7291-09-0Relevant articles and documents
Tris(hydridosilylethyl)boranes: Highly reactive synthons for polymeric silicon compounds
Weinmann, Markus,Kamphowe, Thomas W.,Fischer, Peter,Aldinger, Fritz
, p. 115 - 127 (1999)
Two methods for the synthesis of tris(hydridosilylethyl)boranes B[C2H4Si(CH3)nH3-n] 3 (C2H4 = CHCH3, CH2CH2; n = 0, 1, 2; 5a-c) are reported. In the first route, tris(chlorosilylethyl)boranes B[C2H4Si(CH3)nCl3-n] 3 (n = 0, 1, 2; 3a-c) are reacted with LiAlH4 in diethyl ether solution. Compounds 3a-c are prepared by hydroboration of the respective vinyl chlorosilanes (H2C=CH)Si(CH3)nCl3-n (n = 0, 1, 2; 1a-c) with borane dimethylsulfide, BH3·S(CH3)2. Hydroboration of hydrido vinylsilanes (H2C=CH)Si(CH3)nH3-n (n = 0, 1, 2; 6a-c) with BH3·S(CH3)2 represents an alternative route, which produces 5a-c in much higher yield. The intermediates 6a-c are obtained from 1a-c and LiAlH4 in diethyl ether solution and, because of their difficult handling, reacted in situ. Detailed NMR studies prove boron addition to the olefinic moieties to be not regioselective, since resonance signals for products formed by α- and β-boron addition to the vinyl functions are observed. The elemental constitution of 5a-c is established by high-resolution electron ionization mass spectrometry for both the molecular ion peak and a series of fragment ions. Major fragments arise from C-C bond formation in the gas phase between two of the boron side chains in the ion dipole complex.
Infrared and Raman spectra, conformational stability, barriers to internal rotation, normal-coordinate calculations and vibrational assignments for vinyl silyl bromide
Guirgis, Gamil A.,Nashed, Yasser E.,Durig, James R.
, p. 1065 - 1078 (2000)
The infrared (3200-30 cm-1) spectra of gaseous and solid, the Raman spectra (3200-30 cm-1) of the liquid and solid vinyl silyl bromide, CH2CHSiH2Br, have been recorded. Additionally, quantitative depolarization values have been obtained. Both the gauche and cis conformers have been identified in the fluid phases but only the gauche conformer remains in the solid. Variable temperature studies from 0 to -87 °C of the Raman spectrum of the liquid was carried out. From these data, the enthalpy difference has been determined to be 22±6 cm-1 (0.26±0.08 kJ/mol), with the gauche conformer being the more stable form. The predictions from the ab initio calculations up to MP2/6-311++G(2d,2p) basis set favor the gauche as the more stable form. A complete vibrational assignment is proposed for both the gauche and cis conformers based on infrared band contours, relative intensities, depolarization values and group frequencies. The vibrational assignments are supported by normal coordinate calculations utilizing the force constants from ab initio MP2/6-31G(d) calculations and the potential energy terms for the conformer interconversion have been obtained from the same calculations. Complete equilibrium geometries have been determined for both rotamers by ab initio calculations employing a variety of basis sets up to 6-311++G(2d,2p) at levels of restricted Hartree-Fock (RHF) and/or Moller-Plesset (MP) to second order. The results are discussed and compared to those obtained for some similar molecules.
GASEOUS DIELECTRICS WITH LOW GLOBAL WARMING POTENTIALS
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, (2010/12/31)
A dielectric gaseous compound which exhibits the following properties: a boiling point in the range between about ?20° C. to about ?273° C.; non-ozone depleting; a GWP less than about 22,200; chemical stability, as measured by a negative standard enthalpy of formation (dHf0); a toxicity level such that when the dielectric gas leaks, the effective diluted concentration does not exceed its PEL; and a dielectric strength greater than air.
Compounds which mimic the chemical and biological properties of discodermolide
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, (2008/06/13)
Compounds which mimic the chemical and/or biological activity of discodermolide are provided and intermediates useful in their preparation.
