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
In order to study the polar substituent effect almost with no steric effect in organophosphorus chemistry,a series of 4-substituted-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane 1-oxides(1)and p-substituted phenylphospho...In order to study the polar substituent effect almost with no steric effect in organophosphorus chemistry,a series of 4-substituted-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane 1-oxides(1)and p-substituted phenylphosphonates(2)and corresponding mono hexyl esters(3)as model were synthesized.^(31)P-NMR chemical shifts of compounds(1)in methanol and deuterioacetone were determined.The Δδ values reflect 4-sbstituent po- lar effect.The ^(31)P-NMR of compounds(2)and(3)and the pKa of compounds(3)were also measured.The results showed that the trend of polar effects of substituents in both carboxylic and organophosphates chemistry are similar,and the change of polar effects in variation with the alkyl groups is not significant.展开更多
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 National Science Foundation of China.
文摘In order to study the polar substituent effect almost with no steric effect in organophosphorus chemistry,a series of 4-substituted-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane 1-oxides(1)and p-substituted phenylphosphonates(2)and corresponding mono hexyl esters(3)as model were synthesized.^(31)P-NMR chemical shifts of compounds(1)in methanol and deuterioacetone were determined.The Δδ values reflect 4-sbstituent po- lar effect.The ^(31)P-NMR of compounds(2)and(3)and the pKa of compounds(3)were also measured.The results showed that the trend of polar effects of substituents in both carboxylic and organophosphates chemistry are similar,and the change of polar effects in variation with the alkyl groups is not significant.
