Single-Pot Ethane Carboxylation Catalyzed by New Oxorhenium(V) Complexes with N,O Ligands

Abstract

The oxorhenium(V) chelates [ReOCl-(N,O-L) (1), in refluxing methanol, with N,N-bis(2-hydroxy-) 2 ], respectively, with ligand esterification in the cases of 3 and 5. All these complexes have been characterized by IR and multinuclear NMR spectroscopy, FAB þ -MS, elemental and X-ray diffraction structural analyses. They act as catalysts, in a single-pot process, for the carboxylation of ethane by CO, in the presence of potassium peroxodisulfate K 2 S 2 O 8 , in trifluoroacetic acid (TFA), to give propionic and acetic acids, in a remarkable yield (up to ca. 30%) and under relatively mild conditions, with some advantages over the industrial processes. The picolinate complex 4 provides the most active catalyst and the carboxylation also occurs, although much less efficiently, by the TFA solvent in the absence of CO. The selectivity can be controlled by the ethane and CO pressures, propionic acid being the dominant product for pressures about ca. 7 and 4 atm, respectively (catalyst 4), whereas lower pressures lead mainly to acetic acid in lower yields. These reactions constitute an unprecedented use of Re complexes as catalysts in alkane functionalization.

Nucleophilic addition of water to 1-isoquinolinyl phenyl ketone. The synthesis, spectroscopic investigation, crystal and molecular structure and DFT calculations of [ReOBr2(iquinpk-OH)(PPh3)]

“…The attention of scientists concentrates on synthetic aspects, structural, physicochemical properties and reactivity, as well as on topics with an applied character such as the development of radiotherapeutic cancer agents, nitrogen fixation and catalysis [1][2][3][4][5][6][7][8][9][10].…”

Synthesis, spectroscopic characterization, X-ray structure and DFT calculations of [ReOCl2(8-Sqn)(OPPh3)]

“…Methyltrioxorhenium and its derivatives are among the most versatile catalysts for olefin oxidation reactions, aldehyde olefination and olefin metathesis [4]. The oxorhenium(V) chelates [ReOCl 2 (O-N)(PPh 3 )] with pyridinecarboxylate ligands exhibit a remarkable catalytic activity for the carboxylation of ethane by CO in the presence of K 2 S 2 O 8 , under relatively mild conditions, to a mixture of propionic and acetic acids in a single-pot process with various advantages over the industrial ones [5].…”

Synthesis, spectroscopic characterization, X-ray structure, and DFT calculations of [ReOBr2(hmquin-7-COOH)(AsPh3)]

“…Methyltrioxorhenium and its derivatives are among the most versatile oxidation catalysts known to date [4]. The oxorhenium(V) chelates [ReOCl 2 (O-N)(PPh 3 )] with pyridinecarboxylate ligands exhibit a remarkable catalytic activity for the conversion of ethane, under relatively mild conditions, to a mixture of propionic and acetic acids in a single-pot process with various advantages over the industrial ones [5].…”