摘要
以单取代苯为模型,建立并论证了取代基诱导效应参数RI、共轭效应参数RC及诱导和共轭共同作用效应参数R,RI=128.5-δ1,RC=642.5-∑6n=2δn,R=771-∑6n=1δn,δn(n=1～6)是单取代苯苯环上6个碳原子Cn(n=1～6)的化学位移,δ1是取代位C1的化学位移,128.5为苯的13C化学位移。当参数R>0时,取代基对苯环有给电子效应。一般而言,RI<0、RC>0、R>0时,取代基是典型的使苯环活化的邻对位定位基;RI<0、RC<0、R<0时,取代基是使苯环钝化的间位定位基;其余情况参考δn的具体数值判定取代基的作用。能与苯环形成最佳共轭的基团,其与苯环直接相连的是与碳原子同周期的B、C、N、O、F。
Using monosubstituted benzene as model, inductive effect parameter, eonjugative effect parameter, the sum of inductive effect and conjugative effect can be expressed as follows respectively：R1=128.5-δ1,Rc=642.5-∑^6 n=2δn,R=771-∑^6 n=1 δn,δn（n=1～6） refers to the 13^C chemical shift of monosubstituted benzene ring, δ1 is the chemical shift of carbon connected with substitutent directly and 128.5 is the 13^C chemical shift of benzene. When parameter R is zero plus, the substituent has electron-donating effect. Generally speaking, when R1 〈 0, Rc 〉 0, R 〉0, substituent can activate benzene ring and has p-and o-position orientation effect; when R1 〈 0, Rc 〈 0, R 〈 0, substituent can deactivate the benzene ring and has m-position orientation effect; otherwise, δn, is used to confirm orientation effect. Substituents have the strongest eon iugative effect with benzene ring on condition that the atom connected with benzene ring is in the same period with carbon, for example, B, C, N, O and F.
出处
《化学通报》
CAS
CSCD
北大核心
2006年第5期331-336,共6页
Chemistry
关键词
单取代苯
化学位移
诱导效应参数
共轭效应参数
定位效应
Monosubstituted, Chemical shift, Inductive effect parameter, Conjugative effect parameter, Orientation effect
