阅读说明：本技术 一种合成和萃取纯化3-己炔-2,5-二醇的方法 (Method for synthesizing and extracting and purifying 3-hexyne-2, 5-diol ) 是由 王南 王林生 李果 于 2021-08-30 设计创作，主要内容包括：一种合成和萃取纯化3-己炔-2,5-二醇的方法,采用三聚乙醛为乙醛原料来源,以氢氧化钾为催化剂,在脂肪烃或芳香烃有机溶剂中,与低于0.15MPa压力的乙炔进行反应生成3-己炔-2,5-二醇。反应终点物料是“液-液”两相体系,经两相分离和水解,得到含目标产物和氢氧化钾的水溶液,再用与水相溶性小的醇类有机溶剂萃取,将目标产物与氢氧化钾分开,再精馏得到目标产物3-己炔-2,5-二醇。本发明合成反应过程在0.15MPa安全乙炔压力以下进行,消除了爆炸危险,具有生产安全、产品收益高、产品纯度高等特点。(A method for synthesizing and extracting and purifying 3-hexyne-2, 5-diol adopts paraldehyde as acetaldehyde raw material source, uses potassium hydroxide as catalyst, and makes it react with acetylene whose pressure is less than 0.15MPa in aliphatic hydrocarbon or aromatic hydrocarbon organic solvent to produce 3-hexyne-2, 5-diol. The material at the end of the reaction is a liquid-liquid two-phase system, an aqueous solution containing a target product and potassium hydroxide is obtained through two-phase separation and hydrolysis, the aqueous solution is extracted by an alcohol organic solvent with small water solubility, the target product and the potassium hydroxide are separated, and the target product 3-hexyne-2, 5-diol is obtained through rectification. The synthetic reaction process is carried out under the safe acetylene pressure of 0.15MPa, so that the explosion hazard is eliminated, and the method has the characteristics of safe production, high product yield, high product purity and the like.)

1. A method for synthesizing and extracting and purifying 3-hexyne-2, 5-diol, which is characterized by comprising the following steps:

(1) preparation of an acetaldehyde solution

Carrying out acid catalytic depolymerization on the initial raw material paraldehyde, and then absorbing and dissolving the initial raw material paraldehyde by using an organic solvent to prepare an acetaldehyde solution;

(2) preparation of catalyst suspension slurry

Grinding an organic solvent and a catalyst potassium hydroxide into slurry, stirring and heating to make the slurry transparent or semitransparent, and cooling to prepare a catalyst suspension slurry;

(3) synthesis reaction

Introducing acetylene into the prepared catalyst suspension slurry, firstly, fully activating the reaction of acetylene and the catalyst, then, uniformly adding the acetaldehyde solution prepared in the step (1), continuously controlling the temperature and keeping the acetylene pressure for reaction, wherein the material at the end point of the reaction is a liquid-liquid two-phase system consisting of an organic solvent and micro liquid particles of a hexynediol-catalyst complex dispersed in the organic solvent;

(4) two-phase separation and hydrolysis

Carrying out two-phase separation on the reaction end point material, and respectively collecting a hexynediol-catalyst complex liquid phase and an organic solvent phase;

stirring and hydrolyzing the hexynediol-catalyst complex phase and clear water to generate aqueous phase liquid containing 3-hexynediol-2, 5-diol and potassium hydroxide and a small amount of organic solvent phase;

(5) extraction separation and purification

Mixing and extracting the obtained aqueous phase liquid and an organic extraction solvent in extraction equipment, and respectively collecting an organic extraction phase containing 3-hexyne-2, 5-diol and a raffinate aqueous phase containing potassium hydroxide;

and (3) rectifying and separating the organic extraction phase to obtain the high-purity 3-hexyne-2, 5-diol.

2. The method for synthesizing and extracting and purifying 3-hexyne-2, 5-diol according to claim 1, wherein the organic solvent used in step (1) and step (2) simultaneously satisfies the following three conditions:

the material has high solubility to acetaldehyde, and the solubility of the acetaldehyde in the organic solvent is more than 20 percent;

② the solubility of 3-hexyne-2, 5-diol is small, the solubility of 3-hexyne-2, 5-diol in the organic solvent is less than 2%;

the solubility of the compound and water is very low; further, the organic solvent is selected from n-hexane, 2-methylpentane, 3-methylpentane, heptane, octane, mineral spirits, petroleum ether, toluene, o-xylene, m-xylene, p-xylene, mixed xylenes or ethylbenzene.

