有机酸及表面活性剂对Fe（Ⅲ）－5硝基－邻菲罗啉体系光化学还原反应影响的研究

Effects of Various Carhoxylic Acids on Rates of Photoreduced Reaction for Fe(Ⅲ)-5-Nitro-1, 10-Phenanthroline System

Ｆｅ（Ⅲ）与５─硝基─邻菲罗啉（５－Ｎ－Ｐｈｅｎ）可形成无色的Ｆｅ（５－Ｎ－Ｐｈｅｎ）３３＋。配合物，在紫外光照射下，可发生光化学反应，生成红色的Ｆｅ（５－Ｎ－Ｐｈｅｎ）３２＋配合物。本工作以低压汞灯作为光源，研究了各种有机酸、溶液酸度和表面活性剂等对Ｆｅ（Ⅲ）─５－Ｎ－Ｐｈｅｎ体系光化学还原反应速率的影响规律，并与邻菲罗啉和ａ－ａ’－联吡啶光化学还原反应作了比较，初步探讨了有机酸在光化学还原反应中的作用原理。实验表明，Ｆｅ（Ⅲ）－５－Ｎ－ｐｈｅｎ体系的光化学还原反应为零级反应，各种有机酸对光化学还原反应速率有明显影响。

The complex produced by binding the ferric ion with 5-nitro-1, 10--phenanthroline is readily reduced by ultraviolot light. Using a lamp filled with mercury vapor at low pressure as the light source, the effects of various carboxylic acids and the pH value of the solution on the rates of the photoreduced reaction for Fe (5-N-Phen)3+ are investigated, and the mechanism for the effects of carboxy acids on the rates of the photoreduced reaction is preliminarily discussed. It is found that the photoreduced reaction is zero-order and that the carboxylic acids affect the rates of the photoreduced reaction evidently. The equilibrium constants for the dissociation step is related to the rate of the photoreduced reaction for Fe (5-N-Phe)3+.