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  • Chemistry  (2)
  • General Chemistry  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 3 (1997), S. 20-28 
    ISSN: 0947-6539
    Keywords: ab initio calculations ; Henry reaction ; nitroaldol reactions ; reaction mechanisms ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio calculations (up to MP4SDQ/6-31+G*//MP2(FU)/6-31+G* + δZPVE) on several model nitroaldol (Henry) reactions have been performed. It is found that the free nitronate anions react with aldehydes via transition states in which the nitro and carbonyl dipoles are antiperiplanar to each other. This kind of reaction yields anti (erythro) nitroalcohols as major products. The Henry reaction between lithium nitronates and aldehydes is predicted to occur via cyclic transition structures yielding syn nitroalcohols as major products. The stereocontrol in these model reactions is low. The factors affecting the stereoselectivity in the reaction between dilithiated nitronates and aldehydes are also discussed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 18 (1997), S. 9-19 
    ISSN: 0192-8651
    Keywords: Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A G2 search of the triplet [H4, Si, P]+ potential energy surface (PES) was carried out, along with a study of a number of mechanisms for the reaction of the P+ (3P) ion with silane. The most stable isomer, which corresponds to the species resulting from transferring three hydrogen atoms from the silicon to the phosphorus atom, lies 67.3 kcal/mol below the reactants' level. The P+—SiH4 ion-molecule complex also has remarkable stability, 20.4 kcal/mol. Bond properties were calculated and are discussed for all the stable species found on the PES. Various exothermic reaction paths were also fully characterized. The abstractions of a hydrogen molecule and a hydrogen atom, yielding species with P—Si bonds, have comparable kinetic hindrance, although release of molecular hydrogen was found to be more exothermic. Finally, hydrogen and/or charge transfer reactions between P+ (3P) and silane are also discussed. © 1997 by John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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