title: Efficient hydrogenation of organic carbonates, carbamates and formates indicates alternative routes to methanol based on CO2 and CO.
abstract: Catalytic hydrogenation of organic carbonates, carbamates and formates is of significant interest both conceptually and practically, because these compounds can be produced from CO2 and CO, and their mild hydrogenation can provide alternative, mild approaches to the indirect hydrogenation of CO2 and CO to methanol, an important fuel and synthetic building block. Here, we report for the first time catalytic hydrogenation of organic carbonates to alcohols, and carbamates to alcohols and amines. Unprecedented homogeneously catalysed hydrogenation of organic formates to methanol has also been accomplished. The reactions are efficiently catalysed by dearomatized PNN Ru(II) pincer complexes derived from pyridine- and bipyridine-based tridentate ligands. These atom-economical reactions proceed under neutral, homogeneous conditions, at mild temperatures and under mild hydrogen pressures, and can operate in the absence of solvent with no generation of waste, representing the ultimate 'green' reactions. A possible mechanism involves metal-ligand cooperation by aromatization-dearomatization of the heteroaromatic pincer core.
authors.affiliation: Department of Organic Chemistry, The Weizmann Institute of Science, Rehovot, 76100, Israel.
authors.forename: Ekambaram
authors.initials: E
authors.lastname: Balaraman
authors.forename: Chidambaram
authors.initials: C
authors.lastname: Gunanathan
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.forename: Linda J W
authors.initials: LJ
authors.lastname: Shimon
authors.forename: David
authors.initials: D
authors.lastname: Milstein
mesh_terms: D002219:Carbamates / Q000737:chemistry*; D002245:Carbon Dioxide / Q000737:chemistry*; D002248:Carbon Monoxide / Q000737:chemistry*; D002255:Carbonic Acid / Q000737:chemistry*; D002384:Catalysis; D005561:Formates / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry*; D000432:Methanol / Q000737:chemistry*; D008958:Models, Molecular; D014961:X-Ray Diffraction
chemical_list: D002219:Carbamates; D005561:Formates; C030544:formic acid; D002245:Carbon Dioxide; D002255:Carbonic Acid; D002248:Carbon Monoxide; D006859:Hydrogen; D000432:Methanol