阅读说明：本技术 用丙烯腈副产氢氰酸工业化合成2-羟基戊酸甲酯的方法 (Method for industrially synthesizing 2-hydroxy methyl valerate by using acrylonitrile byproduct hydrocyanic acid ) 是由 张善荣 于 2021-01-26 设计创作，主要内容包括：本发明公开了一种用丙烯腈副产氢氰酸工业化合成2-羟基戊酸甲酯的方法,涉及化工技术领域,采用丙烯腈副产氢氰酸作为起始原料,经过合成、水解酯化、中和、分离、精馏等制得2-羟基戊酸甲酯。本发明扩展了丙烯腈副产氢氰酸综合开发利用的途径,使得丙烯腈副产氢氰酸得到更合理高效的利用,提升丙烯腈装置整体的生产运行经济效益。(The invention discloses a method for industrially synthesizing 2-hydroxy methyl valerate from acrylonitrile byproduct hydrocyanic acid, which relates to the technical field of chemical industry. The method expands the way of comprehensively developing and utilizing the acrylonitrile byproduct hydrocyanic acid, so that the acrylonitrile byproduct hydrocyanic acid is utilized more reasonably and efficiently, and the overall production operation economic benefit of an acrylonitrile device is improved.)

1. A method for industrially synthesizing 2-hydroxy methyl valerate by using acrylonitrile byproduct hydrocyanic acid is characterized by comprising the following steps: the method adopts acrylonitrile byproduct hydrocyanic acid as a starting material and comprises the following steps:

(1) preparation of butyraldehyde cyanohydrin:

the proportioning is as follows: hydrocyanic acid, wherein the hydrocyanic acid is n-butyraldehyde =1: 0.01-0.015: 2.3-2.8;

sequentially adding n-butyraldehyde and a catalyst in a proportioning ratio into the synthesis kettle, uniformly stirring, and then adding the mixture into the synthesis kettle

Dropwise adding hydrocyanic acid according to the proportion of ingredients, controlling the reaction temperature not to exceed 10 ℃, preserving the temperature for 15 minutes after the hydrocyanic acid is dropwise added to obtain butyraldehyde cyanohydrin, and transferring the butyraldehyde cyanohydrin into a butyraldehyde cyanohydrin metering tank after metering;

(2) preparation of hydrochloric acid methanol:

the proportioning is as follows: hydrogen chloride, namely absolute methanol =1: 1.8-2.3;

synthesizing hydrochloric acid by falling film absorber cyclic absorption method according to the proportion of hydrogen chloride and anhydrous methanol

Controlling the temperature in the falling film absorber to be-10 ℃ to-11 ℃ when preparing the hydrochloric acid methanol, and transferring the prepared hydrochloric acid methanol into a hydrochloric acid methanol metering tank;

(3) crystallization and salt formation reaction:

the proportioning is as follows: butyraldehyde cyanohydrin, namely hydrochloric acid methanol =1: 0.55-0.85;

transferring the methanol hydrochloride prepared in the step (2) into a salt forming kettle, and dripping the methanol hydrochloride into the salt forming kettle in a stirring and cooling state

Adding the butyraldehyde cyanohydrin prepared in the step (1), controlling the reaction temperature not to exceed 30 ℃ in the dripping process, controlling the temperature in a salifying kettle to be 30-45 ℃ after the dripping is finished, and carrying out heat preservation reaction for 4 hours to obtain an imido ester hydrochloride solution;

(4) hydrolysis esterification reaction:

the proportioning is as follows: the hydrocyanic acid in the step (1) is pure water and methanol =1: 0.24-0.29: 1.45-1.85;

transferring the imino ester hydrochloride solution prepared in the step (3) into a hydrolysis esterification kettle, and stirring the solution

Adding pure water and methanol in a proportioning ratio under the state, heating the materials to 50-60 ℃, and carrying out hydrolysis esterification reaction for 3-5 hours;

(5) and (3) neutralization reaction:

transferring the material subjected to hydrolysis esterification reaction in the step (4) into a neutralization kettle, and introducing ammonia gas and the material

