Aliaga Carolina, Almodovar Iriux, Rezende Marcos Caroli
Facultad de Química y Biología, Universidad de Santiago de Chile, Casilla 40 Correo 33, Santiago, Chile.
J Mol Model. 2015 Jan;21(1):12. doi: 10.1007/s00894-015-2572-x. Epub 2015 Jan 24.
Relative to the corresponding value of phenol, the bond-dissociation energies (BDE) of substituted phenols correlate well with a single descriptor: the Mulliken charge on the oxygen atom of the phenoxyl radical. However, the correlation fails for phenols ortho-substituted with polar groups. Internal reaction coordinates (IRC) for the model reaction of hydrogen abstraction by the hydroperoxyl radical from various 2- and 4-substituted phenols were calculated in order to investigate the role of intra-molecular hydrogen bonds and steric effects on the process. Calculations yielded theoretical values in good agreement with experimental ΔBDE values. The hydrogen-abstraction process was further analyzed in terms of density functional theory (DFT)-based reactivity indices such as local electrophilicity, the Fukui function for nucleophilic attack, and dual descriptor values of the phenolic hydroxyl oxygen along the IRC.
相对于苯酚的相应值，取代苯酚的键解离能（BDE）与一个单一描述符密切相关：苯氧基自由基氧原子上的穆利肯电荷。然而，对于被极性基团邻位取代的苯酚，这种相关性并不成立。为了研究分子内氢键和空间效应在该过程中的作用，计算了氢过氧自由基从各种2-和4-取代苯酚上夺取氢的模型反应的内禀反应坐标（IRC）。计算得到的理论值与实验ΔBDE值吻合良好。根据基于密度泛函理论（DFT）的反应活性指标，如局部亲电性、亲核进攻的福井函数以及沿IRC的酚羟基氧的双描述符值，对氢夺取过程进行了进一步分析。
