Isobutanol (

IUPAC nomenclature A chemical nomenclature is a set of rules to generate systematic names for chemical compounds. The nomenclature used most frequently worldwide is the one created and developed by the International Union of Pure and Applied Chemistry (IUPAC). Th ...

: 2-methylpropan-1-ol) is an

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. Th ...

with the

formula In science, a formula is a concise way of expressing information symbolically, as in a mathematical formula or a ''chemical formula''. The informal use of the term ''formula'' in science refers to the general construct of a relationship betwe ...

(CH₃)₂CHCH₂OH (sometimes represented as ''i''-BuOH). This colorless, flammable liquid with a characteristic smell is mainly used as a solvent either directly or as its esters. Its

isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Is ...

s are 1-butanol,

2-butanol 2-Butanol, or ''sec''-butanol, is an organic compound with formula C H3CH( OH)CH2CH3. Its structural isomers are 1-butanol. isobutanol, and ''tert''-butanol. 2-Butanol is chiral and thus can be obtained as either of two stereoisomers designa ...

, and ''tert''-butanol, all of which are important industrially.

Production

Isobutanol is produced by the

carbonylation Carbonylation refers to reactions that introduce carbon monoxide into organic and inorganic substrates. Carbon monoxide is abundantly available and conveniently reactive, so it is widely used as a reactant in industrial chemistry. The term carbon ...

propylene Propylene, also known as propene, is an unsaturated organic compound with the chemical formula CH3CH=CH2. It has one double bond, and is the second simplest member of the alkene class of hydrocarbons. It is a colorless gas with a faint petro ...

. Two methods are practiced industrially,

hydroformylation Hydroformylation, also known as oxo synthesis or oxo process, is an industrial process for the production of aldehydes from alkenes. This chemical reaction entails the net addition of a formyl group (CHO) and a hydrogen atom to a carbon-carbon ...

is more common and generates a mixture of

isobutyraldehyde Isobutyraldehyde is the chemical compound with the formula (CH3)2CHCHO. It is an aldehyde, isomeric with n-butyraldehyde (butanal). Isobutyraldehyde is made, often as a side-product, by the hydroformylation of propene. Its odour is described as ...

and

butyraldehyde Butyraldehyde, also known as butanal, is an organic compound with the formula CH3(CH2)2CHO. This compound is the aldehyde derivative of butane. It is a colorless flammable liquid with an unpleasant smell. It is miscible with most organic solvent ...

: :CH₃CH=CH₂ + CO + H₂ → CH₃CH₂CH₂CHO The reaction is catalyzed by cobalt or rhodium complexes. The resulting aldehydes are

hydrogenate Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to reduce or saturate organ ...

d to the alcohols, which are then separated. In Reppe

, the same products are obtained, but the hydrogenation is effected by the water-gas shift reaction..

Laboratory synthesis

Propanol and

methanol Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical and the simplest aliphatic alcohol, with the formula C H3 O H (a methyl group linked to a hydroxyl group, often abbreviated as MeOH). It is ...

can be reacted to produce isobutyl alcohol via Guerbet condensation.

Biosynthesis of isobutanol

''E. coli'' as well as several other organisms has been genetically modified to produce C4 alcohols from glucose, including isobutanol, 1-butanol, 2-methyl-1-butanol, 3-methyl-1-butanol, and 2-phenylethanol. The host's highly active amino acid biosynthetic pathway is shifted to alcohol production. α- Ketoisovalerate, derived from

valine Valine (symbol Val or V) is an α-amino acid that is used in the biosynthesis of proteins. It contains an α- amino group (which is in the protonated −NH3+ form under biological conditions), an α- carboxylic acid group (which is in the deprotona ...

, is prone to decarboxylation to give

, which is susceptible to reduction to the alcohol: :(CH₃)₂CHC(O)CO₂H → (CH₃)₂CHCHO + CO₂ :(CH₃)₂CHCHO + NADH + H⁺ → (CH₃)₂CHCH₂OH + NAD⁺

Applications

The uses of isobutanol and n-butanol are similar. They are often used interchangeably. The main applications are as varnishes and precursors to esters, which are useful solvents, e.g.

isobutyl acetate The chemical compound isobutyl acetate, also known as 2-methylpropyl ethanoate (IUPAC name) or β-methylpropyl acetate, is a common solvent. It is produced from the esterification of isobutanol with acetic acid. It is used as a solvent for lacque ...

. Isobutyl esters of phthalic, adipic, and related dicarboxylic acids are common

plasticizer A plasticizer ( UK: plasticiser) is a substance that is added to a material to make it softer and more flexible, to increase its plasticity, to decrease its viscosity, and/or to decrease friction during its handling in manufacture. Plasticiz ...

s. Isobutanol is also a component of some

biofuels Biofuel is a fuel that is produced over a short time span from biomass, rather than by the very slow natural processes involved in the formation of fossil fuels, such as oil. According to the United States Energy Information Administration (EIA ...

Safety and regulation

Isobutanol is one of the least

toxic Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a sub ...

of the butanols with an of 2460 mg/kg (rat, oral). In March 2009, the

Government of Canada The government of Canada (french: gouvernement du Canada) is the body responsible for the federal administration of Canada. A constitutional monarchy, the Crown is the corporation sole, assuming distinct roles: the executive, as the ''Crown-i ...

announced a ban on isobutanol use in

cosmetics Cosmetics are constituted mixtures of chemical compounds derived from either natural sources, or synthetically created ones. Cosmetics have various purposes. Those designed for personal care and skin care can be used to cleanse or protec ...

References

External links

* * * * {{Authority control Alcohol solvents Primary alcohols GABAA receptor positive allosteric modulators Sedatives Hypnotics Alkanols