Performing neutralization reaction on hydrogen chloride which does not participate in the reaction to generate ammonium chloride, and controlling the pH value of the neutralized material to be within the range of 5-7;

(6) centrifugal solid-liquid separation:

transferring the material obtained after the neutralization reaction in the step (5) to a centrifugal machine for solid-liquid separation, and separating the material

The liquid centrifugate enters a centrifugal ground groove, and is transferred to a centrifugate storage tank after standing and precipitating;

(7) rectification and separation:

transferring the centrifugate generated in the step (6) into a rectifying tower, and respectively rectifying the front cut fraction and the 2-hydroxyl

And (3) transferring the front fraction to a front fraction separation tower, transferring the 2-hydroxy methyl valerate to a finished product storage tank, and transferring the kettle residual liquid to a kettle residual liquid storage tank.

2. The method for industrially synthesizing methyl 2-hydroxypentanoate from acrylonitrile by-produced hydrocyanic acid according to claim 1, characterized in that: the catalyst in the step (1) is sodium hydroxide or potassium hydroxide or sodium carbonate or sodium methoxide or sodium ethoxide or trimethylamine or triethylamine.

3. The method for industrially synthesizing methyl 2-hydroxypentanoate from acrylonitrile by-produced hydrocyanic acid according to claim 1, characterized in that: and (4) performing centrifugal solid-liquid separation in the step (6) to obtain a solid byproduct ammonium chloride.

4. The method for industrially synthesizing methyl 2-hydroxypentanoate from acrylonitrile by-produced hydrocyanic acid according to claim 1, characterized in that: and (4) transferring the front fraction rectified in the step (7) into a front fraction separation tower to distill and separate methanol and pure water, and transferring into the step (4) to perform hydrolysis esterification reaction for recycling.

Technical Field

The invention relates to the technical field of chemical industry, in particular to a method for industrially synthesizing 2-hydroxy methyl valerate by using acrylonitrile byproduct hydrocyanic acid.

Background

Methyl 2-hydroxypentanoate, formula: C6H12O3, flash point: 76 ℃, density: 1.029, boiling point: 204 ℃.

The 2-hydroxy methyl valerate is a bifunctional compound containing hydroxyl and ester groups, can participate in various reactions to synthesize a plurality of compounds, is a key intermediate for preparing propiconazole, has important application in the industries of medicines, pesticides, fine chemical surfactants, polyester fibers and the like, can be used as a cosmetic additive, and is an organic chemical raw material and an intermediate with wide application.

At present, little information is provided about research and development experiments and development of synthesizing 2-methyl hydroxypentanoate by using acrylonitrile byproduct hydrocyanic acid in China, and information about related industrial production of 2-methyl hydroxypentanoate is not common.

Disclosure of Invention

The invention aims to solve the technical problem of providing a method for industrially synthesizing 2-hydroxy methyl valerate by using acrylonitrile byproduct hydrocyanic acid.

In order to solve the technical problems, the invention provides the following technical scheme: a method for industrially synthesizing 2-hydroxy methyl valerate by using acrylonitrile byproduct hydrocyanic acid adopts the acrylonitrile byproduct hydrocyanic acid as a starting material, and comprises the following steps:

(1) preparation of butyraldehyde cyanohydrin:

the proportioning is as follows: hydrocyanic acid, wherein the hydrocyanic acid is n-butyraldehyde =1: 0.01-0.015: 2.3-2.8;

sequentially adding n-butyraldehyde and a catalyst in a proportioning ratio into a synthesis kettle, uniformly stirring, dropwise adding hydrocyanic acid in the proportioning ratio into the synthesis kettle, controlling the reaction temperature to be not more than 10 ℃, keeping the temperature for 15 minutes after the dropwise adding of the hydrocyanic acid is finished, obtaining butyraldehyde cyanohydrin, and transferring the butyraldehyde cyanohydrin into a butyraldehyde cyanohydrin metering tank after metering;

