CN117843527A - Preparation method of isophorone nitrile - Google Patents

Abstract

The invention relates to a preparation method of isophorone nitrile, which comprises the steps of obtaining isophorone nitrile by reacting isophorone with hydrocyanic acid in the presence of an alkaline catalyst, and purifying a reaction product by distillation, wherein the alkaline catalyst is aliphatic amine of pKb 2-4, and the reaction product is added with acid for neutralization before distillation. The invention reduces the generation of heavy components and isophorone nitrile isomers, improves the yield of isophorone nitrile, and avoids the problem of precipitation caused by the addition of acid.

Description

Preparation method of isophorone nitrile

Technical Field

The invention relates to a method for preparing isophorone nitrile, in particular to a method for preparing isophorone nitrile by adopting a catalyst with alkalinity within a certain range.

Background

Isophorone nitrile, chemical name 3-nitrile-3, 5-trimethyl cyclohexanone (IPN), is used in industry to synthesize isophorone diamine, and the compound can be used as curing agent and cross-linking agent of epoxy resin paint, and can be further reacted with phosgene to synthesize isophorone diisocyanate. The synthesizing process of isophorone nitrile is to heat and react hydrocyanic acid and isophorone in the presence of an alkaline catalyst, and obtain a reaction liquid, and then neutralizing, desolventizing, rectifying and purifying the reaction liquid to obtain the product isophorone nitrile.

It is known that isophorone and hydrocyanic acid undergo a number of side reactions during the reaction, including polymerization of HCN itself, polymerization, oxidation of isophorone, and isomers formed by the reaction of both. In order to improve the yield and purity of the isophorone nitrile as a reaction product, a plurality of patents at home and abroad are respectively started from the following aspects to improve.

By researching different catalysts, the catalysts mainly used at present are alkaline catalysts, wherein the alkaline catalysts are divided into inorganic alkali and organic alkali. Inorganic base catalysts such as oxides, hydroxides, cyanides, alkoxides of alkali metals, alkaline earth metals, carbonates of alkali metals, alkaline earth metals, and the like. For example: US5254711 uses sodium methoxide as catalyst and isophorone and hydrocyanic acid are reacted in a series reactor to give isophorone nitrile in 96% yield (calculated as HCN). CN1729162 and US5091554 react isophorone with hydrocyanic acid to obtain isophorone nitrile with lithium hydroxide as catalyst. US6822110 uses calcium hydroxide as a catalyst, isophorone and hydrocyanic acid undergo an addition reaction under 1-3 atmospheres to obtain isophorone nitrile with a yield of 97%. US5142090 uses an aqueous alkali cyanide solution as a catalyst, and isophorone and hydrocyanic acid react in a solvent to obtain isophorone nitrile. JP4112862 uses calcium carbonate as catalyst, isophorone and hydrocyanic acid react in solvent to obtain isophorone nitrile, the selectivity is 99%, and the yield is 86%. The other is an organic base catalyst such as quaternary ammonium base/salt, quaternary phosphonium base/salt, diazole, guanidine, etc. For example: the method uses quaternary ammonium base as a catalyst in US5516928, US50119368 and the like, isophorone and hydrocyanic acid react to generate isophorone nitrile, and the yield is 96%. The method comprises the steps of reacting isophorone with hydrocyanic acid under the condition of solvent or no solvent by taking quaternary phosphonium salt as a catalyst in US5179221, JP61033157, US4299775 and the like, wherein the selectivity is more than 90%, and the yield is more than 90%.

By studying different reaction temperatures and pressures, it is generally known from the patent that the reaction temperature is between 100 and 200℃and the reaction pressure is either normal or elevated. The reaction temperature is 130-180 ℃ and the reaction pressure is normal pressure in the published patent US 5254711; the reaction temperature is 150-200 ℃ and the reaction pressure is 1-3bar in the published patent CN 1729162; in the publication US5011968, the reaction is carried out at a reaction temperature of 110-115℃and under normal pressure.

