Substitution at saturated carbon. Part XI. Substitution of tetraethyltin by mercury(II) salts in acetonitrile

Abstract

The substitution of tetraethyltin by mercury(II) chloride in acetonitrile, reaction (1; X = Cl), follows second-order kinetics (first-order in each reactant) and is subject to positive kinetic salt effects and to positive co-solvent effects Et₄Sn + HgX₂→ EtHgX + Et₃SnX (1) of added water. It is concluded that reaction (1; X = Cl) proceeds by mechanism S_E2(open). The analogous substitution (1; X = l) is also subject to positive kinetic salt effects in solvent acetonitrile, and mechanism S_E2(open) is again suggested. Activation parameters for reaction (1; X = Cl or l) are reported; values of ΔS‡, on the molar scale, are –28 and –31 cal deg^–1 mol^–1 respectively. Relative rate coefficients for reaction (1) in acetonitrile are 4·5 (X = OAc), 1·0 (X = Cl), and 1·8 (X = l) whereas in methanol they are 250 (X = OAc), 1·0 (X = Cl), and 0·8 (X = l).