Pulse radiolysis and product analysis of 1,1-diphenyl-ethylene and related compounds in methanol

Abstract

Pulse radiolysis of 1,1-diphenylethylene (DPE) in methanol in the presence of oxygen, as well as of 1,1-diphenyl-2-chloroethylene (DPE-2-Cl), 1,1-diphenyl-1-chloroethane (DP-1-Cl-Et) and 1,1-diphenyl-2-chloroethane (DP-2-Cl-Et) in methanol saturated with argon, was performed. The products formed under pulse-radiolysis conditions were also analysed. Spectroscopic and kinetic data of the corresponding transients are presented. The reaction rate constants determined in methanol are k(e^–_s+ O₂)=(2.0 ± 0.1)× 10¹⁰ dm³ mol^–1 s^–1, k(e^–_s+ DPE-2-Cl)=(1.1 ± 0.1)× 10¹⁰ dm³ mol^–1 s^–1, k(e^–_s+ DP-1-Cl-Et)⩽ 1.5 × 10¹⁰ dm³ mol^–1 s^–1, k(e^–_s+ DP-2-Cl-Et)=(1.3 ± 0.2)× 10¹⁰ dm³ mol^–1 s^–1, k(H + DPE-2-Cl)=(2.0 ± 0.6)× 10¹⁰ dm³ mol^–1 s^–1, k(H + DP-1-Cl-Et)⩽ 8 × 10⁹ dm³ mol^–1 s^–1, k(H + DP-2-Cl-Et)⩽1 × 10⁸ dm³ mol^–1 s^–1. It has been established that the solutes are primarily attacked by e^–_s and H, whereas the CH₂OH species (or O₂) react with the intermediates thus produced. Reaction mechanisms consistent with the spectroscopic and kinetic data are presented.