1,1,1-Trifluoropropan-2-one and 1,1,1-trifluoropentane-2,4-dione in hydrogen bromide–dibromodifluoromethane; evidence for the formation of α-bromo alcohols

Abstract

N.m.r. analysis of solutions of 1,1,1-trifluoropropan-2-one (TFP) and 1,1,1-trifluoropentane-2,4-dione (TFPD) in the strong acid system HBr–CBr₂F₂ shows the formation of the 2-bromo alcohol analogues of TFP and TFPD at temperatures below 250 K. In the latter system equilibrium constants for the formation of the bromo alcohol at various temperatures and acid ratios have been measured, from which the enthalpy of formation, ΔH°=–25.2 kJ mol^–1, has been calculated. 1,1,1,5,5,5-Hexafluoropentane-2,4-dione (HFPD) does not react to form a bromo alcohol.