(2) preparation of hydrochloric acid methanol:

the proportioning is as follows: hydrogen chloride, namely absolute methanol =1: 1.8-2.3;

synthesizing hydrochloric acid methanol by adopting a falling film absorber cyclic absorption method according to the proportion of hydrogen chloride and anhydrous methanol, controlling the temperature in the falling film absorber to be between-10 ℃ and-11 ℃ when preparing the hydrochloric acid methanol, and transferring the prepared hydrochloric acid methanol into a hydrochloric acid methanol metering tank;

(3) crystallization and salt formation reaction:

the proportioning is as follows: butyraldehyde cyanohydrin, namely hydrochloric acid methanol =1: 0.55-0.85;

transferring the hydrochloric acid methanol prepared in the step (2) into a salt forming kettle, dropwise adding the butyraldehyde cyanohydrin prepared in the step (1) in a stirring and cooling state, controlling the reaction temperature not to exceed 30 ℃ in the dropwise adding process, controlling the temperature in the salt forming kettle to be 30-45 ℃ after the dropwise adding is finished, and carrying out heat preservation reaction for 4 hours to obtain an imido ester hydrochloride solution;

(4) hydrolysis esterification reaction:

the proportioning is as follows: hydrocyanic acid, namely pure water, wherein the ratio of methanol is 1: 0.24-0.29: 1.45-1.85;

transferring the imino ester hydrochloride solution prepared in the step (3) into a hydrolysis esterification kettle, adding pure water and methanol in a proportioning ratio under a stirring state, heating the materials to 50-60 ℃, and carrying out hydrolysis esterification reaction for 3-5 hours;

(5) and (3) neutralization reaction:

transferring the material subjected to hydrolysis esterification reaction in the step (4) into a neutralization kettle, introducing ammonia gas and unreacted hydrogen chloride in the material to perform neutralization reaction to generate ammonium chloride, and controlling the pH value of the neutralized material to be within a range of 5-7;

(6) centrifugal solid-liquid separation:

transferring the material neutralized in the step (5) into a centrifugal machine for solid-liquid separation, and allowing liquid centrifugate to enter a centrifuge

A core-ground tank, which is transferred to a centrifugate storage tank after standing and precipitating;

(7) rectification and separation:

transferring the centrifugate in the centrifugate storage tank to a rectifying tower, respectively rectifying to obtain a front fraction, 2-hydroxy methyl valerate and kettle residue, transferring the front fraction to a front fraction separation tower, transferring the 2-hydroxy methyl valerate to a finished product storage tank, and transferring the kettle residue to a kettle residue storage tank.

Preferably, the catalyst in step (1) is sodium hydroxide or potassium hydroxide or sodium carbonate or sodium methoxide or sodium ethoxide or trimethylamine or triethylamine.

Preferably, the solid by-product obtained by centrifugal solid-liquid separation in step (6) is ammonium chloride.

Preferably, the front cut fraction rectified in the step (7) is transferred to a front cut fraction separation tower to be distilled and separated into methanol and pure water, and the front cut fraction is transferred to the step (4) for hydrolysis esterification reaction and recycling.

The invention adopts the structure and has the following advantages:

1. on the basis of the development and utilization of the conventional acrylonitrile byproduct hydrocyanic acid, a new way for utilizing the acrylonitrile byproduct hydrocyanic acid is developed, so that the acrylonitrile byproduct hydrocyanic acid is utilized more reasonably and efficiently;

2. the invention develops a new synthesis process of 2-hydroxy methyl valerate, and industrial production can be realized through flow design;

3. the synthetic process designed by the invention has reasonable and clear flow path, and although no mature and referable technical data exist, the equipment configuration can adopt a reaction kettle, a machine pump and a rectifying tower which are made of conventional materials and have conventional specifications according to the physicochemical properties of various raw materials and intermediates, thereby being convenient for realizing industrial mass production.

Drawings

FIG. 1 is a process flow diagram of the present invention.

Detailed Description

To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings.

