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 nature of the groups attached to the carbonyl carbon determines whether the compound is an aldehyde, ketone, or carboxylic acid.

• Aldehydes: The carbonyl group is bonded to at least one hydrogen atom.

• Ketones: The carbonyl group is bonded to two carbon atoms.

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

The general structures are:

• Aldehyde:

• Ketone:

• Carboxylic Acid:

Nomenclature and Structure of Carbonyl Compounds

The naming of carbonyl compounds follows IUPAC rules, but many also have common names. The functional group (F.G.) and suffixes/prefixes used in naming are as follows:

• Aldehydes:

  • Functional group:

  • Suffix: -al (e.g., ethanal)

  • Prefix: formyl- (when used as a substituent)

• Ketones:

  • Functional group: (within the carbon chain)

  • Suffix: -one (e.g., propanone)

  • Prefix: keto- or oxo- (when used as a substituent)

Common Names of Carbonyl Compounds

Many simple carbonyl compounds are known by their common names, which are often derived from the Latin or Greek names of their sources or the number of carbon atoms present. The prefixes for the number of carbons are:

These prefixes are combined with the type of compound to form common names (e.g., formaldehyde, acetaldehyde).

Examples of Aldehydes and Ketones

Key Points:

• The IUPAC system names aldehydes by replacing the terminal -e of the parent alkane with -al.

• Ketones are named by replacing the -e of the parent alkane with -one, and indicating the position of the carbonyl group if necessary.

• Common names are still widely used, especially for simple compounds.

Summary Table: Suffixes and Prefixes in Nomenclature

Example: The compound CH3COCH3 is called acetone (common name) or propanone (IUPAC name).

Additional info: Carboxylic acids are named by replacing the -e of the parent alkane with -oic acid (e.g., ethanoic acid for acetic acid). Their functional group is .