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  • 11
    Electronic Resource
    Electronic Resource
    Vapor—Liquid equilibrium for binary mixtures of isomericaln-octenes with some solvents (1981)
    Springer
    Monatshefte für Chemie 112 (1981), S. 415-420 
    Details
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es werden thermodynamische Daten (isobare Siedetemperatur—Zusammensetzung der flüssigen Phase) und die Azeotrope der binären Systeme aus 1-Octen,cis-4-Octen undtrans-4-Octen mit Methylcellosolv (2-Methoxyethanol), 1-Butanol und Tetrachlorethen bei Drücken von 760 mm Hg (101,325 kPa) und 200 mm Hg (26,664 kPa) angegeben. DieWilsongleichung wurde zur Vorhersage der Aktivitätskoeffizienten in flüssiger Phase eingesetzt. Die so erhaltenen415-2 Funktionen werden für Mischungen der drei isomerenn-Octene mit jeweils einem gemeinsamen Lösungsmittel verglichen.
    Notes: Abstract Measurements of isobaric temperature—liquid composition are reported in the binary systems formed from 1-octene,cis-4-octene andtrans-4-octene with methyl cellosolve (2-methoxyethanol), 1-butanol and tetrachloroethene at pressures of 760 and 200 mm Hg (101.325 and 26.664 kPa). These systems have minimum boiling azeotropes. TheWilson equation is used to predict the liquid phase activity coefficients. The γ i −χ i functions thus obtained are compared in the systems containing a solvent common to the three isomericn-octenes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00901819
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  • 12
    Electronic Resource
    Electronic Resource
    Gas chromatographic investigation of adsorption of normal alkenes C6−C10 on graphitized thermal carbon black (1971)
    Springer
    Chromatographia 4 (1971), S. 448-454 
    Details
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wurden die Retentionsvolumina, differentielle Adsorptionswärmen, Änderungen des chemischen Potentials und Entropieänderungen des Adsorbates bei geringer Belegung der Oberfläche des graphitierten thermischen Rußes (GTR) für die Reihe der n-Alkene C6−C10 bestimmt. Die Retention von n-Alkenen auf einer homogenen unspezifischen Oberfläche (GTR) wird grundsätzlich durch cis-trans-Isomerie bestimmt, ebenso hängt sie auch von der Lage der Doppelbindung ab. Bei gleichem Molekulargewicht werden zuerst die cis-Isomere eluiert. Ihre Retentionszeiten verlängern sich mit der Verlagerung der Doppelbindung aus der Mitte zum Ende des Moleküls. Den cis-Isomeren folgen trans-Isomere in derselben Reihenfolge. Die Trennbarkeit der geometrischen Isomere vergrößert sich in der Reihe: 3-Alkene〈2-Alkene〈4- und 5-Alkene. Die Differenzen der isosterischen Adsorptionswärmen für die geometrischen Isomere betragen 0.2–0.5 kcal Mol−1. Für die analytische Trennung von cis-trans-Isomeren der n-Alkene kann die Adsorptions-Gas-Chromatographie auf GTR empfohlen werden.
    Abstract: Résumé On a déterminé les volumes de rétention, les chaleurs d'adsorption, les changements de potentiel chimique d'adsorbat et d'entropie d'adsorption sur le Noir de carbone graphitisé par voie thermique (NCTG) pour des n-alcènes C6−C10, dans le cas où le taux de recouvrement de la surface de l'adsorbant est faible. Les différences de rétention des n-alcènes sur la surface adsorbante non spécifique et très homogène du Noir de carbone graphitisé par voie thermique (GTCB) sont principalement dûes à l'isomérie cis-trans, mais également, à la position de la double liaison dans la molécule d'alcène. A masses moléculaires égales, les isomères cis sont élués les premiers. Leurs temps de rétention croit lorsque la double liaison s'éloigne du centre de la molécule. Dans tous les cas, l'isomère cis est suivi par l'isomère trans. La résolution des pics correspondant aux isomères cis et trans croit dans l'ordre: 3-alcènes〈2-alcènes〈4-alcènes et 5-alcènes. Les différences dans les chaleurs isostériques d'adsorption des isomères géométriques sont comprises entre 0,2 et 0,5 kcal·mole−1. On peut recommander l'emploi du Noir de carbone graphitisé par voie thermique (GTCB) pour la séparation des isomères cis-trans des n-alcènes par chromatographie gaz-solide.
