A COMPARATIVE STUDY OF METHODS OF THE SALICYLIC ACID CHLORINATION FOR FURTHER PRODUCTION OF ANTIHELMINTHIC DRUGS

Abstract

With the help of thin-layer and high-performance liquid chromatography, the change in the composition of the reaction mass during the chlorination of salicylic acid was studied by three methods: molecular chlorine in acetic acid, sodium hypochlorite in an aqueous alkaline solution and oxidative chlorination with a mixture of hydrogen peroxide and hydrochloric acid in an acetic acid environment. It is shown that the most complete transformation of salicylic acid into 3,5-dichlorosalicylic acid is observed in the reaction with sodium hypochlorite, and the least complete - in the reaction of oxidative chlorination. It was found that the adverse reaction of the ipso-replacement of the carboxyl group with the formation of 2,4,6-trichlorophenol to the greatest extent occurs in chlorination of salicylic acid with gaseous chlorine in the acetic acid and with sodium hypochlorite in the aqueous alkaline medium. It is established that recrystallization technical 3,5-dichlorosalicylic acid of 50% aqueous 2-propanol to most effectively allows you to remove the admixture of 2,4,6-trichlorophenol, and to a lesser extent, admixture chlorosalicylic acids.

Keywords

• 3,5-dichlorosalicylic acid
• anthelmintic drug substances
• chlorine
• sodium hypochlorite
• hydrogen peroxide
• hydrochloric acid