¹³C NMR spectra of pyridinium betaines and related compounds

Abstract

Abstract 13 C NMR spectra of 1‐methyl‐, 1‐phenyl‐ and 1, 6‐dimethyl‐pyridinium‐3‐oxide, 3‐methylphthalazinium 1‐oxide and anhydro‐3‐methanesulphonamido‐1‐methylpyridinium hydroxide, together with the corresponding amines and quaternary salts, were determined with and without proton noise‐decoupling. The assignment of resonances was based on the analysis of the fine splitting pattern caused by long range couplings whenever appropriate. A procedure for the estimation of chemical shifts of the salts and betaines is proposed.