Pulse radiolysis of butyl acrylate in aqueous solution

Abstract

Abstract The pulse radiolysis of n -butyl acrylate (nBA) in aqueous solution was studied. The rate constant of the reaction of nBA with hydroxyl radicals was calculated as 1.5×10 10 dm 3 mol −1 s −1 . The absorption spectrum of the OH · –nBA adduct appeared to have a broad maximum at 300 nm. This spectrum was attributed to the α-carbon centred radicals. It decayed with the first-order rate constant k =1.5×10 4 s −1 (pH 10.8). The rate constant of the nBA reaction with hydrated electrons was determined as k =1.6×10 10 dm 3 mol −1 s −1 . The spectrum of H · –nBA adduct was similar to that recorded for OH · adduct. It decayed with first-order kinetics at k =1.0×10 4 s −1 . Spectra of the electron adduct were characterised by the band with a maximum at 285 nm (pH 10.0) or at 280 nm (pH 4.0) with ϵ =10 500 dm 3 mol −1 cm −1 . In acidic solution, radical anion formed upon addition of hydrated electrons to the nBA molecule, undergoes fast, reversible protonation. The decay of the reversibly protonated electron adduct was a second-order process at k =2.5×10 9 dm 3 mol −1 s −1 . This reaction took place at the carbonyl oxygen. Slow, irreversible protonation of the electron adduct at high pH takes place at the β-carbon atom at k =2.9×10 4 s −1 .