Ethane
Ethane (USˈɛθeɪn , UKˈiː- ) is an organic chemical compound with chemical formula C2H6. At standard temperature and pressure, ethane is a colorless, odorless gas. Like many hydrocarbons, ethane is isolated on an industrial scale from natural gas and as a petrochemical by-product of petroleum refining. Its chief use is as feedstock for ethylene production. Related compounds may be formed by replacing a hydrogen atom with another functional group; the ethane moiety is called an ethyl group. For example, an ethyl group linked to a hydroxyl group yields ethanol, the alcohol in beverages. Ethane was first synthesised in 1834 by Michael Faraday, applying electrolysis of a potassium acetate solution. He mistook the hydrocarbon product of this reaction for methane and did not investigate it further. During the period 1847–1849, in an effort to vindicate the radical theory of organic chemistry, Hermann Kolbe and Edward Frankland produced ethane by the reductions of propionitrile (ethyl cyanide) and ethyl iodide with potassium metal, and, as did Faraday, by the electrolysis of aqueous acetates. They mistook the product of these reactions for the methyl radical (), of which ethane () is a dimer. This error was corrected in 1864 by Carl Schorlemmer, who showed that the product of all these reactions was in fact ethane. Ethane was discovered dissolved in Pennsylvanian light crude oil by Edmund Ronalds in 1864. At standard temperature and pressure, ethane is a colorless, odorless gas. It has a boiling point of and melting point of . Solid ethane exists in several modifications. On cooling under normal pressure, the first modification to appear is a plastic crystal, crystallizing in the cubic system. In this form, the positions of the hydrogen atoms are not fixed; the molecules may rotate freely around the long axis. Cooling this ethane below ca. changes it to monoclinic metastable ethane II (space group P 21/n). Ethane is only very sparingly soluble in water. The bond parameters of ethane have been measured to high precision by microwave spectroscopy and electron diffraction: rC−C = 1.
