Alcohols and Amines Classification and Naming

Overview

This lecture covered the classification and systematic naming of alcohols and amines, outlining the rules for identifying, naming, and prioritizing these functional groups in organic compounds.

Classification of Alcohols

• Alcohols are classified as primary, secondary, or tertiary based on the number of carbons attached to the carbon bonded to the -OH group.
• Primary: -OH is on a carbon attached to one other carbon; Secondary: attached to two carbons; Tertiary: attached to three carbons.

Common and Systematic Naming of Alcohols

• Common names use the alkyl group name plus “alcohol” (e.g., isopropyl alcohol).
• Systematic (IUPAC) naming: replace the “-e” ending of the parent hydrocarbon with “-ol”.
• Indicate the position of -OH by number (e.g., 3-pentanol or pentan-3-ol).
• The parent chain must include the -OH group, even if not the longest carbon chain.
• Number the chain to give the -OH group the lowest possible number.
• If multiple -OH groups, use suffixes like “diol”, “triol”, etc., and indicate positions (e.g., 2,4-hexanediol).
• When substituents are present, list them alphabetically.

Classification and Naming of Amines

• Amines are classified by the number of alkyl groups attached to the nitrogen: primary (one), secondary (two), tertiary (three).
• Unlike alcohols, classification is based on the nitrogen atom, not the carbon chain.
• Common names: list all alkyl groups in alphabetical order followed by “amine” (e.g., methylpropylamine).
• IUPAC names: parent chain name with “-amine” suffix; indicate the nitrogen’s position (e.g., butan-1-amine).
• Alkyl groups on nitrogen are denoted with “N-” (e.g., N-ethylbutan-1-amine).
• Use “N,N-” for multiple identical groups (e.g., N,N-dimethyl).

Quaternary Ammonium Salts

• Have four alkyl groups attached to a positively charged nitrogen.
• Named by listing alkyl groups alphabetically, adding “ammonium”, and then the anion (e.g., tetramethylammonium chloride).
• Always exist as salts due to positive nitrogen.

Key Terms & Definitions

• Alcohol — Organic compound with an -OH (hydroxyl) functional group.
• Amine — Organic compound containing a nitrogen bonded to alkyl or aryl groups.
• Primary/Secondary/Tertiary Alcohol — Classification by the number of carbons bonded to the carbon with -OH.
• Primary/Secondary/Tertiary Amine — Classification by the number of alkyl groups attached to nitrogen.
• Functional Group — An atom or group of atoms that determines chemical properties and reactivity.
• Quaternary Ammonium Salt — Compound with a nitrogen bonded to four alkyl groups and bearing a positive charge.

Action Items / Next Steps

• Review additional naming examples in course materials.
• Complete in-class problems on alcohol and amine nomenclature.
• Ask questions if any naming conventions or classifications remain unclear.