Pulse radiolysis of aqueous solutions of acetic acid 2‐hydroxyethyl ester. Fast elimination of acetic acid from a primary radical

Abstract

Abstract The reaction of OH radicals with acetic acid 2‐hydroxyethyl ester, (1), in aqueous solutions has been studied. A rate constant of k (OH + 1) = 8.5 · 10 8 M −1 s −1 was obtained. The transients a few μs after pulse consist of ∼83% formylmethyl radicals, CH 2 CHO, the remainder being mainly CH 3 C(O)OCHCH 2 OH radicals, (3). γ‐radiolysis of 1 in N 2 O saturated aqueous solutions led to G (acetic acid)=5.0 without contribution of a chain reaction. It is concluded that the OH attack on 1 leads mainly to the redical CH 3 C(O)OCH 2 CHOH, (2), which undergoes a fast fragmentation into acetic acid and the formylmethyl radical: A lower limit of the rate constant of this reaction, at 20°C, κ 5·10 5 s − , was derived from pulse radiolysis studies and an upper limit of κ ≤ 5·10 6 s −1 was estimated from scavenging experiments with oxygen under Co 60 ‐γ‐irradiation. At higher concentrations of 1, and/or higher temperatures CH 2 CHO attacks 1, leading to a chain decomposition of 1 yielding acetic acid and acetaldehyde. Succinic aldehyde was identified as a product of the dimerization of CH 2 CHO.