Alcohol (chemistry)

This article is about the class of chemical compounds. For the alcohol found in alcoholic drinks, see Alcohol (drug). For other uses, see Alcohol (disambiguation).

In chemistry, alcohol is a general term which refers to many organic compounds used in industry and science as reagents, solvents, and fuels. Common alcohols include rubbing alcohol, grain alcohol, wood alcohol, ethylene glycol, glycerin, and phenol.

Simple alcohols are made of an alkyl group with one or more hydroxyl (−OH) groups bound to its carbon atoms. They are often transparent colorless liquids.

Names for alcohol

There are two ways of naming alcohols: Common names, and IUPAC names.

• Common names often are made by taking the name of the alkyl group, and adding the word "alcohol". For example, "methyl alcohol" or "ethyl alcohol".
• IUPAC names are made by taking the name of the alkane chain, removing the last "e", and adding "ol". Examples of this are "methanol" and "ethanol".

Properties

The hydroxyl (OH) group makes alcohols polar, and they can form hydrogen bonds. Alcohols are weakly amphoteric, meaning they are both a weak acid and a weak base: they react with strong bases to make alkoxide anions, and strong acids to make oxonium cations.

Most alcohols are highly flammable.

Common alcohols

The simplest two alcohols are methanol (or methyl alcohol) and ethanol (or ethyl alcohol), which have the following structures:

• 
  Methanol
• 
  Ethanol

IUPAC nomenclature is used when describing more complex alcohols.

In common usage, "alcohol" often means ethanol or "grain alcohol". (See also: alcoholic proof).

Other commonly used alcohols include:

• Isopropyl alcohol (sec-propyl alcohol, propan-2-ol, 2-propanol) H₃C−CH(OH)−CH₃, or "rubbing alcohol"
• ethylene glycol (ethane-1,2-diol) HOCH₂−CH₂OH, which is the main substance in antifreeze
• glycerin (or glycerol, propane-1,2,3-triol) HOCH₂−CH(OH)−CH₂OH, bound in natural fats and oils, which are triglycerides (esters of glycerol and fatty acids)
• phenol C₆H₅OH, an alcohol where the hydroxyl group is bound to a benzene ring.

Possible long term side effects in humans