Alkane spectrometry/spectroscopy

Also important is the use of the modem chromatographic methods to separate and identify individual components in commercial cmde shale oil. The use of efficient gas chromatographic columns coupled with ancillary techniques such as mass spectrometry and vapor-phase IR spectroscopy allows the identification of individual shale oil components. A principal part of this study is the comparison of diflFerent types of open tubular columns for the separation of the alkane-alkene fraction of shale oil WCOT, SCOT, and PLOT columns are examined. Gas chromatographic separation of shale oil acids and bases also is performed allowing the identification of these components. The potential utility of subtractive pre-columns in HPLC analysis is illustrated also. 

The application of and N.M.R. spectroscopy, gas chromatography (G.C.) and mass spectrometry (M.S.) in the separation and identification of alkanes extracted from fossil fuels is illustrated with three Turkish lignites (including one extracted by supercritical gas), coal tar and petroleum crude. Elution of hydrocarbons from a silica-gel column may be monitored by N.M.R. and molecular-sieve sub-fractionation into normals and branched/cyclics by G.C., together with... 

Over the last two decades, developments in G.C., mass spectrometry (M.S.), N.M.R. spectroscopy and other physical techniques have appreciably extended the ability of chemists to undertake detailed analyses of fractions extracted from coal and other fossil fuels. In this paper, we survey some of the characterization techniques for alkanes, emphasising particularly... 

Gas Chromatography, Spectroscopy and Spectrometry. Gas chromatography on a Pye IO5 instrument with flame-ionization detector was used for monitoring the separation of normals from total alkanes and for identification of individual n-alkanes. 

In the last decade, deuterium labelling of alkanes or solid acid catalysts has proved to be a preferred tool for mechanistic studies. The availability of high resolution multinuclear NMR spectroscopy and mass spectrometry has facilitated the interpretation of the experimental results. It appears that despite the differences in media between liquid and solid acids, all results in acid-catalysed hydrocarbon chemistry can be rationalised by mechanisms involving solvated carbenium ion intermediates, as known from classical organic chemistry. Nevertheless, the determination of the real nature of the... 

Alkenyl hydrogens (and carbons) are deshielded and give rise to relatively low-field NMR signals compared with those in saturated alkanes (Section 11-4). In contrast, alkynyl hydrogens have chemical shifts at relatively high field, mnch closer to those in alkanes. Similarly, the sp-hybridized carbons absorb in a range between that recorded for alkenes and alkanes. Alkynes, especially terminal ones, are also readily identified by IR spectroscopy. Finally, mass spectrometry can be a useful tool for identification and structure elucidation of alkynes. 

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