Oxidation Of Primary Benzylic Alcohols Research Articles

Microwave assisted synthesis of ErxYbyCa1-x-yMoO4 nano-phosphor for efficient temperature sensing and catalytic applications

Here, Er/Yb Co-doped CaMoO4 materials (ErxYbyCa1−x−yMoO4 NPs where x = 0, 0.01 and y = 0, 0.05, 0.10, 0.15, 0.20) were prepared by microwave-assisted method and its pure-tetragonal structure were confirmed by X-ray diffraction spectra (XRD), Rietveld-refinement and Raman-vibrational spectra. The transmission-electron microscopy (TEM) study indicates the formation of nearly spherical shaped nanomaterial with average size of ~ 15 nm. Additionally, absorption and emission properties were studied by UV–Visible–NIR and photoluminescence (PL) spectrometer. The UV–Visible–NIR spectra attribute absorption of Er3+ ion in visible region (380–700 nm) and absorption of Yb3+ ion in near-infrared region (700–1400 nm). Moreover, PL up-conversion spectra of the sample recorded under excitation wavelength 980 nm. The PL peaks were observed at 530, 544–552, and 656–670 nm. Prominent PL-intensity was observed for Er0.01Yb0.15Ca0.84MoO4 phosphor. Temperature dependent PL study reveals that present phosphor is robust phosphor for temperature sensor. In addition, Er3+/Yb3+ doped CaMoO4 nanomaterials exhibited excellent activity and selectivity in the aerial oxidation of benzoin over benzyl under oxidant-free reaction conditions. The synergistic effect Er3+/Yb3+ co-doing in CaMoO4 matrix was observed, where only CaMoO4 material found to be inactive towards above oxidation reaction. Moreover, the oxidation of primary benzyl-alcohols was furnished in presence of tertiary butyl hydroperoxideas oxidant.

Selective oxidation of primary benzylic alcohols to aldehydes using NaNO3 under ball milling

A facile method for oxidation of primary benzylic alcohols to the corresponding aldehydes is reported using NaNO3/P2O5 under high-speed ball-milling conditions. This approach is clean, efficient, and exhibits broad functional group compatibility.

Design and development of natural and biocompatible raffinose-Cu2O magnetic nanoparticles as a heterogeneous nanocatalyst for the selective oxidation of alcohols

Natural polymers are recently playing a vital role as a support for the noble metals. In the present study, raffinose from the classes of oligosaccharide polymer with a high capacity of magnetization was used as active support for the copper metal. The copper immobilized on the raffinose-based magnetic nanoparticles (MNPs) which can be used as a recyclable heterogeneous nanocatalyst for the selective oxidation of primary benzyl alcohols (PBA) to benzaldehyde (BAD) derivatives. The morphology and structure of the recoverable magnetic nanocatalyst were characterized using different microscopic and spectroscopic techniques including FT-IR, GC, VSM, XRD, TEM, TGA, FESEM and EDS analyses. Also, the optimum conditions of co-reactant, reaction time, oxidant, temperature and amount of the nanocatalyst for oxidation reaction were investigated. Moreover, the Fe3O4@raffinose-Cu2O NPs had a significant effect to enhance yield and reduce the reaction time.

Enhanced singlet oxygen generation by hybrid Mn-doped nanocomposites for selective photo-oxidation of benzylic alcohols

Transition-metal ions doped nanocrystals (NCs), specifically Mn-doped NCs, hold great potential in the field of photocatalysis, especially, to improve photocatalytic performance for singlet oxygen (1O2) generation. Here, we report the design of a novel Mn-doped NC-based nanocomposites, specifically, silica-coated Mn-doped CdS/ZnS NCs decorated with Pt NCs (denoted as Mn-NCs@SiO2-Pt), which enhance photocatalytic 1O2 generation. Owing to the long-lived Mn excited state (on the order of ms), the energy-transfer between Mn-NCs and molecular oxygen is facilitated with the assistance of the Pt NCs adhered to the Mn-NC@SiO2 surface. Therefore, the Mn-NCs@SiO2-Pt composites, integrate the advantages of Mn-doped NCs, a protective silica layer, and Pt NCs to exhibit excellent catalytic activity and selectivity for the selective oxidation of primary benzylic alcohols to aldehydes through an 1O2 engaged oxidation process under visible-light irradiation. This work paves the way for enhancing catalytic performance via facilitated energy transfer relaxation by utilizing the long-lived excited-state of Mn2+ dopant ions in nanocomposites.

