Failed mauveine syntheses and the mechanistic insight they provide into the role of linear trimers in mauveine synthesis

A mixed ligand ZnCl 2 complex of N -tolyl- p -phenylenediamine, ZnCl 2 (C 13 H 14 N 2 ) 2 , was unexpectedly formed in situ in the Zn/EtOH/H + reduction of 4-nitrophenylaminotoluene and was characterised by an X-ray single crystal structure determination. The Zn 2+ cations were presumably formed by oxidation with the cHCl in EtOH used to clean the zinc metal surface. Two failed mauveine syntheses with preformed building blocks suggest that linear trimers are mauveine precursors in the William Henry Perkin 1856 mauveine synthesis. An unusual synthesis of phenyliminoquinone (C 13 H 13 N 3 O 2 ) is reported which provides further evidence on the mechanism of mauveine formation.