A Mechanistic Study of Ni‐catalyzed Carbon Dioxide Coupling with Ethylene towards the Manufacture of Acrylic Acid. Issue 3 (20th February 2014)

• Record Type: Journal Article
• Authors: Yang, Gang; Schäffner, Benjamin; Blug, Matthias; Hensen, Emiel J. M.; Pidko, Evgeny A.
• Is Part Of: ChemCatChem. Volume 6:Issue 3(2014:Mar.)
• Page Start: 800
• Page End: 807
• Publication Date: 2014-02-20
• Subjects: Catalysis -- Periodicals; 541.39505
• DOI: 10.1002/cctc.201301051
• Languages: English
• ISSNs: 1867-3880

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>The reaction mechanism of CO<sub>2</sub> coupling with C<sub>2</sub>H<sub>4</sub> by homogeneous Ni‐complexes bearing bidentate phosphorous ligands was studied by means of density functional theory calculations. The reaction is initiated by sequential coordination of C<sub>2</sub>H<sub>4</sub> and CO<sub>2</sub> to the Ni center, followed by a facile coupling step, which results in a stable nickelalactone intermediate. Subsequent decomposition of this intermediate through <italic>β</italic>‐H transfer is the rate‐determining step. Together with the following reductive elimination step to form acrylic acid they represent a strongly kinetically‐hampered process. Destabilization of the nickelalactone intermediate in the presence of large bite angle bidentate ligands has only a minor effect on the overall reaction energetics. Modifying the electronic properties of ligands is also not effective to drive the reaction in a catalytic manner. These studies indicate that the coupling reaction has to be enforced through an alternative route. It is predicted here that a base‐assisted decomposition of the nickelalactone intermediate represents a favorable reaction channel. The factors affecting the reactivity of this route are investigated. The best reactivity corresponds to the CH<sub>3</sub>OH‐solvated CH<sub>3</sub>ONa that allows the <italic>β</italic>‐H transfer step to proceed with a barrier of only 49 kJ mol<sup>−1</sup>.</p> </abstract>