甘草酸水溶液的辐解

RADIOLYSIS OF AQUEOUS SOLUTION OF GLYCYRRHIZIC ACID

甘草酸的辐解可分为两个过程:(1)生色团α、β不饱和酮的破坏;(2)抽氢反应导致甘草酸结构破坏,但生色团不破坏。用HPLC分离出四个辐解产物,其一是甘草次酸并测定了它们的G值。用加入俘获剂(甲酸钠)的方法,证明OH·自由基的作用可使配糖键断裂,生成甘草次酸和未知辐解产物Ⅱ,OH·和HO_2的作用可生成未知辐解产物Ⅰ,未知辐解产物Ⅲ是次级产物。用竞争反应动力学得到OH·自由基与甘草酸的反应速率约为10^(10)L·mol^(-1)·s^(-1)。

A study was made on radiolysis of glycyrrhizic acid in diluteaqueous alkaline solution. Radiolysis of glycyrrhizic acid would be divided intotwo processes: (1) Chromophore (unsaturated ketones) was destroyed; (2) Structureof glycyrrhizic acid was destroyed due to hydrogen abstraction reaction, but chro-mophore was not destroyed. The G values of radiolysis of glycyrrhizic acid underdifferent atmospheres have been determined. Four radiolytic products were separatedby HPLC. Using scavenger method, it showed that glycyrrhetinic acid and unknownproducts are formed by OH attack. OH attack leads to glucosidic bond rupture. Unk-nown product is formed by OH and HO_2. Unknown Ⅲ may be secondary product.Using competition kinetics ko_(H-GAH)～10^(10)dm^3mol^(-1)S^(-1) was got.