13C and 1H spectra of some methylnaphthalenes

Abstract

The 13C spectra of the two methylnaphthalenes and ten dimethylnaphthalenes have been examined. Analysis of the 1H spectra allowed unequivocal assignments for the protonated carbons in nine derivatives by selective proton decoupling. From these data, parameters describing the methyl substituent effects on the aryl carbon shieldings were defined and their utility was demonstrated by comparison of the predicted shieldings with those observed for the three additional dimethyl derivatives. As expected, the methyl substituent parameters are invalid for systems having ortho- or peri-methyl groups and the deviations for these systems are discussed. A comparison of the 13C shieldings with some CNDO/2 electron distributions was examined briefly. © 1974.