Synthesis of 1,3-dialkylimidazolium-2-carboxylates by direct carboxylation of 1,3-dialkylimidazolium chlorides with CO2

1,3-Dialkylimidazolium-2-carboxylates 1a and 1b are obtained in good to excellent yield and selectivity by carboxylation of the corresponding 1,3-dial kylimidazoli um chloride salts with a CO2/Na2CO3 system at temperatures ranging from 80 to 135 degrees C. The effect of temperature and reaction time on the yield and the selectivity of the carboxylation products has been studied. Coupling the CO2-based synthesis of 1,3-dialkylimidazolium-2-carboxylates with the transcarboxylation reaction described earlier [Tommasi, I.; Sorrentino, F.; Tetrahedron Lett., 2005, 46, 2141] allows us to set up a new synthetic procedure for the synthesis of organic carboxylates and alkylearbonate anions avoiding the use of strong bases. (c) 2006 Published by Elsevier Ltd.