The electronic structures of 17 perchlorofluoroolefins and perfluoroolefins were calculated using the MNDO method.Based on these calculations combined with the perturbation theory,a good structure-reactivity relations...The electronic structures of 17 perchlorofluoroolefins and perfluoroolefins were calculated using the MNDO method.Based on these calculations combined with the perturbation theory,a good structure-reactivity relationship of perchlorofluoroolefins has been established.In the case of internal ole- fins,the direction of nucleophilic attack is governed not only by the perturbation energy of the ground state,but also by the stability of the anionic intermediate and the activation energy of the reaction.展开更多
MNDO and MM2(85)methods were used to study the conformation and the structure- reactivity relationship of neutral and acidic phosphorus esters.The calculation results indicate that for the most stable conformation,the...MNDO and MM2(85)methods were used to study the conformation and the structure- reactivity relationship of neutral and acidic phosphorus esters.The calculation results indicate that for the most stable conformation,the charge density of phosphoryl oxygen(q_O)is determined not only by the electronegativity of the substituents,but also by the conformation of the alkoxyl groups on the phosphorus atom.Meanwhile,the conformation of the alkoxyl group provides,as a rule, more important influence on the charge density of the phosphoryl oxygen.However,the energy of the highest occupied molecular orbital(EHOMO)is basically dependent on the eletronegativity of the substituents,while the donating ability or the withdrawing ability of the neutral phosphorus com- pounds is mainly governed by the EHOMO but not the q_O.This is also true for other kinds of the neutral oxygen-containing compounds.展开更多
During the etherification of 1,2-O-isopropylidene-4,6-di-O-benzyl myo-inositol, the specific regioselectivity on 3- or 8-hydroxyl group was showed to be determined by the nature of the O-alkylating agents used. As dem...During the etherification of 1,2-O-isopropylidene-4,6-di-O-benzyl myo-inositol, the specific regioselectivity on 3- or 8-hydroxyl group was showed to be determined by the nature of the O-alkylating agents used. As demonstrated by MM and MNDO calculation, the regioselectivity of the reaction mentioned can be rationalized by steric and/or electronic effect.展开更多
基金Part Ⅶ was published in Tetrahedron Letter,31,1307 (1990).
文摘The electronic structures of 17 perchlorofluoroolefins and perfluoroolefins were calculated using the MNDO method.Based on these calculations combined with the perturbation theory,a good structure-reactivity relationship of perchlorofluoroolefins has been established.In the case of internal ole- fins,the direction of nucleophilic attack is governed not only by the perturbation energy of the ground state,but also by the stability of the anionic intermediate and the activation energy of the reaction.
基金the National Natural Science Foundation of China and the Key Laboratory of Computer Chemistry of Chinese Academy of Sciences.
文摘MNDO and MM2(85)methods were used to study the conformation and the structure- reactivity relationship of neutral and acidic phosphorus esters.The calculation results indicate that for the most stable conformation,the charge density of phosphoryl oxygen(q_O)is determined not only by the electronegativity of the substituents,but also by the conformation of the alkoxyl groups on the phosphorus atom.Meanwhile,the conformation of the alkoxyl group provides,as a rule, more important influence on the charge density of the phosphoryl oxygen.However,the energy of the highest occupied molecular orbital(EHOMO)is basically dependent on the eletronegativity of the substituents,while the donating ability or the withdrawing ability of the neutral phosphorus com- pounds is mainly governed by the EHOMO but not the q_O.This is also true for other kinds of the neutral oxygen-containing compounds.
基金Project supported by the National Natural Science Foundation of China.
文摘During the etherification of 1,2-O-isopropylidene-4,6-di-O-benzyl myo-inositol, the specific regioselectivity on 3- or 8-hydroxyl group was showed to be determined by the nature of the O-alkylating agents used. As demonstrated by MM and MNDO calculation, the regioselectivity of the reaction mentioned can be rationalized by steric and/or electronic effect.
