A carbonate ester (organic carbonate or organocarbonate) is an ester of carbonic acid. This functional group consists 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.