Bipyridine-functionalized amphiphilic block copolymers as support materials for the aerobic oxidation of primary alcohols in aqueous media

Abstract

A micellar catalytic version of the aerobic oxidation of primary alcohols was successfully developed based on core-functionalized polymer nanoparticles.

Effect of basicity on the catalytic properties of Ni-containing hydrotalcites in the aerobic oxidation of alcohol

“…Moreover, heterogeneous catalysts in the liquid-phase offer several advantages over homogeneous ones, such as an ease of recovery and recycling, atom utility, and enhanced stability in the oxidation reactions. Unfortunately, most of these catalytic processes using O 2 needed high pressure of oxygen, high reaction temperature or additives, including base [21][22][23], coreductant [24,25], NHPI [26,27] and TEMPO [28,29], et al…”

Chemoenzymatic one-pot reaction of noncompatible catalysts: combining enzymatic ester hydrolysis with Cu(i)/bipyridine catalyzed oxidation in aqueous medium

“…Although in the classical Cu(I)/bipyridine mediated oxidation of alcohols small amounts of water as co-solvent led to a drastic reduction of product yield, 16 we were recently able to transfer this reaction to an aqueous medium by site-isolation of the Cu(I)/ bipyridine catalyst in micelles prepared from polymeric amphiphiles. 29 Oxidation of benzyl alcohol as a model compound was shown to be quantitative at room temperature aer 3 h (with 5 mol% Cu(I)Br; 5 mol% polymer ligand, 5 mol% TEMPO and 10 mol% NMI as a base) in water as reaction medium, suggesting that the micellar core-shell like structure is able to protect the catalyst very efficiently from the aqueous phase. Therefore, our thought was to combine the enzymatic ester cleavage with the micellar catalytic oxidation in a one-pot two-step system by using benzyl acetate as a model substrate.…”

Bipyridine copper functionalized polymer resins as support materials for the aerobic oxidation of alcohols

“…The coordination of the metal compound was achieved by dropping a solution of Cu(I)Br in acetonitrile into a stirred suspension of TG2 or MR2 . Cu(I)Br was chosen as the copper source because of its higher stability in aqueous media compared to [Cu(MeCN) 4 ]OTf which is preferred in organic media . Cu(I)Br was also used for the experiments in organic solvents because of the comparability.…”

“…In general, the best results were found only in solvent‐free systems, e.g. when the copper bipyridine catalyst was located in a micellar core or when solvents such as toluene were used that do not interact with copper catalysts …”

“…More recently, Stahl and coworkers described a (bpy)Cu(I)/nitroxyl co‐catalyst system that enables the efficient and selective aerobic oxidation of a broad range of primary and secondary alcohols to the corresponding aldehydes and ketones . Only few reports have dealt with the immobilization of Cu(I)‐bipyridine catalysts on support materials to investigate the aerobic oxidation of alcohols to carbonyl compounds using either magnetic nanoparticles, MCM‐41, polytetrafluoroethylene‐membrane flow reactors, polymer micelles or porous coordination polymers …”