Instituto Tecnologico e Nuclear, UCQR, Estrada Nacional No 10, Apartado 21, 2686-953 Sacavém, Portugal.
J Hazard Mater. 2009 Dec 30;172(2-3):1185-92. doi: 10.1016/j.jhazmat.2009.07.122. Epub 2009 Aug 4.
Polyphenols, like gallic acid (GA) released in the environment in larger amount, by inducing some unwanted oxidations, may constitute environmental hazard: their concentration in wastewater should be controlled. Radiolytic degradation of GA was investigated by pulse radiolysis and final product techniques in dilute aqueous solution. Subsidiary measurements were made with 3,4,5-trimethoxybenzoic acid (TMBA) and 3,4,5-trihydroxy methylbenzoate (MGA). The hydroxyl radical and hydrogen atom intermediates of water radiolysis react with the solute molecules yielding cyclohexadienyl radicals. The radicals formed in GA and MGA solutions in acid/base catalyzed water elimination decay to phenoxyl radicals. This reaction is not observed in TMBA solution. The hydrated electron intermediate of water decomposition adds to the carbonyl oxygen, the anion thus formed protonates on the ring forming cyclohexadienyl radical or on the carbonyl group forming carbonyl centred radical. The GA intermediates formed during reaction with primary water radicals in presence of oxygen transform to non-aromatic molecules, e.g., to aliphatic carboxylic acids.
多酚，如在环境中以较大量释放的没食子酸（GA），通过诱导一些不需要的氧化反应，可能构成环境危害：应控制其在废水中的浓度。在稀水溶液中通过脉冲辐射分解和最终产物技术研究了 GA 的辐射降解。用 3,4,5-三甲氧基苯甲酸（TMBA）和 3,4,5-三羟基苯甲酸甲酯（MGA）进行了辅助测量。水辐射分解的羟基自由基和氢原子中间体与溶质分子反应生成环己二烯基自由基。在酸/碱催化水消除过程中形成的 GA 和 MGA 溶液中的自由基衰减为苯氧自由基。在 TMBA 溶液中未观察到该反应。水分解的水合电子中间体添加到羰基氧，形成的阴离子在环上质子化形成环己二烯基自由基或在羰基上形成羰基中心自由基。在有氧存在下与初级水自由基反应形成的 GA 中间体转化为非芳族分子，例如，转化为脂肪族羧酸。
