An accurate theoretical study of energy barriers of alkaline hydrolysis of carboxylic esters

作者：Wang Huajing^*

来源：Research on Chemical Intermediates, 2012, 38(9): 2175-2190.

DOI：10.1007/s11164-012-0535-8

• Density functional theory
• Mechanisms
• Alkaline ester hydrolysis

Hydrolysis of esters is one of the most important and frequently used reactions in both organic synthesis and biochemistry. While the reaction mechanism in solution is reasonably well understood, many questions still remain to be answered. In the present study, the combination method, MPW1B95/6-311++G(3df,2p)//B3LYP/6-31+G(d)//HF//CPCM/UA0, was found to be reliably predict the energy barriers of alkaline hydrolysis of various esters. The MAD and RMSE were equal to 1.03 and 1.06 kcal/mol, respectively. With this authorized theoretical protocol in hand, we systematically studied the mechanisms of alkaline hydrolysis of ethyl benzoate. The acyl-oxygen cleavage B(AC)2 route is preferred over the alkyl-oxygen cleavage B(AL)2 route. Then, the total activation energy barriers of B(AC)2 and B(AL)2 routes of over 40 esters have been calculated. And this large body of data allows us to systematically study the various effects controlling the alkaline ester hydrolysis, including the polar effect, the steric effect, and the remote substituent effect. Also, the solvent effect has been extensively studied in this work. Furthermore, the differences between B(AC)2 and B(AL)2 routes of these effects are also discussed. The results enable us to predict the energy barrier of the hydrolysis of cyhalofop-butyl in aquatic solution.

• 出版日期2012-11