The reaction of tris(4-methoxyphenyl)methyl chloride with sodium methoxide—non-operation of single electron transfer pathways

Abstract

Tris(4-methoxyphenyl)methyl chloride (2) and sodium methoxide furnish, in methanol as well as in aprotic solvents, the normal substitution product methyl tris(4-methoxyphenyl)methyl ether (3) with partial replacement of the p-methoxy-groups of the substrate by the reagent. No reduction to tris(4-methoxyphenyl)methane takes place unlike the reaction in the absence of sodium methoxide (during which reaction exchange of methoxy-groups between substrate and methanol occurs to a much greater extent) and no single electron transfer products are formed unlike the reaction of triphenylmethyl halides (1a, b) and sodium methoxide. These differences are rationalized by invoking the irreversibility of formation of compound (3) by attack of methoxide at the central carbon atom of cation (12) as contrasted to the reversibility of formation of the conjugate acid of (3), (14), resulting from attack of methanol at the same site, and also the different stabilities and tendencies of formation of the tris(4-methoxyphenyl)carbenium (12) and triphenylcarbenium ions, respectively.