Green synthesis of carbamates from CO₂, amines and alcohols

Abstract

Various carbamates can be prepared in a halogen-free way starting from cheap and readily available reagents such as amines, alcohols and carbon dioxide. Basic catalysts were able to convert both linear and branched aliphatic amines to the corresponding carbamates with good yields, in mild reaction conditions (2.5 MPa CO 2 ) and even in the absence of dehydrating agents.

Worldwide innovations in the development of carbon capture technologies and the utilization of CO2

“…ref. 4,[152][153][154][155][156][157][158][159]. Active catalysts are available for coupling carbon dioxide with energy-rich unsaturated substrates such as epoxides, 13 butadiene or acetylene.…”

Influence of the Nanostructure of Gallium Oxide Catalysts on Conversion in the Green Synthesis of Carbamates

“…Yields to carbamate were also higher for the surfactant-synthesized nanostructures. Although these yields are moderate, these are in the typical range of most oxides [46]. The other observed product from the reaction was urea.…”

Activation of Carbon Dioxide

“…Carbamic esters have also been obtained under mild conditions (25 bar CO 2 pressure) from various amines, alcohols, and CO 2 with basic catalysts such as Cs 2 CO 3 with up to 56% amine conversion and 79% carbamate selectivity. 89 One important side reaction of urethane production is N-alkylation of the amine leading to loss of reactive primary or secondary amines. Preformed ammonium carbamates were successfully transformed to urethanes in the presence of crown ethers, which directed the reaction into O-alkylation.…”