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  • 1
    ISSN: 1612-1112
    Keywords: Gas-solid chromatography ; Graphitized thermal carbon black ; Thermodynamics of adsorption ; Nitrogen compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary To study the role of the nitrogen atom in various valence states in the adsorption of nitrogen-containing molecules on the surface of hydrogen-treated graphitized thermal carbon black (HGTCB) gas chromatography was applied to determine the thermodynamic characteristics of adsorption: Henry's constants and heats of adsorption at zero surface coverage of nitriles, amines and indols on HGTCB. Adsorption characteristics of nitrogen-containing organic compounds and corresponding hydrocarbons are compared. It is shown that the logarithm of the retention volume and the heat of adsorption of n-alkylamines and n-alkylnitriles linearly depend on the number of carbon atoms in the molecule and on the average polarisability of the molecule. Relationship has been established between the Henry's constant as well as the heat of adsorption and the geometry of the molecule's disposition on HGTCB surface. Examples are given for the separation of a number of amines on the basis of the geometry of their molecules.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1612-1112
    Keywords: Gas-solid chromatography ; Graphitized carbon black ; Aromatic hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This paper defines values of retention volumes for zero surface coverage (Henry's constant) at different temperatures, retention indices and variations of the internal energy (differential heats of adsorption) of diphenyl and its alkyl derivatives, terphenyls, diphenylmethane, triphenylmethane, diphenylethanes and fluorene on graphitized thermal carbon black (GTCB). Adsorption on GTCB takes place in accordance with the geometry of these molecules, the strongest adsorption being observed for para-terphenyl with least inhibited internal rotation of the molecule, while the weakest adsorption occurs for 2,6,2′,6′-tetramethyldiphenyl with the most inhibited internal rotation of the molecules. The flat molecules of fluorene are adsorbed on GTCB more readily than the nonflat molecules of diphenylmethane.
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  • 3
    ISSN: 1612-1112
    Keywords: Gas adsorption chromatography ; Packed capillary columns ; Modification of BaSO4 ; Separation of isomeric unsaturated and aromatic hydrocarbons ; Selectivity and dipole moment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Isomeric hydrocarbons with molecules having similar geometry but differing in the electron density distribution were separated on capillary columns packed with barium sulphate, a non-porous ionic adsorbent. Samples of BaSO4 were washed free of foreign ions and modified by solutions of alkaline metal halides. The selectivity of the separation of unsaturated and aromatic hydrocarbons can be controlled by varying the conditions of the BaSO4 treatment. Capillary columns packed with the ionic adsorbent were successfully used to separate all xylene and butene isomers, as well as isomers of cis and trans octene-2.
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  • 4
    ISSN: 1612-1112
    Keywords: Geometric isomers ; Gas-solid chromatography ; Graphitized carbon black ; Packed capillaries ; Polycyclic hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Using the example of perhydrophenanthrene, perhydroanthracene and cyclopentanodecalin isomers a possibility is shown to use packed capillary columns containing graphitized thermal carbon black for a complete separation of high-boiling mixtures of polycyclic saturated hydrocarbon isomers in accordance with the geometric structure of their molecules.
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  • 5
    ISSN: 1612-1112
    Keywords: Gas-solid chromatography ; Retention on graphitized carbon black ; Phenylcyclanes, phenyl- and biphenylalkenes and ; alkines, bicyclohexyl, bicyclohexylmethane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Retention volume values for zero cample size (Henry's constants) at different temperatures, retention indices and differential adsorption heats of phenylethylene, phenylacetylene, C9–C12 phenylcyclanes, biphenylethylenes, biphenylacetylene, bicyclohexyl and bicyclohexylmethane have been determined on graphitized thermal carbon black (GTCB). The molecules of all these hydrocarbons are capable of internal rotation. The values of the thermodynamic adsorption characteristics of phenylcyclanes increase with increasing number of carbon atoms in the cycle. Bicyclohexyl is retained on GTCB considerably weaker than biphenyl while bicyclohexylmethane is retained stronger than biphenylmethane. Symmetric and nonsymmetric biphenylethylenes are retained much stronger than the corresponding biphenylethanes. Phenylethylene (styrene) and trans-biphenylethylene (trans-stilbene) are stronger retained on GTCB than phenylacetylene and biphenylacetylene (tolane), respectively. The relationship between the structure of these molecules and their retention on GTCB is discussed.
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  • 6
    ISSN: 1612-1112
    Keywords: Gas adsorption chromatography ; Graphitized thermal carbon black ; Cyclic ethers and ketones ; Atom-atom oxygen … carbon potentials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The paper is concerned with molecular-statistical determination of retention volumes of oxygen-containing organic substances such as cyclic ethers and ketones by presenting the potential energy of intermolecular interaction of the molecules with a monoatomic adsorbent having homogeneous flat surface (graphitized thermal carbon black) as a sum of atom-atom potentials. In order to eliminate the specific interactions of ethers and ketones with the traces of surface oxygen compounds on graphitized thermal carbon black, the latter was treated additionally with hydrogen. Comparison is made between the experimentally measured retention volumes and the Henry constants calculated for reference molecules of ethers (dioxane) and ketones (cyclohexanone) to correct the atom-atom potentials. It is shown that the atom-atom potentials obtained for the reference molecules can be used for other ethers and ketones of known structure with the subsequent calculation of the corresponding values of the retention volumes in terms of molecular statistics. When the structure is not known its parameters are optimized using the chromatostructural method (chromatoscopy). The calculated heat of adsorption values agree well with those determined from the chromatographic measurements. Chromatograms showing the full separation of mixtures of the ethers and ketones studied were obtained.
