Unsaturated compounds containing nitrogen. Part I. The synthesis and disproportionation of 1-chloro-azines, and their reactions with nucleophiles
A general method is described for the synthesis of 1-chloro-azines, ArCCl:N·N:CHAr′, from the corresponding aroylhydrazones of aromatic aldehydes by treatment with thionyl chloride. 1-Chloro-1,4-diphenyl-2,3-diazabuta-1,3-diene disproportionates into benzaldazine and 1,4-dichloro-1,4-diphenyl-2,3-diazabuta-1,3-diene in refluxing ethanol, and similar disproportionation reactions of other azines are discussed. The reaction of 1-chloro-1,4-diphenyl-2,3-diazabuta-1,3-diene with Grignard reagents provides an alternative route to ketoaldazines, PhCR:N·-N:CHPh, and its reaction with ammonia gives, besides the expected 1-amino-azine, PhC(NH2):N·N:CHPh, benzaldazine, and 3,5-diphenyl-1,2,4-triazole, probably by disproportionation and elimination of ammonia.