Determination of Reactivities by Molecular Orbital Theory (). Sigma MO Treatment on C6H5YCH2Cl

[摘要] Extended H ckel Theory and CNDO/2 MO calculation methods have been applied to C6H5YCH2Cl(Y = None, -CH2-, -O-, -S-, -CO-, -SO2-). It has been shown that charge distributions in molecules are mainly controlled by the migration of valence inactive electron, giving the order of ¥ò-acceptor and ¥ð-donor effects -O- > -S- > -CH2- > -SO2-. The -CO- group exceptionally acts as ¥ò-donor and ¥ð-acceptor. It was also predicted that, SN2 reactivities of C6H5YCH2Cl would be in the order of -O-¡Ö-CO- ¡í -S- ¡Ö None > -CH2-, neglecting solvent effect. From the results of our studies, we conclude that the structural factors influencing SN reactivities will be: (1) positive charge developments on reaction center carbon atom (2) energy level of ¥ò-antibonding unoccupied MO with respect to C-Cl bond. (3) ¥ò-antibonding strength of C-Cl bond at that level.

[学科分类] 化学（综合）