REACTIONS OF PHENYL-SUBSTITUTED HETEROCYCLIC COMPOUNDS: V. NITRATIONS OF 1,3- AND 1,5-DIPHENYLPYRAZOLES

Abstract

Dinitration of 1,3- or 1,5-diphenylpyrazole in sulphuric acid yields the corresponding di(p-nitrophenyl) compounds, while nitric acid–acetic anhydride yields the 4-nitro-1-p-nitrophenyl compounds.Mononitration at the 4-position occurs when the diphenylpyrazoles and several other 1-phenylpyrazoles are nitrated at 0° by nitric acid–acetic anhydride.Possible explanations of the dependence of orientation on the nature of the nitrating agent-are discussed.Nuclear magnetic resonance (n.m.r.) spectroscopy was used in demonstrating the structures of many of the nitration products, and a general discussion of the n.m.r. spectra of substituted 1-phenylpyrazoles is given.