3. The method for synthesizing and extracting and purifying 3-hexyne-2, 5-diol according to claim 1, wherein the concentration of the acetaldehyde solution prepared in the step (1) is 20% to 50%, and further, preferably, the concentration of the acetaldehyde solution is 35% to 45%.

4. The method for synthesizing and extracting and purifying 3-hexyne-2, 5-diol according to claim 1, wherein in the step (2), the catalyst used is potassium hydroxide, and the weight ratio of potassium hydroxide (pure) to the organic solvent is 0.3:1 to 0.6:1, and further, the weight ratio of potassium hydroxide (pure) to the organic solvent is preferably 0.4:1 to 0.5: 1.

5. The method for synthesizing and extracting and purifying 3-hexyne-2, 5-diol according to claim 1, wherein in the step (3), the molar ratio of acetaldehyde to potassium hydroxide in the reaction initial material is controlled to be not less than 1, and further, the molar ratio of acetaldehyde to potassium hydroxide is preferably 1.1:1 to 1.2: 1; in the step (3), the reaction temperature is controlled within the range of 18-56 ℃; the acetylene pressure is always kept less than or equal to 0.15MPa in the reaction process, and further, the acetylene pressure is preferably 0.08MPa to 0.15 MPa.

6. The method for synthesizing and extracting and purifying 3-hexyne-2, 5-diol according to claim 1, wherein in the step (4), the ratio of clear water to the hexyne-diol-catalyst complex phase is = 1: 1-3: 1 (weight ratio), and further, preferably, the ratio of clear water to the hexyne-diol-catalyst complex phase is = 1.5: 1-2.5: 1 (weight ratio); the hydrolysis temperature is 30-50 ℃, and the hydrolysis reaction time is 30-60 minutes.

7. The method for synthesizing and extractive purification of 3-hexyne-2, 5-diol according to claim 1, wherein in the step (5), the organic extraction solvent used is an alcoholic solvent less miscible with water, and further, the organic solvent selected is n-butanol, iso-butanol, n-pentanol, iso-pentanol, n-hexanol, 2-ethylbutanol, 2-ethylhexanol, or n-octanol; the organic extraction solvent is aqueous phase liquid = 0.5: 1-1: 1 (weight ratio), and the extraction temperature is 30-50 ℃.

Technical Field

The invention relates to a method for safely synthesizing, separating and purifying 3-hexyne-2, 5-diol by reacting with acetylene from paraldehyde.

Background

The 3-hexyne-2, 5-diol is a chemical intermediate, can be used for preparing a surfactant in the chemical industry, is used as a steel corrosion inhibitor in the steel industry, and is used as an electroplating brightener, a leveling agent and the like in the electroplating industry. The downstream product 2, 5-hexanediol prepared by hydrogenating 3-hexyne-2, 5-diol is also an important raw material for synthesizing chiral drugs such as hypotensor captopril, diltiazem and the like and other various chiral chemicals.

In the method for synthesizing 3-hexyne-2, 5-diol, a Grignard reagent synthesis method has been reported in the early days, and the method has complicated production operation, high equipment requirement, many side reactions and no industrialization because of the Grignard reagent. At present, the industrialized method for synthesizing 3-hexyne-2, 5-diol at home and abroad is mainly a Reppe method, namely, acetaldehyde water solution and acetylene gas are used as starting materials, copper-bismuth salt is used as a catalyst, and the 3-hexyne-2, 5-diol is synthesized under the pressure of 0.6 MPa-1.0 MP. Improved methods for Reppe methods are also reported in China, such as the invention patent CN201510461575, the process for synthesizing 3-hexyne-2, 5-diol by using a slurry bed acidity control method, the invention patent CN201210385912, the process for synthesizing 3-hexyne-2, 5-diol by using a slurry bed low-pressure method, the invention patent CN201110152117, the synthesis method of 3-hexyne-2, 5-diol and the like, but all methods need to be carried out under acetylene pressure higher than 0.5 MPa. And the reaction is carried out under the condition that the safety pressure of the acetylene is 0.15MPa higher than the safety pressure of the acetylene, so that the requirement on reaction equipment is higher, and the danger of explosion of the acetylene under high pressure exists.

