Novel process for preparing alpha-acetyl-gamma-butyrolactone

Abstract

The invention discloses a novel process for preparing alpha-acetyl-gamma-butyrolactone, and belongs to the field of chemical synthesis. The method comprises the following steps: reversely flowing acidic gas into a condensation solution of alpha-acetyl-gamma-butyrolactone, carrying out a neutralization reaction to obtain a neutralization solution, enabling the neutralization solution to pass through a ceramic nanofiltration membrane to obtain a penetrating fluid and a concentrated solution, enabling the penetrating fluid to pass through a methanol rectification device to recover methanol, and evaporating and concentrating residual liquid of a tower kettle to obtain sodium salt, a concentrated solution enters a diethyl methyl ester rectification device to recover unreacted diethyl methyl ester, and a tower kettle high-boiling residue enters an alpha-acetyl-gamma-butyrolactone rectification device to obtain a finished product. Through cross-flow filtration of the ceramic nanofiltration membrane, a neutralization solution flows at a high speed on the surface of a membrane layer on the inner side of the membrane tube under a certain pressure, methanol penetrates through the nanofiltration membrane in the direction perpendicular to the neutralization solution, and diethyl methyl ester and alpha-acetyl-gamma-butyrolactone are intercepted by the membrane, so that the repeated utilization rate is high; and meanwhile, the problems of environmental pollution, difficult separation and energy consumption of subsequent solvent separation caused by the extraction agent are avoided.

Description

Technical Field

[0001] The present invention relates to the field of chemical synthesis, and particularly to a new process for preparing α-acetyl-γ-butyrolactone. Background Art

[0002] α-acetyl-γ-butyrolactone (ABL) is an important organic chemical raw material, an intermediate for preparing chlorophyll, and can also be used in the pharmaceutical industry to manufacture anti-angina drugs. It is a raw material for preparing vitamin B1 and can also be used as an intermediate for synthesizing 3,4-disubstituted pyridine and 5-(β-hydroxyethyl)-4-methylthiazole, and its uses are very extensive.

[0003] At present, there are two methods for industrial production of α-acetyl-γ-butyrolactone: The current mainstream process mainly uses γ-butyrolactone and methyl acetate as raw materials to carry out Claisen condensation in the presence of strong base substances (such as sodium metal, potassium metal, sodium alkoxide, sodium amide, etc.) to prepare α-acetyl-γ-butyrolactone, with a relatively high yield, but sodium metal is required, which poses a safety problem. The second method is to condense and close the ring of ethyl acetoacetate (or methyl acetoacetate) with ethylene oxide to obtain it, with an average yield of nearly 60% and a crude product content of 90%, suffering from the problems of low yield and low product content. The existing synthesis methods are as follows:

[0004] Patent CN115417838A reports a process for preparing α-acetyl-γ-butyrolactone. In the presence of sodium alkoxide, γ-butyrolactone and acetate are subjected to acylation reaction. During the acylation reaction, part of the acetate and the generated alcohol are subjected to azeotropic distillation at the same time. After removing the acetate by vacuum distillation, it is dispersed with an organic solvent and water. Subsequently, dilute sulfuric acid is added to the dispersion for neutralization reaction, and the obtained emulsion is allowed to stand for liquid separation. The aqueous phase is concentrated to obtain by-product sodium sulfate, and the organic phase is subjected to solvent recovery to obtain a crude product of α-acetyl-γ-butyrolactone, and the product yield can reach 95%. However, this process uses toluene as a solvent for extraction and separation, resulting in relatively large pollution.

[0005] Patent CN 114933575 A reports a process for preparing α-acetyl-γ-butyrolactone. Using γ-butyrolactone and acetic anhydride as raw materials, the reaction is catalyzed by a co-catalytic system formed by DMAP and tripropylamine. The product α-acetyl-γ-butyrolactone is obtained by holding the reaction at 95-110 °C for 36 h. This invention uses DMAP as a catalyst and forms a co-catalytic system with tripropylamine. The reaction is mild, and no organic solvent is used for extraction. γ-butyrolactone itself is used as a solvent, which not only saves costs but also avoids environmental pollution caused by introducing solvents. However, this process is cumbersome and the yield is not high.

