Splitting of 1H NMR Signal of Long Methylene Chain with Various Terminal Substituent in Aromatic Solvent

The splitting of the methylene peaks in 1H NMR spectra was studied for alkyl compounds with various substituents in 1-chloronaphthalene solutions. The solvent shifts for the higher field split methylene peak and the α-methylene peak varied with a dependence on the magnitude of the electric group moment of the terminal substituent; those for the lower- and middle-field split methylene peaks and the terminal methyl peak remained constant. It was found that the different behaviors of the solvent shifts of the methylene signals could be ascribed to the origin of the peak splitting observed for long alkyl compounds.