Gruen Henry, Görner Helmut
Max-Planck-Institut für Bioanorganische Chemie, Mülheim an der Ruhr, Germany.
Photochem Photobiol Sci. 2008 Nov;7(11):1344-52. doi: 10.1039/b811372f. Epub 2008 Aug 29.
The photoreactions of 1-nitro-9,10-anthraquinone (N1) and 2-methyl-1-nitro-9,10-anthraquinone (N2) were studied in benzene and acetonitrile in the presence of 1-phenylethanol. For N2, a short-lived 10 ns transient observed upon flash photolysis is attributed to a triplet state, which can be intercepted by 1-phenylethanol to form a monohydro radical of N2 and a spectroscopically not detectable donor-derived radical. The decay of radicals yields the corresponding nitroso compound and eventually 1-amino-2-methyl-9,10-anthraquinone (A2) as photoproduct. The final reduction step requires participation of the anthraquinone carbonyl groups. The yield of radicals and the quantum yield (Phi(NH(2))) of conversion to A2 are small in inert solvents and increase with the donor concentration, approaching Phi(NH(2)) = 0.2. No triplet state was observed in the flash photolysis of N1, but a N1-derived radical and 1-amino-9,10-anthraquinone (A1) as final products were found. Various mechanistic aspects of complete photoreduction of nitroarenes to aminoarenes are discussed.
在苯和乙腈中，于1-苯乙醇存在的条件下，对1-硝基-9,10-蒽醌（N1）和2-甲基-1-硝基-9,10-蒽醌（N2）的光反应进行了研究。对于N2，闪光光解时观察到的一个寿命为10纳秒的短寿命瞬态归因于三重态，该三重态可被1-苯乙醇捕获，形成N2的单氢自由基和一种光谱上无法检测到的供体衍生自由基。自由基的衰变产生相应的亚硝基化合物，并最终生成光产物1-氨基-2-甲基-9,10-蒽醌（A2）。最终的还原步骤需要蒽醌羰基的参与。在惰性溶剂中，自由基的产率和转化为A2的量子产率（Phi(NH(2))）较小，并随着供体浓度的增加而增大，接近Phi(NH(2)) = 0.2。在N1的闪光光解中未观察到三重态，但发现了一种源自N1的自由基和最终产物1-氨基-9,10-蒽醌（A1）。讨论了硝基芳烃完全光还原为氨基芳烃的各种机理方面。
