Proton magnetic resonance spectra of several types of substituted ammonium ions.

Proton magnetic resonance spectra of substituted ammonium ions were studied in deuterium oxide, being classified in methylammonium, ethylammonium, β-substituted ethylammonium, and vinylammonium ions. The chemical shifts of the methyl groups are discussed in terms of inductive effects of other substituents on nitrogen atoms. From the internal chemical shifts of ethyl groups, the electronegativity of (Alkyl)3N+ were derived to be 3.16 according to Cavanaugh and Dailey's equation. Spin-coupling constants between 14N and protons were usually observed in the cases where the electric field at the 14N nucleus is thought to be homogeneous. We suggest that the sign of J14N-C-CH3 in ethyltrialkylammonium ions might be positive. Interestingly, spin-couplings between 14N and the vinyl protons in trimethyl-vinylammonium bromide were evidently observed even at room temperature.