13C‐ and 1H‐NMR. Spectra of ortho‐benzoquinones. On the assignment problem in 13C spectra

Abstract
13C‐ and 1H‐NMR. spectra of ortho‐benzoquinone 1 and its methyl derivatives have been analysed. By means of heteronuclear double resonance experiments it is shown that assignments given in the literature for the olefinic carbon resonances of 1 and of a series of substituted ortho‐benzoquinones have to be inverted. 13C‐carbonyl frequencies of various six‐membered cyclic ketones are presented.