium methoxide into an autoclave, and then use a pressure balance tank to balance and add a mixture of 135 kg of γ-butyrolactone and 350 kg of methyl acetate (mixed in advance), and heat the materials to 80-90° C. under stirring, and keep the temperature for 3-5 hours to carry out acylation reaction. The pressure in the autoclave is 0.2 MPa;

[0092] Cooling and filtering sodium salt: After the insulation is completed, the material in the autoclave is cooled to below 0°C using chilled water, and then the material is removed from the autoclave, and acetyl butyrolactone sodium salt is centrifuged and filtered out using a centrifuge. The obtained acetyl butyrolactone sodium salt is washed twice using 50 kg of methyl acetate;

[0093] Sodium salt drying; the washed acetobutyrolactone sodium salt is dried under negative pressure to obtain 231 kg of acetobutyrolactone sodium salt dry product, with a sodium butyrolactone content of 95% (equivalent to 187.3 kg of pure acetobutyrolactone by conversion, with a butyrolactone yield of 93.2%);

[0094] (b) Chlorination: The obtained acetylbutyrolactone sodium salt dry product was dissolved in 250 kg of water, then neutralized with 25% hydrochloric acid to a pH of 7, then 123 kg of sodium bicarbonate was added, and 135 kg of chlorine was introduced under a temperature control of 5 to 10 ° C and stirring;

[0095] After the chlorine is passed, the temperature is kept for 30 minutes, and the chlorine is removed by vacuum for 1 hour. The resulting material is allowed to stand for more than 3 hours, and 235 kg (content 98%) of chlorinated ester in the lower oil phase is separated, and the chlorination yield is 97%.

[0096] The product chloroester obtained in this comparative example is 235 kg, with a content of 98%; the combined yield of the two steps from γ-butyrolactone to chloroester is 90.4%.

[0097] In this comparative example, 25% hydrochloric acid is used to neutralize the pH of the sodium butyrolactone salt aqueous solution to 7, and then sodium bicarbonate is added in the process amount, and chlorine is introduced for chlorination. The two-step combined yield of γ-butyrolactone to chloroester in this process is 90.4%. Compared with comparative example 1, although the loss of acetyl butyrolactone in the extraction process and the distillation process is reduced, the two-step combined yield is increased by 7.95%, but the process still uses neutralizing acid and sodium bicarbonate, and a large amount of carbon dioxide is also generated during the chlorination process, resulting in a certain amount of chlorine carryover.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing chloroester from γ-butyrolactone, characterized in that: The following steps are involved: (a) acylation reaction of a mixture of γ-butyrolactone and methyl acetate in the presence of sodium methoxide to obtain acetylbutyrolactone sodium salt; (b) adding the sodium salt of acetylbutyrolactone into water while passing chlorine gas to carry out chlorination reaction to obtain the chloroester; The temperature of the chlorination reaction is 5 to 10°C; The pH condition of the chlorination reaction is 3.5 to 5; The added acetyl butyrolactone sodium salt is a dry product of acetyl butyrolactone sodium salt.

2. The method according to claim 1, characterized in that The temperature of the acylation reaction is 80-90° C., and the time of the acylation reaction is 3-5 hours.

3. The method according to claim 1 or 2, characterized in that: After the acylation reaction, the method further comprises the step of cooling the material to below 0°C.

4. The method according to claim 3, characterized in that The material cooled to below 0° C. is separated into solid and liquid to obtain the sodium salt of acetylbutyrolactone.

5. The method according to claim 4, characterized in that The solid-liquid separation method includes filtration.

6. The method according to claim 5, characterized in that The filtration step further includes washing the product with methyl acetate.

7. Use of the method according to any one of claims 1 to 6 in chemical production.

Images