[0006] Patent CN114195745 A provides a method for preparing α-acetyl-γ-butyrolactone. After γ-butyrolactone, an acylating reagent, a basic reagent, and a benzene reagent are mixed, an acylation reaction is carried out. During the acylation reaction, the acylating reagent, the benzene reagent, and the by-products are azeotroped to remove the by-products. After acid neutralization, α-acetyl-γ-butyrolactone is obtained. Although it solves the technical problems of potential safety hazards in manual feeding caused by solid basic reagents, low yield of acylation reaction, and complex operation of purifying products, the use of benzene reagents causes environmental pollution.

[0007] Patent CN111620844A provides a method for preparing α-acetyl-γ-butyrolactone. An acylation reaction occurs between γ-butyrolactone, CH3COOR1, and R2ONa to obtain a material containing sodium salt of α-acetyl-γ-butyrolactone. In the presence of water, the material containing sodium salt of α-acetyl-γ-butyrolactone is contacted with CO2 gas to carry out a neutralization reaction. However, the process has the problem of high energy consumption in the separation process of the extractant.

[0008] Patent CN111620844A provides a method for continuous production of α-acetyl-γ-butyrolactone. γ-butyrolactone, acetate, and liquid sodium metal are continuously added to a condensation reactor for condensation reaction. After the condensation reaction is completed, the condensation reaction solution is continuously transferred to a neutralization reactor, cooled, and phosphoric acid is added for neutralization. The neutralized solution is transferred by a pump to a phase separator for static phase separation. The aqueous phase is separated, and the oil phase is transferred to a distillation system for atmospheric distillation and vacuum rectification to obtain α-acetyl-γ-butyrolactone. By adopting a continuous production method, hermeticity and automation are realized. Not only does it not require the addition of benzene substances as reaction solvents or extractants, but also the reaction yield is increased, and the product quality is more stable. However, this process generates more phosphorus-containing wastewater.

[0009] Patent CN110804031A provides a method for preparing α-acetyl-γ-butyrolactone. In an inert gas atmosphere, sodium metal is added and heated to the melting point of sodium metal to obtain liquid sodium metal in a molten state. In a second reaction kettle, γ-butyrolactone and acetate are added, and after heating to the reflux of the system, liquid sodium metal in a molten state is added dropwise to the system for condensation reaction. After the dropwise addition of liquid sodium metal is completed, the system is kept refluxing for 1-16 h. After the condensation reaction is completed, it is neutralized with an acid solution, phase-separated, and the organic phase is distilled and vacuum rectified to obtain α-acetyl-γ-butyrolactone. By adopting a solvent-free method and controlling the dropping rate of liquid sodium metal to control the reaction process, it has the characteristics of stable and safe reaction, but there are problems of low product yield and content.

[0010] The disadvantages of the original process are:

[0011] 1) The separation of the existing target product requires the use of toluene or xylene solvents. The extraction organic phase after extraction is separated by vacuum distillation to separate the extractant, with relatively high energy consumption;

[0012] 2) The extractant is not completely separated, and a small amount of the extractant enters the ABL distillation unit, affecting the product purity;

[0013] 3) In the traditional process, an acid solution is used for neutralization, the neutralization yield is not high, and the quality of the product is poor. Summary of the Invention

[0014] The object of the present invention is to provide a new process for preparing α-acetyl-γ-butyrolactone to solve the problems of incomplete separation of the extractant for α-acetyl-γ-butyrolactone, high energy consumption for recovering the extractant, and low neutralization yield.

[0015] The present invention relates to a new process for preparing α-acetyl-γ-butyrolactone. Using the condensation liquid of α-acetyl-γ-butyrolactone as the raw material, an acidic gas is introduced for countercurrent neutralization to obtain a neutralized liquid. The neutralized liquid passes through a ceramic nanofiltration membrane to obtain a permeate and a concentrate. The permeate passes through a methanol distillation unit to recover methanol, and the bottom residue of the tower kettle is concentrated by evaporation to obtain a sodium salt. The concentrate enters a diethyl methyl ester distillation unit to recover the unreacted diethyl methyl ester, and the high-boiling substances at the bottom of the tower enter an α-acetyl-γ-butyrolactone distillation unit to obtain the finished product. This process does not use an extractant compared with the traditional process, and is more energy-saving and environmentally friendly.

