Orthoester

In organic chemistry, an orthoester is a functional group containing three alkoxy groups attached to one carbon atom. The name can also refer to any organic compound that contains this functional group. An example of an orthoester is ethyl orthoacetate, CH3C(OCH2CH3)3. Orthoesters are used in organic synthesis as protecting groups for esters. Although orthoesters are not an ester themselves, they are called as such due to the ester function that appears when the orthoester is hydrolized. For example, trimethyl orthoformate ( CH(OCH3)3 )may be hydrolyzed (under acidic conditions) to methylformate and methanol.

Preparation
Orthoesters can be prepared by the reaction of nitriles with alcohols under acid catalysis:
 * RCN + 3 R’OH &rarr; RC(OR’)3 + NH3

Esterification
Orthoesters are readily hydrolyzed in mild aqueous acid to form esters:
 * RC(OR’) 3 + H2O &rarr; RCO2R’ + 2 R’OH