Abstract
Flash photolysis of phenyldiazoacetic acid and the methyl, n-butyl, and isobutyl esters of benzoylformic acid in aqueous solution generated a transient species that was identified, through product determination and the form of acid−base catalysis plus solvent isotope effects on its decay, as the enol of mandelic acid, 1. When benzoylformate esters were the flash photolysis substrates, the enol was formed by hydration of phenylhydroxyketene, 5, itself generated by Norrish type II photoelimination of the esters, and when phenyldiazoacetic acid was the substrate, the enol was formed by hydration of phenylcarboxycarbene, 6, produced by dediazotization of the diazo acid. Rates of enolization of mandelic acid were also determined, by monitoring the incorporation of deuterium into its α-position from a D2O solvent, and combination of these with rates of ketonization gave the keto−enol equilibrium constant, pKE = 16.19. The acidity constant of the enol ionizing as an oxygen acid was determined as well, p = 6.39, ...
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
