BASE CATALYZED ENOLIZATION AND HYDROGEN EXCHANGE OF TRIFLUOROACETONE. A COMPARISON TO ACETONE

Article abstract of DOI:10.1016/S0022-1139(00)81448-7

The kinetics of the pyridine catalyzed hydrogen exchange of 1,1,1-trifluoroacetone in 50percent D2O-dioxane have been measured using 1H-NMR.Rates of hydrogen exchange of acetone were also measured under comparable conditions and the rate of deuterium uptake by trifluoroacetone was found to exceed that of acetone by a factor of 1700 at 25 deg C.However trifluoroacetone is known to be extensively hydrated under these conditions.The hydrogen exchange of trifluoroacetone is interpreted as most probably proceeding through proton abstraction by pyridine from the free ketone to form the enolate followed by deuteration on carbon, with the rate of proton abstraction from trifluoroacetone exceeding that of acetone by a factor of 10⁵ to 10⁶.Other possibilities are also considered.