Electron-Withdrawing Substituents Decrease the Electrophilicity of the Carbonyl Carbon. An Investigation with the Aid of <sup>13</sup>C NMR Chemical Shifts, ν(CO) Frequency Values, Charge Densities, and Isodesmic Reactions To Interprete Substituent Effects on Reactivity
作者:Helmi Neuvonen、Kari Neuvonen、Andreas Koch、Erich Kleinpeter、Paavo Pasanen
DOI:10.1021/jo020121c
日期:2002.10.1
electron-withdrawing substituents destabilize the carbonyl derivatives investigated. So, a significant ground-state destabilization of carboxylic acid esters, and carbonyl compounds in general, due to the decreased resonance stabilization, is proposed as a novel concept to explain both the increase in their reactivity and the changes in the chemical shifts and carbonyl frequencies induced by electron-withdrawing
已测量了几个系列的苯基或酰基取代的乙酸苯酯和酰基取代的乙酸甲酯的(13)C NMR化学位移和nu(C [双键] O)频率,以研究取代基引起的亲电变化碳的特征。电荷密度,键序和能量计算也已执行。光谱和电荷密度结果表明,与常规想法相反,吸电子取代基不会增加羰基碳的亲电性,反而会降低它。另一方面,设计的等渗反应的反应能表明,吸电子取代基使所研究的羰基衍生物不稳定。因此,羧酸酯的显着基态失稳,