取代基性质与饱和碳及饱和碳上质子化学位移的关系

CORRELATION OF CHEMICAL SHIFTS OF SATURATED ^(13)C AND PROTONS ON SATURATED CARBON WITH SUBSTITUENTS

根据多元线性回归分析，得到一个表达去屏蔽参数△Ha与基团电负性XG的关系式：XG＝（2．6△Ha－n）／5＋2．6．13CNMR去屏蔽参数△Ca与电负性之间的关系可表达为：XG＝（△Ca＋5n）／40＋2．由上述二式计算出的基团电负性与文献中提供的数据相仿，说明氢谱和碳谱化学位移主要与取代基电负性及其变形性有线性关系．不过由化学位移或去屏蔽参数计算出的基团电负住不能反映芳环等具有各向异性效应基团的诱导效应．

A simple relation is presented to calculate group electronegativity (XG), viz., XG = (2.6△Ha-n)/5 + 2.6. △Ha is the group deshielding parameter in 1H NMR, proposed by author. n is the principalquantum number of center atom in the group. The relation of XG with chemical shift parameter in 13CNMR is also drawn as XG = (△Ca + 5n)/40 + 2. The resulting values of electronegativities for some 46groups/ atoms are similar to those obtained in previous papers, but calculated values from deshieldingparameters of aromatic ring and anisotropic groups do not stand for their inductive effect. As a result,the principal quantum number of outer layer electrons in molecular orbital, maybe the deformation ofMO, is a factor to influence the chemical shift.