Electrochemical carboxylation of alcohols. Synthesis of organic carbonates

Several methods for the synthesis of organic carbonates using electrochemical syntheses will be discussed. These methodologies avoid the use of toxic and harmful reagents such as phosgene, carbon monoxide and isocyanates. Carbon dioxide, a cheap, safe and abundant reagent is used as starting material. High to excellent yields of cyclic carbonates are obtained by reaction of alcohols bearing a leaving group in a or in13 position with tetraethylammonium carbonate (TEAC) or tetraethylammonium peroxocarbonate (TEAPC) respectively obtained by direct or indirect electrochemical reduction of carbon dioxide. Only moderate yields of linear carbonates are obtained from primary or secondary alcohols after addition of a suitable alkylating reagent. Alternatively, the use of electrogenerated base associated with carbon dioxide allows the conversion of primary alcohols in excellent yields and of secondary alcohols in moderate yields. In addition, the application o f the above reported methodologies allows the conversion of 1,2-diols into cyclic carbonates in moderate to good yields.