阅读说明：本技术 一种2,2,4-三甲基-1,3-戊二醇单异丁酸酯的制备方法 (Preparation method of 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate ) 是由 崇明本 冯建成 冯子涵 袁野 于 2020-08-27 设计创作，主要内容包括：本发明涉及有机合成技术领域,具体是一种制备2,2,4-三甲基-1,3-戊二醇单异丁酸酯的方法。本发明提供的制备2,2,4-三甲基-1,3-戊二醇单异丁酸酯的方法,将异丁醛在离子液体催化剂存在下进行缩合反应,得到2,2,4-三甲基-1,3-戊二醇单异丁酸酯,本发明方法采用阳离子为烷基咪唑类阳离子或苯并咪唑类阳离子,阴离子为选自氢氧根离子、醋酸根离子中的至少一种的离子液体作为催化剂,一步法制备2,2,4-三甲基-1,3-戊二醇单异丁酸酯,反应条件温和,反应转化率高,选择性好,后续产品易于分离。(The invention relates to the technical field of organic synthesis, in particular to a method for preparing 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate. According to the method for preparing 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate, isobutyraldehyde is subjected to condensation reaction in the presence of an ionic liquid catalyst to obtain the 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate, the method adopts ionic liquid as a catalyst, wherein cations are alkyl imidazole cations or benzimidazole cations, and anions are at least one selected from hydroxyl ions and acetate ions, the 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate is prepared by a one-step method, the reaction conditions are mild, the reaction conversion rate is high, the selectivity is good, and subsequent products are easy to separate.)

1. A preparation method of 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate is characterized in that isobutyraldehyde is subjected to condensation reaction in the presence of an ionic liquid catalyst to obtain the 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate.

2. The method for preparing 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate according to claim 1, wherein the cation of the ionic liquid catalyst is one or a mixture of alkyl imidazole cations or benzimidazole cations.

3. The method for preparing 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate according to claim 1 or 2, wherein the anion of the ionic liquid catalyst is either one or a mixture of hydroxide ion and acetate ion.

4. The method for preparing 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate according to claim 2, wherein the alkyl imidazole cationic liquid catalyst has the following structural formula:

wherein R is₁Is C1-10 alkyl, R₂Is an alkyl group or an ester group having 2 to 10 carbon atoms.

5. The method for preparing 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate according to claim 4, wherein the benzimidazole-based cationic liquid catalyst has the following structural formula:

6. The method for preparing 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate according to any one of claims 4 to 5, wherein the mass ratio of isobutyraldehyde to ionic liquid catalyst is (1-20): 1.

7. the method of claim 1, wherein the condensation reaction is carried out at a temperature of 40 ℃ to 100 ℃.

8. The method according to claim 7, wherein the condensation reaction is carried out under a pressure of 0.1 to 5 MPa.

9. The process for preparing 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate according to claim 7, comprising the following steps:

s1, adding isobutyraldehyde and an ionic liquid catalyst into a three-necked bottle with a reflux condenser pipe and a stirrer, and stirring, wherein the reaction pressure is 0.1-5 MPa;

s2, raising the temperature of the reaction system to 40-100 ℃, and continuously stirring for reaction for 2 hours;

s3, cooling the reaction system to room temperature, removing unreacted raw materials, carrying out reduced pressure distillation separation, and collecting to obtain 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate.

Technical Field

The invention relates to the technical field of organic synthesis, in particular to a preparation method of 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate.

Background

2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate, commonly called alcohol ester twelve, also called Texanol alcohol ester, is a water-insoluble high-boiling point dihydric alcohol ester, has good resin compatibility, viscosity, good film forming performance and low melting point, can effectively reduce the film forming temperature of latex paint with high glass transition temperature, and has been widely used as a film forming aid of coating.

Currently, in the industrial production of alcohol ester twelve, isobutyraldehyde is used as a raw material, and the product is obtained through aldol condensation, Cannizzaro reaction and separation under the action of a basic catalyst. At present, the commonly used catalyst is inorganic base, particularly alkali metal hydroxide is the most common, a few reports that alkali metal oxide and alkaline earth metal strong oxide are also used as the catalyst, in addition, organic base is also reported as the catalyst, sodium methoxide is the most common, and two-stage reaction process is mostly adopted in industrial production, wherein alcohol ester condensation reaction is carried out in the first stage, and Cannizzaro reaction is carried out in the second stage to generate monoester. But the two-stage reaction has the disadvantages of complex operation, long process route, high energy consumption and wastewater discharge which mostly does not meet the requirements of low energy consumption and environmental protection. And the sodium alkoxide is used as a catalyst, the reaction is violent, the bumping is easy, and the sodium alkoxide and a reaction product cannot be directly separated by rectification, and the sodium alkoxide and the reaction product need to be separated by a method of firstly washing with water or acid and then standing and layering a water phase and an oil phase. The separation method needs to introduce water, water and isobutyraldehyde form an azeotrope, and the azeotrope is difficult to rectify and separate, and the catalytic activity of the inorganic base catalyst generated after water washing is obviously reduced relative to that of organic base.

