Geminal H,D spin-spin coupling and isotope effects in partially deuterated methyl-aromatic compounds

Abstract

Seventeen methyl-aromatic compounds were selectively, partially deuterated by catalytic hydrogen exchange. The proton magnetic resonance (p.m.r.) spectra of the partially deuterated compounds showed that the geminal H,D coupling constant is approximately 2.2 c/s and that it does not vary significantly with the type of substitution in the ring. The deuterium isotope effect on the chemical shift of the remaining protons in the methyl group is approximately 0.7-1.1 c/s in the upfield direction for the introduction of one deuterium atom.