Acetonide

General structure of a 1,2-acetonide. The diol is shown in blue, the acetone part in red.

In organic chemistry, an acetonide is the functional group composed of the cyclic ketal of a diol with acetone. The more systematic name for this structure is an isopropylidene ketal. Acetonide is a common protecting group for 1,2- and 1,3-diols. The protecting group can be removed by hydrolysis of the ketal using dilute aqueous acid.

The acetonides of small di- and triols, as well as many sugars and sugar alcohols, are common. The hexaol mannitol reacts with 2,2-dimethoxypropane to give the bis-acetonide, which oxidizes to give the acetonide of glyceraldehyde:

(CHOHCHOHCH2OH)2 + 2 (MeO)2CMe2 → (CHOHCHCH2O2CMe2)2 + 4 MeOH (CHOHCHOCH2OCMe2)2 + [O] → 2 OCHCHCH2O2CMe2 + H2O

An example of its use as a protecting group in a complex organic synthesis is the Nicolaou Taxol total synthesis. It is a common protecting group for sugars and sugar alcohols, a simple example being solketal.

The acetonides of corticosteroid are used in dermatology, because their increased lipophilicity leads to better penetration into the skin.

• Fluclorolone acetonide

• Fluocinolone acetonide

• Triamcinolone acetonide

• Acetophenide

• Acroleinide

• Aminobenzal

• Cyclopentanonide

• Pentanonide

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