气相酸性理论(Ⅰ)——脱质子能与氢电荷的相关  

Theory of Gas-Phase Acidity (Ⅰ)——Correlation of Deprotonation Energy with Hydrogen Charge

作　　者：陈志行[1] Chen Zhixing(Chemistry Department,Zhongshan University,Guangzhou)

机构地区：[1]中山大学化学系

出　　处：《高等学校化学学报》1985年第7期637-641,共5页Chemical Journal of Chinese Universities

摘　　要：采用半经验自洽场法中的cNDO/2法和MNDO法作全几何优化,计算了多种酸及其共轭碱的电荷分布。考察了气相酸的脱质子能实验数据与酸性氢原子以及相连原子和共轭碱亲核原子的电荷,表明前者相关性比后两者好得多。说明酸性氢原子上的电荷是影响酸性的重要因素,而后两者并不重要。由此推断电荷分散使负离子趋于稳定的观点不能成为酸性规律的主要解释。The charge distributions of various acids and their conjugate bases arc calculated by using CNDO/2 and MNDO with full geometry optimization. The deprotonalion energy is found to be better correlated with the charge on the acidic hydrogen than with the charge on the atom linking to the hydrogen and with the charge on the neucleophilic atom of the conjugate base. This shows that the charge on the acidic hydrogen has an important effect on acidity, whereas the effect of the charge on the linking atom and on the neucleophilic atom of the conjugate base is not imporant. It can thus be deduced that the view of stabilization of the anion due to spreading the negative charge is not the significant explanation of acidity.

关 键 词：共轭碱 电荷分布 氢原子 实验数据 脱质子能 MNDO法 气相酸性 

分 类 号：O64[理学—物理化学]