Reduction by dissolving metals. Part XX. Some biphenyl derivatives

Abstract

Metal–ammonia reductions of biphenyl and of 2- and 4-methoxybiphenyl in the presence and in the absence of proton sources have been examined. Reaction probably proceeds, respectively, through one-electron and one-proton additions, and through two-electron and two successive proton additions. The differences in observed product ratios can be partly explained by the higher ratio of the conjugated diene (3) to the unconjugated diene (2) produced by protonation of the intermediate anion (1) with alcohols as compared with ammonium chloride.