用密度泛函活性理论和Hammett常数预测单双取代苯酚的酸性(英文)

Molecular Acidity of Singly and Doubly Substituted Phenols:Predictions from Density Functional Reactivity Theory and Hammett Constants

用从头算和密度泛函理论准确预测分子的酸碱性仍然是一个悬而未决的理论和计算难题.近年来运用密度泛函活性理论(DFRT)发展的分子静电势和价自然原子轨道等概念为该问题的解决提供了一个简单而有效的途径.最近我们还提出用Hammett常数预测分子酸碱性,并发现对苯甲酸衍生物其预测精度与DFRT方法一致.本文将这两个新方法运用于苯酚衍生物体系以验证其普适性,一共计算了83个体系.发现二者均可以得到较好的预测精度,且DFRT方法比Hammett常数结果稍好.对进一步从局部和整体角度理解分子性质的起源以及这些性质的决定因素提供了有益启示.该文同时还验证了Hammett常数求和规则的普适性.

Accurate prediction of molecular acidity with ab initio and density functional theory approaches is of great interest,but remains a challenging task.Density functional reactivity theory （DFRT） with quantum descriptors,such as molecular electrostatic potential and valence natural atomic orbital energies,has recently been developed and used for this purpose.Our previous study of substituted benzoic acids revealed a novel approach to quantitatively predict molecular acidity using the Hammett constant,which gave the same prediction accuracy as that of DFRT.In this work,we applied these two approaches to singly and doubly substituted phenol systems,a total of 83 molecules,confirming their effectiveness and robustness.High accuracy was obtained using both approaches,with the DFRT approach achieving slightly higher accuracy than the Hammett approach in general.These results shed further light on the molecular features governing physiochemical properties such as acidity and basicity,both locally on the atomic level and globally on the functional group or molecular level.Our present results confirm the validity of the sum rule of Hammett constants for doubly and multiply substituted compounds.