In the synthesis method reported in CN201210126216 method for preparing 3-hexyne-2, 5-diol under normal pressure, acetylene and acetaldehyde are taken as raw materials, xylene is taken as a solvent, potassium tert-butoxide is taken as a catalyst, the reaction is carried out in a normal pressure reaction kettle to synthesize the 3-hexyne-2, 5-diol, then water is used for stirring and washing the organic phase of the reaction solution, reduced pressure rectification is carried out, and distillate at 119-123 ℃ is collected to obtain the product 3-hexyne-2, 5-diol. In the experimental verification of the reported method, the inventor finds that after the oil phase of the reaction liquid is stirred and washed by the water phase, the 3-hexyne-2, 5-diol and the potassium hydroxide have strong water solubility, and almost all the potassium hydroxide generated by the hydrolysis of the catalyst potassium tert-butoxide and the product 3-hexyne-2, 5-diol in the oil phase of the reaction liquid are transferred and dissolved into the water phase liquid. When the aqueous phase liquid is subjected to vacuum rectification, water is distilled out firstly, the concentration of potassium hydroxide is increased along with the reduction of the water and gradually separated out, and when the boiling point of the 3-hexyne-2, 5-diol is not reached, the rectification residual material is already a thick slurry formed by mixing suspended potassium hydroxide, the 3-hexyne-2, 5-diol and water, and the material is difficult to distill even if the temperature is raised to 130 ℃ or higher. It was confirmed that the 3-hexyne-2, 5-diol was distilled off in the aqueous phase containing a large amount of potassium hydroxide, and this was difficult to achieve in the production.

Disclosure of Invention

The invention aims to provide a method for synthesizing and extracting and purifying 3-hexyne-2, 5-diol under safe acetylene pressure.

The purpose of the invention is realized as follows: the synthesis, separation and purification of 3-hexyne-2, 5-diol are carried out by taking paraldehyde and acetylene as initial raw materials, potassium hydroxide as a catalyst, and an organic solvent as a dispersing solvent and an extracting agent according to the following technical scheme.

1. Preparation of an acetaldehyde solution

Depolymerizing initial raw material paraldehyde by acid catalysis, absorbing and dissolving the initial raw material paraldehyde into an acetaldehyde solution by an organic solvent, and sealing the acetaldehyde solution for later use.

The feeding proportion of the paraldehyde and the organic solvent is controlled to control the content of the acetaldehyde in the prepared acetaldehyde solution to be 20-50%, and the concentration of the acetaldehyde solution is preferably 35-45%.

Paraldehyde is a liquid compound, has stable chemical properties, is convenient to store and transport, and can be depolymerized into acetaldehyde by heating under the catalysis of acid.

The organic solvent used in this operation must simultaneously satisfy the following three points, (1) a greater solubility for acetaldehyde, the solubility of acetaldehyde in this organic solvent being greater than 20%; (2) the solubility of 3-hexyne-2, 5-diol is small, and the solubility of 3-hexyne-2, 5-diol in the organic solvent is less than 2 percent; (3) has little solubility with water. The organic solvent satisfying the three conditions is preferably aliphatic hydrocarbon solvent such as n-hexane, 2-methylpentane, 3-methylpentane, heptane, octane, solvent oil, petroleum ether, etc. Secondly, aromatic hydrocarbon solvents such as toluene, o-xylene, m-xylene, p-xylene, mixed xylene, ethylbenzene and the like can also be selected,

2. preparation of catalyst suspension slurry

Grinding an organic solvent and a catalyst into slurry in grinding equipment, then transferring the slurry into reaction equipment, stirring and heating the slurry to 60-80 ℃, keeping the temperature for 1-2 hours, and continuously stirring and slowly cooling the slurry to a specified reaction temperature range when the material is in a transparent or nearly transparent state, namely the catalyst is completely or partially dissolved in the organic solvent. After the temperature was lowered, the organic solution gradually became a translucent turbid state, and the catalyst was dispersed in the organic solution as a finely suspended particulate in a partially dissolved portion. After the catalyst suspension slurry is prepared, the next step of 'synthetic reaction' operation is carried out as soon as possible without stopping stirring.

