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The Energetics of Halogenated Ethylenes (Ethynes) and 1,3-Butadienes (Butadiynes): A Computational and Conceptual Study of Substituent Effects and “Dimerization”

Carol A. Deakyne ; Department of Chemistry, University of Missouri-Columbia, Columbia, MO 65211-7600, USA
Lawrence H. Warfel IV ; Department of Chemistry, University of Missouri-Columbia, Columbia, MO 65211-7600, USA
Haunani M. Thomas ; Department of Chemistry, University of Missouri-Columbia, Columbia, MO 65211-7600, USA
Dhananjaya Nauduri ; Analytical Core Chemistry, Department of Pathology and Molecular Toxicology, University of Texas Medical Branch, Galveston, TX 77555, USA
Toyosi Esther A. Ajibowo ; Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA
Nicole J. Carbonaro ; Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA
Alec G. Simpson ; Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA
Joel F. Liebman ; Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA

Sažetak

The energetics of ethylenes and 1,3-butadienes may be interrelated by the reaction:
RHC=CH₂ + H₂C=CHR' → RHC=CH−CH=CHR' + H₂.
Shown earlier to be nearly enthalpically thermoneutral for a variety of hydrocarbon cases, we are now interested in the related energetics of halogenated alkenes and alkynes. Using quantum chemical calculations, we have studied this as recast as the isodesmic reactions:
2(H₂C=CHX) + H₂C=CH−CH=CH₂ → p,q-di-X-1,3-butadiene + 2H₂C=CH₂
2(HC≡CX) + HC≡C−C≡CH → di-X-butadiyne + 2HC≡CH.
Here p,q- = 1,3-; 1,4- and 2,3- with X = F, Cl, Br, and I. The halogen and location-dependent deviations from near enthalpic thermoneutrality are discussed.

Ključne riječi

dienes; diynes; halogenated compounds; resonance (conjugation) energy; isodesmic reactions; ab initio calculations

Hrčak ID:

38654

URI

https://hrcak.srce.hr/38654

Datum izdavanja:

30.6.2009.

Posjeta: 1.852 *