Ruthenium-catalyzed hydrogenation of CO2 as a route to methyl esters for use as biofuels or fine chemicals

Abstract

A novel robust diphosphine–ruthenium(II) complex has been developed that can efficiently catalyze both the hydrogenation of CO₂ to methanol and its in situ condensation with carboxylic acids to form methyl esters; a TON of up to 3260 is achievable for the CO₂ to methanol step. Both aromatic and aliphatic carboxylic acids can be transformed to their corresponding methyl esters with high conversion and selectivity (17 aliphatic and 18 aromatic examples). On the basis of a series of experiments, a mechanism has been proposed to account for the various steps involved in the catalytic pathway. More importantly, this approach provides a promising route for using CO₂ as a C1 source for the production of biofuels, fine chemicals and methanol.