Example 1

(1) Adding 230 kg of n-butyl aldehyde and 1 kg of sodium hydroxide into a reaction kettle, cooling to-10 ℃ under stirring, keeping the temperature of the reaction kettle between-10 ℃ and-5 ℃, adding 100 kg of hydrocyanic acid into the reaction kettle, reacting to generate butyraldehyde cyanohydrin, and then transferring into a butyraldehyde cyanohydrin metering tank;

(2) adding 150 kg of anhydrous methanol into a methanol hydrochloride synthesis kettle, cooling, introducing 83 kg of hydrogen chloride, and keeping the temperature of the introduced hydrogen chloride below minus 5 ℃ for 10 minutes;

(3) transferring 233 kg of hydrochloric acid methanol synthesized in the step (2) into a salt forming kettle, adding 24 kg of pure water, slowly and uniformly dripping 330 kg of butyraldehyde cyanohydrin synthesized in the step (1) under the state of cooling and stirring, controlling the dripping reaction temperature to be 25-30 ℃, keeping the reaction temperature within the range of 25-35 ℃ after finishing dripping, reacting for 6 hours to generate imino ester hydrochloride, and then adding 145 kg of anhydrous methanol to dissolve a salt forming material;

(4) transferring the material after the reaction in the step (3) into a hydrolysis esterification kettle, and starting hydrolysis esterification for 4-6 hours;

(5) transferring the materials after the esterification reaction into a neutralization kettle, cooling to 35-45 ℃ under a stirring state, and introducing ammonia gas for neutralization reaction;

(6) feeding the material after the neutralization reaction into a centrifugal machine for solid-liquid separation, wherein the solid is ammonium chloride, and the centrifugate is a semi-finished product synthetic liquid of 2-hydroxy methyl valerate;

(7) standing the semi-finished product synthetic liquid for precipitation, and then transferring the semi-finished product synthetic liquid into a rectifying tower for rectifying separation to obtain 415.5 kg of a finished product of the 2-hydroxy methyl valerate, wherein the reaction yield is calculated to be 94.43%;

(8) and (4) enabling the distillate before rectification to enter a front fraction separation tower to recover methanol and water, recycling the methanol and water until the salt forming reaction in the step (3), and after the rectification is finished, transferring the kettle residual liquid into a special storage tank to be subjected to centralized recovery treatment.

Example 2

(1) Adding 245 kg of n-butyl aldehyde and 1.2 kg of potassium hydroxide into a reaction kettle, cooling to-10 ℃ under stirring, keeping the temperature of the reaction kettle between-10 ℃ and-5 ℃, adding 100 kg of hydrocyanic acid into the reaction kettle, reacting to generate butyraldehyde cyanohydrin, and then transferring into a butyraldehyde cyanohydrin metering tank;

(2) adding 165 kg of anhydrous methanol into a methanol hydrochloride synthesis kettle, then cooling, introducing 83 kg of hydrogen chloride, and keeping the temperature of the introduced hydrogen chloride below minus 5 ℃ for 10 minutes;

(3) transferring 248 kg of hydrochloric acid methanol synthesized in the step (2) into a salt forming kettle, adding 26 kg of pure water, slowly and uniformly dripping 345 kg of butyraldehyde cyanohydrin synthesized in the step (1) under the state of cooling and stirring, controlling the dripping reaction temperature to be 25-30 ℃, keeping the reaction temperature to be 25-35 ℃ after finishing dripping, reacting for 6 hours to generate imino ester hydrochloride, and then adding 160 kg of anhydrous methanol to dissolve a salt forming material;

(4) transferring the material after the reaction in the step (3) into a hydrolysis esterification kettle, and starting hydrolysis esterification for 4-6 hours;

(5) transferring the materials after the esterification reaction into a neutralization kettle, cooling to 35-45 ℃ under a stirring state, and introducing ammonia gas for neutralization reaction;

(6) feeding the material after the neutralization reaction into a centrifugal machine for solid-liquid separation, wherein the solid is ammonium chloride, and the centrifugate is a semi-finished product synthetic liquid of 2-hydroxy methyl valerate;

(7) standing the semi-finished product synthetic fluid for precipitation, and then transferring the semi-finished product synthetic fluid into a rectifying tower for rectifying separation to obtain 419 kg of a finished product of the 2-hydroxy methyl valerate, wherein the reaction yield is calculated to be 95.23%;

(8) and (4) enabling the distillate before rectification to enter a front fraction separation tower to recover methanol and water, recycling the methanol and water until the salt forming reaction in the step (3), and after the rectification is finished, transferring the kettle residual liquid into a special storage tank to be subjected to centralized recovery treatment.

