Substituent and Solvent Effects on HCN Elimination from l-Aryl-l,2,2-tricyanoethanes [1]

1,2,2-Tricyanoethanes, Elimination of HCN The elimination of HCN from 9-dicyanomethyl-fluorene (2), 1,1-diphenyl-1,2,2tricyanoethane (3), and 2-phenyl-I,l,2-tricyano-propane (4) in anhydrous methanol has been studied and shown to occur via an (E l)anion mechanism. Elimination of HCN from 2 in acidic, buffered and MeO~/MeOH solutions have also been studied. Addition of water or benzene to the reaction medium shifts the mechanism to (E 1 CB)R. Elimination of HCN from N,N-dimethyl-4-(I,I,2-tricyanoethyl) aniline (5) in anhydrous methanol occurs via an (E 1 CB)r mechanism and the kinetics indicate that addition of HCN to the product alkene occurs. Activation parameters, isotope effects and solvent effects have been examined in an effort to obtain information about the nature of the transition states of these reactions.