Aldehydes, Ketones, and Carboxylic Acids

Introduction to Carbonyl Compounds

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

• Aldehydes: The carbonyl group is bonded to at least one hydrogen atom. General formula: R-CHO.

• Ketones: The carbonyl group is bonded to two carbon atoms. General formula: R-CO-R'.

• Carboxylic Acids: The carbonyl group is bonded to a hydroxyl group (-OH). General formula: R-COOH.

Nomenclature and Structure of Carbonyl Groups

Naming Aldehydes and Ketones

The nomenclature of aldehydes and ketones follows IUPAC rules, with specific suffixes and prefixes to indicate the presence of the carbonyl group.

• Aldehydes:

  • Suffix used: -al (e.g., ethanal)

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

  • Functional group notation: -CHO

• Ketones:

  • Suffix used: -one (e.g., propanone)

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

  • Functional group notation: >C=O

Example: The compound CH3CHO is named ethanal (IUPAC) or acetaldehyde (common name).

Common Names of Carbonyl Compounds

Root Names Based on Carbon Chain Length

Common names for aldehydes and related compounds often use specific roots to indicate the number of carbons in the main chain:

These roots are combined with the appropriate suffix to form the common name (e.g., formaldehyde, acetaldehyde).

Examples of Aldehydes and Their Common/IUPAC Names

Summary Table: Suffixes and Prefixes for Carbonyl Compounds

Key Points

• The carbonyl group is a defining feature of several important classes of organic compounds.

• Nomenclature involves both IUPAC and common naming systems, with specific roots and suffixes.

• Understanding the structure and naming of these compounds is essential for further study in organic and general chemistry.