Study on the Synthesis of Dye Intermediate 4-Hydroxy-6-Amino-N-methyl--2-Naphthlenesulfonamide

Dye intermediate 4-hydroxy-6-amino-N-methyl-2-naphthlenesulfonamide was synthesized from 4-hydroxy-6-amino-2-naphthlenesulfonic acid through four steps including acetylation of amido group and hydroxyl group, chloridation of the sulfonic group, amidation and hydrolysis.SOCl2 / ClSO3H was used as the reagent of chloridation at 40-45℃ with the molar ratio of 4-acetyloxy-6-acetylamino-2-naphthlenesulfonic acid Na salt:ClSO3H:SOCl2 = 1:7:3.The amidation reaction was carried out at 0-2℃ for 1 h and then at 40-45℃ for another one hour.The pH value was controlled at 10-11.The product was characterized by IR, EA and MS.