The kinetic curves for oxidation of dopamine hydrochloride in aqueous solution in the presence of ammonium peroxydisulfate were obtained by UV–vis spectroscopy and potentiometry. It was shown that the reaction follows the first‐order kinetic equation and proceeds at a low rate. The values for the activation energy and the preexponential factor were determined as 75 kJ × mol⁻¹ and 4 × 10⁸ s⁻¹, respectively. The activation entropy was found having a negative value of −89 J × mol⁻¹ × K⁻¹. The first reaction order, the low preexponential factor and the negative activation entropy value for the reaction between the 2‐(3,4‐dihydroxyphenyl)ethanammonium cation and the peroxydisulfate anion were explained by the formation of ionic associates, which slowly enter into the internal redox reaction.

中文翻译：

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带相反电荷的离子异常缓慢的反应：过氧二硫酸铵氧化多巴胺盐酸盐的动力学

通过紫外-可见光谱和电位计，获得了在过氧二硫酸铵存在下盐酸多巴胺盐酸盐氧化的动力学曲线。结果表明，该反应遵循一级动力学方程，并且以较低的速率进行。活化能和指数前因子的值分别确定为75 kJ×mol ^-1和4×10 ⁸  s ^-1。发现活化熵的负值为-89 J×mol ^-1  ×K ^-1。第一个反应顺序，低的指数前因子和2-（3,4-二羟基苯基）乙铵阳离子与过氧二硫酸根阴离子之间反应的负活化熵值是由离子缔合体的形成解释的，离子缔合体缓慢进入内部氧化还原反应。