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利用各种芳基格氏试剂与四氟乙烯在四氢呋喃中的反应,合成了六个取代三氟苯乙烯,其中取代基分别为:p-CH_3O,p-CH_3,m-CH_3,p-Cl,m-Cl和m-CF_3,还合成了α-与β-三氟萘乙烯. 研究了在已合成的取代三氟苯乙烯化合物(1)中取代基的电子效应对~(19)F NMR参数的影响.建立了取代基的Hammett常数σ分别与下列~(19)F NMR参数间的线性相关关系;化学位移δ(F~1)-δ(F~2)、偶合常数J_12及化学位移之差Δδ_(3-1)=δ(F~3)-δ(F~1)(或者Δδ_(3-2),证实了过去的预计.建议以Δδ_(3-1)值作为衡量三氟乙烯类化合物中π键极化程度的尺度.并把这一定量的“歪电子云”概念与有关的化学事实联系起来.
Six substituted trifluorostyrenes were synthesized by the reaction of various aryl Grignard reagents with tetrafluoroethylene in tetrahydrofuran. The substituents were p-CH 3 O, p-CH 3, m-CH 3, p-Cl, m-Cl and m-CF_3, α-and β-trifluoronaphthacene were also synthesized.The electronic effect of the substituent on the substituted ~ (19) F NMR parameter The linear correlation between the Hammett constant σ of the substituent and the ~ 19 F NMR parameters was established. The chemical shift δ (F ~ 1) -δ (F ~ 2), the coupling constant J_12 and the chemical shift The difference Δδ_ (3-1) = δ (F~3) -δ (F~1) (or Δδ_ (3-2)) confirms past predictions. It is suggested that Δδ_ (3-1) Class compounds in the degree of π bond polarization scale and this quantitative “crooked electron cloud” concept associated with the relevant chemical facts.