基于三角架配体的硝酸钴配合物的酯催化水解动力学与机理研究

摘要

利用三脚架配体-钴(Ⅱ)配合物作为催化剂进行了水解催化4-硝基苯酚醋酸酯(NA)的研究.在pH 7.5-9.4范围生成钴(Ⅱ)金属配合物(配体:钴离子=1:3),在25℃和不同的pH值条件下(pH 7.5-9.4),通过观察4-硝基苯酚的释放速率研究了钴配合物催化4-硝基苯酚醋酸酯的水解反应动力学.结果表明,钴(Ⅱ)配合物可以作为有效的亲核试剂催化NA酯水解,水解速率v=(kobsML[ML]+kOH[OH-]+k0)[NA],二级水解速率常数为0.197 mol-1·dm3·s-1.%The CoⅡ complex with a tripod ligand (L) has been examined as a catalyst for the hydrolysis of 4-nitrophenyl acetate (NA) ester, which was investigated kinetically by observing the rates of the release of p-nitrophenol in the buffers at 25 ℃ and different pH values. The ligand forms a 1: 3(L:Co) complex in the pH range of 7.5-9.4. The kinetic studies have been perand pH 7.5-9.4. The results show that the CoⅡ complex serves as a good nucleophile that effectively catalyzes NA hydrolysis. The hydrolysis rate follows the law v= (kobsML[ML]+kOH[OH-]+k0) [NA]. The second order hydrolysis rate constant using Co3LH-1is 0.197 mol-1·dm3·s-1.