Synthesis of cyclic carbonates from diols and CO2 catalyzed by carbenes.

Felix D Bobbink,Paul J Dyson,Martin Hulla,Shoubhik Das,Weronika Gruszka

doi:10.1039/c6cc05730f

Abstract

The synthesis of cyclic carbonates from epoxides and CO2 is a well-established reaction, whereas the synthesis of cyclic carbonates from diols and CO2 is considerably more challenging, and few efficient catalysts are available. Here, we describe heterocyclic carbene catalysts, including one derived from a cheap and efficient thiazolium salt, for this latter reaction. The reaction proceeds at atmospheric pressure in the presence of an alkyl halide and Cs2CO3. Reaction mechanisms for the transformations involved are also proposed.

Highlights

The synthesis of cyclic carbonates from epoxides and CO2 is a wellestablished reaction, whereas the synthesis of cyclic carbonates from diols and CO2 is considerably more challenging, and few efficient catalysts are available
From a thermodynamic perspective, oxygenated cyclic carbonates are suitable synthetic targets from CO2. These compounds have been exploited as electrolytes for lithium ion batteries,[2] building blocks for polymeric materials,[3,4] solvents[5,6] and intermediates in the synthesis of compounds such as dimethyl carbonate (DMC)[7] and ethylene glycol.[8]
More stable, biodegradable 1,2-diols have been proposed as promising alternatives for the synthesis of cyclic carbonates with CO2.13 Their reaction with CO2 is, neither kinetically nor thermodynamically-favored due to the formation of water as the sole by-product.[14]

Summary

Introduction

The synthesis of cyclic carbonates from epoxides and CO2 is a wellestablished reaction, whereas the synthesis of cyclic carbonates from diols and CO2 is considerably more challenging, and few efficient catalysts are available. It should be noted that the reaction proceeds in low yield using Cs2CO3 as the base in the absence of CO2 (Table S2, entry 2, ESI†).

Results

Conclusion