[0016] The new process for preparing α-acetyl-γ-butyrolactone described above includes the following steps:

[0017] (1) An acidic gas is introduced into the condensation liquid in a countercurrent manner to obtain a neutralized liquid;

[0018] (2) The neutralized liquid passes through a ceramic nanofiltration membrane to obtain a permeate and a concentrate. The permeate passes through a methanol distillation unit to recover methanol, and the concentrate enters a diethyl methyl ester distillation unit to recover the unreacted diethyl methyl ester, obtaining high-boiling substances at the bottom of the tower;

[0019] (3) The high-boiling substances at the bottom of the tower enter an α-acetyl-γ-butyrolactone distillation unit to obtain the α-acetyl-γ-butyrolactone finished product.

[0020] Further, in step 1), the condensation liquid is the reaction liquid obtained by condensing the substitution liquid of diketene and sodium methoxide with ethylene oxide, and the concentration of α-acetyl-γ-butyrolactone in the condensation liquid is 10% - 30%.

[0021] Further, the acidic gas in step (1) is CO 2 、NO 2 、HCl、SO 2 One or more of them.

[0022] Further, the flow rate of the acidic gas in step (1) is 5 - 10 mL / min.

[0023] Further, the pH value of the neutralizing solution in step (1) is 4.5 - 5.0.

[0024] Further, the material of the ceramic nanofiltration membrane in step (2) is SiO 2 , γ-Al 2 O 3 , TiO 2 , ZrO 2 single-component materials or Y 2 O 3 -ZrO 2 , TiO 2 -ZrO 2 composite materials.

[0025] Further, the relative molecular mass cut-off of the ceramic nanofiltration membrane in step (2) is 100 - 110 Da.

[0026] Further, the vacuum degree when passing through the ceramic nanofiltration membrane in step (2) is 0.1 - 0.2 MPa.

[0027] Further, the type of packing in the methanol rectification device in step (2) is Raschig ring.

[0028] Further, the type of packing in the diethyl methyl ester rectification device in step (2) is Pall ring.

[0029] Further, the vacuum degree in the diethyl methyl ester rectification device in step (2) is controlled at 740 - 760 mmHg, the reflux ratio R is adjusted to 3 - 5, the kettle temperature is 85 - 90 °C, and the distillate distillation temperature is 38 - 40 °C.

[0030] Further, the type of packing in the α-acetyl-γ-butyrolactone rectification device in step (3) is triangular ring.

[0031] Further, the vacuum degree in the α-acetyl-γ-butyrolactone rectification device in step (3) is controlled at 740 - 760 mmHg, the reflux ratio is controlled at 5 - 10, the kettle temperature is 118 °C - 135 °C, and the distillate distillation temperature is 94 - 96 °C.

[0032] Application of the above method of the present invention in the field of α-acetyl-γ-butyrolactone preparation.

[0033] Beneficial effects

[0034] 1. No extractant is used in the separation process. The traditional process uses toluene extractant to extract α-acetyl-γ-butyrolactone, and then removes the extractant by negative pressure distillation to obtain crude α-acetyl-γ-butyrolactone, which has high energy consumption. The present invention replaces the traditional extractant with a ceramic nanofiltration membrane to intercept diethyl methyl ester and α-acetyl-γ-butyrolactone components, with a high reuse rate, while avoiding environmental pollution caused by the extractant, separation difficulties, and energy consumption of subsequent separation solvents.

[0035] 2. Improved product yield and content. The conventional process uses acid solution for neutralization, and the neutralization yield is not high. The present invention uses acid gas countercurrent neutralization, which makes the contact with the condensation liquid more complete, and improves the neutralization yield and product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0037] The condensation liquid of α-acetyl-γ-butyrolactone used in the embodiment is a reaction liquid of diketene, a substitution liquid of sodium methoxide and ethylene oxide for condensation, and the concentration of α-acetyl-γ-butyrolactone in the condensation liquid is 10% to 30%.

[0038] Example 1

[0039] CO 2 The gas is countercurrently passed into a condensation liquid with an α-acetyl-γ-butyrolactone concentration of 10%, and the gas flow rate is controlled to be 5 mL / min to obtain a neutralized solution with a pH value of 4.5. The neutralized solution is passed through a 100Da ceramic nanofiltration membrane device, and the vacuum degree is controlled to be 0.1 MPa to intercept α-acetyl-γ-butyrolactone and diethyl methyl ester to obtain a concentrated solution containing α-acetyl-γ-butyrolactone and diethyl methyl ester and a filtrate containing methanol. The filtrate enters a methanol distillation device to recover methanol, and the filler type is Raschig ring. The concentrated solution enters a diethyl methyl ester distillation device, and the filler type is Ball. The vacuum degree of the diethyl methyl ester distillation device is controlled at 740 mmHg, the reflux ratio R is adjusted to 5, the kettle temperature is 85°C, and the distilled liquid at the top temperature of 38°C is collected as diethyl methyl ester. The high-boiling materials in the bottom of the diethyl methyl ester distillation device enter the α-acetyl-γ-butyrolactone distillation device. The filler type is triangular ring. The vacuum degree of the α-acetyl-γ-butyrolactone distillation process is controlled at 760 mmHg, the reflux ratio is controlled to 5, the kettle temperature is 118°C, and the liquid distilled at the top temperature of 94°C is collected as the finished α-acetyl-γ-butyrolactone product, with a yield of 95.5% and a content of 99.51%.

