| Popis: |
The dehydrogenation of diphenyl-2 carboxylic acid to the lactone (II; R = H) has been accomplished by oxidation with chromic acid or hydrogen peroxide and its derivatives, by decomposition of the diacyl peroxide derived from this acid, and by electrolysis of its sodium salts. From the effects of several 3′-substituents (R = OMe, NHCOCH3, CH, NO2) on these reactions it has been concluded that the oxidations with chromic acid and hydrogen peroxide etc. proceed through attachment of the oxidising agent to the carboxylic group and subsequent cationoid substitution in the neighbouring ring. The free radicals (III) are believed to be intermediates in the other two cyclisations. |
