A simple, high yielding catalytic method for the multigram scale selective epoxidation of electron-rich alkenes using near-stoichiometric H2O2 under ambient conditions is reported. The system consists of a Mn(II) salt (<0.01 mol %), pyridine-2-carboxylic acid (<0.5 mol %), and substoichiometric butanedione. High TON (up to 300 000) and TOF (up to 40 s–1) can be achieved for a wide range of substrates with good to excellent selectivity, remarkable functional group tolerance, and a wide solvent scope. It is shown that the formation of 3-hydroperoxy-3-hydroxybutan-2-one from butanedione, and H2O2 in situ, is central to the activity observed.

The oxidation of alkenes, alkanes, and alcohols with H 2 O 2 is catalyzed efficiently using an in situ prepared catalyst comprised of a Mn II salt and pyridine-2-carboxylic acid (PCA) together with a ketone in a wide range of solvents. The mechanism by which these reactions proceed is elucidated, with a particular focus on the role played by each reaction component: i.e., ketone, PCA, Mn II salt, solvent, etc. It is shown that the equilibrium between the ketone cocatalysts, in particular butanedione, and H 2 O 2 is central to the catalytic activity observed and that a gem-hydroxyl-hydroperoxy species is responsible for generating the active form of the manganese catalyst. Furthermore, the oxidation of the ketone to a carboxylic acid is shown to antecede the onset of substrate conversion. Indeed, addition of acetic acid either prior to or after addition of H 2 O 2 eliminates a lag period observed at low catalyst loading. Carboxylic acids are shown to affect both the activity of the catalyst and the formation of the gem-hydroxyl-hydroperoxy species. The molecular nature of the catalyst itself is explored through the effect of variation of Mn II and PCA concentration, with the data indicating that a Mn II :PCA ratio of 1:2 is necessary for activity. A remarkable feature of the catalytic system is that the apparent order in substrate is 0, indicating that the formation of highly reactive manganese species is rate limiting.

A new, sustainable catalytic route for the synthesis of tetrahydrofuran-2,5-dicarboxylic acid (THFDCA), a compound with potential application in polymer industry, is presented starting from the bio-based platform chemical 5-(hydroxymethyl)furfural (HMF). This conversion was successfully achieved via oxidation of tetrahydrofuran-2,5-dimethanol (THFDM) over hydrotalcite (HT)-supported gold nanoparticle catalysts (∼2 wt %) in water. THFDM was readily obtained with high yield (>99%) from HMF at a demonstrated 20 g scale by catalytic hydrogenation. The highest yield of THFDCA (91%) was achieved after 7 h at 110 °C under 30 bar air pressure and without addition of a homogeneous base. Additionally, Au−Cu bimetallic catalysts supported on HT were prepared and showed enhanced activity at lower temperature compared to the monometallic gold catalysts. In addition to THFDCA, the intermediate oxidation product with one alcohol and one carboxylic acid group (5-hydroxymethyl tetrahydrofuran-2-carboxylic acid, THFCA) was identified and isolated from the reactions. Further investigations indicated that the gold nanoparticle size and basicity of HT supports significantly influence the performance of the catalyst and that sintering of gold nanoparticles was the main pathway for catalyst deactivation. Operation in a continuous setup using one of the Au−Cu catalysts revealed that product adsorption and deposition also contributes to a decrease in catalyst performance.

Oxidized starch can be efficiently prepared using H 2 O 2 as an oxidant and iron(III) tetrasulfophthalocyanine (FePcS) as a catalyst, with properties in the same range as those for commercial oxidized starches prepared using NaOCl. Herein, we performed an in-depth study on the oxidation of potato starch focusing on the mode of operation of this green catalytic system and its fate as the reaction progresses. At optimum batch reaction conditions (H 2 O 2 /FePcS molar ratio of 6000, 50 °C, and pH 10), a high product yield (91 wt %) was obtained with substantial degrees of substitution (DS COOH of 1.4 and DS CO of 4.1 per 100 AGU) and significantly reduced viscosity (197 mPa•s) by dosing H 2 O 2 . Model compound studies showed limited activity of the catalyst for C6 oxidation, indicating that carboxylic acid incorporation likely results from C−C bond cleavage events. The influence of the process conditions on the stability of the FePcS catalyst was studied using UV−vis and Raman spectroscopic techniques, revealing that both increased H 2 O 2 concentration and temperature promote the irreversible degradation of the FePcS catalyst at high pH. The rate and extent of FePcS degradation were found to strongly depend on the initial H 2 O 2 concentration where also the rapid decomposition of H 2 O 2 by FePcS occurs. These results explain why the slow addition of H 2 O 2 in combination with low FePcS catalyst concentration is beneficial for the efficient application in starch oxidation.

Separation of racemates in microreactors using liquid–liquid extraction with 1-octanol as the solvent is successfully demonstrated.