[0040] Example 2

[0041] No 2The gas is introduced into the condensation liquid with a 20% concentration of α-acetyl-γ-butyrolactone in a countercurrent manner, and the gas flow rate is controlled at 5 mL / min to obtain a neutralized liquid with a pH value of 5.0. The neutralized liquid is passed through a 100 Da ceramic nanofiltration membrane device, and the vacuum degree is controlled at 0.1 MPa to intercept α-acetyl-γ-butyrolactone and diethyl methyl ester, obtaining a concentrated liquid containing α-acetyl-γ-butyrolactone and diethyl methyl ester and a filtrate containing methanol. The filtrate enters a methanol rectification device to recover methanol, and the packing type is Raschig ring. The concentrated liquid enters a diethyl methyl ester rectification device, and the packing type is Pall ring. The vacuum degree of the diethyl methyl ester rectification device is controlled at 760 mmHg, the reflux ratio R is adjusted to 5, the kettle temperature is 85 °C, and the distillate liquid with a top temperature of 40 °C is collected as diethyl methyl ester. The high-boiling substances at the bottom of the diethyl methyl ester rectification device enter an α-acetyl-γ-butyrolactone rectification device, and the packing type is triangular ring. The vacuum degree of the α-acetyl-γ-butyrolactone rectification process is controlled at 760 mmHg, the reflux ratio is controlled at 10, the kettle temperature is 118 °C, and the distillate liquid with a top temperature of 95 °C is collected as the α-acetyl-γ-butyrolactone finished product, with a yield of 96.5% and a content of 99.53%.

[0042] Example 3

[0043] Introduce CO 2 The gas is introduced into the condensation liquid with a 20% concentration of α-acetyl-γ-butyrolactone in a countercurrent manner, and the gas flow rate is controlled at 5 mL / min to obtain a neutralized liquid with a pH value of 5.0. The neutralized liquid is passed through a 100 Da ceramic nanofiltration membrane device, and the vacuum degree is controlled at 0.1 MPa to intercept α-acetyl-γ-butyrolactone and diethyl methyl ester, obtaining a concentrated liquid containing α-acetyl-γ-butyrolactone and diethyl methyl ester and a filtrate containing methanol. The filtrate enters a methanol rectification device to recover methanol, and the packing type is Raschig ring. The concentrated liquid enters a diethyl methyl ester rectification device, and the packing type is Pall ring. The vacuum degree of the diethyl methyl ester rectification device is controlled at 750 mmHg, the reflux ratio R is adjusted to 5, the kettle temperature is 90 °C, and the distillate liquid with a top temperature of 38 °C is collected as diethyl methyl ester. The high-boiling substances at the bottom of the diethyl methyl ester rectification device enter an α-acetyl-γ-butyrolactone rectification device, and the packing type is triangular ring. The vacuum degree of the α-acetyl-γ-butyrolactone rectification process is controlled at 750 mmHg, the reflux ratio is controlled at 8, the kettle temperature is 118 °C, and the distillate liquid with a top temperature of 95 °C is collected as the α-acetyl-γ-butyrolactone finished product, with a yield of 95.5% and a content of 99.61%.

