Butanol

Source: Wikipedia, the free encyclopedia.

Butanol (also called butyl alcohol) is a four-carbon

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.

Isomers

The unmodified term butanol usually refers to the

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 sec-butyl alcohol (2-butanol) 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

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.

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

Main article: Butanol fuel

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

Main article: Butanol fuel

Butanols are normally present in fusel alcohol.

Since the 1950s, most butanol in the

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.

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

References

  • Merck Index, 12th Edition, 1575.
  1. S2CID 4413113
    .
  2. 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. S2CID 253700629
    .
  8. doi:10.1002/er.3458
    .
  9. 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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