Butanol 56139 222619212 2008-06-30T08:26:34Z 85.2.242.8 /* Isomers */ '''Butanol''' or butyl alcohol (sometimes also called ''biobutanol'' when produced biologically), is a [[primary alcohol]] with a 4 [[carbon]] structure and the [[molecular formula]] of [[Carbon|C]]<sub>4</sub>[[Hydrogen|H]]<sub>10</sub>[[Oxygen|O]]. It belongs to the higher alcohols and branched-chain alcohols. <ref>[http://www.nature.com/nature/journal/v451/n7174/abs/nature06450.html Non-fermentative pathways for synthesis of branched-chain higher alcohols as biofuels : Abstract : Nature<!-- Bot generated title -->]</ref> It is primarily used as a solvent, as an intermediate in chemical synthesis, and as a fuel. There are four [[isomer]]ic structures for butanol. ==Isomers== The unmodified term ''butanol'' usually refers to the straight chain isomer with the alcohol [[functional group]] at the terminal carbon, which is also known as [[N-Butanol|''n''-butanol]] or 1-butanol. The straight chain isomer with the alcohol at an internal carbon is ''sec''-butanol or [[2-butanol]]. The branched isomer with the alcohol at a terminal carbon is [[isobutanol|isobutanol; 2-methyl-1-propanol]], and the branched isomer with the alcohol at the internal carbon is [[Tert-Butanol|''tert''-butanol; 2-methyl-2-propanol]]. {|border="1" style="text-align: center; margin: 0 0 1em 1em;" |- |[[Image:Butan-1-ol-2D-skeletal.png|138px]] |[[Image:Butan-2-ol-2D-skeletal.png|93px]] |[[Image:Isobutanol-2D-skeletal.png|113px]] |[[Image:Tert-butanol-2D-skeletal.png|100px]] |- |[[N-Butanol|''n''-butanol]] |[[2-Butanol|''sec''-butanol]] |[[isobutanol]] |[[Tert-Butanol|''tert''-butanol]] |} Butanol isomers, due to their different structures, have somewhat different melting and boiling points. All are moderately [[miscible]] in water, less so than [[ethanol]], and more so than the higher (longer carbon chain) alcohols. This is because all alcohols have a hydroxyl group which makes them polar which in turn tends to promote solubility in water. At the same time the carbon chain of the alcohol resists solubility in water. Methanol, ethanol and propanol, are fully miscible in water because the hydroxyl group predominates while butanol is moderately miscible because of the balance between the two opposing solubility trends. ==Toxicity== Like many alcohols, butanol is considered toxic. It has shown low order of toxicity in single dose experiments to laboratory animals.<ref> 16 ECETOC JACC No. 41 n-Butanol (CAS No. 71-36-3), European Centre for Ecotoxicology and Toxicology of Chemicals, Brussels, December 2003, pages 3-4.</ref> <ref>[http://www.dow.com/productsafety/finder/nbut.htm#HealthInfo n-Butanol<!-- Bot generated title -->]</ref> and is considered safe enough for use in cosmetics. Brief, repeated overexposure with the skin can result in depression of the [[central nervous system]], as with other [[short-chain alcohol]]s. Exposure may also cause severe eye irritation and moderate skin irritation. The main dangers are from prolonged exposure to fumes. In extreme cases this includes suppression of the central nervous system and even death. Under most circumstances, butanol is quickly metabolized to [[carbon dioxide]]. It has not been shown to [[genotoxicity|damage DNA]] or cause [[cancer]]. ==Uses== ===Biobutanol=== {{Main|Butanol fuel}} Butanol is considered as a potential [[biofuel]] ([[butanol fuel]]). Butanol at 85 percent strength can be used in cars designed for gasoline (petrol) without any change to the engine (unlike 85% ethanol), and it contains more energy for a given volume than ethanol and almost as much as gasoline, so a vehicle using butanol would return fuel consumption more comparable to gasoline than ethanol. {{Fact|date=June 2008}} ===Other uses=== Butanol sees use as a [[solvent]] for a wide variety of chemical and textile processes, in organic synthesis and as a chemical intermediate. It is also used as a [[paint thinner]] and a solvent in other coating applications where it is used as a relatively slow evaporating latent solvent in lacquers and ambient-cured enamels. It finds other uses such as a component of [[hydraulic fluid|hydraulic]] and [[brake fluid]]s.<ref>[http://www.chemicalland21.com/petrochemical/ISO-BUTANOL.htm Isobutanol at chemicalland21.com]</ref> It is also used as a base for [[perfumes]], but on its own has a highly alcoholic aroma. [[Salt]]s of butanol are chemical intermediates for example [[alkali metal]] salts of tert-butanol are '''tert-butoxides'''. ==Production== {{Main|Butanol fuel}} Since the 1950s, most butanol in the [[United States]] is produced commercially from [[fossil fuel]]s. The most common process starts with [[propene]], which is run through an [[hydroformylation]] reaction to form [[butanal]], which is then reduced with [[hydrogen]] to butanol. Butanol can also be produced by [[fermentation (biochemistry)|fermentation]] of [[biomass]] by bacteria. Prior to the 1950s, ''[[Clostridium acetobutylicum]]'' was used in industrial [[fermentation (biochemistry)|fermentation]] processes producing butanol. Research in the past few decades showed results of other microorganisms that can produce butanol through [[fermentation (biochemistry)|fermentation]]. ==See also== * [[A.B.E. process]] * [[Algal fuel]] * [[Butanol fuel]] * [[Solvent]] ==References== *''Merck Index'', 12th Edition, '''1575'''. {{reflist}} {{Alcohols}} [[Category:Alcohols]] [[Category:Alcohol solvents]] [[Category:Alternative propulsion]] [[Category:Branched-chain alcohols]] [[Category:Biotechnology products]] [[Category:Direct biofuels]] [[Category:Gasoline substitutes]] [[Category:Liquid fuels]] [[Category:Oxygenates]] [[bs:Butanol]] [[cs:Butanol]] [[de:Butanole]] [[ja:ブタノール]] [[la:Butanol]] [[no:Butanol]] [[nn:Butanol]] [[pt:Butanol]] [[ru:Бутиловый спирт]] [[sl:Butanol]] [[fi:Butanoli]] [[sv:Butanol]] [[zh:丁醇]]