水相中~·OH,~·H和e_(aq)^-与2-氯酚反应机理研究

Mechanism Studies on Reactions of ~·OH,~·H and e_(aq)^- with 2-Chlorophenol in Aqueous Solutions

利用脉冲电子束辐解水产生· OH自由基、· H及水合电子 (e- aq) ,研究了这些活性粒子在多种条件下与水相中 2 -氯酚的微观反应机理 ,对其瞬态光谱中的主要吸收峰做了归属 ,并初步考察了这些瞬态物种的生长、衰减等行为 .研究表明 ,· OH自由基与 2 -氯酚在碱性条件下可直接反应生成邻氯代酚氧自由基 ,速率常数为 1 .0× 1 0 9L· mol- 1 · s- 1 ,也有部分· OH自由基与 2 -氯酚反应先生成 OH-加合物 ,再进一步消除水分子生成邻氯代酚氧基 ;在酸性条件下要经过 OH-加合物 .· H则与 2 -氯酚反应生成 H-加合物 ;e- aq可直接从 2 -氯酚分子夺氯 ,在近中性和碱性环境中 ,该反应的速率常数分别为 1 .2 5× 1 0 9L· mol- 1 ·s- 1 和 6.3×1 0 8L·mol- 1· s- 1 .

Pulse radiolysis of aqueous 2-chlorophenol in dilute solutions under different conditions was studied. The main characteristic peaks in these transient absorption spectra were attributed and the build-up/decay trends of several transient species were investigated. Under alkaline conditions, the reaction of ·OH radical and 2-chlorophenol produces o-chlorinated phenoxyl radical with a rate constant of 1.0×10 9 \{L·mol -1·s -1\}; while under acid conditions, the initial product is mainly OH-adduct. The reaction between ·H and 2-chlorophenol produces H-adduct. In alkaline and nearly neutral solutions, e - aq can capture Cl directly from 2-chlorophenol with a rate constant 1.25×10 9 L·mol -1·s -1 and 6.3×10 8 L·mol -1·s -1, respectively.