The invention discloses an environment-friendly production method for permanent violet RL, which comprises the following: (1) a step of
alkylation which is to prepare liquid caustic soda, add a
carbazole raw material, a catalyst and pure
benzene in turn, drip
bromoethane, stand the solution and separate out N-ethyl
carbazole; (2) a step of
nitration, which is to add the N-ethyl
carbazole and
chlorobenzene, drip
nitric acid of which the weight percentage concentration is 36.5 to 37.5 percent, and separate out an intermediate 3-nitro-N-ethyl carbazole; (3) a step of reduction, which is to add
chlorobenzene, 3-nitro-N-ethyl carbazole and an
iron catalyst in turn, drip hydrazine
hydrate to obtain a solution of 3-animo-N-ethyl carbazole and ortho-
dichlorobenzene; (4) a step of condensation, which is to add ortho-
dichlorobenzene into the solution of 3-animo-N-ethyl carbazole and ortho-
dichlorobenzene, add tetrachlorobenzoquinone, drip
sodium acetate and obtain a permanent violet RL condensation compound; and (5) a step of ring-closing reaction, which is to add
benzene sulfonyl chloride, filter the solution, wash a
filter cake, dry and obtain coarse permanent violet RL. The method has high conversion rate and is environment-friendly.