Reference

Anodic oxidation of aryl olefins

Anodic oxidation of aryl olefins. Engels, Rainer; Schaefer, Hans J.; Steckhan, Eberhard (Org.-Chem. Inst., Univ. Goettingen, Goettingen, Ger.). Justus Liebigs Ann. Chem., (2), 204-24 (German) 1977. CODEN: JLACBF. DOCUMENT TYPE: Journal CA Section: 72 (Electrochemistry) Section cross-reference(s): 22 Four styrene derivs. and indene are oxidatively dimerized in an undivided cell at a graphite anode in MeOH/NaClO4 or MeOH/Na camphorsulfonate to form 1,4-dimethoxy-1,4-diphenylbutane or 1,4-diphenylbutadiene derivs., resp., in up to 50% yield. In some cases product distribution is strongly dependent on the anode potential and the supporting electrolyte. .beta.-Alkyl substituents drastically lower the dimer yield (1-cyclopentenylbenzene) or favor the formation of dimethoxylated monomers (indene). 1501-05-9 and 100-42-5 are also in the experiment. The aryl olefins are irreversibly oxidized at peak potentials between Ep = +0.63 and +1.38 V (vs. Ag/AgCl) with n-values of .apprx.2 at the limiting current; the peak potentials of p-substituted sytrenes correlate linearly with their .sigma.p+-values. The dimers are probably formed via radical cations that adds as electrophiles to the aryl olefin with formation of a 1,4-radical cation which, after oxidn. undergoes solvolysis of deprotonation. .