Results 161 to 170 of about 1,373 (200)

Characterization of all-benzenoid hydrocarbons

Journal of Molecular Structure: THEOCHEM, 1991
Abstract A benzenoid hydrocarbon is said to be all-benzenoid if its Clar formula contains only aromatic sextets and no double bonds. It is shown that the all-benzenoid hydrocarbons are characterized by the absence of fissures and coves in their perimeters.
I. Gutman, D. Babić
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Estimation of the number of benzenoid hydrocarbons

Chemical Physics Letters, 1988
Abstract A method for the estimation of B h , the number of benzenoid systems with h hexagons, is presented. B 13 is predicted to lie between 3.200×10 6 and 3.202×10 6 . This is a significant improvement on the earlier result which located B 13 between 3.080×10 6 and 3.300×10 ...
David Aboav, Ivan Gutman
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Mathematics of Periodic Tables for Benzenoid Hydrocarbons

Journal of Chemical Information and Modeling, 2007
AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
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A Periodic Table for Benzenoid Hydrocarbons

1990
The formulas for all benzenoid hydrocarbons are found in Table PAH6 which has x,y-coordinates of (d s , NIc). Recursive construction of this table was accomplished using an aufbau principle. This table complies to a sextet rule analogous to the octet rule for the periodic table of elements, and d s is analogous to the outer-shell electronic ...
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On dioxo derivatives of benzenoid hydrocarbons

Journal of Molecular Structure: THEOCHEM, 1999
Abstract Extending a problem occurring in connection with the stability order of the tautomers of hypericin, we examine the topological factors influencing the stability of the isomeric dioxo derivatives of benzenoid hydrocarbons, in particular the rules determining the number of Kekule structures in them. Depending on the position of the oxo groups,
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Enumeration and classification of benzenoid hydrocarbons

Journal of Molecular Structure: THEOCHEM, 1990
New principles in the enumeration of benzenoid systems are reported. They imply a class of benzenoids referred to as special catacondensed systems. The techniques are applied to catacondensed (branched) benzenoids of regular trigonal (D3h) symmetry. The results of enumeration up to h = 25 are given.
R. Tošić, Z. Budimac, J. Brunvoll, S.J. Cyvin   +3 more
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Enumeration and classification of benzenoid hydrocarbons

Journal of Computational Chemistry, 1987
AbstractThe enumeration of benzenoids is studied with the aid of different modifications of a computer program. Known values for the number of cata‐condensed and of all benzenoids withh(number of hexagons) up to eight are reproduced. These benzenoids are classified into (a) unbranched of different symmetries and branched cata‐condensed, and (b) normal,
J. Brunvoll, S. J. Cyvin, B. N. Cyvin
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Benzenoid hydrocarbons in space: The evidence and implications

1990
Many different celestial objects emit an infrared sprectrum which has been attributed to infrared fluorescence from a family of highly vibrationally excited benzenoid hydrocarbons referred to as polycyclic aromatic hydrocarbons (PAHs). The most intense emitters contain between 20 to 50 carbon atoms, although larger species also contribute to the ...
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Giant Benzenoid Hydrocarbons. Superphenalene Resonance Energy

Polycyclic Aromatic Compounds, 1999
Abstract We calculated molecular resonance energy for “0superphenalene”, a recently reported giant benzenoid which can be viewed as obtained from three fused “superbenzenes” (hexa-peri-hexabenzocoronenes). Using the Method of Conjugated Circuits we derived quantitative characterization of Clar's qualitative description of the considered benzenoids as ...
Randic, M., Guo, X. F.
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Thermochemical parameters for benzenoid hydrocarbons

Thermochimica Acta, 1974
Abstract The heats of atomization of aromatic hydrocarbons are correlated with an incremental 5-term scheme that includes CH and CC bond energy terms, resonance energies, and two steric parameters. Regression analysis of the experimental data with respect to the proposed parameters gives reasonable values for each term.
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