Publication Details (including relevant citation information):
Steven E. Warren, 1978.
Field ionization studies of substituted acetophenones and their related 1,3-dioxolanes undergoing methyl group cleavage are reported. The sigma-rho plot for the para substituted ketones revealed two different mechanisms in operation. Electron withdrawing substituents yielded the same increased cleavage rate relative to acetophenone itself, while the electron donating substituents yielded the expected sloped line with cleavage rates dependent on donation capacities of the substituents. It is proposed that ionization for the electron donating substituted acetophenones occurs in the substituent or the ring, while ionization for the electron withdrawing group substituted acetophenones is primarily ionized on the carbonyl oxygen.
The related para substituted 1,3-dioxolanes from acetophenones suggested only a single ionization mechanism by virtue of a single-sloped linear sigma-rho plot.
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