Pulse radiolysis of 1, 2-DI(α-naphthyl) ethane in deoxygenated methanol and tetrahydrofuran

Abstract

Pulse radiolysis of 1,2-di(α-naphthyl)ethane (1,2-DNE) was performed in deoxygenated pure methanol and tetrahydrofuran (THF). Absorption spectra and kinetics of 1,2-DNE − in both solvents are presented. In methanol 1,2-DNE − is formed with k( e − s + 1,2- DNE) = (6 ± 0.5) × 10 9 dm 3 mol -1 s -1 possessing λ max = 330 nm ( ϵ 330 = 1000 ± 30 m 2 mol -1) and decays by a second order reaction with k = 5.45 × 10 9 dm 3 mol −1 s -1. No cleavage of benzylic C—C bond occurs as has been observed in the presence of alkali metals in ethers. 1–5 Hence, it can be concluded that the assistance of the metal cations is necessary for the reductive bond splitting process. For comparison, 1-bromomethylnaphalene (Br-MN) and 1,2-diphenylethane (1,2-DPE) were investigated in deoxygenated methanol. It was found that k( e - s + Br- MN) = (2.6 ± 0.5) × 10 10 dm 3 mol -1 s -1, for the resulting transient C 10H 7CH 2, λ max at 280 nm (ϵ 280 = 683 m 2mol -1), 327 nm (ϵ 327 = 495 m 2mol -1) and 355 nm (ϵ 355 = 375 m 2mol -1). It disappears in a second-order reaction with k = (8 ± 0.6 × 10 9 dm 3 mol -1 s -1. It was found further that k( e - s + 1,2- DPE) = (2.0 ± 0.4) × 10 7 dm 3 mol -1 s -1. Probable reaction mechanisms are presented.