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Home Chemistry Compounds in Everyday Life Alcohol Chemical Structure of Alcohols
 
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Chemical Structure of Alcohols

The functional group of an alcohol is a hydroxyl group bonded to an sp3 hybridized carbon.

Primary, Secondary, and Tertiary Alcohols

There are three major subsets of alcohols - 'primary', 'secondary' and 'tertiary', which is dependent upon the number of carbons the C-OH carbon is bonded to. Ethanol and methanol, shown below, are both 'primary' alcohols. The simplest secondary alcohol is propan-2-ol, and a simple tertiary alcohol is 2-methylpropan-2-ol.

General formula

The general formula is CnH2n+1OH.

Methanol and ethanol

The simplest and most commonly used alcohols are methanol and ethanol (common names methyl alcohol and ethyl alcohol, respectively), which have the following structures:

H H H | | | H-C-O-H H-C-C-O-H | | | H H H methanol ethanol

In common usage, "alcohol" often refers simply to ethanol or "grain alcohol".

Other common alcohols

  • isopropyl alcohol (sec-propyl alcohol, propan-2-ol, 2-propanol) H3C-CH(OH)-CH3, or "rubbing alcohol"
  • ethylene glycol (ethane-1,2-diol) HO-CH2-CH2-OH, which is the primary component in antifreeze
  • glycerin (or glycerol, propane-1,2,3-triol) HO-CH2-CH(OH)-CH2-OH bound in natural fats and oils, which are triglycerides (triacylglycerols)
  • phenol is an alcohol where the hydroxyl group is bound to a benzene ring.

    Fatty alcohols

    These are derived from natural fats and oils. Those with common names include:

  • erucyl alcohol
  • ricinolyl alcohol
  • arachidyl alcohol
  • capryl alcohol
  • capric alcohol
  • behenyl alcohol
  • lauryl alcohol (1-dodecanol) -- 12 carbon atoms
  • myristyl alcohol (1-tetradecanol) -- 14 carbon atoms
  • cetyl (or palmityl) alcohol (1-hexadecanol) -- 16 carbon atoms
  • stearyl alcohol (1-octadecanol) -- 18 carbon atoms
  • isostearyl alcohol
  • oleyl alcohol (cis-9-octadecen-1-ol) -- 18 carbon atoms, unsaturated
  • palmitoleyl alcohol
  • linoleyl alcohol (9Z, 12Z-octadecadien-1-ol) -- 18 carbon atoms, polyunsaturated
  • elaidyl alcohol (9E-octadecen-1-ol)
  • elaidolinoleyl alcohol (9E, 12E-octadecadien-1-ol)
  • linolenyl alcohol (9Z, 12Z, 15Z-octadecatrien-1-ol)
  • elaidolinolenyl alcohol (9E, 12E, 15-E-octadecatrien-1-ol)

    The smaller molecules are used in cosmetics and food, and as industrial solvents. Some of the larger molecules are important as biofuels.

    Uses

    Alcohols are in wide use in industry and science as reagents, solvents, and fuels. State-of-the-art engineering has achieved replacement of gasoline (and other hydrocarbons which produce toxic fumes) with forms of alcohol such as ethanol or methanol (which burn more cleanly). Because of its low toxicity and ability to dissolve non-polar substances, ethanol is often used as a solvent in medical drugs, perfumes, and vegetable essences such as vanilla.

    Sources

    Many alcohols can be created by fermentation of fruits or grains with yeast, but only ethanol is commercialy produced this way, chiefly for fuel and drink. Other alcohols are generally produced by synthetic routes from natural gas, oil, or coal feedstocks.

    • Home Chemistry Compounds in Everyday Life Alcohol Chemical Structure of Alcohols

    Last Update: 2004-12-21