STOICHIOMETRY OF PROTONATION OF AROMATIC HYDROCARBON RADICAL-ANIONS BY WEAK PROTON DONORS - A MARKED DISCREPANCY BETWEEN THE NUMBER OF PROTONS USED AND THOSE INCORPORATED INTO THE AROMATIC STRUCTURE

The stoichiometries of the reaction between alkali metal radical anion s of biphenyl, naphthalene, phenanthrene and anthracene, and methanol and/or other proton donors have been determined by the magnetic titrat ion technique. In the case of naphthalene radical anion and, for examp le, methanol as the proton source, the stoichiometry was found to be c ation-dependent: Li, 2:1; Na, 1.75:1; K, 1.33:1. The reaction products using the experimentally determined stoichiometric conditions were ca . 95% naphthalene and 5% dihydronaphthalene(s). Thus, a marked discrep ancy is observed between the protons used and those incorporated into the naphthalene molecule. Radical anions, at concentrations comparable with those of preparative reactions, react with carbon acids or amine s according to the first-order kinetic law, although the initial conce ntrations of the two reactants were of the same order of magnitude or even equal. Lithium anthacene radical anion reacts with phenylacetylen e and diethylamine at comparable rates, although the two ''acids'' dif fer in their acidities by ca. 10 orders of magnitude. A deuterium isot ope effect of 2.49 +/- 0.05 was observed in the reaction between lithi um anthracene radical anion and diethylamine. A general reaction schem e is proposed that involves electron transfer to the proton donor and hydrogen-atom attack on the neutral hydrocarbon as the key reaction st eps.