作者:Timothy B. Patrick、Sadegh Khazaeli、Sourena Nadji、Katy Hering-Smith、Dirk Reif
DOI:10.1021/jo00055a026
日期:1993.1
The reaction of xenon difluoride with primary carboxylic acids involves a free-radical mechanism. Trifluoroacetic acid (1) decarboxylates in benzene to give (trifluoromethyl)benzene (2). 6-Hexenoic acid (3) produces a free radical in a radical clock reaction in which the k(abs) (25-degrees-C) for XeF2 Was determined as 1.1 X 10(6) M-1 s-1. The primary radical from hexanoic acid was spin-trapped to give ESR signals diagnostic for the alkyl radical. Secondary acids were shown to proceed through a trivalent intermediate, but its exact nature was not proven. The acid 6 gave a rearranged product (7) characteristic of carbocations, whereas the diacid 8 gave difluoro compounds without stereoselectivity. The tertiary bicyclic acids 13 and 15 gave products only from solvent hydrogen abstraction strongly indicative of free radicals.