Amino-anthraquinone prodn. from nitro-anthraquinone - by over-hydrogenation in inert organic solvent and re-oxidation to give pure prod.

摘要

In the prodn. of aminoanthraquinones (I) by redn. of nitroanthraquinones (II), (II) is over-hydrogenated partly beyond the amino stage with gaseous H2 in an inert organic solvent (III), in which (I) is soluble, at least when hot, in the presence of a solid hydrogenation catalyst (IV) and the over-hydrogenated prod. (V) is re-oxidised to (I) using a suitable anthraquinone-N cpd. (VI) with a higher degree of oxidn. than the corresp. (I). Pure and uniform (I) can be produced in high yield. (I) and (II) pref. are the 1-amino and 1-nitro cpds., (III) is a (substd.) aromatic hydrocarbon, aryl alkyl ether, aliphatic ether or ester and (IV) an opt. support noble metal (Pt or Pd) catalyst. Hydrogenation takes plate at 50-200 (80-160) degrees C and a H2 partial pressure of up to 15 at .g. to up to 7% over-hydrogenation.