The invention belongs to the technical field of sulfonamide synthesis, and particularly relates to a green and environment-friendly sulfonamide amidation preparation method. Comprising the following steps: adding
chlorosulfonic acid into a reactor, stirring, heating, adding o-
nitrochlorobenzene, carrying out staged heat preservation, cooling, and adding
thionyl chloride to obtain 2-nitro-4-
chlorine sulfonate-
chlorobenzene; the method comprises the following steps: separating and filtering 2-nitro-4-
chlorine sulfonate-
chlorobenzene, adding
ammonia water, stirring, preserving heat, and carrying out filter pressing to obtain 2-nitro-4-amine
sulfonate-
chlorobenzene; the preparation method comprises the following steps: adding liquid caustic soda into 2-nitro-4-amine sulfonate-chlorobenzene, stirring, heating, and adjusting the pH value to obtain 2-nitro-4-amine sulfonate-
phenol; the method comprises the following steps: adding water, a catalyst and hydrazine
hydrate into 2-nitro-4-amine sulfonate-
phenol, heating, stirring, and carrying out filter pressing to obtain 4-sulfonamide-2-amino-
phenol. According to the preparation method of sulfonamide, generated
tail gas is subjected to falling film absorption treatment, and the product prepared by the preparation method is high in purity.