By studying different reaction processes, the method is divided into batch type and continuous type. The prior art reports a lot of batch processes, such as the published patent US3270044A1, the published patent US4299775, the published patent CN201010559261.9 and the like, and the batch processes are characterized by strong adaptability, simple equipment, high raw material conversion rate and high yield, but simultaneously, the batch processes have the problems of more needed matched equipment, large energy consumption, large occupied space, complex driving and the like. The methods of adopting a multi-kettle, fixed bed or reaction tube to realize continuous reaction in the published patent CN201610182680.2, CN201110083804.9, CN20130145143.7 and the like have a plurality of problems such as uneven material mixing, low mass and heat transfer efficiency, more byproducts and the like

The above prior art measures can improve the production efficiency or the reaction yield to some extent, but are not ideal for suppressing isophorone polymerization, isophorone nitrile decomposition, and the like. Therefore, there is a need to develop a new process for preparing isophorone nitrile to solve the problem of unstable isophorone and isophorone nitrile during the reaction.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, and provides a method for preparing isophorone nitrile by using a catalyst with alkalinity within a certain range, which enhances the high-temperature stability of isophorone and isophorone nitrile and ensures the process safety.

The inventor of the application finds that an alkaline substance with pKb less than or equal to 4 can be used as a catalyst to improve the reaction rate of isophorone and hydrocyanic acid, the polymerization rate of isophorone is accelerated along with the enhancement of alkalinity, and isophorone nitrile generated after the reaction is over can be reversely decomposed under the action of strong alkali to generate isophorone and hydrocyanic acid. Therefore, according to the discovered rule in the experimental process, amine substances with catalytic effect and relatively weak alkalinity are selected as catalysts, so that the safe, low-impurity and high-efficiency reaction effect is achieved. In addition, it has surprisingly been found that the selectivity to 3-cyano-3, 5-trimethylcyclohexanone is increased and the isomer content at the 2-or 4-position is reduced by the use of the above catalyst.

In order to achieve the above purpose, the invention adopts the following technical scheme:

a process for preparing isophorone nitrile includes such steps as reacting isophorone with hydrocyanic acid in the presence of basic catalyst, which is the aliphatic amine of pKb 2-4, adding acid to neutralize the reaction product, and distilling.

In the present invention, a substance as a basic catalyst is required to have an excellent dispersing effect and a strong base catalyst effect in an organic reaction system of isophorone and hydrocyanic acid, and aliphatic primary, secondary and tertiary amines can all well satisfy the above-mentioned requirements while considering that tertiary amines generally have a large steric hindrance and affect catalytic activity, so that the aliphatic amine is selected from aliphatic primary or secondary amines having 3 or more carbon atoms, preferably aliphatic primary or secondary amines having 4 to 20 carbon atoms, and is required to satisfy pKb in the range of 2 to 4, preferably pKb in the range of 2 to 3. Specifically, for example, one or more aliphatic amines selected from propylamine, diethylamine, dipropylamine, n-butylamine, piperidine, pyrrolidine, ethanolamine, 1, 4-butanediamine, 1, 5-pentanediamine, 1, 6-hexanediamine, isophoronediamine, 4' -diaminodicyclohexylmethane, 1, 4-cyclohexanediamine and the like, preferably one or more aliphatic amines selected from diethylamine, dipropylamine, piperidine and pyrrolidine.

In the invention, the molar ratio of isophorone to hydrocyanic acid to catalyst is 1:1:0.002-0.05, preferably 1:1:0.005-0.02. In practice, to achieve the above molar ratio of the raw materials, a mass flow meter is generally used for control, wherein the mass ratio of isophorone to hydrocyanic acid is 5.1:1.

