Functional Groups in Organic Molecules

Introduction to Functional Groups

Functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. Recognizing functional groups is essential for understanding organic chemistry reactions and nomenclature.

• Carboxylic Acid: Contains a carbonyl group (C=O) bonded to a hydroxyl group (OH) and a carbon atom. General structure: -COOH.

• Amide: Contains a carbonyl group (C=O) bonded to a nitrogen atom (N). General structure: -CONR2.

• Alcohol: Contains a hydroxyl group (OH) bonded to a saturated carbon atom. General structure: -C-OH.

• Ketone: Contains a carbonyl group (C=O) bonded to two carbon atoms. General structure: RC(=O)R'.

Degree Designation: The degree (primary, secondary, tertiary) of alcohols and amides is determined by the number of carbon groups attached to the central atom (oxygen for alcohols, nitrogen for amides).

• Secondary (2°) Alcohol: The carbon bearing the OH group is attached to two other carbons.

• Secondary (2°) Amide: The nitrogen is attached to two carbon groups.

Example: In the provided molecule, the functional groups present are carboxylic acid, amide, and alcohol. Ketone is not present because the carbonyl group is not bonded to two carbon atoms.

IUPAC Nomenclature of Organic Compounds

Introduction to IUPAC Naming

The International Union of Pure and Applied Chemistry (IUPAC) system provides a standardized method for naming organic compounds. The name of a compound is constructed from three main components: prefix, infix, and suffix.

Key Terms and Definitions

• Parent Chain: The longest continuous carbon chain in the molecule.

• Substituent: A group bonded to the parent chain.

• Alkyl Group: A substituent derived by removal of a hydrogen from an alkane.

Alkane and Alkyl Group Names

General Parent-Chain Nomenclature

The IUPAC name is constructed as prefix-infix-suffix:

• Prefix: Indicates the number of carbon atoms in the parent chain.

• Infix: Indicates the nature of the carbon-carbon bonds (single, double, triple).

• Suffix: Indicates the class of compound (hydrocarbon, alcohol, aldehyde, amine, ketone, carboxylic acid).

Prefix Table

Infix Table

Suffix Table

Constructing the IUPAC Name

Combine the prefix, infix, and suffix to name the compound. For example:

• Ethanamine: Parent chain length: eth- (2 carbons), all single bonds: -an-, amine: -amine. Name: ethanamine.

• Propene: Parent chain length: prop- (3 carbons), one double bond: -en-, hydrocarbon: -e. Name: propene.

• Butanone: Parent chain length: but- (4 carbons), all single bonds: -an-, ketone: -one. Name: butanone.

Locants (Numbering Substituents)

Locants are numerical positions assigned to substituents, functional groups, or multiple bonds in the parent chain. The goal is to assign the lowest possible numbers to these groups.

• Number the parent chain to give the substituents the lowest possible locants.

• Example: 3-methylhexane vs 4-methylhexane – choose the numbering that gives the methyl group the lowest number.

Summary Table: IUPAC Naming Components

Additional info: These notes provide foundational knowledge for identifying functional groups and naming organic compounds according to IUPAC rules, which is essential for success in college-level organic chemistry.