Copper(I)- and Mesoionic-Hydroxyamide-Catalyzed Chemoselective Aerobic Oxidation of Primary Benzylic Alcohols

A new aerobic oxidation system consisting of Cu(I)I, 2,2'-bipyridine, N-methyl imidazole, and a mesoionic hydroxyamide was developed, with which selective oxidation of a broad range of benzylic alcohols was achieved.

Controlled Aerobic Oxidation of Primary Benzylic Alcohols to Aldehydes Catalyzed by Polymer-Supported Triazine-Based Dendrimer–Copper Composites

A controlled aerobic oxidation of primary benzylic alcohols to the corresponding benzaldehydes by using polystyrene–poly­(ethylene glycol) (PS–PEG) resin-supported triazine-based polyethyleneamine dendrimer–copper complexes [PS–PEG-TD2–Cu(II)] was developed. In particular, PS–PEG-TD2–Cu(OAc)2 efficiently catalyzed the aerobic oxidation of benzylic alcohols in the presence of a catalytic amount of TEMPO under atmospheric conditions to give the corresponding aldehydes in up to quantitative yield. The catalyst was readily recovered by simple filtration and reused four times without significant loss of its catalytic activity.

Bimetallic Cu-Pd Nanoparticles Supported on Bio-silica as an Efficient Catalyst for Selective Aerobic Oxidation of Benzylic Alcohols

A new bimetallic heterogeneous catalyst consisting of copper and palladium nanoparticles supported on bio-silica is presented. The use of TEMPO as co-catalyst allowed the aerobic oxidation of primary benzylic alcohols into the corresponding aldehydes with excellent selectivity and good activity. The methodology could be applied to the oxidation of allylic and heterobenzylic alcohols. The catalyst is easy to prepare from commercial starting materials and can be recovered and reused without apparent loss of activity.

Tungstate ions (WO4=) supported on imidazolium framework as novel and recyclable catalyst for rapid and selective oxidation of benzyl alcohols in the presence of hydrogen peroxide

Tungstate salt with imidazolium framework is found to be a recoverable and heterogeneous system favouring the highly selective oxidation of primary benzylic alcohols to corresponding aldehydes with 30% H2O2 as a green oxidant under neutral aqueous reaction conditions. Furthermore, in order to demonstrate the recyclability of the catalyst, it was recovered and efficiently reused in seven succeeding reaction cycles without any significant loss. The use of green solvent, very short reaction time with excellent yields and recyclability of the catalyst make this protocol highly advantageous.

Aerobic oxidation of benzyl alcohols using a novel combination of N-hydroxyphthalimide (NHPI) with HNO3 and CuBr2

A new catalytic system for oxidation of alcohols with oxygen catalyzed by N-hydroxyphthalimide (NHPI) combined with HNO3 and CuBr2 has been developed. This system can effectively catalyze oxidation of primary benzylic alcohols to corresponding aldehydes with high selectivities (up to 100 %). A mechanism for the oxidation of alcohols catalyzed by NHPI/HNO3/CuBr2 is proposed.

Quantitative Aerobic Oxidation of Primary Benzylic Alcohols to Aldehydes Catalyzed by Highly Efficient and Recyclable P123-Stabilized Pd Nanoclusters in Acidic Aqueous Solution

Quantitative oxidation of benzylic alcohols to aldehydes catalyzed by P123-stabilized Pd nanoclusters was first developed in acidic aqueous solution with air at near ambient temperature. The Pd nanocluster colloidal system showed high conversion rates for aerobic oxidation of benzylic alcohols and could easily be recovered by a simple process for multiple recycling reactions without significant loss of activity.