In the invention, the reaction of isophorone and hydrocyanic acid is usually carried out in a solvent, and the solvent can be isophorone, or one or more of aromatic hydrocarbon solvents or carboxylic ester solvents; the aromatic hydrocarbon solvent is at least one selected from benzene, toluene, xylene, ethylbenzene, isopropylbenzene, butylbenzene, cyclohexylbenzene, tetrahydronaphthalene, chlorobenzene, o-dichlorobenzene, methylnaphthalene, biphenyl, triphenylmethane and the like; the carboxylic ester solvent is at least one selected from amyl acetate, methyl salicylate, diethyl isophthalate, dimethyl phthalate, dibutyl phthalate, methyl benzoate and the like; at least one of isophorone, amyl acetate, o-dichlorobenzene, and the like is preferable.

According to the process for preparing isophorone nitrile of the present invention, the ratio by mass of isophorone to the above solvent is 1:0.5 to 5, for example 1:0.5, 1: 1.1: 1.5, 1:2. 1:2.5, 1:3. 1:3.5, 1:4. 1:4.5, 1:5, etc., preferably 1:1-2.

In the present invention, the reaction temperature of isophorone and hydrocyanic acid in the presence of the basic catalyst is 100 to 200 ℃, for example, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃, 150 ℃, 160 ℃, 170 ℃, 180 ℃, 190 ℃, 200 ℃, etc., preferably 130 to 180 ℃; the reaction time is 0.5 to 5 hours, for example, 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, etc., preferably 1 to 3 hours; the reaction pressure is 0 to 0.5MPaG, for example, 0, 0.1, 0.2, 0.3, 0.4, 0.5MPaG, etc., preferably 0.1 to 0.3MPaG.

In the invention, raw material hydrocyanic acid enters the reactor in the form of liquid or gaseous high-purity product, and the reaction form is continuous or semi-continuous kettle reaction.

In the invention, in order to improve the stability of a reaction product isophorone nitrile or residual raw material isophorone in a separation system, an acid is needed to be added to neutralize the residual basic catalyst after the reaction is finished, wherein the acid is aliphatic or aromatic sulfonic acid or carboxylic acid, preferably aliphatic or aromatic sulfonic acid; preferably, the acid has a pKa < 3, preferably a pKa in the range of 0-2. Specifically, the acid is at least one selected from oxalic acid, monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, methanesulfonic acid, ethanesulfonic acid, methylbenzenesulfonic acid, dimethylbenzenesulfonic acid, benzenesulfonic acid, naphthalenesulfonic acid and the like; at least one of methanesulfonic acid, p-toluenesulfonic acid, naphthalenesulfonic acid and the like is preferable.

In the present invention, the molar ratio of sulfonic acid groups and/or carboxyl groups in the acid to amino groups in the reaction residual catalyst is 0.9 to 1.1:1, for example 0.9: 1. 0.95: 1.1: 1. 1.05:1. 1.1:1, etc., preferably 0.95-1.05:1. After the acid is added, the system is maintained in a neutral or neutral environment, so that unnecessary decomposition or polymerization reaction of isophorone nitrile reaction liquid in a subsequent separation system can be reduced, and the neutralization product quaternary ammonium salt has higher solubility in IPN and solvent, can not be separated out in isophorone nitrile reaction liquid, and finally can enter heavy components for incineration. The molar amount of amino in the residual catalyst can be theoretically regarded as the molar amount of amino in the fed catalyst, and the amino is directly added with a certain proportion of acid for neutralization according to the theoretical molar amount of amino without further detection in the actual operation process.

In the present invention, after the addition of the acid, isophorone nitrile reaction solution is distilled and purified. Typically, the rectification is carried out under reduced pressure. Specific purification process operations are well known in the art and will not be described in detail.

Compared with the prior art, the technical scheme provided by the invention has the following beneficial effects:

in the method for preparing isophorone nitrile, alkaline primary amine or secondary amine with pKb in the range of 2-3 is preferably used as a catalyst, so that the limit that strong alkali is needed in the traditional reaction process is broken, the self-polymerization of isophorone and HCN is reduced, and the stability of isophorone nitrile is improved. In addition, the selectivity of the 3-cyano-3, 5-trimethylcyclohexanone is obviously improved, and the content of the 2-or 4-isomer is obviously reduced.

