A new Synthesis of 1-Amino-4-butylaminoanthraquinone from 1-Aminoanthraquinone Promoted by Metal Ions

Article abstract of DOI:10.1246/bcsj.53.2552

In the presence of some metal ions and atmospheric oxygen, 1-aminoanthraquinone (1) reacts readily with butylamine to give 1-amino-4-butylaminoanthraquinone(2a), along with a small amount of 1,4-diaminoanthraquinone, which is produced by the dealkylation of 2a.The activity of the metal ions decreased in the following order: Co(II) >> Ni(II) above Cu(II) above Al(III).The reaction is remarkably affected by the substitution of an alkyl group into the amino group of 1, the addition of a chelating agent, the counter anion of metal ions, and the reaction temperature.By the use of cobalt(II) chloride, the reaction proceeds most smoothly at about 30 deg C.Both anthraquinone and 2-aminoanthraquinone show no sign of the reaction under the same conditions.A possible mechanism involving the formation of a metal complex, followed by the nucleophilic attack of amine at the 4-position and the oxidative abstraction of the hydride anion by atmospheric oxygen is proposed.