PREPARATION OF 2-AMINO-4-CHLOROPHENOL

PURPOSE:To obtain the titled compound useful as an intermediate for dye or drugs in high yield, by hydrolyzing 2,5-dichloronitrobenzene in a prescribed alkali concentration range to give 2-nitro-4-chlorophenolate, reducing, and neutralizing it. CONSTITUTION:Hydrolysis of 2,5-dichloronitrobenzene is started at 3.5-6% alkali concentration (weight ratio to water), and the alkali concentration in the middle of the reaction is limited to 1-6% and the compound is hydrolyzed to give 2-nitro-4-chlorophenolate, which is reduced, and nutralized to give the aimed 2-amino-4-chlorophenolate. As for the hydrolyzing conditions, by-products are increased and yield is lowered when the alkali concentration exceeds 6%, the reaction is slightly started when the alkali concentration at the beginning of the reaction is lower than 3.5%, and the reaction rate is extremely low and the hydrolysis is not practical when the alkali concentration in the middle of the reaction is