[0044] Example 4

[0045] HCl gas is introduced into the condensation liquid with a concentration of 30% of α-acetyl-γ-butyrolactone in a countercurrent manner, and the gas flow rate is controlled at 5 mL / min to obtain a neutralized liquid with a pH value of 5.0. The neutralized liquid is passed through a 100 Da ceramic nanofiltration membrane device, and the vacuum degree is controlled at 0.1 MPa to intercept α-acetyl-γ-butyrolactone and diethyl methyl ester, obtaining a concentrated liquid containing α-acetyl-γ-butyrolactone and diethyl methyl ester and a filtrate containing methanol. The filtrate enters a methanol rectification device to recover methanol, and the type of packing is Raschig ring. The concentrated liquid enters a diethyl methyl ester rectification device, and the type of packing is Pall ring. The vacuum degree of the diethyl methyl ester rectification device is controlled at 760 mmHg, the reflux ratio R is adjusted to 5, the kettle temperature is 85 °C, and the distillate liquid with a top temperature of 40 °C is collected as diethyl methyl ester. The high-boiling substances at the bottom of the diethyl methyl ester rectification device enter an α-acetyl-γ-butyrolactone rectification device, and the type of packing is triangular ring. The vacuum degree of the α-acetyl-γ-butyrolactone rectification process is controlled at 760 mmHg, the reflux ratio is controlled at 10, the kettle temperature is 118 °C, and the distillate liquid with a top temperature of 95 °C is collected as the finished product of α-acetyl-γ-butyrolactone, with a yield of 96.5% and a content of 99.53%.

[0046] Comparative Example 1

[0047] CO 2 gas is introduced into the condensation liquid with a concentration of 10% of α-acetyl-γ-butyrolactone in a countercurrent manner, and the gas flow rate is controlled at 5 mL / min to obtain a neutralized liquid with a pH value of 4.5. The neutralized liquid is passed through a 100 Da ceramic nanofiltration membrane device, and the vacuum degree is controlled at 0.1 MPa to intercept α-acetyl-γ-butyrolactone and diethyl methyl ester, obtaining a concentrated liquid containing α-acetyl-γ-butyrolactone and diethyl methyl ester and a filtrate containing methanol. The filtrate enters a methanol rectification device to recover methanol, and the type of packing is Raschig ring. The concentrated liquid enters a diethyl methyl ester rectification device, and the type of packing is Pall ring. The vacuum degree of the diethyl methyl ester rectification device is controlled at 500 mmHg, the reflux ratio R is adjusted to 5, the kettle temperature is 85 °C, and the distillate liquid with a top temperature of 40 °C is collected as diethyl methyl ester. The high-boiling substances at the bottom of the diethyl methyl ester rectification device enter an α-acetyl-γ-butyrolactone rectification device, and the type of packing is triangular ring. The vacuum degree of the α-acetyl-γ-butyrolactone rectification process is controlled at 760 mmHg, the reflux ratio is controlled at 5, the kettle temperature is 118 °C, and the distillate liquid with a top temperature of 97 °C is collected as the finished product of α-acetyl-γ-butyrolactone, with a yield of 84.5% and a content of 90.51%.

[0048] Comparative Example 2

[0049] CO 2The gas is introduced into the condensation liquid with a concentration of 20% of α-acetyl-γ-butyrolactone in a countercurrent manner, and the gas flow rate is controlled at 5 mL / min to obtain a neutralized liquid with a pH value of 4.5. The neutralized liquid is passed through a 100 Da ceramic nanofiltration membrane device, and the vacuum degree is controlled at 0.1 MPa to intercept α-acetyl-γ-butyrolactone and diethyl methyl ester, obtaining a concentrated liquid containing α-acetyl-γ-butyrolactone and diethyl methyl ester and a filtrate containing methanol. The filtrate enters a methanol rectification device to recover methanol, and the type of packing is Raschig ring. The concentrated liquid enters a diethyl methyl ester rectification device, and the type of packing is Pall ring. The vacuum degree of the diethyl methyl ester rectification device is controlled at 760 mmHg, the reflux ratio R is adjusted to 5, the kettle temperature is 85 °C, and the distillate liquid with a top temperature of 38 °C is collected as diethyl methyl ester. The high-boiling substances in the kettle of the diethyl methyl ester rectification device enter an α-acetyl-γ-butyrolactone rectification device, and the type of packing is triangular ring. The vacuum degree of the α-acetyl-γ-butyrolactone rectification process is controlled at 500 mmHg, the reflux ratio is controlled at 5, the kettle temperature is 118 °C, and the distillate liquid with a top temperature of 102 °C is collected as the α-acetyl-γ-butyrolactone finished product, with a yield of 80.6% and a content of 82.15%.

[0050] Comparative Example 3

[0051] This comparative example is the comparative example of Example 1, in which only the type of packing in the diethyl methyl ester rectification device is replaced with θ ring, and other steps and parameters remain unchanged. Finally, the yield of the α-acetyl-γ-butyrolactone finished product is 93.11% and the content is 96.23%.

