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Theoretical Analysis of the Mechanism for the Oxidative Carbonylation of Toluene to p-Toluic Acid by Rhodium Complexes

“…Factors Inhibiting the Activity of Rh(III). Experimental studies of the oxidative carbonylation of toluene by Rh(III) dissolved in a mixture of TFAH and TFAA has shown that the presence of H 2 O, an excessively high CO partial pressure, and high Rh concentrations can lead to a loss of catalyst activity. ,, Each of these factors was examined in the course of the present study.…”

“…At present, p -toluic acid is made by the selective oxidation of p -xylene; however, because toluene is a less-expensive feedstock than p -xylene, there is an interest in assessing whether p -toluic acid can be made by the oxidative carbonylation of toluene. Several studies have shown that this reaction can be catalyzed by either Rh(III) or Pd(II) cations. − One component of the reaction medium used in all of these investigations is trifluoroacetic acid (TFAH). Because the concentration of TFAH is high, it is believed that trifluoroacetate anions are the ligands associated with the catalyst in its active state.…”

Ohne dirigierende Gruppen: übergangsmetallkatalysierte C‐H‐Aktivierung einfacher Arene

“…[81,82] ¾hnliche Reaktivität wurde auch für die Verwendung von Rhodium-Katalysatoren beschrieben, wobei die Substratbreite zurzeit noch gering ist. [83] Einen alternativen Weg repräsentiert die dehydrierende Kupplung von Arenen mit Ameisensäure. [84,85] Die Kombination der Palladium(II)-Quelle Pd(TFA) 2 und einem Phosphenium-Liganden lieferte ein effektives Katalysatorsystem für diese Umsetzung, mit der Benzoesäuren in bis zu 93 % Ausbeute unter erstaunlich milden Bedingungen hergestellt werden konnten (30 8C, 48 h).…”

Oxidative carbonylation of toluene to p-toluic acid catalyzed by rhodium in the presence of vanadium and oxygen

“…In subsequent studies, Kalinovskii and coworkers have shown that the oxidative carbonylation of arenes can also be catalyzed using rhodium(III) or palladium(II) cations [6][7][8][9], and they have proposed a mechanism for the synthesis of toluic acid from toluene [9]. Since Rh(III) is reduced to Rh(I) and Pd(II) is reduced to Pd(0) in the course of the reaction, it was necessary to provide a means for reoxidizing the reduced metal.…”

“…In the case of Pd, this could be done effectively using Cu(II) cations together with O 2 in a Wacker-type process [6]. FeC 2 O 4 , (NH 4 ) 6 Mo 7 O 24 , (NH 4 )VO 3 , and V 2 O 5 in combination with O 2 were also shown to work effectively as oxidants for both Pd and Rh [7]. The reoxidation of Pd could also be achieved using MnO 2 but in the absence of O 2 [8].…”