Anastassopoulou J D, Rakintzis N T, Theophanides T
Laboratory of Physical Chemistry, National Technical University, Campus of Zografou, Athens, Greece.
Anticancer Res. 1988 May-Jun;8(3):511-5.
The mechanism of the gamma-radiolysis of the free nitroxyl radicals BAPO and CATPO in neutral deaerated as well as in N2O-saturated aqueous solutions was investigated. The decomposition of BAPO and CATPO was followed spectrophotometrically by measuring the absorbance at 249 and 233 nm, respectively. The yields G(-BAPO) and G(-CATPO) observed under several conditions are reported and discussed in relation to the yield of OH radicals, H atoms and e-aq, produced in irradiated aqueous solutions. It was found, on the analogy of other nitroxyls, that the corresponding hydroxylamines were formed when BAPO and CATPO react with H atoms, e-aq and hydroxyalkyl radicals. The H atoms and e-aq also react partly with BAPO and CATPO by addition to the aromatic nucleus and by elimination of NH3, respectively. The OH radicals react with BAPO by addition to the aromatic nucleus and by abstraction of H atoms from the 3 or 5 positions or from the methyl groups of the 2 or 6 positions. The reaction of OH radicals with CATPO consists in the abstraction of H atoms from the 3 or 4 positions or from the methyl groups of the 2 or 5 positions. The EPR spectra suggest that in both nitroxyls the final radiolysis products are stable biradicals and other paramagnetic compounds.
研究了中性除氧水溶液以及N₂O饱和水溶液中游离硝酰自由基BAPO和CATPO的γ辐解机理。分别通过测量249 nm和233 nm处的吸光度，用分光光度法跟踪BAPO和CATPO的分解。报道了在几种条件下观察到的产率G(-BAPO)和G(-CATPO)，并结合辐照水溶液中产生的OH自由基、H原子和水合电子的产率进行了讨论。与其他硝酰类似，发现当BAPO和CATPO与H原子、水合电子和羟烷基自由基反应时，会形成相应的羟胺。H原子和水合电子也分别通过加成到芳环上和消除NH₃的方式与BAPO和CATPO发生部分反应。OH自由基通过加成到芳环上以及从3或5位或2或6位的甲基上夺取H原子的方式与BAPO反应。OH自由基与CATPO的反应包括从3或4位或2或5位的甲基上夺取H原子。电子顺磁共振光谱表明，在这两种硝酰中，最终的辐解产物都是稳定的双自由基和其他顺磁性化合物。
