The reaction of 3, 3, 3-trifluoropropylmagne~ ium bromide with methyl trifluoroacetate and 1, 1, 1, 5, 5, 5-hexafluoro-2-penta-none in both ether and tetrahydrofuran has shown the Grignard to be only a weak reducing agent. In the case of methyl trifluoroacetate, the principal product was a solid which on hydrolysis yielded the hydrate of 1, 1, 1, 5, 5, 5- hexafluoro-2-penta-none. Evidence for the structure of this solid intermediate, CFsCH&H& ...