allylester

An allylester, commonly written as an allyl ester, is an organic compound in which an allyl group (CH2=CH-CH2-) is bound to a carboxylate oxygen, giving the general structure R-CO-O-CH2-CH=CH2. The term encompasses esters derived from allyl alcohol and various carboxylic acids.

Preparation: Allyl esters are typically prepared by esterification of carboxylic acids with allyl alcohol, using acid catalysts such as p-toluenesulfonic acid or other coupling reagents. They can also be formed by transesterification from other esters with allyl alcohol, or by allylation of carboxylates.

Properties and reactivity: The physical properties of allyl esters depend on the R group attached to the carbonyl. Allyl esters are generally stable under many conditions but can be hydrolyzed or cleaved to release the carboxylic acid. The allyl group serves as a removable protecting group for carboxyl functions in organic synthesis and can be cleaved under methods such as palladium-catalyzed deprotection or hydrogenolysis.

Applications: In organic synthesis, allyl esters are widely used as protecting groups for carboxyl functions, enabling selective transformations on other parts of a molecule. They are also used as intermediates in polymer chemistry and as precursors in fragrance and flavor chemistry.

See also: allyl group; ester; protecting group; deprotection.