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  • 1
    ISSN: 1573-1561
    Keywords: Conformational analysis ; molecular mechanics ; structure-activity relationships ; periplanone ; periplanone analogs ; sex pheromone ; Periplaneta americana L. ; American cockroach ; Orthoptera ; Blattidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Conformational parameters of pheromonally active analogs (1 and 2) of periplanones, the sex pheromones of the American cockroach, were investigated by molecular mechanics calculations. They existed in several conformers with small energy differences. These results were supported by NMR analysis. The structural features of the conformers of the analogs were compared with X-ray structures of periplanones.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 28 (1990), S. 668-674 
    ISSN: 0749-1581
    Keywords: Karplus equation ; Vicinal proton-proton coupling ; Non-additive substituent effects ; MM2 ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Karplus equation is expanded to contain 11 mutually independent structural terms and 22 adjustable parameters. These terms are selected on an empirical basis and combined linearly (Eqn 4). The new equation reproduces 198 NMR vicinal 1H-1H coupling constants determined in less polar solvents with a standard deviation of 0.33 Hz. The equation can be applied to norbornene derivatives, for which some of the previous modifications did not work well. Among new factors introduced in this modification to the Karplus-type equation are Mullay's group electro-negativity used in the evaluation of the α- and β-substituent effects, the C—C length and the C—C—H valence angles of the coupled H—C—C—H system, and the through-space interactions between a coupled proton and a non-bonded atom within the molecule. The four most important terms are the two cosine functions, originally used by Karplus, one form of the α-substituent effect and the C—C—H valence angles. These four terms alone give an accuracy of 0.42 Hz.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0570-0833
    Keywords: Molecular mechanics ; Molecular dynamics ; Quantum mechanics ; Force field calculations ; Theoretical chemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various problems arising in experimental organic chemistry can be clarified by molecular mechanics or force field calculations: molecular dynamics (conformational analysis and internal rotation), the search for the most stable isomer of various polycyclic hydrocarbons, reactivity calculations, including solvolysis of bridgehead substituted systems. Such calculations are shown to be useful in elucidating the mechanism of multistep carbonium ion rearrangement, for predicting the structure and stability of anti-Bredt olefins, and also offer an explanation for the selectivity observed in the hydrogenolysis of strained polycyclic smallring hydrocarbons, for the identification of long bonds and electronic effects, for the analysis of late transition states, and for the product distribution in complex reactions.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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