Example 3

(1) Adding 270 kg of n-butyl aldehyde and 1.2 kg of sodium carbonate into a reaction kettle, cooling to-10 ℃ under stirring, keeping the temperature of the reaction kettle between-10 ℃ and-5 ℃, adding 100 kg of hydrocyanic acid into the reaction kettle, reacting to generate butyraldehyde cyanohydrin, and then transferring into a butyraldehyde cyanohydrin metering tank;

(2) adding 165 kg of anhydrous methanol into a methanol hydrochloride synthesis kettle, then cooling, introducing 83 kg of hydrogen chloride, and keeping the temperature of the introduced hydrogen chloride below minus 5 ℃ for 10 minutes;

(3) transferring 248 kg of hydrochloric acid methanol synthesized in the step (2) into a salt forming kettle, adding 26 kg of pure water, slowly and uniformly dripping 370 kg of butyraldehyde cyanohydrin synthesized in the step (1) under the state of cooling and stirring, controlling the dripping reaction temperature to be 25-30 ℃, keeping the reaction temperature to be 25-35 ℃ after finishing dripping, reacting for 6 hours to generate imino ester hydrochloride, and then adding 170 kg of anhydrous methanol to dissolve a salt forming material;

(4) transferring the material after the reaction in the step (3) into a hydrolysis esterification kettle, and starting hydrolysis esterification for 4-6 hours;

(5) transferring the materials after the esterification reaction into a neutralization kettle, cooling to 35-45 ℃ under a stirring state, and introducing ammonia gas for neutralization reaction;

(6) feeding the material after the neutralization reaction into a centrifugal machine for solid-liquid separation, wherein the solid is ammonium chloride, and the centrifugate is a semi-finished product synthetic liquid of 2-hydroxy methyl valerate;

(7) after standing and precipitating the semi-finished product synthetic fluid, transferring the semi-finished product synthetic fluid into a rectifying tower for rectifying and separating to obtain 419.5 kg of a finished product of the 2-hydroxy methyl valerate, and calculating the reaction yield to be 95.34%;

(8) and (4) enabling the distillate before rectification to enter a front fraction separation tower to recover methanol and water, recycling the methanol and water until the salt forming reaction in the step (3), and after the rectification is finished, transferring the kettle residual liquid into a special storage tank to be subjected to centralized recovery treatment.

Example 4

(1) Adding 270 kg of n-butyl aldehyde and 1.2 kg of trimethylamine into a reaction kettle, cooling to-10 ℃ under stirring, keeping the temperature of the reaction kettle between-10 ℃ and-5 ℃, adding 100 kg of hydrocyanic acid into the reaction kettle, reacting to generate butyraldehyde cyanohydrin, and transferring to a butyraldehyde cyanohydrin metering tank;

(2) adding 170 kg of anhydrous methanol into a methanol hydrochloride synthesis kettle, cooling, introducing 74 kg of hydrogen chloride, and keeping the temperature of the introduced hydrogen chloride below minus 5 ℃ for 10 minutes;

(3) transferring 244 kg of hydrochloric acid methanol synthesized in the step (2) into a salt forming kettle, adding 28 kg of pure water, slowly and uniformly dripping 370 kg of butyraldehyde cyanohydrin synthesized in the step (1) under the condition of cooling and stirring, controlling the dripping reaction temperature to be 25-30 ℃, keeping the reaction temperature to be 25-35 ℃ after finishing dripping, reacting for 6 hours to generate imino ester hydrochloride, and then adding 170 kg of anhydrous methanol to dissolve a salt forming material;

(4) transferring the material after the reaction in the step (3) into a hydrolysis esterification kettle, and starting hydrolysis esterification for 4-6 hours;

(5) transferring the materials after the esterification reaction into a neutralization kettle, cooling to 35-45 ℃ under a stirring state, and introducing ammonia gas for neutralization reaction;

