Capillary column isomeric

Gas chromatographic analysis of the product (Hewlett-Packard fused silica, cross-linked methyl silicone capillary column, 25 m x 20 mm, column temperature 100-270°C, injection temperature 250°C) shows that the product is over 99% chemically and isomerically pure, (Z,E)-l-Phenyl-l,3-octadiene shows the following spectral properties IR (neat) cm 1640, 1595, 1490, 985 ... 

The catalytic experiments were carried out in a fixed bed flow-type apparatus in the gas phase at atmospheric pressure (p,otai 100 kPa). The carrier gas (N2, nominal purity 99.99 vol.-%) was loaded with vapors of the reactant(s) in (a) thermostated saturator(s). The mass of dry catalyst was ca. 200 mg. In the isomerization experiments, the partial pressure in the feed and the modified residence time were Pi M-Np = 2.0 kPa and W/Fi.M.Np =110 g-h/mol, respectively. In the alkylation experiments, the partial pressures in the feed amounted to P2-M-NP = 1-9 kPa and p oH = 0.95 kPa, and W/I -Np was 170 g h/mol. Product analysis was done by automatic on-line sampling and high resolution glc using a capillary column of 50 m length, OV-1 as stationary phase and H2 as carrier gas. Various temperature programs were employed depending on the product mixture to be analyzed. 

All boiling points are uncorrected. GLC analysis was performed on a Perkin-Elmer model F 11 instrument equipped with a 50 mt capillary column coated with polypropylenglycol at 60°C. The isomeric esters were separated by a Perkin-Elmer model F 21 GLC preparative instrument. 

Gas chromatography, first described by James and Martin in 1952, has become one of the most frequently used separation technique for the analysis of gases, volatile liquids, and solids. The major breakthrough of GC was the introduction of the open mbular column by Golay and Desty in 1958 and the adoption of fused silica capillary columns by Dandeneau and Zerenner in 1979. Today, using of the capillary columns can solve many analytical problems, such as isomeric separation and analysis of complex mixtures of natural products and biological samples. 

Gas chromatographic analysis of the trimethylsilyl ether using a 25-m PEG-HT capillary column at 100°C indicated a purity of 931 (retention time 11.2 min). Under the present conditions, neither the starting perillyl alcohol nor the isomeric monocyclopropanatlon product (l-hydroxymethyl-4-isopropenylbicyclo[4.1.0]heptane) were detected. Dicyclopropanation products amounted to less than 5X. 

Liquid products were first hydrogenated over a Pd-on-charcoal catalyst to simplify the analytical problem of identifying the many isomeric olefins formed (no skeletal isomerization occurred during this treatment). Hydrogenated product was then analysed by gas chromatography on a 50m SE-30 coated capillary column, and the identity of individual isomers determined by gc/ms. 

Lee, W. and Chang-Chien, G., All-hydrocarbon liquid crystalline polysiloxane polymer as stationary phase in gas chromatography capillary column for separation of isomeric compounds of polynuclear aromatic hydrocarbons. Anal. Chem., 70, 4094-4099, 1998. 

Preparation of these derivatives allowed useful separation of some isomeric compounds by GC, e.g. the four possible isomers of methylsalicyclic acid DTBS derivatives were resolved to baseline on a capillary column coated with an apolar stationary phase (OV-1 Figure 11). The El spectra of the DTBS derivatives generally showed M ions which were of greater abundance in the case of the aromatic compounds that were tested. 

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