The catalyst used in this step is potassium hydroxide (technical grade, purity 92% -94%).

The organic solvent used in this step is the same as that used previously to prepare the acetaldehyde solution.

The feeding ratio of the catalyst to the organic solvent is potassium hydroxide (pure) to the organic solvent =0.3:1 to 0.6:1 (weight ratio), and preferably potassium hydroxide (pure) to the organic solvent =0.4:1 to 0.5:1 (weight ratio).

3. Synthesis reaction

And after the temperature of the catalyst suspension slurry prepared in the reaction equipment is controlled within a specified reaction temperature range, introducing acetylene into the material, keeping the acetylene pressure in the reaction equipment within the specified range, and reacting for about 1 hour to ensure that the acetylene and the catalyst are fully reacted and activated to generate active acetylene. Then adding the prepared acetaldehyde solution into a reaction device in a uniform flow manner, continuously controlling the temperature and keeping the acetylene pressure, and carrying out addition reaction on the acetaldehyde and the active acetylene until the catalyst (active acetylene) in the material is converted by more than 99%.

In the one-step operation, the adding amount of the acetaldehyde solution is determined by the acetaldehyde concentration and the potassium hydroxide amount in the catalyst suspension slurry, namely, the acetaldehyde to potassium hydroxide ratio in the reaction initial material is controlled to be more than or equal to 1 (molar ratio), preferably, the acetaldehyde to potassium hydroxide ratio in the reaction initial mixed material is = 1.1:1 to 1.2:1 (molar ratio), namely, the acetaldehyde molar amount in the reaction material is always ensured to be more than the active acetylene molar amount. Controlling the excess acetylene in the reaction materials can ensure that the catalyst (active acetylene) and the reaction intermediate butyne-3-alcohol are basically consumed, and the reaction product is mainly the target product 3-hexyne-2, 5-diol.

The initial reaction temperature is controlled at 18-20 deg.c, and the reaction temperature is raised gradually and the later reaction temperature is raised to 54-56 deg.c.

The acetylene pressure is always kept less than or equal to 0.15MPa, preferably 0.08MPa to 0.15MPa in the reaction process.

The reaction time is usually 3-5 hours, and the reaction end point can be reached.

In the operation, acetylene reacts with the suspended catalyst continuously to generate active acetylene and is dissolved in the organic solvent, active acetylene molecules collide with acetaldehyde molecules in the organic solvent to generate addition reaction, an intermediate butyne-3-alcohol-catalyst complex which can be dissolved in the organic solvent is generated firstly, and then the intermediate butyne-3-alcohol-catalyst complex is re-added with acetaldehyde to generate a hexynediol-catalyst complex. The hexynediol-catalyst complex has low solubility in the organic solvent, so that the molecules of the hexynediol-catalyst complex formed by the reaction are aggregated into a fine precipitate and suspended and dispersed in the organic solvent. Along with the reaction, the suspended catalyst particles in the reaction materials are gradually converted into active acetylene and disappear, the generated hexynediol-catalyst complex is continuously separated out, and the separated hexynediol-catalyst complex particles are converted from solid particles into liquid particles along with the increase of the temperature of the reaction material system. After the reaction end point is reached, the reaction mass becomes a "liquid-liquid" two-phase system consisting of the organic solvent and the hexynediol-catalyst complex particles dispersed therein.

4. Two-phase separation and hydrolysis

And transferring the reaction termination material to a settling separation device after the reaction termination, separating the hexynediol-catalyst complex phase from the organic solvent phase, and collecting the two phases respectively.

The residual acetaldehyde is dissolved in the organic solvent and recycled together with the organic solvent,

mixing the hexynediol-catalyst complex phase with clear water, wherein the hexynediol-catalyst complex is hydrolyzed and decomposed into 3-hexyn2, 5-diol and potassium hydroxide, and the 3-hexyn2, 5-diol and the potassium hydroxide are dissolved into the water phase. Separating the two phases, and respectively collecting an aqueous phase liquid (containing 3-hexyne-2, 5-diol and potassium hydroxide) and a residual small amount of organic solvent phase. Wherein the organic solvent is recovered for reuse, and the aqueous phase liquid enters the next operation.

