Pulse Radiolysis of Acryloyl-L-Proline Methyl Ester in Dilute Aqueous Solution

Abstract

The reactions of hydroxyl radical, hydrogen atom, and hydrated electron intermediates of water radiolysis with a hydrogel monomer, acryloyl-proline methyl ester, were studied by pulse radiolysis in dilute aqueous solutions. In reactions of OH and H, α-carboxyalkyl radicals form; they absorb the light with a maximum at 460–480 nm, ε_max ≈ 1000 mol⁻¹·dm³·cm⁻¹. The electron adduct reversibly protonates, and the protonated form absorbs the light with λ_max = 290 nm and λ_max = 8000 mol⁻¹·dm³·cm⁻¹. In addition to the reversible protonation, there is also an irreversible protonation which produces also α-carboxyalkyl radicals. These radicals at low concentration (0.1–1 mmol·dm⁻³) and high dose/pulse (10–100 Gy) decay in second-order self-termination reactions with 2k = 3 × 10⁸ mol⁻¹·dm³·s⁻¹.