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  • 7
    ISSN: 1612-1112
    Keywords: Gas adsorption chromatography ; Molecular structure and adsorption ; Graphitized carbon black ; Capillary packed adsorption columns ; Tricyclic hydrocarbon separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Due to their high efficiency capillary columns packed with graphitized thermal carbon black (GTCB) permit to realize high selectivity in the chromatographic separation of isomers on the flat surface of this adsorbent. However, the increase in the efficiency is connected to a considerable increase of the pressure drop across the column which hinders the determination of the thermo-dynamic adsorption characteristics. The optimum conditions for the preparation of such columns designed both for analytical purposes and for thermodynamic measurements of the individual isomers have been established. The retention volumes for small (zero) sample size (Henry constants for adsorption on GTCB) of six isomers of tricyclo(8,4,0,02,7)tetradecane (perhydrophenanthrene), seven isomers of tricyclo-(7,4,0,02,6)tridecane (1,2-cyclopentanodecalin) and six isomers of tricyclo(7,3,0,02,6)dodecane have been determined. The Henry constants increase with the flattening of the isomeric molecules in these hydrocarbon series. A qualitative procedure of identification of the isomers on the basis of optimum orientation of their molecules on a flat surface has been considered.
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  • 8
    ISSN: 1612-1112
    Keywords: Gas-solid chromatography ; Gas-adsorption chromatography ; Henry's constants measurements, calculations ; Aromatic, cyclic hydrocarbons ; Chromatoscopy of tetralin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Retention volumes at zero sample size (Henry's constants) on graphitized thermal carbon black have been measured at a number of temperatures for benzene, all its methyl-substituted and some of alkyl-substituted derivatives, naphthalene, diphenyl, phenanthrene, anthracene, tetralin, cis- and trans-decalin, cyclohexane, adamantane and diamantane. The earlier published thermodynamic characteristics of adsorption of the aromatic hydrocarbons have been revised. A molecular statistical calculation of thermodynamic characteristics of adsorption using the atom-atom approximation for the energy of intermolecular interaction between adsorbate and adsorbent has been carried out for polycyclic hydrocarbons: adamantane, diamantane, cis- and trans-decalin. The measured retention volumes of tetralin have been used for the calculation of some parameters of geometric structure of the molecule.
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  • 9
    ISSN: 1612-1112
    Keywords: Gas adsorption chromatography ; Graphitized thermal carbon black ; Indan ; Indan-type hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es werden die Werte der Retentionsvolumina, der Retentionsindices und andere thermodynamische Adsorptionscharakteristiken von zehn Indan- und Inden-Kohlenwasserstoffen mit 9–11 Kohlenstoffatomen auf graphitiertem thermischem Ruß (GTR) bestimmt. Es wurde festgestellt, daß auf GTR die Kohlenwasserstoffe der Inden-Reihe am stärksten adsorbiert werden und am schwächsten cis-Hydrandan, was mit den Besonderheiten der geometrischen Struktur dieser Verbindungen zusammenhängt. Es wird die Möglichkeit der Anwendung von GTR für die vollständige Trennung der cis- und trans-Isomeren von Hydrindan gezeigt.
    Notes: Summary The retention volumes, retention indices and other thermodynamic values characteristic of the adsorption of ten indan-hydrocarbons having 9–11 carbon atoms were determined on graphitized thermal carbon black (GTCB). It is shown that GTCB adsorbs strongest the hydrocarbons of the indan series and weakest cis hydrindan. This is related to the peculiarities of the geometric structure of the compounds. The possibility of the application of GTCB for the complete separation of cis and trans hydrindan is shown.
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  • 10
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 32 (1992), S. 81-84 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A new approach to the quantitative evaluation of the thickness hi and the volume fraction Vi of the interfacial layer in polyimide coatings has been developed using the model of a one-sided polymer coating as a three-phase system (a substrate, an interfacial layer and a polymer matrix) and the method of differential scanning calorimetry. The new approach is characterized by the fact that a “pure” polymer matrix is modeled with the help of free films obtained on mercury. The formulas for the calculation of the thickness and volume fraction of the interfacial layer have been proposed. The value hi has been determined in polymer coatings of different thicknesses on aluminium foil. This parameter has been shown to be independent of the film thickness if the latter is not larger than the length of the interfacial layer. An assumption has been made about the “mechanical” origin of thick (〉 1-5 μm) interfacial layers, and their relaxation character has been revealed.
    Additional Material: 4 Ill.
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