Method for preparing high-purity 4,4'-difluorobenzophenone

Abstract

The invention discloses a method for preparing high-purity 4,4'-difluorobenzophenone. p-fluorotoluene is used as an initial raw material and oxidation reaction, chloroformylation reaction and condensation reaction are carried out, so that the target product 4,4'-difluorobenzophenone is finally obtained; the melting point of the product is 107-109 DEG C; the purity of the product is greater than or equal to 99.9 percent and accords with the purity requirement for synthesis of polyether-ether-ketone (PEEK). Moreover, according to the preparation method disclosed by the invention, the used raw material is cheap and is easy to obtain, the synthetic process conditions are mild and in the synthesizing process, a used reagent is relatively green and environmental-friendly, and thus, the method has wide application prospect and high industrial value.

Description

technical field [0001] The invention relates to the field of preparation of fluorine-containing intermediates, in particular to a method for preparing high-purity 4,4'-difluorobenzophenone. Background technique [0002] 4,4′-Difluorobenzophenone is an important fluorine-containing intermediate, which is an important intermediate for the synthesis of fluorine-containing drugs flunarizine, lomerizine, and almitrigine. Its special application lies in its It is the monomer of special high-performance engineering plastic polyetheretherketone (PEEK). In the chemical and military fields, polyetheretherketone (PEEK) is a special polymer material. It has physical and chemical properties such as high temperature resistance and chemical corrosion resistance. It is a kind of high temperature resistant structural material and electrical insulation material. It can be combined with glass fiber or carbon fiber to prepare reinforced materials. A class of polyarylether polymers obtained by ...

AI Technical Summary

Problems solved by technology

[0003] At present, there are many routes for public reports on 4,4'-difluorobenzophenone, mainly as follows: (1) Patent EP 178184 reports that fluorobenzene and p-fluorobenzoyl chloride are used as raw materials in trichlorination Under the catalysis of aluminum, product is made, and this method yield is higher, and the purity of product is also relatively high, but the cost of the raw material p-fluorobenzoyl chloride of reaction is on the high side, is unfavorable for suitability for industrialized production; (2) China Pharmaceutical Industry Journal, 40(10), 737-738; 2009 Using fluorobenzene as raw material, the product was obtained under the direct catalysis of phosgene and aluminum trichloride, but the content of the isomer 2,4'-difluorobenzophenone in the product Higher, in addition phosgene is highly toxic, and the yield of this route is also low; (3) Journal of Hebei University of Science and Technology, 29 (1), 20-22; 2008 reported that fluorobenzene was used as raw material, carbon tetrachloride Under the catalysis of aluminum chloride, 4,4'-difluorodiphenyldichloromethane is generated, and then hydrolyzed under acidic conditions to obtain the product. This method is simple to operate, but the by-product isomer 2,4'-difluorobenzophenone More, not conducive to purification, and the yield is also low; (4) patent JP 61221146 uses fluorobenzene as raw material, in the presence of CO and air, with PdCl 2 and FeCl 3 The product is obtained by reacting the catalyst, which requires high temperature and pressure, and the catalysis of the reaction is relatively expensive, so it is not easy to realize the cost control of industrialization; (5) Patent US 4453009 reports the use of 4,4'-dichloro Benzophenone is used as the starting raw material, and 4,4'-difluorobenzophenone is obtained through KF fluorination. The raw material of this method is not easy to prepare, and the conversion is not complete, and it is difficult to obtain a product with a purity that meets the requirements; (6) Patent EP 0004710 reported 4,4'-diaminodiphenylmethane as starting material, and NaNO 2 4,4′-difluorodiphenylmethane is produced by Sandmeyer reaction with HF, and then oxidized by nitric acid at low temperature. This route has been industrialized, but the reaction time is long, the equipment is seriously corroded, and there are hidden dangers of explosion, etc. limitation