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用停止-流动分光光度法研究了Eu~(2+)与二甲酚橙(XO)间快速电子转移反应的动力学规律。求得了速控步骤的动力学参数。如反应级数(n=2)、几个不同温度下的速率常数(k_(278K)=5.7×10~8L·mol~-·s~(-1),k_(s38K)=1.01×10~9L·mol~(-1)·s~(-1))、活化能(E=7.6×10~3J·mol~(-1)),以及指前因子(A=1.5×10~(10)L·mol~(-1)·s~(-1)),并判断出其为溶液中扩散控制型反应。根据实验现象与测试结果,提出了Eu~(2+)与XO的反应分别在Eu~(2+)相对过量和在XO过量时的反应机理,并判断了各反应步骤速率常数之间的相对关系。
The kinetics of the fast electron transfer reaction between Eu 2+ and xylenol orange (XO) was studied by the stop-flow spectrophotometry. The kinetic parameters of the quick control step are obtained. For the reaction order (n = 2), the rate constants (k_ (278K) = 5.7 × 10 ~ 8L · mol ~ - · s -1 and k s38K = 1.01 × 10 ~ The activation energy (E = 7.6 × 10 -3 J · mol -1) and the pre-exponential factor (A = 1.5 × 10 10) L · mol ~ (-1) · s ~ (-1)), and it is judged that it is diffusion-controlled reaction in solution. According to the experimental phenomena and the test results, the reaction mechanism between Eu 2+ and XO in the excess of Eu 2+ and the excess of XO is proposed respectively. The relative rate constant of each reaction step is determined relationship.