2-Chloronitrobenzene is reacted with sodium disulfide at 80 ℃ in aqueous ethanol to give 2,2' -dinitrodiphenyl disulfide, which is isolated and treated with chlorine in mineral acid medium in the presence of nitric
acid to produce 2-nitrobenzenesulfonyl chloride by oxidative chlorination. This is hydrolyzed in dilute alkali, and the liquor of the resulting 2-Nitrobenzenesulfonic Acid is reduced with Fe – acid or H2 – catalyst to orthanilic acid [88-21-1], an important diazo component in reactive dyes for cotton.
