Hydrogenation under Hydroformylation Conditions: Observations, Kinetics, and Mechanism

High‐pressure CO, H2, CO2 and Ethylene Pulses Applied in the Hydrogenation of CO to Higher Alcohols over a Bulk Co‐Cu Catalyst

“…When the threshold value of y(ethylene) is surpassed, a sufficiently high coverage of adsorbed ethylene is present for CO insertion to the corresponding Co‐acyl complex. This complex can then undergo hydrogenation to the corresponding aldehyde, which is then further hydrogenated to the branched or linear alcohol [31] . This hydroformylation‐hydrogenation tandem reaction is known in literature, but is heavily dependent on the catalyst having a high chemoselectivity towards the hydrogenation of the C=O bond and not of the C=C bond of the alkene [32] .…”

“…This complex can then undergo hydrogenation to the corresponding aldehyde, which is then further hydrogenated to the branched or linear alcohol. [31] This hydroformylation-hydrogenation tandem reaction is known in literature, but is heavily dependent on the catalyst having a high chemoselectivity towards the hydrogenation of the C=O bond and not of the C=C bond of the alkene. [32] Further calibration of the FTIR analytics with propionaldehyde, which is the intermediate of the hydroformylation of ethylene to 1-PrOH, was performed, but due to a rather low molar amount and the short lifetime of such a reactive intermediate, no specific band for propionaldehyde was found in the recorded gas-phase spectra.…”

Production of alcohols via hydroformylation

“…38 Thiophene or water may hamper hydrogenation with unmodified Co catalysts. 39 Various organic ligands have been tested to modify the intrinsic chemoselectivity of unmodified Co catalysts. 40 Only aldehydes were formed with methylidyne ligands in the tetrahedral cobalt clusters MeCCo 3 IJCO) 9 .…”

Use of Transition Metal Complexes as Selective Hydrogenation Catalysts

“…Second, the aldehyde becomes a-bonded to cobalt by a cobalt-oxygen bond rather than a cobalt-carbon bond in XIX. This mode of bonding helps to explain the production of formate esters which would result from the hydrogenation of XXL Other workers, however, have proposed that a carboncobalt ir-bond is formed in the reduction of aldehydes to alcohols (Aldridge and Jonassen, 1963). Third, the alcohols result from the hydrogenation of XIX by molecular hydrogen rather than by attack by HCo(CO)4.…”