In view of the above-mentioned drawbacks of the conventional method for preparing 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate, the present inventors have conducted extensive practical experience and professional knowledge for many years in designing and manufacturing such products, and have conducted reasonable application and active research and innovation to develop a method for preparing 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate, so as to improve the reaction conversion rate of the method for preparing 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate and make it more practical. After continuous research and design and repeated trial production and improvement, the invention with practical value is finally created.

Disclosure of Invention

The invention aims to provide a method for preparing 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate (alcohol ester twelve), which has the advantages of mild reaction conditions, high reaction conversion rate, good selectivity and easy separation of subsequent products, and can realize separation by adopting direct distillation and reduced pressure distillation without water washing.

The technical purpose of the invention is realized by the following technical scheme:

according to the preparation method of 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate, isobutyraldehyde is subjected to condensation reaction in the presence of an ionic liquid catalyst to obtain the 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate. The method adopts the ionic liquid as the catalyst to prepare the 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate by a one-step method, has the advantages of mild reaction conditions, high reaction conversion rate, good selectivity and easy separation of subsequent products.

Furthermore, the cation of the ionic liquid catalyst is one or a mixture of several of alkyl imidazole cation or benzimidazole cation.

Further, the anion of the ionic liquid catalyst is any one or a mixture of two of hydroxide ion and acetate ion.

Further, the alkyl imidazole cationic liquid catalyst has the following structural formula:

wherein R is₁Is C1-10 alkyl, R₂Is an alkyl group or an ester group having 2 to 10 carbon atoms.

Further, the structural formula of the benzimidazole cationic liquid catalyst is as follows:

wherein R is₁Is C1-10 alkyl, R₂Is alkyl or ester group with 2-10 carbon atoms, R₃Is C1-10 alkyl or H, R₄Is alkyl with 1-5 carbon atoms or H.

Further, the mass ratio of isobutyraldehyde to ionic liquid catalyst is (1-20): 1.

furthermore, the mass ratio of isobutyraldehyde to the ionic liquid catalyst is (2-10): 1.

Further, the reaction temperature of the condensation reaction is 40 ℃ to 100 ℃.

Furthermore, the reaction temperature of the condensation reaction is 50-90 DEG C

Further, the reaction pressure of the condensation reaction is 0.1-5 MPa.

Further, the reaction pressure of the condensation reaction is 0.2-2 MPa.

Further, the preparation method of the 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate provided by the invention comprises the following operation steps:

s1, adding isobutyraldehyde and an ionic liquid catalyst into a three-necked bottle with a reflux condenser pipe and a stirrer, and stirring, wherein the reaction pressure is 0.1-5 MPa;

s2, raising the temperature of the reaction system to 40-100 ℃, and continuously stirring for reaction for 2 hours;

s3, heating the product after the reaction to 140-200 ℃ and the pressure of 0.01-0.1 MPa, and removing unreacted raw materials, byproducts and the like; and then distilling at 200-260 ℃ and under the pressure of 0.01-0.1 MPa, and collecting to obtain a product 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate.

And S4, recovering the ionic liquid after the unreacted raw materials and the products are removed by distillation and continuously using the ionic liquid as a catalyst.

In conclusion, the invention has the following beneficial effects:

according to the method for preparing 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate (alcohol ester twelve), 2, 4-trimethyl-1, 3-pentanediol monoisobutyrate is prepared by a one-step method by using an ionic liquid as a catalyst, wherein cations are alkyl imidazole cations or benzimidazole cations, and anions are at least one of hydroxide ions and acetate ions, so that the reaction conversion rate is improved, the complexity of two-stage reaction processes of inorganic base catalysis is avoided, and the bumping risk of a sodium alkoxide process is also avoided. The method achieves the aims of simple process, high single-pass yield, small catalyst consumption, low energy consumption, safety and environmental protection.

Detailed Description

To further illustrate the technical means and effects of the present invention adopted to achieve the predetermined objects, the detailed description of the method for preparing 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate according to the present invention, the specific embodiments, features and effects thereof are described as follows.

The ionic liquids used in the experiments were as follows:

ionic liquid catalyst a: [ Bmim ] OH:

ionic liquid catalyst B: [ Bmim ]]CH₃COO：

Ionic liquid catalyst C: [ Bzmebim ] OH:

ionic liquid catalyst D: [ Bzmebim]CH₃COO：