Aliphatic hydrocarbons, abundance

Several factors indicate that the amino acids detected in all of these carbonaceous chondrites are indigenous and that they must have originated abiotically. First, the presence of protein and non-protein amino acids, with approximately equal quantities of D and L enantiomers points to a nonbiological origin and precludes terrestrial contamination. In addition, the non-extractable fraction of the Murchison is significantly heavier in 13C than terrestrial samples. Finally, the relative abundances of some compounds detected resemble those of products formed in prebiotic synthesis experiments. The aliphatic hydrocarbons are randomly distributed in chain length, and the C2, C3, and C4 amino acids have the highest concentrations (i.e., the most easily synthesized amino acids with the least number of possible structures are most abundant) [4]. 

Moreover, sp3 C-H bond activation is one of the most significant subjects because aliphatic hydrocarbons including methane exist abundantly in nature. 

Huang L, Sturchio NC, Abrajano T, Heraty LJ, Holt BD (1999) Carbon and chlorine isotope fractionation of chlorinated aliphatic hydrocarbons by evaporation. Org Geochem 30(8A) 777-785 Jambon A, Deruelle B, Dreibus G, Pineau F (1995) Chlorine and bromine abundance in MORB the contrasting behavior of the Mid-Atlantic Ridge and East Pacific Rise and implications for chlorine geodynamic cycle. Chem Geol 126 101-117... 

Saturated and unsaturated aliphatic hydrocarbons with straight as well as branched chains occur abundantly in natural foodstuffs, but they contribute to the odor and taste only to a limited extent. The highly unsaturated hydrocarbons l,3-fra y-5-ci5-undecatriene [51447-08-6] and l,3-trany-5-tran -undecatriene [19883-29-5], however, contribute to the odor of galbanum oil [10]. 

Carbonaceous material (Fig. 12.8b) is intimately mixed with silicates and is very abundant (carbon abundance averages 13% and varies up to 50%) in CP IDPs. Some carbon is elemental (graphite), but C-H stretching resonances in infrared spectra show that aliphatic hydrocarbons are also present. Polycyclic aromatic hydrocarbons (PAHs) also occur. Nanodiamonds have been identified in cluster IDPs, but not in smaller CP IDPs. Enormous D/H and 15N/14N anomalies have been measured in bulk IDPs, and the hydrogen isotopic anomalies are correlated with organic-rich domains. Ratios of D/H as high as 25 times the solar ratio suggest the presence of molecular cloud materials. 

The principal components of the coal liquids were the neutral compounds and the aromatic compounds including PNA. See Figure 6— light oil, wash solvent, and recycle solvent.) For the shale oil we analyzed, aliphatic hydrocarbons were most abundant. Lesser amounts of alicyclic... 

Figure 2. Carbon number distributions and relative abundances of unbound aliphatic hydrocarbons normalized to the most abundant hydrocarbon, DSDP Site 603B lower continental rise, U.S. east coast.

A study to determine the absolute content of the volatile component of C. arietinum was conducted after the pod borer (H. armigera) was shown to be attracted to chickpea seed volatiles [14, 88]. GC-MS analysis of headspace material was collected from ground C. arietinum and identified 132 compounds from mass spectrum analysis retention times or Kovats indices (Table 1) along with a further 22 compounds which are not included here because their identities could not be confirmed [89]. The most abundant components were aliphatic hydrocarbons but the next most abundant class was the terpenoids constituting approximately 35% of the volatile fractions of the floured seed. The most abundant compound of all was a-pinene which comprised 12.6% of the total mass of volatile compound. The source of the many aliphatic hydrocarbons in this... 

However rare aromatic hydrocarbons are as products of biosynthesis, among fossil hydrocarbons they are abundant. Because aromatic hydrocarbons are more polar than aliphatic hydrocarbons, they usually dominate the water soluble fraction of crude oils and their products. 

Unsaturated aliphatic hydrocarbons. The addition of a double bond to an alkane increases the abundance of the C H2 i and C H2 " ion series, as shown in the spectrum of 1 -dodecene (Figure 3.5). Note the increasing importance of the C H2 +i alkyl ion series at lower masses. Adding a double bond increases [M ] only for compounds of lower molecular weight. Cis and trans isomers usually have very similar mass spectra. 

The analysis of organosulphur compounds has been greatly facilitated by the flame photometric detector [2], Volatile compounds can be separated by a glass capillary chromatographic column and the effluent split to a flame ionization detector and a flame photometric detector. The flame photometric detector response is proportional to [S2] [3-6]. The selectivity and enhanced sensitivity of the flame photometric detector for sulphur permits quantitation of organosulphur compounds at relatively low concentrations in complex organic mixtures. The flame ionization detector trace allows the organosulphur compounds to be referenced to the more abundant aliphatic and/or polynuclear aromatic hydrocarbons. 

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