Carbonate ester

A carbonate ester is a functional group in organic chemistry consisting of a carbonyl group flanked by two alkoxy groups. The general structure of these carbonates is R1O(C=O)OR2 and they are related to esters R1O(C=O)R and ethers R1OR2 and also to the inorganic carbonates.

Carbonate esters are used as protecting group for diols. A classic reagent is phosgene but more user friendly reagents exist such as carbonyl diimidazole. Ethylene carbonate and Propylene carbonate are used as a solvent. Dimethyl carbonate is used as a methylating reagent.

In many applications a carbonate group replaces an ester group for example in Cholesteryl oleyl carbonate. Polycarbonates are an important class of polymers.

Organic synthesis
Laboratory methods for the synthesis of carbonate ester in the laboratory are:
 * from the corresponding diols.
 * by double oxidation of ketones in a Baeyer-Villiger rearrangement
 * by reaction of an epoxide with carbon dioxide catalysed by a zinc halide