The reaction of formaldehyde arylhydrazones with excess formaldehyde and the acetylation of arylhydrazines

Abstract

A detailed examination of the reaction of excess formaldehyde with formaldehyde phenylhydrazone and formaldehyde 4-bromophenylhydrazone has shown that the products are the respective 3,6-endo-methylene-1,4- diarylhexahydro-s-tetrazines [(4) and (II)], the symmetrical 2?- oxapropano compounds [(8) and (10)] and the unsymmetrical 2?-oxapropano compounds [(7) and (9)]. These products are analogous to those obtained from formaldehyde 4-nitrophenylhydrazone but are formed in markedly different proportions. Analogous products cannot be obtained from formaldehyde 2,4-dinitro-phenylhydrazone which affords 5-(2,4- dinitrophenylamino)dihydro-1,3,5-dioxazine (12).     A study has also been made of the conditions under which formaldehyde phenyl-hydrazone undergoes oxidative dimerization to glyoxal bisphenylhydrazone, and it has been shown that under appropriate conditions 4-anilino-2-phenyl-2,3,4,5-tetrahydro-1,2,4- triazine (13) can be conveniently prepared.     The acetylation of arylhydrazines has been studied and the products characterized by their N.M.R. spectra.