[0052] Comparative Example 4

[0053] This comparative example is the comparative example of Example 1, in which only the type of packing in the α-acetyl-γ-butyrolactone rectification device is replaced with θ ring, and other steps and parameters remain unchanged. Finally, the yield of the α-acetyl-γ-butyrolactone finished product is 91.57% and the content is 92.15%.

[0054] Comparative Example 5

[0055] This comparative example is the comparative example of Example 1, in which only the pH of the neutralized liquid is changed to 3.5, and other steps and parameters remain unchanged. Finally, the yield of the α-acetyl-γ-butyrolactone finished product is 90.23% and the content is 85.39%.

[0056] Comparative Example 6

[0057] This comparative example is the comparative example of Example 1, in which only the molecular weight cut-off of the ceramic nanofiltration membrane is changed to 150 Da, and other steps and parameters remain unchanged. Finally, the yield of the α-acetyl-γ-butyrolactone finished product is 20.89% and the content is 98.39%.

[0058] The above preferred embodiments have disclosed the present invention, but they are not intended to limit the present invention. Any technical solutions obtained by using equivalent substitutions or equivalent changes fall within the protection scope of the present invention.

Claims

1. A new process for preparing α-acetyl-γ-butyrolactone, characterized in that: It includes the following steps: (1) Acid gas is introduced into the condensation liquid in a countercurrent manner to obtain a neutralized liquid; (2) The neutralized liquid passes through a ceramic nanofiltration membrane to obtain a permeate and a concentrate. The permeate passes through a methanol rectification device to recover methanol, and the concentrate enters a diethyl methyl ester rectification device to recover the unreacted diethyl methyl ester, obtaining a bottom high-boiling substance; (3) The bottom high-boiling substance enters an α-acetyl-γ-butyrolactone rectification device to obtain the finished product of α-acetyl-γ-butyrolactone.

2. The new process for preparing α-acetyl-γ-butyrolactone according to claim 1, characterized in that, in step (1), the condensation liquid is a reaction liquid obtained by condensing a substitution liquid of diketene and sodium methoxide with ethylene oxide, and the concentration of α-acetyl-γ-butyrolactone therein is 10% to 30%.

3. The new process for preparing α-acetyl-γ-butyrolactone according to claim 1, characterized in that, In step (1), the acidic gas is CO 2 , NO 2 , HCl, SO 2 or more of them; the flow rate of the acidic gas is 5-10 mL / min.

4. The new process for preparing α-acetyl-γ-butyrolactone according to claim 1, characterized in that, the pH value of the neutralized liquid in step (1) is 4.5 to 5.

0.

5. The new process for preparing α-acetyl-γ-butyrolactone according to claim 1, characterized in that, The material of the ceramic nanofiltration membrane described in step (2) is SiO 2 , γ-Al 2 O 3 , TiO 2 , ZrO 2 single-component materials or Y 2 O 3 -ZrO 2 , TiO 2 -ZrO 2 composite materials.

6. The new process for preparing α-acetyl-γ-butyrolactone according to claim 1, characterized in that, the molecular weight cut-off of the ceramic nanofiltration membrane in step (2) is 100 to 110 Da.

7. The new process for preparing α-acetyl-γ-butyrolactone according to claim 1, characterized in that, in step (2), the vacuum degree in the diethyl methyl ester rectification device is controlled at 740 to 760 mmHg, the reflux ratio R is adjusted to 3 to 5, the bottom temperature is 85 to 90 °C, and the distillate distillation temperature is 38 to 40 °C.

8. The new process for preparing α-acetyl-γ-butyrolactone according to claim 1, characterized in that, in step (3), the vacuum degree in the α-acetyl-γ-butyrolactone rectification device is controlled at 740 to 760 mmHg, the reflux ratio is controlled at 5 to 10, the bottom temperature is 118 °C to 135 °C, and the distillate distillation temperature is 94 to 96 °C.

9. The new process for preparing α-acetyl-γ-butyrolactone according to claim 1, characterized in that, the packing type in the methanol rectification device is Raschig ring; the packing type in the diethyl methyl ester rectification device is Pall ring; the packing type in the α-acetyl-γ-butyrolactone rectification device is triangular ring.

10. Application of the process according to any one of claims 1 to 9 in the field of preparing α-acetyl-γ-butyrolactone.

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