Quinone-Amine Reactions, XXV: 2-Amino-3,5,6-tribromo-1,4-benzoquinones and their instability in daylight

Article abstract of DOI:10.1002/ardp.19873200902

Tetrabromo-1,4-benzoquinone (2) reacts with the amines A-F to give the blue 2-amino-3,5,6-tribromo-1,4-benzoquinones 3a-f, which were isolated by column chromatography.Additionally, the brownish yellow 2,5-diamino-3,6-dibromo-1,4-benzoquinones 4a-f are formed.All 2-amino-3,5,6-tribromo-1,4-benzoquinones (3a-f) are unstable in daylight.Debromination from the amine-neighboring C-3 gives the 2-amino-5,6-dibromo-1,4-benzoquinones 5a-e.The rate of debromination depends on the nature of the amine function.Analysis by thin-layer chromatography indicates that the reaction between 2,3-dibromo-1,4-benzoquinone (6) and the amines A-F does not yield 5a-e. 2-Amino-3,5,6-tribromo- and 2-amino-5,6-dibromo-1,4-benzoquinones were previously unknown, except for derivatives of Desipramine (1).