The Synthesis of 3-Amino-4-hydroxybenzoic Acid

The 3amino4hydroxy benzoic acid was synthesized by using 4chloro3nitrobenzoic acid as the starting material.The result shows that if the hydrolyzed process runs with about 5.0 and 5.5 equivalent of sodium hydroxide for each equivalent of 4chloro3nitrobenzoic acid,its preferred reaction time is 3.5 hours.The intermediate 4hydroxy3nitrobenzoic acid is reduced by hydrogen gas with 5%PdC activator,and the results show: the reactive press of hydrogen gas is 0.25 Mpa,preferable pH being between 5.4 and 5.6,preferable temperature 100℃,preferable dosage of 5% PdC 2.5%.The purity of 3amino4hydroxybenzoic acid(HPLC) is over 99.5%.The total ratio is 84.3%.