ASCORBIC ACID FREE RADICALS .1. PULSE RADIOLYSIS STUDY OF OPTICAL ABSORPTION AND KINETIC PROPERTIES
ASCORBIC ACID FREE RADICALS .1. PULSE RADIOLYSIS STUDY OF OPTICAL ABSORPTION AND KINETIC PROPERTIES
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DOI：
10.1021/ja00751a006
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发表时间：
1971-01-01
影响因子：
15
通讯作者：
BOWEN, RA
中科院分区：
文献类型：
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作者：
BIELSKI, BHJ;COMSTOCK, DA;BOWEN, RA
测定了通过脉冲辐射分解在水溶液（pH-0.3至11）中产生的L-抗坏血酸自由基的吸收光谱。消光系数随 pH 的变化表明自由基可以以质子化形式 (AH2+)、中性形式 (AH·) 和阴离子自由基 (A·-) 存在，yK 值为 1.10 和 4.25。在整个 pH 范围内，自由基通过二级动力学衰减。提出了一种解释所观察到的酸催化衰变的机制。不同 pH 值下的离子强度效应与分配给不同自由基种类的电荷一致。
Absorption spectra of l-ascorbic acid free radicals generated in aqueous solutions (pH—0.3 to 11) by pulse radiolysis were determined. Variation in extinction coefficients with pH suggests that the radicals can exist in a protonated form (AH2+), as a neutral species (AH·), and as anion radicals (A·-), with yK values of 1.10 and 4.25. The radicals decayed by second-order kineticsthroughout the entire pH range. A mechanism is proposed which accounts for the observed acid-catalyzed decay. Ionic strength effects at various pH’s are con-sistent with charges assigned to the various radical species.