The reactions of nine different mono-para-substituted triphenylaminium cations produced by oxidation of the parent amines by Cu(I1) in acetonitrile have been studied. The cation radicals undergo apparent second-order coupling reactions giving rate constants ranging from 4.4 X lo3 to 8.8 X M-' s-l. These values correlate well with rate constants for these reactions previously determined by chronoamperometric measurements and their determination should better establish the reliability of electrochemical methods for studying similar systems.

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XVlIO-C6HsCHCH= CC6H5 \ C6H~CHCHCOC6H5 -* (C6H5CH--CHCOC6Hs) x r C6HsCHCHCOC6H5Reduction of benzalacetophenone under the same conditions but in the presence of carbon dioxide gave a-phenyl-~-benzoylpropionic acid and a small amount of meso-l,3,4,6-tetraphenyl-l,5-hexanedi-one. The latter COO-C6HsCHCHCOC6Hn + CO2C6HsCHCHCOC6H.~ COOcompound resulted from a Michael-type addition of the dianion to a benzalacetophenone molecule as shown in the scheme for the polymer formation.Cinnamaldehyde and crotonaldehyde form much less stable reduction intermediates. In the presence and absence of carbon dioxide only oily products were obtained from the large-scale electrolytic reduction of these compounds. Benzalacetone behaved similarly in the absence of carbon dioxide, but could be carbonated to a-phenyllevulinic acid.Results obtained in the absence of carbon dioxide are similar to those reported by Law (9) for the re-duction of cinnamaldehyde, benzalacetone, and crotonaldehyde at a copper or lead cathode in aqueous medium. Unless the pH of the solution was controlled carefully only resinous material could be obtained.The large-scale electrolysis indicated that a,flunsaturated carbonyl compounds when suitably substituted as in benzalacetophenone will form stable anion-free radicals and dianions which may add to the parent compound. This addition may cause a lower diffusion current in polarographic analysis than what would be expected ordinarily. Such an addition reaction may make a quantitative determination of polymerizable monomers difficult in anhydrous media.

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