Active-alkali metal-promoted reductive cleavage of chlorinated phenols

Abstract

We investigated the degradation of chlorinated phenols under reductive electron transfer reaction conditions. Although Li and Na metal 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. Additionally, efficient dehalogenation of the sodium salts of several mono-, di-, and tri-chlorophenols was obtained by their reduction with an excess of Na metal and a catalytic amount of naphthalene.

Reducing properties of 1,2-dipyridyl-1,2-disodioethanes: chemical validation of theoretical and electrochemical predictions

“…General procedure for the generation of dianions 3a-d 0.1 M solutions of diorganometal 3bNa 2 -dNa 2 in dry THF were prepared as described previously. 9,11,[13][14][15] 0.1 M solutions of diorganometal 3aNa 2 were generated according to a similar procedure by reacting 1-(2-pyridyl)-2-(4-pyridyl)ethene, 1a, under an Ar atmosphere with an excess of Na metal (4 equiv.) in dry THF at 0 C during 12 h. Aer removing the excess of the metal, formation of the desired dianion can be evidenced by quenching separate aliquots of the resulting mixture with H 2 O (or D 2 O), followed by 1 H-and 13 C-NMR analyses of the reaction product, characterized as follows:…”

“…Besides applications as dinucleophiles in the diastereoselective synthesis of trans-1,2-diarylcyclopentanes 9 and borinanes, 10 we previously described their use as electron-transfer reagents for highly effective reductive eliminations in 1,2-hetero-disubstituted compounds 11,12 and degradations of aromatic persistent organic pollutants. [13][14][15][16][17] A comparison between the electroreduction potentials of the 1,2-diarylethenes and the results obtained for the reduction of model compounds with the corresponding 1,2-diaryl-1,2disodioethanes bearing different substituents allowed us to observe that the less delocalized dianions are the most powerful reducing agents, and vice versa. 18 These results were substantiated by establishing that the outcome of the reactions between halogenated arylacetic acids and 1,2-diaryl-1,2disodioethanes strongly depends on the nature of both partners.…”