Alcohol

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Alcohols are organic compounds which contain a hydroxyl functional group (-OH) bounded to a saturated carbon atom.

Types of Alcohols

Alcohols are divide according to type of carbon atom to which the hydroxyl functional group is bonded:

  • Primary alcohols
    • Primary alcohols are ones in which the carbon atom that is bonded to a hydroxyl functional group is bounded to only one other carbon atom.
    • Primary alcohols are oxidized to aldehydes.
  • Secondary alcohols
    • Secondary alcohols are ones in which the carbon atom that is bonded to a hydroxyl functional group is bounded to two other carbon atom.
    • Secondary alcohols are oxidized to ketones.
  • Tertiary alcohols
    • Tertiary alcohols are ones in which the carbon atom that is bonded to a hydroxyl functional group is bounded to three other carbon atom.
    • Tertiary alcohols can not be oxidized.

Nomenclature

Systematic names

Common names

Chemical Formula IUPAC Name Common Name
Monohydric alcohols
CH3OH Methanol Wood alcohol
C2H5OH Ethanol Alcohol
C3H7OH Isopropyl alcohol Rubbing alcohol
C4H9OH Butyl alcohol Butanol
C5H11OH Pentanol Amyl alcohol
C16H33OH Hexadecan-1-ol Cetyl alcohol
Polyhydric alcohols
C2H4(OH)2 Ethane-1,2-diol Ethylene glycol
C3H6(OH)2 Propane-1,2-diol Propylene Glycol
C3H5(OH)3 Propane-1,2,3-triol Glycerol
C4H6(OH)4 Butane-1,2,3,4-tetraol Erythritol, Threitol
C5H7(OH)5 Pentane-1,2,3,4,5-pentol Xylitol
C6H8(OH)6 Hexane-1,2,3,4,5,6-hexol Mannitol, Sorbitol
C7H9(OH)7 Heptane-1,2,3,4,5,6,7-heptol Volemitol
Unsaturated aliphatic alcohols
C3H5OH Prop-2-ene-1-ol Allyl alcohol
C10H17OH 3,7-Dimethylocta-2,6-dien-1-ol Geraniol
C3H3OH Prop-2-in-1-ol Propargyl alcohol
Alicyclic alcohols
C6H6(OH)6 Cyclohexane-1,2,3,4,5,6-hexol Inositol
C10H19OH 2 - (2-propyl)-5-methyl-cyclohexane-1-ol Menthol

Physical and chemical properties

Applications

Preparation

Reactions

Oxidation

Primary alcohols can be oxidized either to aldehydes or to carboxylic acids, while the oxidation of secondary alcohols normally terminates at the ketone stage. Tertiary alcohols are resistant to oxidation.

The direct oxidation of primary alcohols to carboxylic acids normally proceeds via the corresponding aldehyde, which is transformed via an aldehyde hydrate by reaction with water before it can be further oxidized to the carboxylic acid.

File:500px-Alcohol to aldehyde to acid.png
Mechanism of oxidation of primary alcohols to carboxylic acids via aldehydes and aldehyde hydrates

Reagents useful for the transformation of primary alcohols to aldehydes are normally also suitable for the oxidation of secondary alcohols to ketones. These include Collins reagent and Dess-Martin periodinane. The direct oxidation of primary alcohols to carboxylic acids can be carried out using potassium permanganate or the Jones reagent.

Esterification

The esterification is a reaction of an alcohol with an acid, the result is an ester.

More on this page.

Dehydration

Dehydration is a process of separating all the water molecules from the alcohol. This is done with a dehydrating agent which is more hygroscopic than the alcohol, one such example are the alkali metals or dehydrated calcium chloride.

Deprotonation

Nucleophilic substitution

Toxicity

References

  1. http://en.wikipedia.org/wiki/Alcohol