    Notes: Summary The retention volumes, differential heats of adsorption, the standard change in the chemical potential of adsorbate and entropies of adsorption at low surface coverages of graphitized thermal carbon black (GTCB) for n-alkenes C6−C10 have been determined. Differences in retention of n-alkenes on the highly homogeneous non-specific surface of GTCB is determined principally by their cis-trans isomerism but is dependent on the position of the double bond, too. At equal molecular mass cis-isomers are eluted first. Their retention times increase with shifting of the double bond from the centre towards the end of the molecule. Cis-isomers are followed by trans-isomers in the same order. Resolution of cis-trans-isomers increases in order: 3-alkenes〈2-alkenes〈4- and 5-alkenes. Differences in the isosteric heats of adsorption of geometric isomers have been found to be about 0.2–0.5 kcal mole−1. GTCB can be recommended for separating cis-trans isomers of n-alkenes by gas solid chromatography.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02268813
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  • 13
    Electronic Resource
    Electronic Resource
    Identification of normal alkenes, cyclopentenes and cyclohexenes by capillary gas chromatography (1972)
    Springer
    Chromatographia 5 (1972), S. 229-239 
    Details
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wurden die Retentionsindices (I) für die n-Alkene C6−C12, mono-Alkylcyclopentene C6−C10 und-hexene C7−C11 auf Trennkapillaren mit Squalan (SQ), Apiezon L (AP-L) und Polyäthylenglycol 4000 (PÄG) als stationärer Phase bei 50, 60, 80, 100 und 120 °C bestimmt und mit der Struktur der Isomeren korreliert. Es wurden lineare Abhängigkeiten der Retentionsindices von der Säulentemperatur (tc) und von der Zahl der Kohlenstoffatome im Molekül (n) festgestellt. Die beste Trennung der n-Alkene wurde auf PÄG, der Cyclopentene und-hexene auf SQ erreicht.
    Abstract: Résumé Les indices de rétention (I) des alcènes C6−C12, mono-alkylcyclopentènes et-hexènes C6−C11 sur colonnes capillaires à paroi couverte de Squalane (SQ), Apiezon L (AP-L) et polyéthylène glycol 4000 (PEG) à diverses températures (50, 60, 80, 100 et 120°C) on été déterminés et leur relation avec la structure des isomères étudiée. Les relations linéaires existant entre les indices de rétention et la température de la colonne (tc) et le nombre d'atomes de carbone des molécules (n) ont été étudiées. On a obtenu les meilleures séparations pour les n-alcènes sur PEG, et pour les cyclopentènes et-hexènes sur SQ.
    Notes: Summary Retention indices (I) for n-alkenes C6−C12, mono-alkylcyclopentenes C6−C10 and-hexenes C7−C11 on squalane (SQ), Apiezon L (AP-L) and polyethylene glycol 4000 (PEG) capillary columns at 50, 60, 80, 100 and 120°C have been determined and correlated with the structure of isomers. Linear dependences of I on the column temperature (tc) and on the number of carbon atoms in the molecule (n) have been observed. The best resolution for n-alkenes was obtained on PEG, for cyclopentenes and cyclohexenes on SQ.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02270600
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  • 14
    Electronic Resource
    Electronic Resource
    Thermodynamische Untersuchungen ann-Alkan/n-Alkin-Systemen (1980)
    Springer
    Monatshefte für Chemie 111 (1980), S. 607-617 
    Details
    ISSN: 1434-4475
    Keywords: n-Alkynes ; Phase equilibria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The vapour-liquid equilibrium data obtained from isobarict-x-measurements have been used for calculation of the group UNIFAC parameters and excess free enthalpyG E of binary mixturesn-alkanes with isomericn-alkynes. The UNIFAC model gives satisfactory predictions for the systems studied. The temperature dependence ofG E was estimated on the basis of the heats of mixing measured earlier. The influence of the position of triple bond in the molecules ofn-alkynes on the excess thermodynamic functions is considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00903314
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  • 15
    Electronic Resource
    Electronic Resource
    Gas chromatographic investigation of adsorption of C6−C10 normal alkynes on graphitized thermal carbon black (1975)
    Springer
    Chromatographia 8 (1975), S. 327-330 
    Details
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Retention volumes, Vs, 1, and isosteric heats of adsorption, Q1, at low surface coverages on graphitized thermal carbon black for C6−C10 n-alkynes have been determined and correlated with their structure. Linear dependences of log Vs, 1 and Q1 on n the number of carbon atoms in the molecule of the alkyne have been observed. Introduction of the triple bond into the molecule decreases the Vs, 1 and Q1 values compared to those of the corresponding n-alkanes and n-alkenes. Comparison with n-alkenes shows rather small differences between Q1 values for internal n-alkynes and corresponding normal cis-alkenes. For the same n and position of the multiple bond the individual compounds elute in the following order: n-alkyne, cis-n-alkene (sometimes simultaneously), trans-n-alkene, n-alkane. At the same time, the Q1 values increase as the triple bond shifts from the centre of the molecule towards the second carbon atom and then decrease again for 1-n-alkynes The isosteric heats of adsorption of n-1-alkynes are approximately 0.4–1.7 kJ mole−1 lower than those for n-1-alkenes. The regularities of adsorption of C6−C10 nomal alkenes and some 1-alkynes, up to 1-hexyne, on graphitized thermal carbon black (GTCB) have been investigated in previvous papers [1–3]. In this paper the gas chromatographic investigation of adsorption of unsaturated hydrocarbons on GTCB has been extended to isomeric C6−C10 n-alkynes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02350796
