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453-18-9Relevant academic research and scientific papers
Analyse structurale des derives fonctionnels des acides carboxyliques. Partie II. Halogeno et cyanoacetates de methyle
Maury, Catherine,Petrissans, Jean
, p. 267 - 278 (1991)
Methylene bending mode analysis and dipole moment determinations were carried out in solution (CCl4) for some methyl esters ΣCH2CO2Me with Σ =F(I), Cl(II), Br(III), I(IV), CN(V), in order to identify the conformers induced by ΣCH2 group rotating motion and determine their relation amounts.The results are consistent with the existence of two conformations; syn and anti for (I), syn and gauche for (II) and (III).Compounds (IV) and (V) occur almost exclusively in gauche and syn forms respectively.A theoretical study of compounds (I), (II) and (V) by P.C.I.L.O. methods and the Onsager formalism was performed.The collected data show that the conformers have the O-Me bond syn to the carbonyl.The calculated value of ΔE for the equilibrium between the syn and anti rotamers (Ea-Es =600 cal mol-1) is in good agreement with ΔH0298 estimated from the temperature-dependence studies (ΔE =158 cal mol-1).
Conformational analysis. Part 33. An NMR, solvation and theoretical investigation of conformational isomerism in N,N-dimethylfluoroacetamide and N,N-dimethyl-α-fluoropropionamide
Tormena, Claudio F.,Rittner, Roberto,Abraham, Raymond J.,Basso, Ernani A.,Pontes, Rodrigo M.
, p. 2054 - 2059 (2007/10/03)
The solvent and temperature dependence of the 1H and 13C NMR spectra of N,N-dimethylfluoroacetamide (DMFA) and N,N-dimethyl-α-fluoropropionamide (DMFP) are reported and the 5JCF, 1JCF and 4JCF couplings analysed by solvation theory. Density function theory (DFT) at the B3LYP/6-311 +G(d,p) level with ZPE (zero point energy) corrections was used to obtain the conformer geometries. In DMFA, the DFT method gave only two minima for the cis (F-C-C=O, 0°) and gauche (F-C-C=O, 140.6°) rotamers. The trans rotamer was not a minimum in the energy surface. Assuming only the cis and gauche forms, the observed couplings when analysed by solvation theory gave the energy difference (Ecis - Eg) of 2.5 kcal mol-1 in the vapour phase, (cf. the ab initio value of 2.3 kcal mol-1) decreasing to 0.87 kcal mol-1 in CCl4 and to -1.29 kcal mol-1 in DMSO. In DMFP the ab initio calculations gave three minima; the cis (F-C-C=O, 30.4°), gauche-1 (F-C-C=O, 144.7°) and gauche-2 (F-C-C=O, -124.1°) rotamers with (Ecis - Eg2) equal to 2.5 kcal mol-1 and (Eg1 - Eg2) equal to 0.3 kcal mol-1. The observed couplings were analysed by solvation theory assuming one "average" gauche conformer to give (Ecis - Eg(AV)) equal to 2.1 kcal mol-1 in the vapour phase, decreasing to 0.83 kcal mol-1 in CCl4 and to -1.11 kcal mol-1 in DMSO.
Novel and practical preparation of α-fluoro-functionalized esters from fluoroiodoacetates
Zhi, Chengxin,Chen, Qing-Yun
, p. 1741 - 1747 (2007/10/03)
The addition reaction of fluoroiodoacetates 2 to various electron-rich alkenes 3 initiated by iron powder in dry THF at 70-80°C gave 1:1 adducts 4 in good yields. A variety of functionalities in the alkenes such as trimethylsilyl, alkoxy, acetoxy, hydroxy and ester could be tolerated under the reaction conditions. Reduction of the adducts 4 with Zn-AcOH in ethanol or Zn-NiCl2·OH2O in moist THF was readily accomplished, and the overall procedure was amenable to a convenient one-flask procedure. Treatment of fluoroiodoacetates 2 with electron-deficient alkenes 7 in the presence of an Fe-CrCl3·OH2O-bpy bimetal redox system in ethanol at 70-80°C resulted in the formation of iodine-free 1:1 adducts 8 in moderate to good yields. It is proposed that the addition reactions of fluoroiodoacetates 2 to electronrich and electron-deficient alkenes proceeded through a single-electron-transfer mechanism.
A facile synthesis of organofluorine compounds using a semi-molten mixture of tetrabutylammonium bromide and an alkali metal fluoride
Bhadury, Pinaki S.,Pandey, Mamta,Jaiswal, Devendra K.
, p. 185 - 188 (2007/10/02)
A semi-molten mixture of tetrabutylammonium bromide and an alkali metal fluoride (KF or CsF) has been found to be an efficient reagent system for the preparation of organofluorine compounds, e.g., CH3(CH2)7F, CH2=CH-CH2F, FCH2CO2C2H5, C6H5COF, and related compounds through facile fluoride-ion exchange with organohalides.The system provides a simple and convenient alternative to 'anhydrous' tetrabutylammonium fluoride for the synthesis of organofluorine compounds. - Keywords: Semi-molten mixture; Tetrabutylammonium bromide; Alkali metal fluorides; Organofluorine compounds; NMR spectroscopy