Catalytic Conversion of Carbon Dioxide to Long Chain Esters via Formate Hydroesterification

CO2‐based hydroesterification is an attractive route to produce value added ester compounds, which could replace CO‐based hydroesterification processes if sufficient catalytic technologies are developed. One path to CO2‐based hydroesterification is through an organoformate intermediate, which is then used in olefin hydroesterification to generate the desirable esters.  This route creates a net CO2‐based hydroesterification process using tandem catalytic systems for CO2 hydrogenation to organoformate paired with formate‐olefin hydroesterification. The tandem use of tripodal phosphine ruthenium(II) and 1,2‐bis(di‐tert‐butylphosphinomethyl)benzene palladium catalysts were found to successfully produce methyl nonanoate from CO2, H2, methanol and 1‐octene in a single‐stage batch process. The CO2‐based hydroesterification catalysis efficiency was found to be largely limited by the productivity of organoformate generation and competitive 1‐octene reduction.  Catalytic yields of methyl nonanoate can be enhanced by adjustments in reaction procedures, including the use of a two‐stage batch reaction process or delayed introduction of 1‐octene, achieving a yield of up to 32%. Under select conditions, control experiments indicate yields of methyl nonanoate can be improved to ca 75%. Preliminary studies indicate significant interplay between the two ligands employed in the molecular tandem catalytic systems and establish the first catalytic protocol for the selective CO2‐based hydroesterification of olefins via organoformates.