- Trifluoropropynyl derivatives. I. Their preparation and reaction with difluorocarbene
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The trifluoropropynyl derivatives (CH3)2AsC≡CCF3, CH3As(C≡CCF3)2, (CH3)3SiC≡CCF3, and (C2H5)3GeC≡CCF3 can be prepared from CF3C≡CMgI and the appropriate organometallic halide. They react with CF2 [from (CH3)3SnCF3] yielding the novel cyclopropenyl derivatives RnMC=C(CF3)CF2 [RnM = (CH3)2As, (CH3)3Si, or (C2H5)3Ge]. (CH3)2- AsC≡CCF3 is also obtained by the reaction of CF3C≡CH with compounds with As-N, As-S, As-As, and As-O bonds. CF3CH≡CH and ClAs(CH3)2 afford a little (CH3)2AsC≡CCF3, but the main products are the isomers of the 1:1 adduct (CH3)2AsC(CF3)=CHCl.
- Cullen,Leeder
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- Structural Characterization of Hydro-, Chloro- and Fluoroorganylsilanes with Substituents of Varying Electron Withdrawing Character
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We report on the molecular structure of trimethylsilanes Si(CH3)3X in which the substituents X, namely (Z)-pentafluoropropen-1-yl, trifluoropropyn-1-yl, pentafluoroethyl, trifluorovinyl, vinyl, propyn-1-yl, di- and trichloromethyl, display electron withdrawing effects of varying strength. The lengths of the bonds between the silicon and the carbon atoms of X correlate with the hybridization of the respective orbitals and the steric demand of X rather than with the electron withdrawing capability. In case of chlorinated substituents dispersion effects seem to shorten the Si?C bond. Furthermore, a route for generating trifluoropropyn-1-yllithium from the cryogen 2,3,3,3-tetrafluoropropene (HFO-1234yf) and n-butyllithium is described. Tetrafluoropropen-1-yllithium is slowly formed at ?80 °C but even at this temperature spontaneous elimination of LiF occurs. Deprotonation of the formed 3,3,3-trifluoropropyne requires temperatures of above ?60 °C leading to trifluoropropyn-1-yllithium which appears as relatively stable at room temperature.
- Ke?ler, Mira,Porath, Sven,Stammler, Hans-Georg,Hoge, Berthold
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p. 907 - 913
(2021/01/21)
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