In the operation, the adding amount of clear water for hydrolysis is calculated according to the amount of the hexynediol-catalyst complex phase, namely, the clear water and the hexynediol-catalyst complex phase = 1: 1-3: 1 (weight ratio), the concentration of 3-hexyne-2, 5-diol in the aqueous phase liquid after hydrolysis is within the range of 32-13%, and the concentration of potassium hydroxide is within the range of 34-15%. Preferably, the weight ratio of clear water to the hexynediol-catalyst complex phase is = 1.5: 1-2.5: 1, the concentration of 3-hexynediol-2, 5-diol in the aqueous phase liquid after hydrolysis is 24-16%, and the concentration of potassium hydroxide is 26-18%.

The hydrolysis temperature is 30-50 ℃. The hydrolysis reaction time is 30-60 minutes.

5. Extraction separation and purification

And mixing and extracting the obtained aqueous phase liquid and an organic extraction solvent in an extraction device, so that the 3-hexyne-2, 5-diol in the aqueous phase liquid is transferred into the organic solvent phase, and the potassium hydroxide still remains in the aqueous phase liquid, and respectively collecting the organic extraction phase (containing the 3-hexyne-2, 5-diol) and the extraction aqueous phase (containing the potassium hydroxide).

In this step, the amount of the organic extraction solvent is determined according to the content of 3-hexyne-2, 5-diol in the aqueous phase of hydrolysis, and the organic extraction solvent is usually used in a weight ratio of 0.5:1 to 1:1 in the aqueous phase, corresponding to a concentration of 30% to 20% of 3-hexyne-2, 5-diol in the organic extraction phase.

The extraction temperature is 30-50 ℃.

The organic extraction solvent used in the operation is alcohol solvent with small water intersolubility, and the alcohol meeting the condition comprises n-butyl alcohol, isobutyl alcohol, n-amyl alcohol, isoamyl alcohol, n-hexyl alcohol, 2-hexanol, 2-ethylbutanol, 2-ethylhexanol, n-octanol and the like.

Since the solubility of 3-hexyne-2, 5-diol in alcoholic organic solvents is much higher than that in water, during the extraction process 3-hexyne-2, 5-diol is transferred from the aqueous phase to the organic extraction phase, which results in a more concentrated solution. The potassium hydroxide is not dissolved in the organic solvent and remains in the water phase, and the 3-hexyne-2, 5-diol can be effectively separated out by extraction, thereby achieving the purification effect.

The organic extraction phase is treated by adsorption, decoloration and the like, and then is rectified and separated, thus obtaining the high-purity 3-hexyne-2, 5-diol product.

Compared with the prior art, the invention has the following characteristics and advantages:

1. the paraldehyde is used as the starting material to replace acetaldehyde water, so that the raw material is convenient and safe to transport and store.

2. The synthetic reaction process is carried out under the safe acetylene pressure of 0.15MPa, thereby eliminating the explosion hazard and ensuring the production safety.

3. The target product 3-hexyne-2, 5-diol can be effectively separated and purified through operations of two-phase settling separation, hydrolysis separation, extraction separation and the like of reaction materials. In particular, the target product and the potassium hydroxide are extracted and separated by adopting an alcohol organic solvent, so that the defect that the target product is difficult to distill during the rectification operation in the prior art (CN 201210126216) is solved.

4. Excessive acetaldehyde is adopted in the reaction system to ensure the full generation of the target product, and the residual acetaldehyde after the reaction is finished is easy to recycle together with the organic solvent.

Detailed Description

Example 1:

(1) paraldehyde is distilled out by acid catalytic depolymerization, and is absorbed by n-hexane solvent to prepare a solution with the acetaldehyde content of 40.9%, 318g (equivalent to 130g containing acetaldehyde) of the solution is taken and sealed for standby.

(2) 400g of normal hexane and 210g of potassium hydroxide (industrial grade, purity 94%) are sequentially added into a grinder to be ground into slurry, the slurry is transferred into a stainless steel pressure reaction kettle, stirring is started, the temperature is heated to 70-80 ℃ and kept for 1 hour, and then the temperature is reduced to 18-20 ℃ for control.

