The oxidation of representative bio-based benzyl-type alcohols has been successfully carried out in a multiphase (MP) system comprised of three mutually immiscible liquid components as water, isooctane, and a hydrophobic ionic liquid as methyltrioctylammonium chloride ([CH3(CH2)6CH2]3N(Cl)CH3), a heterogeneous catalyst (either ad-hoc synthesized carbon-supported Mo or a commercial 5 % Ru/C), and air as an oxidant. The MP-reaction proceeded as an interfacial process with Mo/C or Ru/C perfectly segregated in the ionic liquid phase and the reactant(s)/products(s) dissolved in the aqueous solution. This environment proved excellent to convert quantitatively benzyl alcohols into the corresponding aldehydes with a selectivity up to 99 %, without overoxidation to carboxylic acids. The nature of the catalyst, however, affected the operating conditions with Ru/C active at a lower T and t (130 °C, 4–6 h) compared to Mo/C (150 °C, 24 h). The phase confinement was advantageous also to facilitate the products isolation and the recycle of the catalyst. Notably, in the Mo/C-catalyzed oxidation of benzyl alcohol, benzaldehyde was achieved with unaltered selectivity (>99 %) at complete conversion, for five subsequent reactions through a semicontinuous procedure in which the catalyst was reused in-situ, without ever removing it from the reactor or treating it in any way.

Selective Multiphase‐Assisted Oxidation of Bio‐Sourced Primary Alcohols over Ru‐ and Mo‐ Carbon Supported Catalysts

Bersani, Chiara;Perosa, Alvise;Selva, Maurizio
2025-01-01

Abstract

The oxidation of representative bio-based benzyl-type alcohols has been successfully carried out in a multiphase (MP) system comprised of three mutually immiscible liquid components as water, isooctane, and a hydrophobic ionic liquid as methyltrioctylammonium chloride ([CH3(CH2)6CH2]3N(Cl)CH3), a heterogeneous catalyst (either ad-hoc synthesized carbon-supported Mo or a commercial 5 % Ru/C), and air as an oxidant. The MP-reaction proceeded as an interfacial process with Mo/C or Ru/C perfectly segregated in the ionic liquid phase and the reactant(s)/products(s) dissolved in the aqueous solution. This environment proved excellent to convert quantitatively benzyl alcohols into the corresponding aldehydes with a selectivity up to 99 %, without overoxidation to carboxylic acids. The nature of the catalyst, however, affected the operating conditions with Ru/C active at a lower T and t (130 °C, 4–6 h) compared to Mo/C (150 °C, 24 h). The phase confinement was advantageous also to facilitate the products isolation and the recycle of the catalyst. Notably, in the Mo/C-catalyzed oxidation of benzyl alcohol, benzaldehyde was achieved with unaltered selectivity (>99 %) at complete conversion, for five subsequent reactions through a semicontinuous procedure in which the catalyst was reused in-situ, without ever removing it from the reactor or treating it in any way.
2025
18
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10278/5098109
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