The isophorone nitrile prepared by the preparation method has the reaction yield of more than or equal to 98 percent, the selectivity of isophorone polymer of less than or equal to 0.5 percent, the content of isophorone nitrile isomer of less than or equal to 1.0 percent, and the isophorone nitrile obtained by separation is used for synthesizing isophorone diamine, and the compound can be used for curing agents, crosslinking agents and the like of epoxy resin coatings; or further synthesizing isophorone diisocyanate for use in coatings, adhesives and the like.

Detailed Description

The invention will be further illustrated with reference to the following examples, but the invention is not limited to the examples listed but encompasses any other known modifications within the scope of the claims which follow.

The raw material sources are as follows:

isophorone, wanhua chemistry, 99.8%;

hydrocyanic acid, wanhua chemistry, 99.0%;

piperidine, enokic, 99.0%;

pyrrolidine, inokai, 99.0%;

isopropylamine, enokic, 99.0%;

1, 4-butanediamine, hiljj, 99.0%;

dipropylamine, wanhua chemistry, 99.0%;

ethanolamine, aledine, 99.0%;

sodium hydroxide, aledine, 99.0%;

lithium hydroxide, aledine, 99.0%.

GC purity testing instrument: agilent, column: DB-5, FID detector, sample inlet temperature 260 ℃, detector temperature 300 ℃, carrier gas: nitrogen (10 mL/min), split ratio 10:1, sample injection amount: 20ul. The initial temperature of the column box is 100 ℃, the column box is kept for 0.5 min, the temperature is raised to 160 ℃ at 15 ℃/min, the column box is kept for 1.5 min, the temperature is raised to 260 ℃ at 20 ℃/min, and the column box is kept for 9 min.

Example 1

138g (1.0 mol) of isophorone and 0.176g (0.002 mol) of 1, 4-butanediamine are taken and added into a 1L reaction kettle, 69g of isophorone is taken as a solvent and added into the mixed solution to be uniformly stirred, 27g (1.0 mol) of hydrocyanic acid is slowly added after heating to 100 ℃, and the dripping is completed within 0.5h. After the completion of the dropwise addition, the reaction temperature was maintained, and the reaction was continued for 5 hours under normal pressure.

After the completion of the reaction, 0.464g of dichloroacetic acid (0.0036 mol) was added to neutralize the reaction mixture after cooling to 70 ℃, and gas chromatography analysis showed that the yield of isophorone nitrile was 98.5% (based on HCN), the content of heavy component was 0.5%, and the content of isomer was 0.6%.

The isophorone nitrile reaction solution is further purified by distillation.

Example 2

138g (1.0 mol) isophorone and 0.295g (0.005 mol) isopropylamine are mixed and then added into a 1L reaction kettle, 138g amyl acetate is added into the mixed solution as a solvent, the mixed solution is stirred uniformly, nitrogen back pressure is introduced to 0.5MPaG, 27g (1.0 mol) hydrocyanic acid is slowly added after heating to 200 ℃, and the dropwise addition is completed for 0.5h. After the completion of the dropwise addition, the reaction temperature was maintained, and the reaction was continued for 0.5h.

After the reaction, 0.248g of oxalic acid (0.00275 mol) was added to neutralize when the temperature was lowered to 70 ℃, and gas chromatography analysis showed that the yield of isophorone nitrile was 98.3% (based on HCN), the content of heavy component was 0.4%, and the content of isomer was 0.4%.

The isophorone nitrile reaction solution is further purified by distillation.

Example 3

138g (1.0 mol) isophorone and 2.02g (0.02 mol) dipropylamine are taken and mixed, then added into a 1L reaction kettle, 276g o-dichlorobenzene is taken as a solvent and added into the mixed solution to be uniformly stirred, nitrogen is introduced to back pressure of 0.1MPaG, 27g (1.0 mol) hydrocyanic acid is slowly added after heating to 130 ℃, and the dropwise addition is completed for 0.5h. After the completion of the dropwise addition, the reaction temperature was maintained, and the reaction was continued for 1 hour.

