Organic Chemistry: Alcohols and IUPAC Nomenclature

Alcohols Nomenclature

• Benzenes with both OH and CH3 groups are called cresols.
• IUPAC rules for naming alcohols with a single hydroxyl group:
  • Rule 1: Name the longest carbon chain to which the hydroxyl group is attached, adding the suffix -ol.
  • Rule 2: Number the chain starting at the end nearest the hydroxyl group, indicating the position of the -OH group.
  • Rule 3: Name and locate any other substituents present.
  • Rule 4: In alcohols with a hydroxyl group attached to a carbon atom in a ring, the hydroxyl group is assumed to be on carbon 1.

Alkyl Alcohol System

• The alkyl alcohol system is a common system of nomenclature.
• The name of an alcohol is derived by combining the name of the alkyl group with the word "alcohol".
• Examples: n-butyl alcohol, isobutyl alcohol, t-butyl alcohol.

Polyhydroxy Alcohols

• Polyhydroxy alcohols are alcohols that possess more than one hydroxyl group.
• They are named with a slight modification of the IUPAC rules.
• Examples: diols (two hydroxyl groups), triols (three hydroxyl groups), etc.
• Examples: 1,2-Ethanediol, 1,2-propanediol, 1,2,3-propanetriol.

Classification of Monohydric Alcohols

• Monohydroxy alcohols are hydrocarbon derivatives with only one -OH group connected to a sp³-hybridized carbon atom.
• General formula: R-OH.
• Names of monohydroxy alcohols are the names of the same hydrocarbons with the added prefix -ol.
• Classification of monohydroxy alcohols: primary (1°), secondary (2°), and tertiary (3°) based on the attachment of the OH group to primary, secondary, and tertiary carbon atoms respectively.

Isomerism of Monohydroxyl Alcohols

• Monohydroxyl alcohols are characterized by structural, geometrical, and optical isomerism.