ANALYSIS OF PROTON MAGNETIC RESONANCE SPECTRA OF MONOSUBSTITUTED BENZENES - ALKYL BENZENES AND AN EMPIRICAL INTERPRETATION OF RING PROTON CHEMICAL SHIFTS

The PMR spectra of alkyl benzenes, i.e., toluene and t-butyl benzene, were analyzed to determine the precise values of chemical shifts at infinite dilution in CCl4 and spin-spin coupling constants between the ring protons. Using the chemical shifts hitherto obtained for typical monosubstituted benzenes at infinite dilution in CCl4, the linear relations of each ring proton chemical shifts are made between Taft's σI and σR constants. Although there are a few exceptions, the main changes of the ring proton chemical shifts due to the substituent may be interpreted by the two common factors. © 1969.