SCILLs as selective catalysts for the oxidation of aromatic alcohols

Abstract

Highlights  SCILL are efficient catalysts for the oxidation of benzyl alcohol with air.  The IL layer modifies the selectivity to aldehyde, and nature of IL is important.  Diluent inert (N2, He, Ar) or (CO2) reactive gases modify the O2 solubility in ILs.  ILs enhances the structural stability of the catalyst.

N-Hydroxyphthalimide on a Polystyrene Support Coated with Co(II)-Containing Ionic Liquid as a New Catalytic System for Solvent-Free Ethylbenzene Oxidation

“…For example, both the PS-NHPI-4 and PS-NHPI-4@[emim] [OcOSO 3 ] achieved conversions around 5%. This indicates that the ionic liquid covering PS-NHPI does not limit the contact between the reactants and the active centers of the catalyst, as is often observed in SCILL systems [38,39,41].…”

“…To date, the SCILL technique has been used mainly in hydrogenation processes, including those involving cyclooctadiene [31], citral [33,34], toluene [35], and propyne [36]. Additionally, several studies regarding oxidation of alcohols and oxidative coupling of thiols have been published [37][38][39]. In 2011, a SCILL system consisting of the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical covalently immobilized on SBA-15 silica (Figure 1a) coated with a [bmim] [Br] (bmim = 1-butyl-3-methylimidazolium) ionic liquid effectively promoted oxidation of alcohols to aldehydes using dioxygen [37].…”

Heterogeneous Catalysis with the Participation of Ionic Liquids

“…Another heterogeneous system presented in this paper is SCILL, which takes advantage of the properties of ionic liquid that covers a solid catalyst with a thin layer to facilitate better access of reagents to the catalyst and thereby improves the process selectivity and yield [88]. The most prevalent process carried out with the participation of SCILL is hydrogenation, albeit recent reports appeared on the processes of oxidation, isomerization, and Knoevenagel condensation [99][100][101][102]. Finally, the third type of heterogeneous systems presented in this paper is porous ionic liquids [104,107], which also include metal-organic frameworks formed with the participation of ionic liquids [129].…”

“…The selective oxidation of benzyl alcohol with air was catalyzed by platinum ( ], respectively. In the presence of the former IL, the conversion of benzyl alcohol on the above catalytic system was 80% and the selectivity for aldehyde was 82% [99]. The oxidative coupling of aromatic thiols to disulfides in the presence of homogeneous catalysts has several shortcomings, whereas the application of heterogeneous catalytic SCILL systems to the aforementioned reactions makes it possible to limit the amount of metal in the product, to easily isolate the catalyst from the post-reaction mixture and to prevent catalyst poisoning.…”

Engineering the Electrochemical Interface of Oxygen Reduction Electrocatalysts with Ionic Liquids: A Review

“…[ 67 ] Meyer et al used a strongly acidic IL to improve the selectivity and activity of n‐octane isomerization, [ 63 ] whereas Podolean et al used ILs to improve the oxidation of aromatic alcohols. [ 68 ] The first application of SCILLs in electrocatalysts dates back to 2010, when Snyder et al used it for the electrochemical reduction of oxygen [ 28 ] (Figure 3a). They selected a hydrophobic, oxygenophilic IL, 7‐Methyl‐1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene bis(pentafluoroethylsulfonyl)imide ([MTDB][BETI]), which they deposited on a nickel–platinum catalyst, obtaining a 40 mV positive shift in half‐wave potential.…”