Butanol

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Butanol (also called butyl alcohol) is a four-carbon alcohol with a formula of C 4 H 9 O H, which occurs in five isomeric structures (four structural isomers), from a straight-chain primary alcohol to a branched-chain tertiary alcohol; [1] all are a butyl or isobutyl group linked to a hydroxyl group (sometimes represented as BuOH, 1-BuOH, i-BuOH, and t-BuOH). These are 1-butanol, two stereoisomers of sec-butyl alcohol, isobutanol and tert-butyl alcohol. Butanol is primarily used as a solvent and as an intermediate in chemical synthesis, and may be used as a fuel. Biologically produced butanol is called biobutanol, which may be n-butanol or isobutanol.

Contents

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 1-butanol. The straight chain isomer with the alcohol at an internal carbon is sec-butyl alcohol 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-butyl alcohol or 2-methyl-2-propanol.

1-Butanol skeletal.svg 2-butanol Line-Structure.svg Isobutanol.svg Tert-butyl-alcohol-2D-skeletal.svg
1-Butanol (n-butanol) 2-Butanol (sec-butyl alcohol) Isobutanol (2-methylpropan-1-ol) tert-butyl alcohol (2-methylpropan-2-ol)

The butanol isomers have different melting and boiling points. 1-Butanol and isobutanol have limited solubility, sec-butyl alcohol has substantially greater solubility, whereas tert-butyl alcohol is miscible with water. The hydroxyl group makes the molecule polar, promoting solubility in water, while the longer hydrocarbon chain mitigates the polarity and reduces solubility.

Toxicity

Butanol exhibits a low order of toxicity in single dose experiments with laboratory animals [2] [3] 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 alcohols. Exposure may also cause severe eye irritation and moderate skin irritation. The main dangers are from prolonged exposure to the alcohol's vapors. 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 damage DNA or cause cancer.

Uses

Primary uses

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. [4]

A 50% solution of butanol in water has been used since the 20th century to retard the drying of fresh plaster in fresco painting. The solution is usually sprayed on the wet plaster after the plaster has been trowelled smooth and extends the working period during which frescos can be painted up to 18 hours. [5]

Butanol is used in the synthesis of 2-butoxyethanol. A major application for butanol is as a reactant with acrylic acid to produce butyl acrylate, a primary ingredient of water based acrylic paint. [6]

It is also used as a base for perfumes, but on its own has a highly alcoholic aroma.

Salts of butanol are chemical intermediates; for example, alkali metal salts of tert-butanol are tert-butoxides.

Recreational Use

2-Methyl-2-butanol is a central nervous system depressant with a similar effect upon ingestion to ethanol. Case reports have been documented demonstrating its potential for abuse. [7]

Biobutanol

Butanol (n-butanol or isobutanol) is a potential biofuel (butanol fuel). [8] Butanol at 85 percent concentration 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, and a vehicle using butanol would return fuel consumption more comparable to gasoline than ethanol. Butanol can also be added to diesel fuel to reduce soot emissions. [9] Photoautotrophic microorganisms, like cyanobacteria, can be engineered to produce 1-butanol indirectly from CO2 and water. [10]

Production

Butanols are normally present in fusel alcohol.

Since the 1950s, most butanol in the United States is produced commercially from fossil fuels. The most common process starts with propene (propylene), which is put through a hydroformylation reaction to form butanal, which is then reduced with hydrogen to 1-butanol and/or 2-butanol. tert-butanol is derived from isobutane as a co-product of propylene oxide production.

Propen Hydroformylierung zu Butanol.svg

Butanol can also be produced by fermentation of biomass by bacteria. Prior to the 1950s, Clostridium acetobutylicum was used in industrial fermentation to produce n-butanol.

See also

Related Research Articles

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In chemistry, an alcohol is a type of organic compound that carries at least one hydroxyl functional group bound to a saturated carbon atom. Alcohols range from the simple, like methanol and ethanol, to complex, like sugar alcohols and cholesterol. The presence of an OH group strongly modifies the properties of hydrocarbons, conferring hydrophilic (water-loving) properties. The OH group provides a site at which many reactions can occur.

<span class="mw-page-title-main">Petrochemical</span> Chemical product derived from petroleum

Petrochemicals are the chemical products obtained from petroleum by refining. Some chemical compounds made from petroleum are also obtained from other fossil fuels, such as coal or natural gas, or renewable sources such as maize, palm fruit or sugar cane.

Isobutane, also known as i-butane, 2-methylpropane or methylpropane, is a chemical compound with molecular formula HC(CH3)3. It is an isomer of butane. Isobutane is a colorless, odorless gas. It is the simplest alkane with a tertiary carbon atom. Isobutane is used as a precursor molecule in the petrochemical industry, for example in the synthesis of isooctane.

