Steric effects in the electronic spectra of substituted benzophenones. I: Symmetrically substituted methyl‐benzophenones

The ultraviolet absorption spectra of benzophenones show well‐defined steric effects arising from ortho‐substitutions. In this paper the experimental data are given for a series of 12 methylsubstituted ketones, including benzophenone. From these data the oscillator strengths f were calculated for the C‐bands; mutual comparison of these f‐values gives and idea of the magnitude of the steric effects caused by ortho‐substituted methyl groups.