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  • 16
    Electronic Resource
    Electronic Resource
    Capillary gas chromatography of monosubstituted cyclopentenes and cyclohexenes (1977)
    Springer
    Chromatographia 10 (1977), S. 115-122 
    Details
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Regularities in the variation of retention indices (I) and index increments (δI/°C, H, ΔI) of monosubstituted cyclopentenes and cyclohexenes with molecular structure on various liquid phases are discussed. An equation for the linear dependence of I on the carbon number is given. Differences in gas chromatographic characteristics between 1- and 3-isomers are more pronounced in the n-alkylcyclopentene series. In the n-alkylcyclohexene series extension of the side chain and increase of column temperature lead to the inversion of the elution order of 1-and 3-isomers. The temperature increments of I for cyclenes are markedly greater than those for open chain hydrocarbons (n-alkenes, n-alkynes).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02297862
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  • 17
    Electronic Resource
    Electronic Resource
    Capillary gas chromatography of C6−C14 n-alkenes on polyphenyl ether and polyethylene glycol 4000 (1977)
    Springer
    Chromatographia 10 (1977), S. 55-64 
    Details
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention indices (I) and their structural increments (σl/°C, H, Δl) of C6−C14 n-alkenes on polyphenyl ether (PFE) and C12−C14 n-alkenes on polyethylene glycol 4000 (PEG) at 20–160 °C have been determined and correlated with the molecular structure of the isomers. A number of common regularities in gas chromatographic behaviour on these liquid phases and squalane (SQ) [1–3] have been found. On PFE the elution order of isomeric n-alkenes is similar to that on SQ (except C8−C10 1-alkenes and cis-4-tetradecene), for pairs with cis- and trans-configuration it depends on the column temperature, position of double bond and the number of carbon atoms (n) in the molecule. On PEG the cis- are always retained longer than the corresponding trans-alkenes. The linear relationships between 1 and n on PFE and PEG are given in equation form.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02274460
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  • 18
    Electronic Resource
    Electronic Resource
    Field ionization mass spectrometry of higher n-alkenes (1978)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 13 (1978), S. 181-183 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In a strong electric field the molecular ions of n-alkenes ≤C-12 decompose via cleavage of the C—C bond β to the double bond to form the characteristic alkenyl ions that may be used for the identification of positional isomers. For 3-alkenes (〉C-10), 4-, 5- and 6-alkenes the formation of the ions with m/e 54 via double β-cleavage is typical. The field ionization mass spectra of the cis and trans isomers are indistinguishable.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210130402
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  • 19
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    A large impact crater beneath Hiawatha Glacier in northwest Greenland (2018)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2018
    Description: 〈p〉We report the discovery of a large impact crater beneath Hiawatha Glacier in northwest Greenland. From airborne radar surveys, we identify a 31-kilometer-wide, circular bedrock depression beneath up to a kilometer of ice. This depression has an elevated rim that cross-cuts tributary subglacial channels and a subdued central uplift that appears to be actively eroding. From ground investigations of the deglaciated foreland, we identify overprinted structures within Precambrian bedrock along the ice margin that strike tangent to the subglacial rim. Glaciofluvial sediment from the largest river draining the crater contains shocked quartz and other impact-related grains. Geochemical analysis of this sediment indicates that the impactor was a fractionated iron asteroid, which must have been more than a kilometer wide to produce the identified crater. Radiostratigraphy of the ice in the crater shows that the Holocene ice is continuous and conformable, but all deeper and older ice appears to be debris rich or heavily disturbed. The age of this impact crater is presently unknown, but from our geological and geophysical evidence, we conclude that it is unlikely to predate the Pleistocene inception of the Greenland Ice Sheet.〈/p〉
    Electronic ISSN: 2375-2548
    Topics: Natural Sciences in General
    Published by American Association for the Advancement of Science (AAAS)
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  • 20
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    Identification of normal alkenes, cyclopentenes and cyclohexenes by capillary gas chromatography (1972)
    Springer
    Details
    Publication Date: 1972-11-01
    Print ISSN: 0009-5893
    Electronic ISSN: 1612-1112
    Topics: Chemistry and Pharmacology
    Published by Springer
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