采用TTA-甲苯溶剂萃取法研究了对羟基苯甲酸甲酯(P-HBAME)对Np(Ⅵ)的还原过程动力学。推导出速率方程为-d[Np(Ⅵ)]/dt=k[NpO_2~(2+)][p-HBAME][H~+]~(-1)。提出了以电子通过苯环上的羟基向Np(Ⅵ)转移的过程为速度控制步骤的反应机理。对于一系列含有羟基和羧基的芳香族化合物还原Np(Ⅵ)的动力学数据进行比较,得出了反应速度常数与羟基的pK_a值的相关关系。 The kinetics of the reduction of Np (Ⅵ) by methyl p-hydroxybenzoate (P-HBAME) was studied by TTA-toluene solvent extraction. The rate equation is derived as -d [Np (Ⅵ)] / dt = k [NpO_2 ~ (2 +)] [p-HBAME] [H ~ +] ~ (-1). The reaction mechanism of electron transfer through the hydroxyl groups on benzene ring to Np (Ⅵ) is proposed. The kinetic data of Np (Ⅵ) reduction of a series of aromatic compounds containing hydroxyl groups and carboxyl groups were compared, and the relationship between the reaction rate constant and the pKa value of hydroxyl groups was obtained.