Proton magnetic resonance study of the configurations of severalΒ-substituted vinylcarbonyl compounds

PMR spectra of several -substituted vinylcarbonyl compounds were studied. Analysis of the spin-spin interaction constants and the chemical shifts leads to the conclusion that the molecules of methyl cis- and trans--chlorovinyl ketone, methylmalondialdehyde, and malondialdehyde exist in a cissoidal conformation. The molecule of cis--chloroacrolein has a transoidal conformation, and a rotation around the C-C bond takes place in trans--chloroacrolein.The results of the experiments are compared with calculated chemical shifts, which are determined by the effect of diamagnetic anisotropy and electrical charges of the C=C, C=O, and C-Cl bonds.