Branched alkanes produce acetamidated fragments when oxidized in CH,CN-Et,N+,BF,-at -45".REACTIONS which cleave the carbon-carbon bonds of alkanes are both unusual and interesting; we report the anodic fragmentation of branched alkanes. This process

Ketones with branching at the a position were potentiostatically oxidized at platinum gauze. The anolyte was acetonitrile-lithium perchlorate and the reference electrode AglO. 1 M AgNO3. a-Cleavage was observed to be the main route of these oxidations. 2,2-Dimethyl-3-butanone, 2,2-dimethyl-3-hexanone, acetyladamantane, 2-methyl-3-butanone, and 2,5-dimethyl-3-pentanone of the general formula RCOR' gave cu-cleavage products of the type RNHCOCH3 and R'COOH. 2,2-Dimethylpropanal and 2,2,4,4-tetramethyl-3-pentanone gave acetylpivaloylimide in addition to acid and amide products. It was found that small amounts of water are necessary for the obtention of high amide (RNHCOCH3) yields. A mechanism involving generation of carbonium ions from n-cleavage of a ketone cation radical is proposed, and analogies with photochemistry and mass spectrometry are drawn.

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The electroreduction of a variety of polycyclic, aromatic hydrocarbons (R) in the presence of either 9,10-dichloro-9,10-dihydro-9,lO-diphenylanthracene (DPACI,) or 1,2-dibromo-l,2-diphenylethane (DPEBr2) was found to result in intense luminescence. In each instance the spectrum of this electrochemiluminescence (ecl) was virtually identical with the singlet emission spectrum of the aromatic hydrocarbon. In general, the efficiency of this luminescence was found to be greater than that of the normal radical anion-radical cation ecl of the same (3) (a) The intensity of the 9.10-diphenylanthracene (DPA) singlet emission obtained for the reaction of DPACI? with electrogenerated D P A .was compared with D P A . -/DPA. + annihilation ecl using the same solvent-supporting electrolyte system. Square wave voltages ( -0.1 to -2.0 V for the DPACl? case, + 1.4 to -2.0 V for the DPA case) of the same frequency were employed and integrated light intensities during negative pulses were compared. (b) For detailed discussion of radical cation-radical anion annihilation ecl, see A.

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