Visible-Light Photocatalytic Highly Selective Oxidation of Alcohols into Carbonyl Compounds by CsPbBr3 Perovskite

Conversion of alcohols into corresponding carbonyl compounds through an oxidation reaction with high conversion and selectivity simultaneously under mild conditions still remains a great challenge. Herein, a cost-effective and highly efficient photocatalytic protocol for selective oxidation of alcohols was developed using CsPbBr3 perovskite as a heterogeneous photocatalyst, which afforded aldehydes/ketones exclusively with a yield of 99% at ambient temperature under an air atmosphere. Moreover, the photocatalyst can be recycled at least 5 times without a significant decrease in catalytic activity. The detailed reaction mechanism was investigated by a series of quenching experiments, including Stern-Volmer experiments and electron paramagnetic resonance spectroscopy analysis as well as DFT calculations.

Bidentate Nitrogen-Ligated I(V) Reagents, Bi(N)-HVIs: Preparation, Stability, Structure, and Reactivity

Hypervalent iodine(V) reagents are a powerful class of organic oxidants. While the use of I(V) compounds Dess-Martin periodinane and IBX is widespread, this reagent class has long been plagued by issues of solubility and stability. Extensive effort has been made for derivatizing these scaffolds to modulate reactivity and physical properties but considerable room for innovation still exists. Herein, we describe the preparation, thermal stability, optimized geometries, and synthetic utility of an emerging class of I(V) reagents, Bi(N)-HVIs, possessing datively bound bidentate nitrogen ligands on the iodine center. Bi(N)-HVIs display favorable safety profiles, improved solubility, and comparable to superior oxidative reactivity relative to common I(V) reagents. The highly modular synthesis and in situ generation of Bi(N)-HVIs provides a novel and convenient screening platform for I(V) reagent and reaction development.

Hydrogen Peroxide as a Green Oxidant for the Selective Catalytic Oxidation of Benzylic and Heterocyclic Alcohols in Different Media: An Overview

Among a plethora of known and established oxidant in organic chemistry, hydrogen peroxide stands in a special position. It is commercially and inexpensively available, highly effective, selective, and more importantly it is compatible with current environmental concerns, dictated by principles of green chemistry. Several chemicals or their intermediates that are important in our daily life such as pharmaceuticals, flavors, fragrances, etc. are products of oxidation of alcohols. In this review, we introduce hydrogen peroxide as an effective, selective, green and privileged oxidant for the catalyzed oxidation of primary and secondary benzylic and heterocyclic alcohols to corresponding carbonyl compounds in different media such as aqueous media, under solvent-free conditions, various organic solvent, and dual-phase system.

Dehalogenative Deuteration of Unactivated Alkyl Halides Using D2O as the Deuterium Source

The general dehalogenation of alkyl halides with zinc using D₂O or H₂O as a deuterium or hydrogen donor has been developed. The method provides an efficient and economic protocol for deuterium-labeled derivatives with a wide substrate scope under mild reaction conditions. Mechanistic studies indicated that a radical process is involved for the formation of organozinc intermediates. The facile hydrolysis of the organozinc intermediates provides the driving force for this transformation.

Catalytic oxidation of alcohols with novel non-heme N4-tetradentate manganese(ii) complexes

We report the preparation and characterisation of a series of novel non-heme N4-tetradentate Mn(OTf)2 complexes of the type, [(L)MnOTf2], where L = R,R and S,S enantiomers of BPMCN, its 6-methyl and 6-bromo derivatives as well as the novel ligand BMIMCN (BPMCN = N,N'-dimethyl-N,N'-bis(2-pyridylmethyl)-(R,R/S,S)-1,2-diaminocyclohexane, BMIMCN = N,N'-dimethyl-N,N'-bis(1-methyl-2-imidazolemethyl)-(R,R/S,S)-1,2-diaminocyclohexane). Solid state structural analysis of the BMIMCN-ligated Mn-triflate complexes (R,R-C4 and S,S-C4) revealed opposite helicity but identical metal site accessibility. This feature was exploited in the catalytic oxidation of primary and secondary alcohols, with hydrogen peroxide as oxidant and acetic acid as co-catalyst. Complexes R,R-C4 and S,S-C4 displayed the highest activity in benzyl alcohol oxidation, attributed to the electron-donating property of the BMIMCN ligand. Complex S,S-C4, displayed high activity for a variety of primary alcohol substrates, but the reaction suffered from reduced selectivity and side-reactions due to the presence of acetic acid. In contrast, secondary alcohol substrates could be oxidised to the corresponding ketone products in excellent isolated yields under mild reaction conditions and short reaction times.

Color conversion of the magnetically separable Al/Fe oxide RNGO in the selective oxidation of benzyl alcohol induced the observation of its morphology change

The morphology changed in accordance with the catalytic performance through the observation of color variation during the lifetime test: with a chaotic layout and a comparable inferior catalytic activity initially, while a waffle or pastry state and a relatively superior activity in the prime time performance.

Direct Selective Oxidative Functionalization of C-H Bonds with H₂O₂: Mn-Aminopyridine Complexes Challenge the Dominance of Non-Heme Fe Catalysts

Non-heme iron(II) complexes are widespread synthetic enzyme models, capable of conducting selective C–H oxidation with H₂O₂ in the presence of carboxylic acid additives. In the last years, structurally similar manganese(II) complexes have been shown to catalyze C–H oxidation with similarly high selectivity, and with much higher efficiency. In this mini-review, recent catalytic and mechanistic data on the selective C–H oxygenations with H₂O₂ in the presence of manganese complexes are overviewed. A distinctive feature of catalyst systems of the type Mn complex/H₂O₂/carboxylic is the existence of two alternative reaction pathways (as found for the oxidation of cumenes), one leading to the formation of alcohol, and the other to ester. The mechanisms of formation of the alcohol and the ester are briefly discussed.

Alcohol oxidation with H2O2 catalyzed by a cheap and promptly available imine based iron complex

A cheap and easily available catalyst for alcohol oxidation with unexpected selectivity features.

Highly efficient oxidation of alcohols catalyzed by a porphyrin-inspired manganese complex

A novel strategy for catalytic oxidation of a variety of benzylic, allylic, propargylic, and aliphatic alcohols to the corresponding aldehydes or ketones has been successfully developed.

The role of carboxylato ligand dissociation in the oxidation of chrysin with H₂O₂ catalysed by [Mn₂(III,IV)(μ-CH₃COO)(μ-O)₂(Me₄dtne)](PF₆)₂

The aqueous and non-aqueous chemistry of the complex [Mn2(III,IV)(μ-CH3COO)(μ-O)2(Me4dtne)](PF6)2 (where Me4dtne = 1,2-bis(4,7-dimethyl-1,4,7-triazacyclonon-1-yl)ethane), which has been demonstrated as an exceptionally active catalyst in the bleaching of raw cotton and especially wood pulp at high pH (>11), is explored by UV/vis absorption, Raman and EPR spectroscopies and cyclic voltammetry. The data indicate that dissociation of the μ-acetato bridge is essential to the catalyst activity and rationalises the effect of sequestrants such as DTPA on its performance.