Triazines and related products. Part X. A re-examination of the reaction between benzil and diaminoguanidine nitrate

Benzil reacts with diaminoguanidine nitrate to yield the nitrate salt of benzil mono[(aminoamidino)hydrazone] (2). The hydrazone (2) is unstable, and cyclises on melting or in solvents to 5,6-diphenyl-3-hydrazino-1,2,4-triazine (3). Diazotisation of the hydrazone (2) and of hydrazine (3) affords the same product, 6,7-diphenyltetrazolo-[1,5-b]-as-triazine (9) which decomposes in boiling secondary amines to yield substituted 3-amino-5,6-diphenyl-1,2,4- triazines and hydrazoic acid. Both the hydrazone (2) and the hydrazine (3) react with triethyl orthoformate or formic acid to give 6,7-diphenyltriazolo[4,3-b]- as-triazine (16), which was also prepared, unambiguously, from benzil and 3,4-diamino-1,2,4-triazole. Although conditions favourable for Dimroth rearrangement were employed, no such transformations were encountered in the reactions of the bicyclic systems (9) and (16).