n-Hexane is sometimes used as a denaturant for alcohol, and as a cleaning agent in the textile, furniture, and leather industries. Hexane and other volatile hydrocarbons ( petroleum ether) present an aspiration risk. The current n-hexane PEL in the US is 500 ppm (1,800 mg/m 3 (0.79 gr/cu ft)). This limit was proposed as a permissible exposure limit (PEL) by the Occupational Safety and Health Administration in 1989 however, this PEL was overruled in US courts in 1992. However, for n-hexane, the current NIOSH REL is 50 ppm (180 mg/m 3 (0.079 gr/cu ft)) over an 8-hour workday. The US National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) for hexane isomers (not n-hexane) of 100 ppm (350 mg/m 3 (0.15 gr/cu ft)) over an 8-hour workday. Chronic occupational exposure to elevated levels of n-hexane has been demonstrated to be associated with peripheral neuropathy in auto mechanics in the US, and neurotoxicity in workers in printing presses, and shoe and furniture factories in Asia, Europe, and North America. Inhalation of n-hexane at 5000 ppm for 10 minutes produces marked vertigo 2500-1000 ppm for 12 hours produces drowsiness, fatigue, loss of appetite, and paresthesia in the distal extremities 2500–5000 ppm produces muscle weakness, cold pulsation in the extremities, blurred vision, headache and anorexia. Commercial samples of n-hexane however often contains methylcyclopentane, which features tertiary C-H bonds, which are incompatible with some radical reactions. Like most alkanes, hexane characteristically exhibits low reactivity and are suitable solvents for reactive compounds. Hexane has considerable vapor pressure at room temperature: The melting points are quite different and the trend is not apparent. The boiling points of the various hexanes are somewhat similar and, as for other alkanes, are generally lower for the more branched forms. The industrial product (usually around 50% by weight of the straight-chain isomer) is the fraction boiling at 65–70 ☌ (149–158 ☏).Īll alkanes are colorless. The exact composition of the fraction depends largely on the source of the oil (crude or reformed) and the constraints of the refining. Hexanes are chiefly obtained by refining crude oil. ( March 2023) ( Learn how and when to remove this template message) Unsourced material may be challenged and removed. Please help improve this section by adding citations to reliable sources. This may result in a solid compound being obtained as an oil and the alkanes may interfere with analysis.
In preparative chromatography, concentration of a large volume of hexanes can result in a sample that is appreciably contaminated by alkanes.
Higher alkanes present as impurities in hexanes have similar retention times as the solvent, meaning that fractions containing hexane will also contain these impurities. Hexanes are commonly used in chromatography as a non-polar solvent. For example, butyllithiums are typically supplied as a hexane solution. Since hexane cannot be easily deprotonated, it is used in the laboratory for reactions that involve very strong bases, such as the preparation of organolithiums. Ī typical laboratory use of hexanes is to extract oil and grease contaminants from water and soil for analysis. They are commonly used in food based soybean oil extraction in the United States, and are potentially present as contaminants in all soy food products in which the technique is used the lack of regulation by the FDA of this contaminant is a matter of some controversy. They are also used to extract cooking oils (such as canola oil or soy oil) from seeds, for cleansing and degreasing a variety of items, and in textile manufacturing. In industry, hexanes are used in the formulation of glues for shoes, leather products, and roofing.
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