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. 1-hexanol is believed to be a component of the odour of freshly mowed grass. It is used in the perfume industry.

Preparation

Hexanol is produced industrially by the oligomerization of ethylene using triethylaluminium followed by oxidation of the alkylaluminium products. An idealized synthesis is shown:

Al(C₂H₅)₃ + 6 C₂H₄ → Al(C₆H₁₃)₃

Al(C₆H₁₃)₃ + 3 O + 3 H₂O → 3 HOC₆H₁₃ + 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.

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.

2-Hexanol

2-Hexanol (or hexan-2-ol) is a six carbon alcohol in which the OH group is located on the second carbon atom. It is an isomer of 1-hexanol, 3-hexanol, 2-methylpentanol, 3-methylpentanol, 2,3-dimethylbutanol, 2-ethylbutanol and many more compounds. Its chemical formula is C₆H₁₄O or C₆H₁₃OH. 2-Hexanol has a chiral center and can be resolved into enantiomers.

References