A kind of synthetic method of 5-bromo-2-chlorobenzoic acid

Abstract

The invention provides a synthesis method of 5-bromo-2-chloro benzoic acid.The method includes the following steps of A, making 2-chlorine benzotrichloride and bromide reagents react under the effect of a catalyst to obtain 2-chloro-5-bromine benzotrichloride, wherein bromide reagents include one or more of bromine, N-bromosuccinimide, dibromohydantoin and hydrobromic acid; B, conducting hydrolysis reaction on 2-chloro-5-bromine benzotrichloride in the step A under the acid condition to obtain 5-bromo-2-chloro benzoic acid.According to the method, 2-chlorine benzotrichloride which is low in price and easy to obtain is adopted as the raw material, operation is easy, intermediates do not need to be purified, 5-bromo-2-chloro benzoic acid is synthesized through a one-pot method, purity is high, yield is high, three-waste emission is little, and production cost is low.It is shown through experiment results that 2-chloro-5-benzoic acid obtained according to the synthesis method has yield larger than 95% and purity of 80-92%.

Description

technical field

[0001] The invention belongs to the technical field of organic synthesis, in particular to a method for synthesizing 5-bromo-2-chlorobenzoic acid. Background technique

[0002] 5-Bromo-2-chlorobenzoic acid is the starting material for the synthesis of the antidiabetic drug Dapagliflozin. Report at present that the synthetic method of 5-bromo-2-chlorobenzoic acid mainly contains following two kinds:

[0003] The synthesis route of 5-bromo-2-chlorobenzoic acid reported in the patent CN1740135 is, starting from 5-bromo-2-chlorobenzotrifluoride, heating and hydrolyzing in oleum, and then adding the reaction solution into crushed ice to precipitate The crude product was recrystallized from toluene to obtain the product. This route adds a lot of sulfuric acid, which cannot be recovered; and produces a large amount of fluorine-containing waste water, which is difficult to handle. In addition, the raw materials used in this synthetic route are very expensive. It ...