method of preparation of nitro anthraquinone virtually free of 2 - nitro - dinitro - anthraquinone and anthraquinone

摘要

Title material contaminated with 2-nitro and dinitroanthraquinone and conventionally purified by treatment with 0.2-0.5 mol. aq. Na2SO3 at 100 degrees C or with 0.5 pts. wt. aq. Na2SO3, is now purified with 0.2-2 pref. 0.4-1.5 mol. aq. H2SO3 salt, specif. Na, K, NH4 sulphite, NaHSO3, at a temp. above the normal atmos. pressure b.pt. of the mixt. and partic. at 100-150 pref. 130 degrees C under 1 atmos. pressure. Reaction mixt. opt. contains additives to give ph 8 pref. 9-12 and a surfactant. Product purity is 90% when temp. is 100 degrees C and 90% at 100 degrees C. Less sulphite waste is produced than when 0.5 pt. wt. Na2SO3 is used.