Hexane

About: Hexane is a research topic. Over the lifetime, 3759 publications have been published within this topic receiving 57996 citations. The topic is also known as: CH3-[CH2]4-CH3 & hexyl hydride.

Determination of hydrocarbon types in petroleum liquids by supercritical fluid chromatography with flame ionization detection

Abstract: Supercritical fluid chromatography using packed columns and carbon dioxide as the mobile phase provides an alternate to the fluorescent indicator adsorption method (FIA) for determining saturates, olefins, and aromatics in petroleum liquids boiling below 350/sup 0/C. Silica and silver nitrate impregnated silica columns are used in series. Standard deviation is in the 0.4 to 0.8 wt % range, depending on sample type. Unlike the FIA method, this technique is suitable for colored samples and for samples containing material lighter than hexane. The separation requires 4 min per sample.

cis-Stilbene photochemistry: solvent dependence of the initial dynamics and quantum yields

Abstract: Photochemical quantum yields for the formation of Trans-stilbene and 4a,4b-dihydrophenanthrene from cis-stilbene have been measured in cyclohexane, hexane, acetonitrile, and methanol solvents. Degassed cis-stilbene samples at 27 o C were irradiated at 280 nm, and the formation of photoproducts was monitored by absorption spectroscopy. The quantum yield for formation of dihydrophenanthrene is two to three times greater in the nonpolar solvents than in the polar ones (15-19% vs 5-8%), while a slight solvent dependence of the yield of trans-stilbene is observed (35-39%in the polar solvents vs 32-35% in the hydrocarbons)

Effect of the extraction solvent polarity on the sesame seeds oil composition

Abstract: This study highlights the effect of solvent polarity on the yield (Y%) and properties of oil extracted from Algerian sesame seeds. Extractions were carried out under Soxhlet conditions with the following solvents: hexane (Hx), ethanol (Eth), acetone (Ac), dichloromethane (Di), isopropanol (Iso), hexane:isopropanol (Hx:Iso), and chloroform:methanol (Chf:Me). The sesame oil yield obtained using different solvents ranged from 28.86 to 52.83%. Fatty acids and sterols analyses were performed by GC on capillary column. γ-Tocopherol was the major tocochromanol compound detected by HPLC-fluorescence. Fourteen fatty acids were identified, with the predominance of oleic and linoleic acids. The main sterol in sesame oil was β-sitosterol, followed by stigmasterol, campesterol, and Δ5-avenasterol which were present in lower concentrations. High correlations were found between arachidic, gadoleic, behenic, and lignoceric acids concentrations; these results were explained by the metabolic biosynthesis pathway of the biologically active long-chain PUFA by successive elongation and desaturation. Principal component analysis (PCA) of the data obtained from sesame oil composition enabled an easy comparison of the different extraction solvents, and correlated their properties with the most characteristic components of the extracted oils with a view to understand solvent–oil interaction, and to establish the effects of extracting solvent on such oil composition. Practical applications: This study showed that the choice of solvent depends largely on the desired fraction to be extracted. Sesame oil was better extracted with less-polar solvents but membrane-associated lipids are more polar and require polar solvents capable of breaking hydrogen bonds or electrostatic forces. Owing to the differences in solvent capacity, the fatty acids, sterols, and tocopherols extracted along with the oil vary, leading to differences in the quality of the extracted oil. The results obtained in this study could be applied in industrial extraction to encourage the use of alternative extraction solvents.