Acetal Definition in Chemistry

General structure of Acetals (Acetal and Ketal)

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An acetal is an organic molecule where two separate oxygen atoms are single bonded to a central carbon atom.
Acetals have the general structure of R2C(OR')2.
An older definition of acetal had one at least one R group as a derivative of an aldehyde where R = H, but an acetal can contain derivatives of ketones where neither R group is a hydrogen. This type of acetal is called a ketal.
Acetals that contain different R' groups are called mixed acetals.

Acetal Examples

Dimethoxymethane is an acetal compound.

Acetal is also a common name for the compound 1,1-diethoxyethane. The compound polyoxymethylene (POM) is a plastic that is also called simply "acetal" or "polyacetal."


  • IUPAC (1997). Compendium of Chemical Terminology (2nd ed.) (the "Gold Book"). "Ketals." doi:10.1351/goldbook.K03376