α-V、Ⅵ主族正离子取代的甲苯和苯乙酮系列中碳-氢键均裂及异裂能量的研究  

Homolytic and Heterolytic C-H Bond Dissociation Energies of a-V (or Ⅵ)-Group Cation-substituted Toluenes and Acetophenones

作　　者：程津培[1] 刘博[1] 鲁云[1] 米江林[1] 还振威[1] 

机构地区：[1]南开大学化学系,天津300071

出　　处：《高等学校化学学报》1997年第7期1080-1085,共6页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金

摘　　要：合成了α-位有第V、Ⅵ主族元素杂正离子取代基的甲苯系列（1）和苯乙酮系列（2）共11个Ylide前体化合物，用重迭指示剂法首次测定了其在二甲亚矾（DMSO）溶剂中的酸性解离常数PKa，同时结合碳负离子（即Ylide）氧化电位的测定，通过热力学循环估测了它们的气相均裂键能（BDE）．根据这些PKa和BDE数据，对16个Ylide前体化合物的C－H键的均裂能和异裂能进行了比较。Eleven α-V (or Ⅵ)-group cation-substituted toluenes (1) and acetophenones (2)were synthesized. The equilibrium acidities (PKa) of these compounds were determined indimethyl sulfoxide solution by the "Overlapping Indicator Method" and the homolytic C-Hbond dissociation energies (BDE) were derived from a thermodynamic cycle combining pKawith oxidation potential of carbanion. The effects of the a-positively charged groups on thethermodynamic stabilities of sixteen Ylide carbanions and the corresponding Ylide-like radi-cals and the remote structral effect have been discussed.

关 键 词：自由基 异裂能 BDE 甲苯 苯乙酮 碳氢键 

分 类 号：O625[理学—有机化学] O642.1[理学—化学]