有机酸对铁（Ⅲ）—邻菲啰啉体系光化学还原反应速率影响的研究

Effects of Various Carboxylic Acids on Rate of Photoreduced Reaction for Fe(Ⅲ)-Phen System

Ｆｅ（Ⅲ）与邻菲啰啉（Ｐｈｅｎ）可形成无色的Ｆｅ（Ｐｈｅｎ）３３＋配合物，在紫外光照射下，上述配合物可发生光化学还原反应，生成红色的Ｆｅ（Ｐｈｅｄ）３２＋配合物。本研究以低压汞灯作为光源，研究了各种有机酸及溶液酸度对Ｆｅ３＋－Ｐｈｅｎ体系光化学还原反应速率的影响规律，并初步探讨了有机酸在光化学还原反应中的作用机理。实验表明，Ｆｅ３＋－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，其一级电离平衡常数的大小与光化学还原反应速率常数问存在一定关系。

The complex produced by binding the ferric ion with phenantheoline is readily reduced by ultlaviolet light. Using a lamp filled with mercury vapor at low pressure as a light source, the effects of various carboxylic acids and pH value of the solution on the rate of the photoreduced reaction for Fe(phen)3 3+ have been investigated, and the mechanism for the effecte of carboxylic acids on the rate of the photoreduced reaction is preliminarily discussed. It is found that the photoreduced reaction is zero-order and the carboxylic acid affects the rate of the photoreduced reaction evidently. The equilibrium constant for the dissociation step is related to the rate of the photoreduced reaction for Fe (phen)3 3+.