Electron-transfer-induced reductive cleavage of chlorinated aryloxyalkanoic acids

We investigated the degradation of chlorinated herbicides, with an aryloxyalkanoic acid skeleton, under reductive electron transfer reaction conditions. Although Li and Na metals proved useless, activated forms of these metals, either their soluble naphthalene radical anions or 1,2-diarylethane dianions, promoted the degradation of the starting materials to various extents. Indeed, lithium naphthalenide promoted both extensive dehalogenation and dealkylation of chlorinated aryloxyalkanoic acids, with formation of the corresponding phenols as the main reaction products. In contrast, the employment of 1,2-diphenyl-1,2-disodioethane as a reducing agent led, in most examples, to the chemoselective recovery of the corresponding dechlorinated acids.