<span class="mw-page-title-main">Biofuel</span> Type of biological fuel

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. Biofuel can be produced from plants or from agricultural, domestic or industrial biowaste. Biofuels are mostly used for transportation, but can also be used for heating and electricity. Biofuels are regarded as a renewable energy source. The use of biofuel has been subject to criticism regarding the "food vs fuel" debate, varied assessments of their sustainability, and possible deforestation and biodiversity loss as a result of biofuel production.

Methyl <i>tert</i>-butyl ether Chemical compound

Methyl tert-butyl ether (MTBE), also known as tert-butyl methyl ether, is an organic compound with a structural formula (CH3)3COCH3. MTBE is a volatile, flammable, and colorless liquid that is sparingly soluble in water. Primarily used as a fuel additive, MTBE is blended into gasoline to increase its octane rating and knock resistance, and reduce unwanted emissions.

<span class="mw-page-title-main">Diisopropyl ether</span> Chemical compound

Diisopropyl ether is a secondary ether that is used as a solvent. It is a colorless liquid that is slightly soluble in water, but miscible with organic solvents. It is used as an extractant and an oxygenate gasoline additive. It is obtained industrially as a byproduct in the production of isopropanol by hydration of propylene. Diisopropyl ether is sometimes represented by the abbreviation DIPE.

<span class="mw-page-title-main">2-Butanol</span> Secondary alcohol

Butan-2-ol, or sec-butanol, is an organic compound with formula CH3CH(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 designated as (R)-(−)-butan-2-ol and (S)-(+)-butan-2-ol. It is normally encountered as a 1:1 mixture of the two stereoisomers — a racemic mixture.

<i>tert</i>-Butyl alcohol Chemical compound

tert-Butyl alcohol is the simplest tertiary alcohol, with a formula of (CH3)3COH (sometimes represented as t-BuOH). Its isomers are 1-butanol, isobutanol, and butan-2-ol. tert-Butyl alcohol is a colorless solid, which melts near room temperature and has a camphor-like odor. It is miscible with water, ethanol and diethyl ether.

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<span class="mw-page-title-main">1-Butanol</span> Chemical compound

1-Butanol, also known as butan-1-ol or n-butanol, is a primary alcohol with the chemical formula C4H9OH and a linear structure. Isomers of 1-butanol are isobutanol, butan-2-ol and tert-butanol. The unmodified term butanol usually refers to the straight chain isomer.

<span class="mw-page-title-main">Butanol fuel</span> Fuel for internal combustion engines

Butanol may be used as a fuel in an internal combustion engine. It is more similar to gasoline than it is to ethanol. A C4-hydrocarbon, butanol is a drop-in fuel and thus works in vehicles designed for use with gasoline without modification. Both n-butanol and isobutanol have been studied as possible fuels. Both can be produced from biomass (as "biobutanol" ) as well as from fossil fuels (as "petrobutanol"). The chemical properties depend on the isomer (n-butanol or isobutanol), not on the production method.

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Acetone–butanol–ethanol (ABE) fermentation, also known as the Weizmann process, is a process that uses bacterial fermentation to produce acetone, n-butanol, and ethanol from carbohydrates such as starch and glucose. It was developed by chemist Chaim Weizmann and was the primary process used to produce acetone, which was needed to make cordite, a substance essential for the British war industry during World War I.

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References

  1. ↑ Atsumi, S.; Hanai, T.; Liao, J. C. (2008). "Non-fermentative pathways for synthesis of branched-chain higher alcohols as biofuels". Nature. 451 (7174): 86–9. doi:10.1038/nature06450. PMID   18172501. S2CID   4413113.
  2. ↑ 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.
  3. ↑ "n-Butanol". Archived from the original on 2015-04-02. Retrieved 2012-02-03.
  4. ↑ Isobutanol at chemicalland21.com
  5. ↑ "diego's assistants | Diego Rivera Mural Project". www.riveramural.org. Retrieved 2019-03-27.
  6. ↑ Harris O.; et al. (August 1998). Toxicological Profile for 2-Butoxyethanol and 2-butoxyethanol acetate. U.S. Dept of Health and Human Services.
  7. ↑ Syed, Alia N.; Leo, Raphael J. (2022). "Recreational 2-Methyl-2-Butanol Use". The Primary Care Companion for CNS Disorders. 24 (6). doi:10.4088/PCC.22cr03292. S2CID   253700629.
  8. ↑ Sampa Maiti; et al. (Dec 10, 2015). "Quest for sustainable bio‐production and recovery of butanol as a promising solution to fossil fuel". Energy Research. 40 (4): 411–438. doi: 10.1002/er.3458 .
  9. ↑ Antoni, D.; Zverlov, V. & Schwarz, W. H. (2007). "Biofuels from Microbes". Applied Microbiology and Biotechnology. 77 (1): 23–35. doi:10.1007/s00253-007-1163-x. PMID   17891391. S2CID   35454212.
  10. ↑ Liu, X., Miao, R., Lindberg, P., & Lindblad, P. (2019). Modular engineering for efficient photosynthetic biosynthesis of 1-butanol from CO 2 in cyanobacteria. Energy & Environmental Science, 12(9), 2765-2777.
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