Furazans and furazan oxides. Part IV. The structures and tautomerism of some unsymmetrically substituted furoxans

Abstract

The furoxan equilibration reaction [(A)⇌(B)] has been studied for a range of derivatives in the monomethyl series. Activation energies are similar to those determined by other workers for dialkyl and aryl(alkyl)(R = Et or Ph) derivatives, and equilibrium constants are close to unity, except for the ether and amine derivatives, in which the isomerisation is more rapid, and the 3-methyl isomers (A) are strongly preferred. Carbonyl stretching frequencies of some carboxy-derivatives, and rotational barriers of NN-dimethylamides, are also investigated.