(3) And introducing acetylene gas, and keeping the acetylene pressure within the range of 0.08MPa to 0.1MPa for reacting for about 1 hour. Then uniformly and slowly adding the prepared acetaldehyde solution into a reaction kettle from an overhead tank, simultaneously keeping the acetylene pressure in the range of 0.08MPa to 0.12MPa for reaction, and gradually raising the temperature to 54 ℃ to 56 ℃ at the speed of raising the temperature by 2 ℃ to 3 ℃ every 10 minutes. After about 4 hours of reaction, the reaction was terminated by detecting that the components in the reaction mass were not substantially changed. Upon discharge, the reaction mass was observed to have changed from an initial white translucent state to a grayish yellow turbid state.

In the reaction starting mixture, acetaldehyde to potassium hydroxide (pure) =1.2 to 1 (molar ratio).

(4) Transferring the reaction termination material into a conical flask, standing to separate the material into two layers, wherein the lower layer is a gray yellow (reaction product) liquid phase, and the upper layer is a nearly transparent colorless n-hexane solvent phase. Discharging and collecting respectively.

(5) Transferring the reaction product phase into a glass reaction kettle, adding 700g of clear water, controlling the temperature to be 30-40 ℃, stirring for 30 minutes, transferring into a conical flask, standing, dividing, and respectively collecting water phase liquid (containing the reaction product and potassium hydroxide) and a small amount of organic solvent.

(6) Transferring the water phase liquid containing the reaction product and potassium hydroxide into a glass reaction kettle, adding 650g of isobutanol, controlling the temperature to be 30-40 ℃, stirring for about 30 minutes, transferring the material into a conical flask, standing and layering. Discharging and respectively collecting an extraction oil phase (containing reaction products) and an extraction water phase (containing potassium hydroxide).

(7) And adsorbing and decoloring the extracted oil phase by using activated carbon, fractionating by using an experimental glass rectifier, and collecting each fraction.

158.2g of 3-hexyne-2, 5-diol is obtained with a purity of 98.7%.

Example 2:

the procedure was followed as in example 1, wherein:

the solvent used in the operation step (1) is petroleum ether, the concentration of the prepared acetaldehyde solution is 38.1%, and 368g (140 g of acetaldehyde) of the solution is weighed for later use.

In the operation step (2), 540g of solvent petroleum ether and 217g of catalyst potassium hydroxide are fed.

In the operation step (3), acetaldehyde/potassium hydroxide = 1.15: 1 (molar ratio) and acetylene pressure is controlled to be 0.1MPa to 0.12 MPa.

The amount of clear water added in operation (5) was 750 g.

The amount of the extraction solvent charged in the operation (6) was 700g of 2-ethylhexanol.

167.2g of 3-hexyne-2, 5-diol is obtained by rectification, and the purity is 98.4%.

Example 3:

the procedure was followed as in example 1, wherein:

the solvent used in the operation (1) was toluene, the concentration of the prepared acetaldehyde solution was 42.7%, and 305g of the solution (containing 130g of acetaldehyde) was weighed for use.

400g of toluene solvent and 210g of potassium hydroxide catalyst are fed in the operation step (2).

In the operation step (3), acetaldehyde/potassium hydroxide = 1.22: 1 (molar ratio) and acetylene pressure is controlled to be 0.12MPa to 0.14 MPa.

The amount of clear water added in the operation step (5) was 700 g.

In the operation step (6), 650g of isobutanol was fed as the extraction solvent.

157.7g of 3-hexyne-2, 5-diol is obtained by rectification, and the purity is 97.8 percent.

Example 4:

the procedure was followed as in example 1, wherein:

the solvent used in the operation step (1) was xylene, the concentration of the prepared acetaldehyde solution was 42.1%, and 333g (containing 140g of acetaldehyde) of the solution was weighed for use.

400g of toluene solvent and 209g of potassium hydroxide catalyst are fed in the operation step (2).

In the operation step (3), acetaldehyde/potassium hydroxide = 1.1:1 (molar ratio) and acetylene pressure is controlled to be 0.08MPa to 0.1 MPa.

The amount of clear water added in operation (5) was 750 g.

The amount of the extraction solvent charged in the operation (6) was 700g of 2-ethylhexanol.

164.9g of 3-hexyne-2, 5-diol is obtained by rectification, and the purity is 98.1 percent.

Concentrations herein are weight percent concentrations.