The rates of epoxidation of
cis-and
trans-α, α′-dimethylstilbene and 4, 4′-dimethoxy, 4, 4′-dimethyl, 4, 4′-dichloro, 4, 4′-dibromo, and 4, 4′-dinitro-derivatives with perbenzoic acid in benzene were determined at three temperatures, and the energies, free energies, and entropies of activation calculated. Values of the entropy of activation were nearly the same for all the cis-compounds and this was also the case for all the
trans-compounds. The electron releasing substitueuts decreased and the electron attracting substituents increased, the free energy of activation. The Hammett treatment of the substituent effect gave an excellent straight line with the exception of the points for 4, 4′-dimethoxy derivatives in both
cis- and
trans-series. The difference in reactivity towards perbenzoic acid between cis-and trans-isomers was discussed.
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