1-hexanol Information
1-Hexanol is an organic alcohol with a six carbon chain and a condensed structural formula of CH3(CH2)5OH. This colorless liquid is slightly soluble in water, but miscible with ether and ethanol. Two additional straight chain isomers of 1-hexanol exist, 2-hexanol and 3-hexanol, both of which differ by the location of the hydroxyl group. Many isomeric alcohols have the formula C6H13OH. It is used in the perfume industry.
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Preparation
Hexanol is produced industrially by the oligomerization of ethylene using triethylaluminium followed by oxidation of the alkylaluminium products.[2] An idealized synthesis is shown:
- Al(C2H5)3 + 6C2H4 → Al(C6H13)3
- Al(C6H13)3 + 1½O2 + 3H2O → 3HOC6H13 + Al(OH)3
The process generates a range of oligomers that are separated by distillation.
Alternative methods
Another method of preparation entails hydroformylation of 1-pentene followed by hydrogenation of the resulting aldehydes. This method is practiced industrially to produce mixtures of isomeric C6-alcohols, which are precursors to plasticizers.[2]
In principle, 1-hexene could be converted to 1-hexanol by hydroboration (diborane in tetrahydrofuran followed by treatment with hydrogen peroxide and sodium hydroxide):
This method is instructive and useful in laboratory synthesis but of no practical relevance because of the commercial availability of inexpensive 1-hexanol from ethylene.
Occurrence in Nature
1-hexanol is believed to be a component of the odour of freshly mown grass. Alarm pheromones emitted by the Koschevnikov gland of honey bees contain 1-hexanol.
See also
Cis-3-Hexenal, another volatile organic carbon biomolecule, also considered responsible for the freshly mowed grass flavor.
References
- ^ "1-hexanol - PubChem Public Chemical Database". The PubChem Project. USA: National Center for Biotechnology Information. Descriptors Computed from Structure. http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=8103&loc=ec_rcs.
- ^ a b Falbe, Jürgen; Bahrmann, Helmut; Lipps, Wolfgang; Mayer, Dieter (2005), "Alcohols, Aliphatic", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.a01_279 .
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Categories: Flavors | Alcohols
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