ALTERNATE PREDOMINANCE IN COMPETITION FOR CONJUGATION IN NITROGEN BRIDGE COMPOUND  

作　　者：蒋明谦 虞忠衡 戴萃辰 

机构地区：[1]Institute of Chemistry, Academia Sinica, Beijing 100021, PRC

出　　处：《Science China Chemistry》1990年第4期409-420,共12页中国科学（化学英文版）

基　　金：Project supported by the National Natural Science Foundstion of China.

摘　　要：It is demonstrated quantitatively that the serial number N is not m + n + 4 in the nitrogen bridge conjugated system (Ⅸ), so the lone pair of electrons on the nitrogen cannot conjugate with acenyl branch and formyl polyenic branch simultaneously. The character of UV spectra and substituent equivalents (△Ns) show that acenyl branch competes for the lone pair of electrons with formyl polyenic branch. If the length m of acenyl branch is lengthened while n keeps constant, a point where the acenyl branch is predominant over formyl polyenic branch in competition, will eventually be reached. On the other hand, the effect of the latter will become greater than the former. The effect of the two branches predominates each other alternately with the alternate increase in m and n values.It is demonstrated quantitatively that the serial number N is not m + n + 4 in the nitrogen bridge conjugated system (Ⅸ), so the lone pair of electrons on the nitrogen cannot conjugate with acenyl branch and formyl polyenic branch simultaneously. The character of UV spectra and substituent equivalents (△Ns) show that acenyl branch competes for the lone pair of electrons with formyl polyenic branch. If the length m of acenyl branch is lengthened while n keeps constant, a point where the acenyl branch is predominant over formyl polyenic branch in competition, will eventually be reached. On the other hand, the effect of the latter will become greater than the former. The effect of the two branches predominates each other alternately with the alternate increase in m and n values.

关 键 词：rolo of HOMOLOGOUS linearity NITROGEN BRIDGE CONJUGATED system alternative COMPETITION for CONJUGATION CONJUGATED stem CONJUGATED polarization. 

分 类 号：O6[理学—化学]