(6) feeding the material after the neutralization reaction into a centrifugal machine for solid-liquid separation, wherein the solid is ammonium chloride, and the centrifugate is a semi-finished product synthetic liquid of 2-hydroxy methyl valerate;

(7) standing the semi-finished product synthetic liquid for precipitation, and then transferring the semi-finished product synthetic liquid into a rectifying tower for rectifying separation to obtain 412.2 kg of a finished product of the 2-hydroxy methyl valerate, wherein the reaction yield is calculated to be 93.68%;

(8) and (4) enabling the distillate before rectification to enter a front fraction separation tower to recover methanol and water, recycling the methanol and water until the salt forming reaction in the step (3), and after the rectification is finished, transferring the kettle residual liquid into a special storage tank to be subjected to centralized recovery treatment.

Example 5

(1) Adding 280 kg of n-butyl aldehyde and 1.4 kg of triethylamine into a reaction kettle, cooling to-10 ℃ under stirring, keeping the temperature of the reaction kettle between-10 ℃ and-5 ℃, adding 100 kg of hydrocyanic acid into the reaction kettle, reacting to generate butyraldehyde cyanohydrin, and then transferring into a butyraldehyde cyanohydrin metering tank;

(2) adding 170 kg of anhydrous methanol into a methanol hydrochloride synthesis kettle, cooling, introducing 74 kg of hydrogen chloride, and keeping the temperature of the introduced hydrogen chloride below minus 5 ℃ for 10 minutes;

(3) transferring 244 kg of hydrochloric acid methanol synthesized in the step (2) into a salt forming kettle, adding 28 kg of pure water, slowly and uniformly dripping 380 kg of butyraldehyde cyanohydrin synthesized in the step (1) under the condition of cooling and stirring, controlling the dripping reaction temperature to be 25-30 ℃, keeping the reaction temperature to be 25-35 ℃ after finishing dripping, reacting for 6 hours to generate imino ester hydrochloride, and then adding 185 kg of anhydrous methanol to dissolve a salt forming material;

(4) transferring the material after the reaction in the step (3) into a hydrolysis esterification kettle, and starting hydrolysis esterification for 4-6 hours;

(5) transferring the materials after the esterification reaction into a neutralization kettle, cooling to 35-45 ℃ under a stirring state, and introducing ammonia gas for neutralization reaction;

(6) feeding the material after the neutralization reaction into a centrifugal machine for solid-liquid separation, wherein the solid is ammonium chloride, and the centrifugate is a semi-finished product synthetic liquid of 2-hydroxy methyl valerate;

(7) standing and precipitating the semi-finished product synthetic liquid, and then transferring the semi-finished product synthetic liquid into a rectifying tower for rectifying and separating to obtain 415 kg of a finished product of the 2-hydroxy methyl valerate, wherein the reaction yield is calculated to be 94.32%;

(8) and (4) enabling the distillate before rectification to enter a front fraction separation tower to recover methanol and water, recycling the methanol and water until the salt forming reaction in the step (3), and after the rectification is finished, transferring the kettle residual liquid into a special storage tank to be subjected to centralized recovery treatment.

Example 6

(1) Adding 270 kg of n-butyl aldehyde and 1.2 kg of trimethylamine into a reaction kettle, cooling to-10 ℃ under stirring, keeping the temperature of the reaction kettle between-10 ℃ and-5 ℃, adding 100 kg of hydrocyanic acid into the reaction kettle, reacting to generate butyraldehyde cyanohydrin, and transferring to a butyraldehyde cyanohydrin metering tank;

(2) adding 170 kg of anhydrous methanol into a methanol hydrochloride synthesis kettle, cooling, introducing 89 kg of hydrogen chloride, and keeping the temperature of the introduced hydrogen chloride below minus 5 ℃ for 10 minutes;

(3) transferring 269 kg of hydrochloric acid methanol synthesized in the step (2) into a salt forming kettle, adding 25 kg of pure water, slowly and uniformly dripping 370 kg of butyraldehyde cyanohydrin synthesized in the step (1) in a cooling and stirring state, controlling the dripping reaction temperature to be 25-30 ℃, keeping the reaction temperature to be 25-35 ℃ after finishing dripping, reacting for 6 hours to generate imino ester hydrochloride, and then adding 150 kg of anhydrous methanol to dissolve a salt forming material;

