CN-122010718-A - Preparation method of 2- (4-hydroxybenzoyl) benzoic acid

Abstract

The invention discloses a preparation method of 2- (4-hydroxybenzoyl) benzoic acid, belonging to the technical field of organic intermediate synthesis. Mixing phenol, phthalic acid, water absorbent and catalyst in hexafluoroisopropanol, and reacting at elevated temperature to obtain 2- (4-hydroxybenzoyl) benzoic acid. The raw materials are available in the market, the HF complex is adopted as the catalyst, the catalyst can be recycled, the catalytic efficiency is high, the phthalic anhydride is adopted as the water absorbent, water generated after condensation of the phthalic acid is absorbed, the activity of the catalyst is kept, and simultaneously, the phthalic anhydride and the water continuously react to generate the phthalic acid which can be continuously used as the raw materials for reaction, so that the method is more environment-friendly.

Inventors

• WANG GANG
• WU LIHAO

Assignees

• 大连中科聚合新材料科技有限公司

Dates

Publication Date

20260512

Application Date

20260112

Claims (6)

1. 1. A preparation method of 2- (4-hydroxybenzoyl) benzoic acid is characterized by comprising the steps of mixing phenol, phthalic acid, a water absorbent and a catalyst in hexafluoroisopropanol, reacting at a heating condition to obtain 2- (4-hydroxybenzoyl) benzoic acid, and mixing phenol, phthalic acid, phthalic anhydride and trifluoromethanesulfonic acid in hexafluoroisopropanol, and reacting at 50-80 ℃ to obtain 2- (4-hydroxybenzoyl) benzoic acid.
2. 2. The method for producing 2- (4-hydroxybenzoyl) benzoic acid according to claim 1 wherein in method A, the water absorbing agent is phthalic anhydride.
3. 3. A process for preparing 2- (4-hydroxybenzoyl) benzoic acid according to claim 1 wherein in Process A the catalyst is selected from the group consisting of Pyridine-9HF, DMPU-12HF and KHSO 4 -13HF.
4. 4. The process for preparing 2- (4-hydroxybenzoyl) benzoic acid according to claim 1 wherein in Process A, the temperature is raised to 20 to 50 ℃.
5. 5. The method for preparing 2- (4-hydroxybenzoyl) benzoic acid according to claim 1 wherein in method A the molar ratio of phenol, phthalic acid, water absorbing agent to catalyst is 1:1-1.2:0.95-1.05:0.3-0.7.
6. 6. The method for producing 2- (4-hydroxybenzoyl) benzoic acid according to claim 1 wherein in method B the molar ratio of phenol, phthalic acid, phthalic anhydride to trifluoromethanesulfonic acid is 1:1.4-2:0.95-1.05:2-4.

Description

Preparation method of 2- (4-hydroxybenzoyl) benzoic acid Technical Field The invention relates to a preparation method of 2- (4-hydroxybenzoyl) benzoic acid, belonging to the technical field of organic intermediate synthesis. Background 2- (4-Hydroxybenzoyl) benzoic acid (CAS No. 85-57-4) is used as important chemical intermediate or raw material, and is mainly used for preparing polymer materials, organic intermediate, catalyst carrier and the like. The field ‌ of polymer materials is that 2- (4-hydroxybenzoyl) benzoic acid and hydrazine hydrate undergo a cyclization reaction to prepare 4- (4-hydroxyphenyl) phthalazine-1 (2H) -ketone (DHPZ, CAS: 152594-70-2), which is a main monomer for synthesizing polymer materials of polyaryletherketone (PPEK). Regarding the synthetic route of 2- (4-hydroxybenzoyl) benzoic acid, there are mainly two kinds of patent and literature [European Journal of Organic Chemistry, 2017, 2017, 3274;WO 2006248 37A1;Journal of Medicinal Chemistry, 2006, 49, 6209;Chemist ry - A European Journal, 2016, 22, 12363], in which phenolphthalein is used as a raw material, and the raw material is reacted under the action of hydroxylamine hydrochloride and alkali, and then the reaction is acidified again to produce 2- (4-hydroxybenzoyl) benzoic acid, and patent and literature [CN118063390A;Research on Chemical Intermediates, 2019, 45, 2007;Journal of Enzyme Inhibition and Medicinal Chemistry, 2012, 27, 748;Journal of Medicinal Chemistry, 2004, 47, 2486], in which phthalic anhydride and phenol are used as raw materials, and in which the Friedel-crafts reaction is carried out under the catalysis of aluminum trichloride to produce 2- (4-hydroxybenzoyl) benzoic acid. The currently reported synthesis method has the defects of high cost of raw materials or byproducts, difficult purification of products and the like, so that the synthesis method of 2- (4-hydroxybenzoyl) benzoic acid is researched and explored, the raw materials which are easy to obtain and cheap are provided, a simple and economic route is provided, the cost of DHPZ/PPEK can be better reduced, and the application range of the method is widened. Disclosure of Invention The present invention has been made to solve the above problems, and an object of the present invention is to provide a production method with high yield and economical route. In order to solve the technical problems, the invention adopts the following technical scheme that phenol and phthalic acid are used as raw materials, and 2- (4-hydroxybenzoyl) benzoic acid is synthesized by a one-step method under the action of a catalyst and a water absorbent. The invention provides a preparation method of 2- (4-hydroxybenzoyl) benzoic acid, which comprises the following steps: Mixing phenol, phthalic acid, a water absorbent and a catalyst in hexafluoroisopropanol, and reacting under the condition of heating to obtain 2- (4-hydroxybenzoyl) benzoic acid; mixing phenol, phthalic acid, phthalic anhydride and trifluoromethanesulfonic acid in hexafluoroisopropanol, and reacting at 50-80 ℃ to obtain 2- (4-hydroxybenzoyl) benzoic acid. The synthetic route of the invention adopts the reaction equation as follows: further, in the above method A, preferably, the water absorbing agent is phthalic anhydride. Further, in the above method A, the catalyst is preferably selected from the group consisting of Pyridine-9 HF, DMPU-12HF and KHSO 4 -13HF. Further, in the above method A, the temperature is preferably raised to 20 to 50 ℃. Further, in the above method A, the molar ratio of the phenol, phthalic acid, water absorbing agent to the catalyst is preferably 1:1 to 1.2:0.95 to 1.05:0.3 to 0.7. Further, in the above method B, the molar ratio of the phenol, the phthalic acid, the phthalic anhydride and the trifluoromethanesulfonic acid is preferably 1:1.4-2:0.95-1.05:2-4. The invention has the following beneficial effects: 1. the invention adopts cheap and easily available phenol and phthalic acid as raw materials to prepare the 2- (4-hydroxybenzoyl) benzoic acid through one-step reaction, and has short route, good operability and high overall yield. 2. In the invention, phthalic anhydride is used as a water absorbent to absorb water generated after condensation of phthalic acid, so that the activity of the catalyst is maintained, and simultaneously, phthalic anhydride and water continuously react to generate phthalic acid which can be continuously used as raw materials for reaction, and excessive phthalic acid can be recycled, so that the cost is reduced. 3. The invention adopts the HF complex as the catalyst, can be recycled, has high catalytic efficiency, avoids the use of aluminum trichloride catalyst to generate waste solids and has low conversion rate. DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION The invention is further illustrated by the following specific examples. These examples should be construed as merely illustrative of the present invention and not limiting the scope of the p