2253-83-0Relevant academic research and scientific papers
Kinetic Isotope Effects for Proton Abstraction from Methanol by Polyhalogenomethyl Carbanions. Cleavage of Me3SiCHX2 and Me3SiCX3 by Base in Methanol.
Eaborn, Colin,Stanczyk, Wlodzimierz A.
, p. 471 - 473 (2007/10/02)
The carbanions XxH(3-x)C- (X=Cl or Br; x=2 or 3) generated by base cleavage of Me3SiCH(3-x)Xx (or some related compounds) in MeOH, show a kinetic isotope kH/kD of ca. 1.1 in proton abstraction from methanol, as given by the product ratio XxH(3-x)CH/XxH(3-x)CD observed for reaction in MeOH-MeOD (1:1) at ca. 21 deg C.The low value of the isotope effect is attributed to the fact that the free electron pair in the carbanion is localized on the carbon centre; carbanions derived from acids of acidities comparable with those of X3CH and X2CH2 but in which the electron pair is conjugatively delocalized, show much larger isotope effects.
High-Field NMR Determination of Magnetic Susceptibility Tensors and Angular Correlation Factors of Halomethanes
Bothner-By, A. A.,Dadok, J.,Mishra, P. K.,Zijl, P. C. M. Van
, p. 4180 - 4184 (2007/10/02)
Quadropolar splittings in the high resolution deuteron spectra of deuterated haloforms (CX3(2)H, X=Cl, Br, I) and methylene halides (CX2H(2)H) have been measured at 14.35 T (93.5 MHz) and used to determine the anisotropy or asymmetry of their molecular magnetic susceptibility tensors.By combination with the known isotropic susceptibilities, the principal susceptibility tensors have been deduced and decomposed into bond susceptibility tensors.Neither the average susceptibilities nor the principal susceptibility tensor elements of the complete halomethane series follow Pascal's additivity rules.The phenomenon is tentatively attributed to a variable paramagnetic contribution perpendicular to the X-bond.Angular correlation Kirkwood g2 factors have been determined for CHCl3 and CHBr3 and are compared with available literature data.