(4) transferring the material after the reaction in the step (3) into a hydrolysis esterification kettle, and starting hydrolysis esterification for 4-6 hours;

(5) transferring the materials after the esterification reaction into a neutralization kettle, cooling to 35-45 ℃ under a stirring state, and introducing ammonia gas for neutralization reaction;

(6) feeding the material after the neutralization reaction into a centrifugal machine for solid-liquid separation, wherein the solid is ammonium chloride, and the centrifugate is a semi-finished product synthetic liquid of 2-hydroxy methyl valerate;

(7) standing the semi-finished synthetic liquid for precipitation, and then transferring the semi-finished synthetic liquid into a rectifying tower for rectifying and separating to obtain 423.6 kg of a finished product of the 2-hydroxy methyl valerate, wherein the reaction yield is calculated to be 96.27%;

(8) and (4) enabling the distillate before rectification to enter a front fraction separation tower to recover methanol and water, recycling the methanol and water until the salt forming reaction in the step (3), and after the rectification is finished, transferring the kettle residual liquid into a special storage tank to be subjected to centralized recovery treatment.

Example 7

(1) Adding 280 kg of n-butyl aldehyde and 1.4 kg of triethylamine into a reaction kettle, cooling to-10 ℃ under stirring, keeping the temperature of the reaction kettle between-10 ℃ and-5 ℃, adding 100 kg of hydrocyanic acid into the reaction kettle, reacting to generate butyraldehyde cyanohydrin, and then transferring into a butyraldehyde cyanohydrin metering tank;

(2) adding 180 kg of anhydrous methanol into a methanol hydrochloride synthesis kettle, cooling, introducing 86 kg of hydrogen chloride, and keeping the temperature of the introduced hydrogen chloride below minus 5 ℃ for 10 minutes;

(3) transferring 266 kg of hydrochloric acid methanol synthesized in the step (2) into a salt forming kettle, adding 25 kg of pure water, slowly and uniformly dripping 370 kg of butyraldehyde cyanohydrin synthesized in the step (1) under the state of cooling and stirring, controlling the dripping reaction temperature to be 25-30 ℃, keeping the reaction temperature to be 25-35 ℃ after finishing dripping, reacting for 6 hours to generate imino ester hydrochloride, and then adding 180 kg of anhydrous methanol to dissolve the salt forming material;

(4) transferring the material after the reaction in the step (3) into a hydrolysis esterification kettle, and starting hydrolysis esterification for 4-6 hours;

(5) transferring the materials after the esterification reaction into a neutralization kettle, cooling to 35-45 ℃ under a stirring state, and introducing ammonia gas for neutralization reaction;

(6) feeding the material after the neutralization reaction into a centrifugal machine for solid-liquid separation, wherein the solid is ammonium chloride, and the centrifugate is a semi-finished product synthetic liquid of 2-hydroxy methyl valerate;

(7) standing the semi-finished product synthetic liquid for precipitation, and then transferring the semi-finished product synthetic liquid into a rectifying tower for rectifying and separating to obtain 424.5 kg of a finished product of the 2-hydroxy methyl valerate, wherein the reaction yield is calculated to be 96.48%;

(8) and (4) enabling the distillate before rectification to enter a front fraction separation tower to recover methanol and water, recycling the methanol and water until the salt forming reaction in the step (3), and after the rectification is finished, transferring the kettle residual liquid into a special storage tank to be subjected to centralized recovery treatment.

