【摘要】 以单取代苯为模型,假定间位共轭效应受阻,诱导效应在共轭体系中的传递因子为1/2,则基团的共轭效应参数:R_C=0.05（△δ_P-△δ_m）或R_C=0.05（△δ_P-△δ_m）△δ_P和△δ_m分别表示单取代苯对位和间位的¹³C NMR化学位移相对于未取代母体增量,δ_P和δ_m分别为单取代苯对位和间位的¹³C NMR化学位移。用上式计算了559个基团的共轭效应参数,其结果与文献报道值颇为一致,且呈明显的变化规律。更多还原

【Abstract】 Using monosubstituted benzene as a model and presuming: (1) the conjugative effect of meta - position is prohibited; (2) the transmit factor of induction effect in the conjugative system is 1/2, the experimental formula for the conjugative effect parameters can be expressed as follows:Where Δδp and Δδm refer to the deviations of 13C NMR chemical shifts of para - and meta - positin of monosubstituted benzenes with respect to unsubsdtuted parent respectively. δp and δm refer to the 13C NMR chemical shifts for para - position and meta - position respectively. Using the formula, conjugative effects parameters for 559 groups are calculated, and the results agree well with the observed values in the literature.更多还原