Predicting the activity of phenolic antioxidants: Theoretical method, analysis of substituent effects, and application to major families of antioxidants
Predicting the activity of phenolic antioxidants: Theoretical method, analysis of substituent effects, and application to major families of antioxidants
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DOI：
10.1021/ja002455u
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发表时间：
2001-02-14
影响因子：
15
通讯作者：
DiLabio, GA
中科院分区：
文献类型：
--
作者：
Wright, JS;Johnson, ER;DiLabio, GA
利用密度泛函理论计算了酚类抗氧化剂分子的气相键解离焓和电离势。我们表明，使用局部密集基集（LDBS）与全基集对单取代酚的结果非常相似，并且LDBS程序与苯溶剂中高取代酚的实验BDE值的变化非常吻合。给出了基于群可加性规则估计O-H BDE的程序并进行了测试。用这些方法研究了几种有趣的酚类抗氧化剂，包括用作食品添加剂的商业抗氧化剂，与维生素E有关的化合物，茶中的类黄酮，氨基酚，与白藜芦醇有关的二苯乙烯，以及位阻酚。基于这些结果，我们能够解释抗氧化剂与自由基反应的相对速率，包括h原子转移和单电子转移机制的比较，并得出结论，在大多数情况下，h原子转移将占主导地位。
A procedure based on density functional theory is used for the calculation of the gas-phase bond dissociation enthalpy (BDE) and ionization potential fur molecules belonging to the class of phenolic antioxidants. We show that use of locally dense basis sets (LDBS) vs full basis sets gives very similar results for monosubstituted phenols, and that the: LDBS procedure gives good agreement with the change in experimental BDE values for highly substituted phenols in benzene solvent. Procedures for estimating the O-H BDE based on group additivity rules are given and tested. Several interesting classes of phenolic antioxidants are studied with these methods, including commercial antioxidants used as food additives, compounds related to Vitamin E, flavonoids in tea, aminophenols, stilbenes related to resveratrol, and sterically hindered phenols. On the basis of these results we are able to interpret relative rates for the reaction of antioxidants with free radicals, including a comparison of both H-atom-transfer and single-electron-transfer mechanisms, and conclude that in most cases H-atom transfer will be dominant.