After the completion of the reaction, 1.824g of methanesulfonic acid (0.019 mol) was added to neutralize the reaction mixture after cooling to 70 ℃, and gas chromatography analysis showed that the yield of isophorone nitrile was 98.1% (based on HCN), the content of heavy component was 0.5%, and the content of isomer was 0.5%.

The isophorone nitrile reaction solution is further purified by distillation.

Example 4

138g (1.0 mol) of isophorone and 3.55g (0.05 mol) of pyrrolidine are taken and mixed, then the mixture is added into a 1L reaction kettle, 138g of isophorone is taken as a solvent and added into the mixed solution to be uniformly stirred, nitrogen back pressure is introduced to 0.3MPaG, 27g (1.0 mol) of hydrocyanic acid is slowly added after the mixture is heated to 180 ℃, and the dropwise addition is completed for 0.5h. After the completion of the dropwise addition, the reaction temperature was maintained, and the reaction was continued for 2 hours.

After the reaction, 9.03g of p-toluenesulfonic acid (0.0525 mol) was added to neutralize the reaction mixture after the completion of the reaction, and gas chromatographic analysis showed that the yield of isophorone nitrile was 98.7% (based on HCN), the content of heavy component was 0.3%, and the content of isomer was 0.8%.

The isophorone nitrile reaction solution is further purified by distillation.

Example 5

138g (1.0 mol) isophorone and 1.702g (0.02 mol) piperidine are taken and mixed and then added into a 1L reaction kettle, 138g isophorone is taken as a solvent and added into the mixed solution to be uniformly stirred, nitrogen back pressure is introduced to 0.2MPaG, 27g (1.0 mol) hydrocyanic acid is slowly added after heating to 150 ℃, and the dropwise addition is completed for 0.5h. After the completion of the dropwise addition, the reaction temperature was maintained, and the reaction was continued for 3 hours.

After the reaction, 4.16g of naphthalenesulfonic acid (0.02 mol) was added to neutralize the reaction mixture after cooling to 70℃and the gas chromatography analysis showed that the yield of isophorone nitrile was 98.8% (based on HCN), the content of heavy component was 0.3% and the content of isomer was 1.0%.

The isophorone nitrile reaction solution is further purified by distillation.

Comparative example 1

138g (1.0 mol) of isophorone and 1.222g (0.02 mol) of ethanolamine are taken and mixed, then added into a 1L reaction kettle, 138g of isophorone is taken as a solvent, added into the mixed solution, uniformly stirred, introduced with nitrogen back pressure to 0.2MPaG, heated to 150 ℃, and then 27g (1.0 mol) of hydrocyanic acid is slowly added, and the dropwise addition is completed for 0.5h. After the completion of the dropwise addition, the reaction temperature was maintained, and the reaction was continued for 3 hours.

After the reaction, 4.16g of naphthalenesulfonic acid (0.02 mol) was added to neutralize the mixture after cooling to 70℃and the gas chromatography analysis showed that the yield of isophorone nitrile was 91.4% (based on HCN), the content of heavy component was 0.3% and the content of isomer was 0.4%.

The isophorone nitrile reaction solution is further purified by distillation.

Comparative example 2

138g (1.0 mol) of isophorone and 0.8g (0.02 mol) of sodium hydroxide are taken and mixed, then added into a 1L reaction kettle, 138g of isophorone is taken as a solvent, added into the mixed solution, uniformly stirred, introduced with nitrogen back pressure to 0.2MPaG, heated to 150 ℃, and then 27g (1.0 mol) of hydrocyanic acid is slowly added, and the dropwise addition is completed for 0.5h. After the completion of the dropwise addition, the reaction temperature was maintained, and the reaction was continued for 3 hours.

After the reaction, 4.16g of naphthalenesulfonic acid (0.02 mol) was added to neutralize the reaction mixture after cooling to 70℃and the gas chromatography analysis showed that the yield of isophorone nitrile was 97.3% (based on HCN), the content of heavy component was 0.8% and the content of isomer was 2.3%.

The isophorone nitrile reaction solution is further purified by distillation.

