Ketal

As ketal is called an acetal, which was created from a ketone. They are characterized by a stability to alkalis, but are split by acid solutions back to their starting materials.

The term has since been banned from the chemical nomenclature, but later introduced as a subgroup of the acetals again. A ketal in this narrow sense has, in contrast to the acetals two alkyl or aryl radicals on Acetalkohlenstoff, not just one ( see picture). Analogously differ thioketals (mono-and dithioketals, depending on whether an oxygen atom is replaced by sulfur, or both) of the thioacetals.

Synthesis

With a monohydric or dihydric alcohol (eg ethylene glycol ): Synthesis of a ketal to a ketone ( cyclohexanone example) is reacted under acid catalysis with elimination of water:

Use

The carbonyl group of ketones is often protected as a ketal in syntheses.