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  • 1
    Electronic Resource
    Electronic Resource
    Determination of thermodynamic functions of sorption for cyclohexyl-, piperidyl-, morpholyl-, and thiomorpholyl-n-alkanes by capillary gas-liquid chromatography (1996)
    Springer
    Russian chemical bulletin 45 (1996), S. 1925-1927 
    Details
    ISSN: 1573-9171
    Keywords: capillary gas-liquid chromatography ; N-alkyl-substituted piperidines ; morpholines and thiomorpholines ; cyclohexyl-n-alkanes ; partial molar free energy ; enthalpy and entropy of sorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The values of partial molar free energy (ΔG), enthalpy (ΔH), and entropy (ΔS) of sorption in the homologous series ofN-alkylpiperidines,N-alkylmorpholines,N-alkyl thiomorpholines, and alkylcyclohexanes were determined. It was found that the free energy of sorption is determined to a greater extent by the enthalpy term than by the entropy one. The free energy of sorption of the first homolog decreases when then-alkyl chain is attached directly to the carbon atom of the cycle and increases in the case ofN-alkylsubstituted heterocycles. The influence of the heteroatom nature on intermolecular interactions of homologs with the nonpolar stationary phase was quantitatively estimated on the basis of thermodynamic data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01457778
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  • 2
    Electronic Resource
    Electronic Resource
    Thermodynamic characteristics of sorption of heterocyclic compounds m capillary gas chromatography (1996)
    Springer
    Russian chemical bulletin 45 (1996), S. 1928-1933 
    Details
    ISSN: 1573-9171
    Keywords: capillary gas chromatography ; thermodynamic characteristics of sorption ; heterocyclic compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Dependences of sorption energies of sulfur-, oxygen-, and nitrogen-containing heterocyclic compounds on the nature of heteroatoms, structure of substituents and their position in the ring were studied. The contributions of heteroatoms, functional and alkyl groups to the energy of dispersive interaction of position isomers with nonpolar stationary phases were determined for imidazoles, piperidines, morpholines, thiomorpholines, dioxalanes, oxathiolanes, dithiolanes, thiophenes, and furans. The nonequivalence of contributions of the same substituents to the sorption energy of each of the heterocyclic compounds, depending on the nature of the heteroatom and position of the substituent, was shown. The obtained values of contributions of heteroatoms and substituents can be used for apriori calculation of retention indices of position isomers of five- and six-membered heterocycles containing one or two heteroatoms in the ring.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01457779
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  • 3
    Electronic Resource
    Electronic Resource
    Sorption characteristics ofN-alkylimidazoles under conditions of capillary chromatography (1995)
    Springer
    Russian chemical bulletin 44 (1995), S. 300-304 
    Details
    ISSN: 1573-9171
    Keywords: capillary gas chromatography ; homologous series ; alkyl substitutedN-alkylimidazoles ; retention indices ; equations ; contributions of alkyl groups at the C and N atoms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The retention indices forN-n-alkyl (C1-C5) substituted imidazoles with Me, Et, Pr, and Bu groups in different positions of the cycle were determined. Two capillary columns with OV-101/KF and PEG-40M/KF were used. The two nitrogen atoms of the imidazole molecule were shown to have different effects on the contributions of the alkyl groups to the retention indices. The maximum and minimum contributions are observed for the substituents at the 5 and 4 positions of the imidazole cycle, respectively. An increase in a size of the C m H2m+1 substituent attached to the N(1) atom has a notable effect only on the contributions of the alkyl groups at the 2 and 5 positions. The retention indices values for a homologous series with ann-alkyl group attached to the N or C(2) atom were described by a universal type equation. The obtained equations can be used for predicting the retention indices of new homologs and identification ofN-alkylimidazoles in complex mixtures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00702140
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