Example 8

(1) Adding 260 kg of n-butyl aldehyde and 1.2 kg of potassium hydroxide into a reaction kettle, cooling to-10 ℃ under stirring, keeping the temperature of the reaction kettle between-10 ℃ and-5 ℃, adding 100 kg of hydrocyanic acid into the reaction kettle, reacting to generate butyraldehyde cyanohydrin, and then transferring to a butyraldehyde cyanohydrin metering tank;

(2) adding 165 kg of anhydrous methanol into a methanol hydrochloride synthesis kettle, cooling, introducing 89 kg of hydrogen chloride, and keeping the temperature of the introduced hydrogen chloride below minus 5 ℃ for 10 minutes;

(3) transferring 254 kg of hydrochloric acid methanol synthesized in the step (2) into a salt forming kettle, adding 22 kg of pure water, slowly and uniformly dripping 360 kg of butyraldehyde cyanohydrin synthesized in the step (1) under the state of cooling and stirring, controlling the dripping reaction temperature to be 25-30 ℃, keeping the reaction temperature to be 25-35 ℃ after finishing dripping, reacting for 6 hours to generate imino ester hydrochloride, and then adding 165 kg of anhydrous methanol to dissolve a salt forming material;

(4) transferring the material after the reaction in the step (3) into a hydrolysis esterification kettle, and starting hydrolysis esterification for 4-6 hours;

(5) transferring the materials after the esterification reaction into a neutralization kettle, cooling to 35-45 ℃ under a stirring state, and introducing ammonia gas for neutralization reaction;

(6) feeding the material after the neutralization reaction into a centrifugal machine for solid-liquid separation, wherein the solid is ammonium chloride, and the centrifugate is a semi-finished product synthetic liquid of 2-hydroxy methyl valerate;

(7) standing the semi-finished product synthetic liquid for precipitation, and then transferring the semi-finished product synthetic liquid into a rectifying tower for rectifying separation to obtain 415.3 kg of a finished product of the 2-hydroxy methyl valerate, wherein the reaction yield is calculated to be 94.39%;

(8) and (4) enabling the distillate before rectification to enter a front fraction separation tower to recover methanol and water, recycling the methanol and water until the salt forming reaction in the step (3), and after the rectification is finished, transferring the kettle residual liquid into a special storage tank to be subjected to centralized recovery treatment.

Example 9

(1) Adding 260 kg of n-butyl aldehyde and 1.2 kg of potassium hydroxide into a reaction kettle, cooling to-10 ℃ under stirring, keeping the temperature of the reaction kettle between-10 ℃ and-5 ℃, adding 100 kg of hydrocyanic acid into the reaction kettle, reacting to generate butyraldehyde cyanohydrin, and then transferring to a butyraldehyde cyanohydrin metering tank;

(2) adding 175 kg of anhydrous methanol into a methanol hydrochloride synthesis kettle, then cooling, introducing 85 kg of hydrogen chloride, and keeping the temperature of the hydrogen chloride below minus 5 ℃ for 10 minutes after the hydrogen chloride is introduced;

(3) transferring 260 kg of hydrochloric acid methanol synthesized in the step (2) into a salt forming kettle, adding 26 kg of pure water, slowly and uniformly dripping 360 kg of butyraldehyde cyanohydrin synthesized in the step (1) under the state of cooling and stirring, controlling the dripping reaction temperature to be 25-30 ℃, keeping the reaction temperature to be 25-35 ℃ after finishing dripping, reacting for 6 hours to generate imino ester hydrochloride, and then adding 175 kg of anhydrous methanol to dissolve a salt forming material;

(4) transferring the material after the reaction in the step (3) into a hydrolysis esterification kettle, and starting hydrolysis esterification for 4-6 hours;

(5) transferring the materials after the esterification reaction into a neutralization kettle, cooling to 35-45 ℃ under a stirring state, and introducing ammonia gas for neutralization reaction;

(6) feeding the material after the neutralization reaction into a centrifugal machine for solid-liquid separation, wherein the solid is ammonium chloride, and the centrifugate is a semi-finished product synthetic liquid of 2-hydroxy methyl valerate;

(7) standing the semi-finished product synthetic liquid for precipitation, and then transferring the semi-finished product synthetic liquid into a rectifying tower for rectifying separation to obtain 419.6 kg of a finished product of the 2-hydroxy methyl valerate, wherein the reaction yield is calculated to be 95.36%;

(8) and (4) recycling methanol and water from the distillate before rectification in a front fraction separation tower, recycling the methanol and water for salt forming reaction in the step (3), and transferring the residue after rectification to a special storage tank for centralized recycling treatment.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.