Aldehydes, Ketones, and Carboxylic Acids

Introduction to Carbonyl Compounds

Organic compounds containing a carbon-oxygen double bond (carbonyl group) are fundamental in organic chemistry. The carbonyl group is represented as C=O and is present in several important classes of compounds, including aldehydes, ketones, and carboxylic acids.

• Aldehydes: Contain the carbonyl group at the end of a carbon chain. General formula: R-CHO

• Ketones: Contain the carbonyl group within the carbon chain (not at the end). General formula: R-CO-R'

• Carboxylic Acids: Contain the carbonyl group bonded to a hydroxyl group. General formula: R-COOH

Structural representations:

• Aldehyde:

• Ketone:

• Carboxylic Acid:

Nomenclature and Structure of Carbonyl Compounds

The naming of aldehydes and ketones follows specific rules based on the functional group and the length of the carbon chain.

Aldehydes

• Functional group:

• Suffix used: -al (e.g., ethanal)

• Prefix used: formyl- (when the group is a substituent)

Ketones

• Functional group: (within the chain)

• Suffix used: -one (e.g., propanone)

• Prefix used: keto- or oxo- (when the group is a substituent)

Common Names of Carbonyl Compounds

Many simple aldehydes and ketones are known by their common names, which are often derived from the names of the corresponding carboxylic acids or the number of carbon atoms in the molecule.

Summary of common names and their corresponding IUPAC names:

Key points:

• The common name is often based on the number of carbons and the corresponding acid name.

• IUPAC names are systematic and indicate the parent alkane with the appropriate suffix.

Example: Formaldehyde (common name) is called methanal in IUPAC nomenclature. Its structure is .

Additional info: The systematic approach to naming helps in identifying the structure and functional group position, which is essential for understanding reactivity and properties in organic chemistry.