Studies of 13C n.m.r. substituent chemical shifts of disubstituted benzenes using multivariate data analysis
Dan Johnels, Ulf G. Edlund, Erik Johansson, Marina Cocchi · Journal of the Chemical Society Perkin Transactions 2 · 1989
The non-additivity in the 13C substituent chemical shifts (SCS) of 1,3-and 1,4-disubstituted benzenes has been studied using multivariate data analytical methods. Most of the non-additivity is systematic and can be predicted with high accuracy (0.2 ppm) from carbon shifts of monosubstituted benzenes. This means that no additional substituent effects are needed and that the non-additivity contributions of the SCS are clustered in the same way as previously noticed for 13C SCS in monosubstituted benzenes.