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Hexane

Hexane is an alkane of six carbon atoms, with the chemical formula C6H14. The term may refer to a mixture of them. In IUPAC nomenclature, hexane is the unbranched isomer. IUPAC uses the term as the root of many compounds with a linear six-carbon backbone, such as 2-methylhexane. Hexanes are significant constituents of gasoline, they are all colorless liquids, odorless when pure, with boiling points between 50 and 70 °C. They are used as cheap safe unreactive, evaporated non-polar solvents. In industry, hexanes are used in the formulation of glues for shoes, leather products, roofing, they are used to extract cooking oils from seeds, for cleansing and degreasing a variety of items, in textile manufacturing. They are used in food based soybean oil extraction in the United States, are present as contaminants in all soy food products in which the technique is used. A typical laboratory use of hexanes is to extract oil and grease contaminants from water and soil for analysis. Since hexane cannot be deprotonated, it is used in the laboratory for reactions that involve strong bases, such as the preparation of organolithiums.

For example, butyllithiums are supplied as a hexane solution. Hexanes are used in chromatography as a non-polar solvent. Higher alkanes present as impurities in hexanes have similar retention times as the solvent, meaning that fractions containing hexane will contain these impurities. In preparative chromatography, concentration of a large volume of hexanes can result in a sample, appreciably contaminated by alkanes; this may result in a solid compound being obtained as an oil and the alkanes may interfere with analysis. Hexanes are chiefly obtained by refining crude oil; the exact composition of the fraction depends on the source of the oil and the constraints of the refining. The industrial product is the fraction boiling at 65–70 °C. All alkanes are colorless; the boiling points of the various hexanes are somewhat similar and, as for other alkanes, are lower for the more branched forms. The melting points are quite different and the trend is not apparent. Hexane has considerable vapor pressure at room temperature: Like most alkanes, hexane characteristically exhibits low reactivity and are suitable solvents for reactive compounds.

Commercial samples of n-hexane however contains methylcyclopentane, which features tertiary C-H bonds, which are incompatible with some radical reactions. The acute toxicity of n-hexane is rather low. Inhalation of n-hexane at 5000 ppm for 10 minutes produces marked vertigo; the National Institute for Occupational Safety and Health has set a recommended exposure limit for hexane isomers of 100 ppm over an 8-hour workday. Hexane and other volatile hydrocarbons present an aspiration risk. N-Hexane is sometimes used as a denaturant for alcohol, as a cleaning agent in the textile and leather industries, it is being replaced with other solvents. Like gasoline, hexane is volatile and is an explosion risk. Occupational hexane poisoning has occurred with Japanese sandal workers, Italian shoe workers, Taiwan press proofing workers, others. Analysis of Taiwanese workers has shown occupational exposure to substances including n-hexane. In 2010–2011, Chinese workers manufacturing iPhones were reported to have suffered hexane poisoning.

Hexane was identified as being the cause of the Louisville sewer explosions on February 13, 1981, that destroyed more than 13 miles of sewer lines and streets in the center of Louisville in Kentucky, United States n-Hexane is biotransformed to 2-hexanol and further to 2,5-hexanediol in the body. The conversion is catalyzed by the enzyme cytochrome P450 utilizing oxygen from air; the pathway is called omega oxidation. 2,5-Hexanediol may be further oxidized to 2,5-hexanedione, neurotoxic and produces a polyneuropathy. In view of this behavior, replacement of n-hexane as a solvent has been discussed. N-Heptane is a possible alternative. Cyclohexane Louisville sewer explosions International Chemical Safety Card 1262 Material Safety Data Sheet for Hexane National Pollutant Inventory – n-hexane fact sheet Phytochemica l database entry Center for Disease Control and Prevention Warning from National Safety Council "COMMON CHEMICAL AFFECTS AUTO MECHANICS" Australian National Pollutant Inventory page "EPA does not consider n-hexane classifiable as a human carcinogen."

Federal Register / Vol. 66, No. 71 / Thursday, 12 April 2001 / Rules and Regulations

Starting a Business Index

The Starting a Business Index is a sub-index of the World Bank Ease of Doing Business Index. This methodology was developed by Simeon Djankov, Rafael La Porta, Florencio Lopez-De-Silanes and Andrei Shleifer in a paper The Regulation of Entry. Simeon Djankov is the creator of the annual Doing Business report, the top-selling publication of the World Bank Group; the Regulation of Entry paper is one of the most-cited papers in all of economics, with 913 references in academic journals and 3,400 citations in working papers and official reports. Since its initial publication in November 2003, Doing Business has generated 9,750,000 media citations, over 7 million copies sold or downloaded; the Doing Business report had its 17th annual book published. In a 2016 article for the Journal of Economic Perspectives Dr Djankov explains how Doing Business started. A November 2017 EconTalk explains the origins and influence of the Doing Business report. Ranking of all nations from 2010 report. Barriers to entry Commercial law Simeon Djankov – Doing business

Roman Catholic Diocese of Linares (Mexico)

The Roman Catholic Diocese of Linares in Mexico is a suffragan diocese of the Archdiocese of Monterrey. Anselmo Zarza Bernal, appointed Bishop of León, Guanajuato Antonio Sahagún López and was appointed Auxiliary Bishop of Guadalajara, Jalisco Rafael Gallardo García, O. S. A. Appointed Bishop of Tampico, Tamaulipas Ramón Calderón Batres Hilario González García Linares, Nuevo León "Diocese of Linares". Catholic-Hierarchy. Retrieved 2007-02-07