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  • Jewish studies  (2)
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  • Jewish studies  (2)
  • 1
    Online Resource
    Online Resource
    Wiley ; 1981
    In:  Israel Journal of Chemistry Vol. 21, No. 2-3 ( 1981-01), p. 105-110
    In: Israel Journal of Chemistry, Wiley, Vol. 21, No. 2-3 ( 1981-01), p. 105-110
    Abstract: In this paper we show that the large number of approaches using apparently unrelated strainless increments for unsubstituted alicyclic hydrocarbons in the literature are neither mathematically nor conceptually unique. We additionally demonstrate that if the strain energy assigned to a compound by any three sets of increments is known, the strain energy any other approach would assign can automatically be determined without considering any further details of the structure of the compound. Equivalently, there are but three mathematically distinct, i.e. linearly independent, strainless incremental approaches for these compounds. Thus the choice of which method to employ in one's own reasoning relative to a chemical problem must be based on personal, rather than strictly chemical or mathematical criteria. We proceed by presenting our criteria and their molecular realization, the concept of diagonal reference states. Diagonal reference states are defined from hydrocarbons composed solely of the group of interest. In particular, 〉 C 〈 , 〉 CH–, –CH 2 – and –CH 3 are derived from diamond, cubane, cyclohexane and ethane with the accompanying enthalpies of formation, +1.9, –9.7, –20.6. and –42.0kJ mol −1 . The virtues and debits of this method are presented in support of our conclusion that this approach is preferable because it is diagonal.
    Type of Medium: Online Resource
    ISSN: 0021-2148 , 1869-5868
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 1981
    detail.hit.zdb_id: 2066481-3
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  • 2
    Online Resource
    Online Resource
    Wiley ; 1983
    In:  Israel Journal of Chemistry Vol. 23, No. 4 ( 1983-01), p. 439-441
    In: Israel Journal of Chemistry, Wiley, Vol. 23, No. 4 ( 1983-01), p. 439-441
    Abstract: The strength of the H‐O bond in H − O 2 should be a good indicator of the chemical reactivity of superoxide, O − 2 , as a hydrogen atom abstractor. This quantity can be calculated if the electron affinity of HO 2 is known. A recent experimental determination of the electron affinity of HO 2 [V. M. Bierbaum, R. J. Schmitt and C. H. DePuy, J. Am. Chem. Soc ., 103 , 6262–6263 (1981)] gave that value as 27.4 ± 0.2 kcal mol −1 . The H‐O bond energy of HO − − 2 can then be calculated from that value to be approximately 66 kcal mol −1 . Various theoretical methods may also be used to approximate the value of the electron affinity of HO 2 . These methods generally give values in accord with the experimental result. Based on the low H—O bond energy of 66 kcal mol −1 for HO − 2 , superoxide is expected to be relatively unreactive, comparable to iodine atoms but less reactive than bromine atoms or HO 2 and much less reactive than chlorine atoms or hydroxyl radicals. Based on our analysis, we predict that superoxide can only react as a hydrogen atom abstractor with substrates that contain relatively weak bonds to hydrogen such as hydroxylamine or hydroquinones.
    Type of Medium: Online Resource
    ISSN: 0021-2148 , 1869-5868
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 1983
    detail.hit.zdb_id: 2066481-3
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
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