Anionic Group 6B metal carbonyls as homogeneous catalysts for carbon dioxide/hydrogen activation. The production of alkyl formates

Homogeneous Hydrogenation of Carbon Dioxide

“…Tests of thermal esterification under basic conditions have been performed separately; acetic acid is esterified, in 25% yield after 44 h at 100 8C, by an excess of methanol in the presence of 1 equiv. Formate ester synthesis by CO 2 hydrogenation in the absence of base has also been observed [45,64,74,84]. The yield of methyl formate from CO 2 is optimum at a temperature which is sufficiently high to allow substantial esterification, but not so high that the hydrogenation catalyst is deactivated.…”

“…Hydrogenolysis involves either oxidative addition of H 2 or coordination of H 2 as a molecular hydrogen ligand, followed by elimination of formic acid, although technically it is possible for hydrogenolysis via a "sigma-bond metathesis" mechanism without prior H 2 [64]. Hydrogenolysis involves either oxidative addition of H 2 or coordination of H 2 as a molecular hydrogen ligand, followed by elimination of formic acid, although technically it is possible for hydrogenolysis via a "sigma-bond metathesis" mechanism without prior H 2 [64].…”

Aspects of carbon dioxide utilization

“…Formic acid esters are prepared by the hydrogenation of carbon dioxide in alcohol solvents as shown in Table 3 [65,[88][89][90][91]. In many cases, amines or other basic additives have a positive effect on the course of the reaction.…”

“…Catalytic systems for the synthesis of formic acid esters by the hydrogenation of CO 2[65,[88][89][90][91] …”

Pentacarbonylhydridochromates M+[HCr(CO)5]−: Reactivity in Organic Synthesis and Homogeneous Catalysis

“…[77] Indeed, η 2 -H 2 bonding has been evidenced (neutron diffraction studies) in some neutral Group 6B transition metal complexes such as H 2 W[P(OMe) 3 ] 5 . [78] Thus, [HM(CO) 5 ] Ϫ salts, which readily undergo insertion of CO 2 with generation of the corresponding [HCO 2 M-(CO) 5 ] Ϫ complexes, appeared to be good candidates for hydrocondensation reactions of carbon dioxide to yield alkyl formates.…”