Iron‐Catalyzed Magnesium‐Mediated Formal Hydroformylation of Alkynes and Alkenes

Abstract

Alkynes and alkenes are routinely converted to corresponding synthetically versatile aldehydes using rhodium-catalyzed hydroformylation. However, rhodium is rare, precious, costly, and depleting at a considerably high rate. Reported here is ironcatalyzed, magnesium-mediated, formal hydroformylation of alkynes and alkenes in the absence of syngas. Readily available FeCl 2 in the presence of alkyl magnesium halide, and dimethyl formamide, catalyzes hydroformylation of various alkynes and selectively produces α,β-unsaturated aldehydes in good to excellent conversion. Mechanistic investigations revealed the presence of vinyl magnesium intermediate, the kinetic study disclosed the first-order dependence of the reaction on iron loading, and the control experiment authenticated the iron catalyst's homogeneous nature. The scope of this methodology was amplified, and 20 alkenes were examined. [Fe(acac) 3 ] in the presence of ligand, alkyl magnesium halide, and dimethyl formamide catalyzed the hydroformylation of alkenes and displayed good to excellent conversion. An earth-abundant iron catalyst offering a syngas cylinder-free safe alternative to highpressure hydroformylation has been reported.

Assessing the Intrinsic Activity of Pt‐Group Electrocatalysts for Carbon Monoxide Oxidation: Best Practices and Benchmarking Parameters

“…The electrochemical CO Oxid on the surface of Pt-group catalysts in or out of alcohol fuel cells is undeniably a complex process, so it is essential to decipher its pathway and mechanisms to improve the catalytic performance of such fuel cells and reduce the CO-poisonous. [22] There are various proposed processes for the CO Oxid process on Pt-group catalysts, but mainly four mechanisms are the most acceptable, including the ligand effect, electronic effect, bi-functional effect, and hydrogen spillover effect, [6] which all start with CO adsorption, followed by diffusion, oxidation at Pt-group active sites, and finally, CO 2desorption (Figure 2a). In the ligand effect, the metal interacts with CO molecules, decreasing the binding energy between CO and the Pt surface and thus easing the CO Oxid .…”

“…Meanwhile, in the bifunctional effect, the delocalized d-orbital electrons on the metal surface induce the electron transfer to the Pt-group. [6,23] In the hydrogen spillover, a hydrogen atom is dissociated from the Pt-group surface and transferred to the metal sites, creating an interaction of COÀ Mo bond, whereas the metalÀ H interaction decreases the bond between CO and metal, resulting in facilitating the CO oxidation on the Pt surface. Various studies reported that Pt-based electrocatalysts with a uniform dispersion of Pt tend to show a stronger spill effect.…”

“…[5] Mainly, Pt-group catalysts are easily poisoned and loose catalytic active sites by adsorption of small traces of adsorbed CO (i. e., 10-100 ppm), so the CO should be promptly removed from the cells via the electrochemical oxidation to allow the long-term operation. [6] Thus, optimization and understanding the fundamental factors controlling the electrocatalytic CO Oxid on Ptbased electrocatalysts is a crucial step toward large-scale utilization of PEMFCs as green and efficient energy resources. [7] Basically, the inherent CO Oxid mechanism, high enthalpy of COadsorption on Pt (i. e., up to 140 kJ/mol at low coverages), and slow oxidation kinetics (i. e., starts over ~0.6 V vs. RHE) are necessary fences.…”

“…Thus, this research arena was comprehensively reviewed in various excellent reviews on Pt-group catalysts for electrocatalytic CO Oxid and others, but not on assessment Factors. [6,16] Thereby, it is urgent to better understand the inherent CO Oxid performance of Ptgroup electrocatalysts, besides precise assessments of parameters for analyzing and optimizing the catalytic performance. [17] This review provides qualitative and quantitative analysis on the effect of state-of-the-art catalysts (i. e., particle size, morphology, and support) and CO oxidation factors (i. e., effect of electrolyte, working electrode, and CO surface diffusion) (Figure 1b).…”

Iron‐Catalyzed Alkoxylation, Dehydrogenative‐Polymerization and Tandem Hydrosilylative‐Alkoxylation

“…We have been investigating the reactivity of various iron complexes in catalysis. [19,20,21,22] In a recent work, we proposed iron dihydride (Scheme 1, A) as an active species for hydroformylation. [23] However, the proposed species A is highly unstable.…”