Aerobic Oxidation of Diverse Primary Alcohols to Methyl Esters with a Readily Accessible Heterogeneous Pd/Bi/Te Catalyst

Abstract

Efficient aerobic oxidative methyl esterification of primary alcohols has been achieved with a heterogeneous catalyst consisting of 1 mol % Pd/charcoal (5 wt %) in combination with bismuth(III) nitrate and tellurium metal. The Bi and Te additives significantly increase the reaction rate, selectivity, and overall product yields. This readily accessible catalyst system exhibits a broad substrate scope and is effective with both activated (benzylic) and unactivated (aliphatic) alcohols bearing diverse functional groups.

A highly active recyclable gold–graphene nanocomposite material for oxidative esterification and Suzuki cross-coupling reactions in green pathway

“…Table 5 provides a comparison of the results obtained for our present catalytic system with those reported in the literature [45][46][47][48]. From Table 5, it is seen that Au-G nanocomposite showed higher catalytic activity over these catalysts.…”

Factors influencing the catalytic oxidation of benzyl alcohol using supported phosphine-capped gold nanoparticles

“…20%) of benzaldehyde was formed after one hour and then depleted over time (Figure 7), suggesting that benzaldehyde is the intermediate in for the formation of benzoic acid and methyl benzoate in benzyl alcohol oxidation. [88][89][90] The effect of the temperature in this 80 reaction was studied from room temperature (25 °C) up to 80 °C (Figure 8). Reduction in the temperature of the catalytic reaction results in the reduction of the catalytic activity.…”

Pd/C-catalyzed aerobic oxidative esterification of alcohols and aldehydes: a highly efficient microwave-assisted green protocol

“…Because of the excellent dielectric properties of charcoal, we tested activated charcoal adsorbed Pd(OAc) 2 and observed complete conversion and good selectivity (Table 1, entry 8). Based on this result and on a recently published study by Stahl et al [40], it was decided that the investigation be broadened to the readily accessible Pd/C. Gratifyingly, full substrate conversion to the desired ester was afforded without catalyst pre-sonication, even at 70 °C (Table 1, entries 9–11).…”

“…Several examples of the heterogeneous oxidative esterification of alcohols in the presence of molecular oxygen or air have been described [23,25,40–43], however, the main limit of this process is its lack of selectivity, as has already been reported. Several Pd-catalyzed procedures have been optimized and Ag [31–32] or Bi salts [40], hydrosilanes [33] or specially designed electron-deficient ligands [9,31] have all been added to the catalyst in an attempt to improve conversion and selectivity. Other examples refer to the use of Pd(II) species in the presence of a cooxidant such as benzyl chloride or desyl chloride [34,44].…”