Flash photolysis of 2-methylbut-1-ene

Abstract

The radicals formed in the flash photolysis of 2-methylbut-1-ene and then subsequent reactions have been investigated by kinetic spectroscopy and gas–liquid chromatography. Less than 10% of products are formed by a molecular mode of fission of the excited olefin, and of the radical modes the relative probabilities of bond fission, β(C—H): β(C—H): α(C—C) are 13:1.37:1. The extinction coefficient of the β methallyl radical measured for the strongest band (238 nm) was ε= 1.32 ± 0.11 × 10⁴ 1. mol^–1 cm^–1. The decay of the methyl and β methallyl radicals was second order. The rate constant for methyl combination was in agreement with the literature value and that for β methallyl combination measured for the first time was 2.6 ± 0.3 × 10¹⁰ mol^–1 1. s^–1 at 295 ± 2 K.