Ketone: structure, properties, and common uses

Structure and nomenclature

Ketones range from simple acyclic molecules to complex cyclic and polyfunctional derivatives. The simplest ketone is acetone (IUPAC: propanone), where a three‑carbon chain bears the carbonyl on the middle carbon. IUPAC names for ketones commonly use the suffix "-one" and indicate the position of the carbonyl when necessary. Cyclic ketones (for example cyclohexanone) have the carbonyl incorporated into a ring.

Preparation and chemical behavior

Many ketones are prepared by oxidation of secondary alcohols; industrial routes include hydration and carbonylation reactions and various rearrangements. Chemically, ketones are electrophilic at the carbonyl carbon and undergo a variety of transformations:

• nucleophilic addition (hydride reduction to secondary alcohols, or addition of organometallic reagents)
• enolization and keto–enol tautomerism
• formation of enolates that participate in alpha‑substitution and condensation reactions

Identification and spectroscopy

Ketones are readily identified by spectroscopic methods. In the infrared region the carbonyl stretch typically appears as a strong absorption near 1690–1715 cm⁻¹, although conjugation or ring strain can shift this frequency. Modern analyses also use NMR, mass spectrometry and other techniques to confirm structure. See general resources on infrared and spectroscopy for interpretation guidance.

Uses, examples, and notable facts

Ketones are widespread in industry and nature. Acetone is a common solvent and chemical intermediate; methyl ethyl ketone is another important solvent. Ketones serve as building blocks in pharmaceuticals, fragrances, polymers and agrochemicals. In biology, small ketones (often called ketone bodies) are produced in metabolism under certain conditions.

Key distinctions: unlike aldehydes, ketones lack a formyl hydrogen; many reactions exploit the acidity of alpha hydrogens next to the carbonyl. The class was recognized and characterized as organic chemistry matured in the 19th century and remains central in both laboratory synthesis and large‑scale manufacturing.