On the nitrosation of N-monosubstituted 1-naphthylamines - Formation of N-monosubstituted 4-nitroso-1-naphthylamine derivatives and benzocondensed indaminium salts

By nitrosation of the mineralic acid salts of N-monosubstituted 1-naphthylamines (7) N-monosubstituted N'-hydroxy-naphthoquinone diiminium salts (9) are formed. These compounds can condense with their naphthylamine educts 7 to deeply colored N-(4-amino-naphthyl)-substituted naphthoquinone diiminium salts 11 which are available by the reaction of the mineralic acid salts of N-monosubstituted 1-naphthylamines 7 with one half equivalent of nitrous acid in acetic acid solution also. The new indaminium salts 11 absorb, in contrast to their deprotonated species 12 which exhibit intense absorption bands at about 550 nm, in the near infrared region very intensively at about 820 nm.