According to the literature, the synthesis methods of this intermediate are 4-chloro-3-nitrobenzenesulfonic acid amination than; o-nitroaniline sulfonation with sulfuric acid or chlorosulfonic acid as sulfonating agent respectively; the first method, the reaction needs to be carried out under a certain pressure, and the synthesis process is also more complicated; the solvent used for the second method is a mixture of monochlorobenzene and dichlorobenzene, and the product yield of sulfuric acid as the sulfonation agent is 89.3%, and the product yield of chlorosulfonic acid as the sulfonating agent is 90%. The second method used a mixture of monochlorobenzene and dichlorobenzene as solvent. The solvent and the chlorosulfonic acid are both more expensive.
