Infrared study of polysubstitution effects in benzophenones and acetophenones: contribution of inter and intracycle interaction mechanisms

Article abstract of DOI:10.1016/0584-8539(81)80141-9

The carbonyl stretching frequencies of substituted 2-Me, 2,6-diMe, 2-MeO benzophenones and 2-Me, 2-MeO acetophenones have been measured in diluted CCl4 solutions.Two interaction mechanisms are observed.In X, Y substituted benzophenones with X on the same cycle as the ortho group and Y on the other cycle, it is shown that for X=Y, the effect of Y is greater than that of X except for very strong electron-releasing substituents.In this last case, the observed enhancement is attributed to the joint effects of intercycle interactions excercised on X and Y and of intracycle interaction on X.These results are corroborated by the study of substituted acetophenones in which only the intracycle mechanism can play a role.