Ketals

Part of speech: noun

Definitions

1. Chemical compounds formed by the reaction of ketones with alcohols resulting in acetal-like structures; used often as protecting groups in organic synthesis; possess stability in neutral and basic conditions
2. Organic molecules composed of two alkoxy groups attached to the same carbon derived from ketones and alcohols; commonly employed to safeguard carbonyl functionalities during reactions; characterized by resistance to basic solvents but susceptible to acidic hydrolysis
3. Substances created when ketone functional groups react with alcohols to form acetal analogs; utilized in synthetic chemistry to temporarily mask reactive sites; typically stable under neutral or basic environments while decomposing under acidic conditions

Etymology: Ketals are the plural of "ketal," and the word is best understood through its parent, "ketone." Ketones are organic compounds with a carbonyl group, a carbon atom double-bonded to oxygen and linked to two other carbon atoms. A ketal forms when that carbonyl carbon is joined to two alkoxy groups, which are oxygen atoms each bonded to an alkyl group. The word's structure, then, is a chemical name built from familiar parts rather than a word with a long folk history. Chemists use ketals chiefly as protecting groups. A reactive ketone can be converted into a ketal so that it survives reactions that would otherwise attack it, such as those involving bases or nucleophiles. When the chemist is done, mild acid restores the original ketone, because ketals break apart readily in acidic conditions. This contrast, stable toward bases yet sensitive to acid, is what makes them useful for temporarily hiding a carbonyl group during a multi-step synthesis.

Synonyms: acetals, ethers, oxides, hemiacetals, carbonyl compounds