稠苯芳杂环及其烷基质子化学位移的计算

本文提出了予测稠苯芳杂环及其烷基链上质子化学位移的计算方法。 将稠苯芳杂环化合物用凯库勒式表示,计算式为为需考虑的苯环内的乙烯基效应。σ_mi,ci为各苯环的环流效应。σ_1,Hc为各芳杂环的屏蔽效应,对杂环上质子它就是该单独芳杂环上相应质子的δ值,对苯环上质子要将它分解为各结构因素的效应,即:σ_1,He=(1/2)^d-1δ_x=y(或σ_z)+σ_c-c·σ_m,H. σ_x-y与σ_z为杂原子或其基团的屏蔽效应,σ_c=c为存在于芳杂环中的乙烯基的效应,σ_m,Hc为芳杂环的环流效应,d为对不同质子所考虑的键数。有取代基时需考虑取代基的效应。计算环上烷基质子的公式为:δ=σ_p,CH3+ασ_c,CH3+βσ_t,CH3+σ_l,G σ_l,G为稠苯芳杂环基的某级效应。

CALCULATIONS OF CHEMICAL SHIFTS OF PROTONS IN RINGS OF FUSED BENZENOID AROMATIC HETEROCYCLICS AND THEIR ALKYL CHAINS

In the present paper the calculation methods of chemical shifts of protons in the rings of fused benzenoid aromatic hcterocyclics and their alkyl chains has been proposed. The chemical shift of fused benzenoid aromatic helerocyclics must be presented by KeKul'e formulas, the calculation formula is: σ_j,c=c are the effects of ethenyls in the benzene rings that must be calculated.σ_mi,Cj are the net ring-current effects of benzene rings.σ_l,Hc are shielding effects of aromatic heterocyclics. If the proton belongs to an aromatic heterocyclic ring,σ_l,Hc is chemical shift of the proton that is in the same position of the single aromatic heterocyclic ring. If the proton belongs to benzene rings,σ_l,Hc must be divided into the effects of the structural units, thus: σ_l,Hc=(1/2)^d-1σ_x=y(or σ_z)+σ_c-c+σ_m,Hc σ_x=y and σ_Z are shielding effects ofheteroatom or hcteroatomic group +σ_c-c is the effect of ethenyl if it is situated in the aromatic heterocyclic ring. σ_m,Hc is net ring current effect of aromatic helerocyclic ring, d is the bond number that is concerned to the different protons. The substituting groups must be considered if they are present. The calculation fomula for the protons of alkyl chains in a ring is:δσ_P,CH3+α σ_S,CH3+β σ_t,CH3+σ_i,G σ_i,G is a certain order effect of fused benzenoid aromatic heterocyclic radical.