Synthesis and properties of the chlorination products of methyl 4‐amino‐2‐hydroxy‐benzoate. I

Abstract

AbstractExhaustive chlorination of methyl 4‐amino‐2‐hydroxy‐benzoate (XIII) (P.A.S. methyl ester) in a mixture of glacial acetic acid and hydrochloric acid (s.g. 1.19) yielded methyl 1,3,3,5,5,6‐hexachloro‐cyclohexanedione‐2,4‐carboxylate‐1 (XIV). Methyl 4‐amino‐3,5‐dichloro‐2‐hydroxy‐benzoate (XV), methyl 2‐amino‐4‐hydroxy‐benzoate (XVI), methyl 2,4‐dihydroxy‐benzoate (XVII), and methyl 3,5‐dichloro‐2,4‐dihydroxy‐benzoate (XVIII) could also be used as starting material for XIV. Reduction of XIV with stannous chloride yielded XVIII. With hypochlorous acid, XIV reacted with ring fission to form 1,1,2,3,5,5,5‐heptachloro‐3‐carbomethoxy‐pentanone‐4‐carboxylic acid‐1 (XIX). Both compounds XIV and XIX decomposed in alkaline medium and yielded monomethyl trichloro‐glutaconate (XX). In the first case the latter compound was accompanied with dichloro‐acetic acid, in the second case trichloro‐acetic acid was the other decomposition product. Glutaconic acid (XXI) was formed when XIX was reduced with sodium amalgam, while the structure of a 5‐carbomethoxy‐6‐trichloromethyl‐pyrone‐2 (XXII) is proposed for the reaction product of XIX with stannous chloride.