Definition and functional group criterion

Summary

In chemistry, an alcohol is an organic compound that contains at least one hydroxyl (–OH) functional group attached to a saturated carbon atom. The presence of the OH group strongly changes the behavior of hydrocarbons by making the molecule more polar and hydrophilic, and it also provides a reactive site where many chemical reactions can occur. A key criterion used to classify alcohols is the number of carbon atoms connected to the carbon bearing the hydroxyl group. Primary alcohols have the general form RCH2OH, secondary alcohols have RR'CHOH, and tertiary alcohols have RR'R"COH. This primary/secondary/tertiary distinction is important because it influences typical reaction pathways and properties of the alcohols.

Key Points

• 1

  An alcohol is defined by having at least one hydroxyl (–OH) group bound to a saturated carbon atom.

• 2

  The hydroxyl group makes alcohols more polar and hydrophilic and provides a site for many reactions.

• 3

  Alcohols are classified as primary, secondary, or tertiary based on how many carbon atoms are attached to the hydroxyl-bearing carbon.