Comparative example 3

138g (1.0 mol) isophorone and 0.48g (0.02 mol) lithium hydroxide are taken and mixed, then added into a 1L reaction kettle, 138g o-dichlorobenzene is taken as a solvent and added into the mixed solution to be uniformly stirred, nitrogen back pressure is introduced to 0.2MPaG, 27g (1.0 mol) hydrocyanic acid is slowly added after heating to 150 ℃, and the dropwise addition is completed for 0.5h. After the completion of the dropwise addition, the reaction temperature was maintained, and the reaction was continued for 3 hours.

After the reaction, 4.16g of naphthalenesulfonic acid (0.02 mol) was added to neutralize the reaction mixture after cooling to 70℃and the gas chromatography analysis showed that isophorone nitrile was 97.5% (based on HCN) and the heavy component was 0.7% and the isomer was.71%.

The isophorone nitrile reaction solution is further purified by distillation.

Those skilled in the art will appreciate that certain modifications and adaptations of the invention are possible and can be made under the teaching of the present specification. Such modifications and adaptations are intended to be within the scope of the present invention as defined in the appended claims.

Claims (10)

1. A process for preparing isophorone nitrile includes such steps as reacting isophorone with hydrocyanic acid in the presence of basic catalyst to obtain isophorone nitrile, and purifying the resultant by distillation, and features that the basic catalyst is aliphatic amine with pKb 2-4, and the resultant is neutralized by adding acid before distillation.

2. The process according to claim 1, wherein the aliphatic amine is selected from aliphatic amines having 3 or more carbon atoms, preferably from 4 to 20 carbon atoms.

3. The preparation method according to claim 1 or 2, characterized in that the basic catalyst is an aliphatic primary or secondary amine of pKb 2-4, preferably an aliphatic primary or secondary amine of pKb 2-3.

4. A process according to any one of claims 1 to 3, wherein isophorone, hydrocyanic acid and basic catalyst are fed in a molar ratio of 1:1:0.002 to 0.05, preferably 1:1:0.005 to 0.02.

5. The method according to any one of claims 1 to 4, wherein the acid is an aliphatic or aromatic sulfonic acid or carboxylic acid, preferably an aliphatic or aromatic sulfonic acid;

preferably, the acid has a pKa < 3, preferably an aliphatic or aromatic sulphonic or carboxylic acid having a pKa in the range of 0-2.

6. The preparation process according to any one of claims 1 to 5, characterized in that the molar ratio of sulfonic acid groups and/or carboxylic acid groups in the acid to amino groups in the residual catalyst of the reaction is 0.9 to 1.1:1, preferably 0.95 to 1.05:1.

7. The preparation method according to any one of claims 1 to 6, wherein the reaction temperature of the reaction is 100 to 200 ℃, preferably 130 to 180 ℃; the reaction time is 0.5 to 5 hours, preferably 1 to 3 hours; the reaction pressure is 0 to 0.5MPaG, preferably 0.1 to 0.3MPaG.

8. The process according to any one of claims 1 to 7, wherein hydrocyanic acid is added in gaseous form or in liquid form.

9. The method of any one of claims 1 to 8, wherein the distillation is performed in a rectification column.

10. The process according to any one of claims 1 to 9, wherein the reaction is carried out in the presence of a solvent;

preferably, the solvent is selected from one or more of isophorone, aromatic hydrocarbon solvents, or carboxylic acid ester solvents;

more preferably, the aromatic hydrocarbon solvent is selected from at least one of benzene, toluene, xylene, ethylbenzene, cumene, butylbenzene, cyclohexylbenzene, tetrahydronaphthalene, chlorobenzene, o-dichlorobenzene, methylnaphthalene, biphenyl, and triphenylmethane; the carboxylic ester solvent is at least one selected from amyl acetate, methyl salicylate, diethyl isophthalate, dimethyl phthalate, dibutyl phthalate and methyl benzoate;

further preferably, the solvent is selected from any one of isophorone, chlorobenzene, o-dichlorobenzene.