Premium
Chemistry of trifluorostyrenes and their dimers: 2. Synthesis of substituted α, β, β‐trifluorostyrenes and α, β, β‐trifluoroethenylnaphthalenes. Hammett correlations of their NMR parameters and the concept of “distorted π‐electron clouds”
Author(s) -
XiKui Jiang,
ChengJiu Wu,
ZhengZhi Wu
Publication year - 1983
Publication title -
acta chimica sinica english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 0256-7660
DOI - 10.1002/cjoc.19830010108
Subject(s) - chemistry , tetrafluoroethylene , tetrahydrofuran , chemical shift , reagent , hammett equation , substituent , coupling constant , fluorine 19 nmr , computational chemistry , electronic effect , medicinal chemistry , reaction rate constant , nuclear magnetic resonance spectroscopy , stereochemistry , organic chemistry , steric effects , kinetics , physics , quantum mechanics , solvent , copolymer , polymer , particle physics
Six α, β, β‐trifluorostyrenes with the following substituents, viz., p ‐MeO, p ‐Me, m ‐Me, p ‐Cl, m ‐Cl, and m ‐CF 3 , were synthesized by the reaction of the corresponding Grignard reagents with tetrafluoroethylene in tetrahydrofuran. Similarly, α‐and β‐trifluoroethenylnaphthalenes were prepared.The substituent electronic effects on the 19 F‐NMR parameters were investigated for the trifluorostyrenes (I). Linear correlations between the Hammett σ constants and the following 19 F‐NMR parameters were established, namely, chemical shifts δ. (F 1 ) and δ (F 2 ), coupling constants J 12 , differences of chemical shifts Δδ 3‐1 (δ (F 3 )—δ(f 1 ) or Δδ 3‐2 . The results are consistent with previous expectations based on the simple concept of “distorted π‐electron clouds”. Facts are presented which indicate that the Δδ 3‐1 (or Δδ 3‐2 ) values may serve as empirical measures of the degree of polarization of the π bonds of these fluoroolefins.