Space-filling models of the ethane molecule

Ethane occurs as a trace gas in the Earth's atmosphere, currently having a concentration at sea level of 0.5 ppb, though its preindustrial concentration is likely to have been only around 0.25 part per billion since a significant proportion of the ethane in today's atmosphere may have originated as fossil fuels. Global ethane quantities have varied over time, likely due to flaring at natural gas fields. Although ethane is a greenhouse gas, it is much less abundant than methane, has a lifetime of only a few months compared to over a decade, and is also less efficient at absorbing radiation relative to mass. In fact, ethane's global warming potential largely results from its conversion in the atmosphere to methane. Ethane can be viewed as two methyl groups joined, that is, a dimer of methyl groups. In the laboratory, ethane may be conveniently synthesized by Kolbe electrolysis. In this technique, an aqueous solution of an acetate salt is electrolyzed. At the anode, acetate is oxidized to produce carbon dioxide and methyl radicals, and the highly reactive methyl radicals combine to produce ethane. Synthesis by oxidation of acetic anhydride by peroxides, is conceptually similar. The chemistry of ethane involves chiefly free radical reactions. Ethane can react with the halogens, especially chlorine and bromine, by free-radical halogenation. This reaction proceeds through the propagation of the ethyl radical. Because halogenated ethane can undergo further free radical halogenation, this process results in a mixture of several halogenated products. In the chemical industry, more selective chemical reactions are used for the production of any particular two-carbon haloalkane. Combustion may also occur without an excess of oxygen, forming a mix of amorphous carbon and carbon monoxide. Combustion occurs by a complex series of free-radical reactions. Computer simulations of the chemical kinetics of ethane combustion have included hundreds of reactions. An important series of reaction in ethane combustion is the combination of an ethyl radical with oxygen, and the subsequent breakup of the resulting peroxide into ethoxy and hydroxyl radicals. The principal carbon-containing products of incomplete ethane combustion are single-carbon compounds such as carbon monoxide and formaldehyde. One important route by which the carbon-carbon bond in ethane is broken, to yield these single-carbon products, is the decomposition of the ethoxy radical into a methyl radical and formaldehyde, which can in turn undergo further oxidation. Some minor products in the incomplete combustion of ethane include acetaldehyde, methane, methanol, and ethanol. Contributor: Junjie Chen, ORCID: 0000-0001-5055-4309, E-mail address: [e-mail], Department of Energy and Power Engineering, School of Mechanical and Power Engineering, Henan Polytechnic University, 2000 Century Avenue, Jiaozuo, Henan, 454000, P.R. China