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(英文)

Kinetics and Mechanism Study of the Catalytic Carboxyester Hydrolysis Using Co~Ⅱ Nitrate with a Tripod Ligand 1,3,5-Tri-(N-α-Pyridylmethylenic Aminomethylenic)Benzene

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pH7.5-9.4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(pH7.5-9.4),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=(koMbsL[ML]+kOH[OH-]+k0)[NA],二级水解速率常数为0.197 mol-1.dm3.s-1.

The Co^Ⅱ 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 performed using the cobalt complex in 10% （V/V） CH3CN-H2O at 25℃, I=0.10 mol· dm^-3 KNO3 and pH 7.5-9.4. The results show that the Co^Ⅱ complex serves as a good nucleophile that effectively catalyzes NA hydrolysis. The hydrolysis rate follows the law v=（kobn^ML[ML]＋kOH [OH^-] ＋ k0） [NA]. The second order hydrolysis rate constant using Co3LH-1 is 0. 197 mol^-1· dm^3· s^-1.