n-Butanol

Butanol1-ButanolButyl alcoholButyl hydrateButylic alcoholButyralcoholButyric alcoholButyryl alcoholn-Butyl alcohol1-Hydroxybutanen-Butanol or n-butyl alcohol or normal butanol is a primary alcohol with a 4-carbon structure and the chemical formula C4H9OH. Its isomers include isobutanol, 2-butanol, and tert-butanol. Butanol is one of the group of 'fusel alcohols' (from the German for 'bad liquor'), which have more than two carbon atoms and have significant solubility in water. n-Butanol or n-butyl alcohol or normal butanol is a primary alcohol with a 4-carbon structure and the chemical formula C4H9OH. Its isomers include isobutanol, 2-butanol, and tert-butanol. Butanol is one of the group of 'fusel alcohols' (from the German for 'bad liquor'), which have more than two carbon atoms and have significant solubility in water. n-Butanol occurs naturally as a minor product of the fermentation of sugars and other carbohydrates, and is present in many foods and beverages. It is also a permitted artificial flavorant in the United States, used in butter, cream, fruit, rum, whiskey, ice cream and ices, candy, baked goods and cordials. It is also used in a wide range of consumer products. The largest use of n-butanol is as an industrial intermediate, particularly for the manufacture of butyl acetate (itself an artificial flavorant and industrial solvent). It is a petrochemical, manufactured from propylene and usually used close to the point of manufacture. Estimated production figures for 1997 are: United States 784,000 tonnes; Western Europe 575,000 tonnes; Japan 225,000 tonnes. 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 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, or 2-methyl-1-propanol, and the branched isomer with the alcohol at the internal carbon is tert-butanol, or 2-methyl-2-propanol. The butanol isomers have different melting and boiling points. n-butanol and isobutanol have limited solubility, sec-butanol has substantially greater solubility, while tert-butanol is fully miscible with water above tert-butanol's melting point. The hydroxyl group makes the molecule polar, promoting solubility in water, while the longer hydrocarbon chain mitigates the polarity and reduces solubility. The shorter-chain molecules of methanol, ethanol, propanol, and tert-butanol are fully miscible with water, while n-butanol is only moderately soluble because of the diminishing polarity in the longer hydrocarbon group. Since the 1950s, most n-butanol in the United States is produced industrially from fossil fuels. The most common process starts with propene, which is put through a hydroformylation reaction (oxo process) to form butanal (butyraldehyde) in the presence of a rhodium-based homogeneous catalyst similar to Wilkinson's catalyst. The butyraldehyde is then hydrogenated to produce n-butanol. tert-butanol is derived from isobutane as a co-product of propylene oxide production. Butanol can also be produced by fermentation of biomass by bacteria. Prior to the 1950s, Clostridium acetobutylicum was used in industrial fermentation to produce butanol. Research in the past few decades showed results of other microorganisms that can produce butanol through fermentation. n-butanol is an intermediate in the production of butyl acrylate, butyl acetate, dibutyl phthalate, dibutyl sebacate, and other butyl esters, butyl ethers such as ethylene glycol monobutyl ether, di- and triethylene glycol monobutyl ether, and the corresponding butyl ether acetates. Other industrial uses include the manufacture of pharmaceuticals, polymers, pyroxylin plastics, herbicide esters, printing (e.g., 2,4-D, 2,4,5-T) and butyl xanthate. It is also used as a diluent/reactant in the manufacture of urea–formaldehyde and melamine–formaldehyde resins. Butanol is used 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 a relatively slow evaporating latent solvent is preferable, as with lacquers and ambient-cured enamels. It is also used as a component of hydraulic and brake fluids.