Pulse Radiolysis of Adrenaline in Acid Aqueous Solutions

Pulse radiolysis of adrenaline in acid aqueous solutions (pH 1–3) was carried out. The rate constants for the reactions of adrenaline with H and OH were determined: k(H + adr.) = (0·9±0·1) × 109 dm3 mol−1s−1; k(OH + adr.) = (1·65±0·15) × 1010 dm3 mol−1s−1. The H-adduct of adrenaline has two λmax, at 280 and 355 nm, with ϵ280 = 420 m2 mol−1 and ϵ355 = 390 m2 mol−1, which disappears according to a first order reaction, k1 = 1·4 × 103 s−1. The spectra formed by OH attack was assigned to the corresponding benzoxy radical with absorption maxima at 285 and 365 nm and ϵ285 = 620 m2 mol−1 and ϵ365 = 105 m2 mol−1. Due to the overlapping of the intermediates, no decay kinetics could be obtained.