35Cl/37Cl one‐bond isotope effects on 13C chemical shifts in a series of para‐substituted chlorobenzenes

One-bond isotope shifts of 35Cl/37Cl natural abundance chlorine isotopomers were measured in the 75.4 MHz 13C NMR spectra of a series of para-substituted chlorobenzenes. The high-field isotope shift effect 1Δ13C(37Cl) was established from the relationship between the chlorine isotopomeric ratio and the carbon peak intensities. It was found that the 1Δ13C(37Cl) values are in the range of −4.0 to −5.2 ppb. The isotope shifts tend to decrease as the electron-attracting character of the substituent increases, providing a linear correlation between the isotope shift and the chemical shift of the chlorine-bearing carbon.