Chlorophenols

Abstract Chlorophenols are generally prepared by chlorinating phenol. Monochlorophenols, dichlorophenols, and trichlorophenols are used as intermediates for the synthesis of agrochemical compounds. Pentachlorophenol is used directly for the protection of wood. Chlorophenols are subjected to particularly severe quality control analyses. As well as quality improvement, the adoption of new analysis technology has resulted in a better understanding of chlorination mechanisms and of the formation of impurities liable to be found in certain chlorophenols. These studies have led to the introduction of new chlorination techniques using specific catalysts that permit controlled selective introduction of chlorine into the core and the elimination of certain products (2,4,5‐trichlorophenol) in 2,4,6‐trichlorophenol. Chemical processing stabilizes chlorophenols at the end of chlorination and avoids their evolution.