Facile open air oxidation of benzylic alcohols in distilled water by in situ made copper(II) complexes

A highly efficient, selective and green catalytic protocol for open air oxidation of primary benzylic alcohols into aldehydes by in situ made N-isopropyl-3,5-di-tert-butylsalicylaldimine (HL3)–Cu(II) complexes and TEMPO (2,2,6,6-tetramethyl-piperidinyloxyl radical) is introduced herein. Distilled water as a solvent the reaction proceeds at 80°C temperature without any auxiliarities such as base and/or co-solvent. For example, benzyl alcohol is quantitatively and selectively oxidized to benzaldehyde within a few hours under optimized reaction conditions [80°C, open air, 0.3mol% CuBr2, 2mol% HL3, 3mol% TEMPO and 5mL of distilled water]. Under anaerobic conditions, the catalyst decomposes to a free ligand and Cu2O nanoparticles (diameter >50nm) via anticipated Cu(I)-hydroxo complex. On the basis of these observations and deuteration studies, a plausible reaction mechanism is proposed for the catalytic system.

A novel and selective oxidation of benzylic alcohols with polymer-supported periodic acid under mild aprotic conditions

Abstract A new polymeric oxidizing reagent was prepared by supporting periodic acid on poly(1,4-phenylene-2,5-pyridine dicarboxyamide). This polymeric reagent was used for the selective oxidation of primary benzylic alcohols to the corresponding benzaldehydes in CH3CN at reflux conditions. Excellent selectivity was observed between primary benzyl alcohols and secondary ones as well as non-benzylic alcohols in the oxidation reactions. Allylic alcohols were also converted to the corresponding aldehydes with good yields.

Aerobic oxidation of primary alcohols under mild aqueous conditions promoted by a dinuclear copper(II) complex

A sugar-discriminating dinuclear copper(II) complex was investigated for its ability to promote aerobic oxidation of primary benzylic alcohols in the presence of TEMPO and base. The transformation of benzyl alcohol to benzaldehyde was chosen as exploratory model reaction. The constitution of the catalytically active species was deducted from isothermal titration calorimetry and kinetic experiments, and the catalytic reaction was characterized both in aqueous organic and aqueous solution. The dinuclear complex is found to selectively oxidize primary over secondary alcohols in aqueous solution at ambient temperature with a turnover rate of 9 h −1. A mechanism for the catalytic cycle is proposed.

A Bipyridyl Palladium Complex Covalently Anchored onto Silica as an Effective and Recoverable Interphase Catalyst for the Aerobic Oxidation of Alcohols.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Catalytic properties of several palladium complexes covalently anchored onto silica for the aerobic oxidation of alcohols

A series of novel silica-supported palladium catalysts bearing N–N, N–S and N–O chelating ligands have been prepared and tested for the aerobic oxidation of alcohols to carbonyl compounds. The most active catalyst, 1, was used for the oxidation of a series of primary and secondary alcohols to carbonyl compounds. The catalyst is highly selective and no over-oxidation products were detected. The catalyst 1 can also be used for the oxidation of primary benzyl alcohols to carbonyl compounds with comparable yields in the presence of atmospheric air.

A Bipyridyl Palladium Complex Covalently Anchored onto Silica as an Effective and Recoverable Interphase Catalyst for the Aerobic Oxidation of Alcohols

A new silica-based Pd(II) interphase catalyst 2 efficiently catalyzes the aerobic oxidation of various types of structurally diverse alcohols to the corresponding carbonyl compounds. The catalyst is also quite effective for the oxidation of primary benzylic alcohols under atmospheric pressure of air. The catalyst shows high thermal stability (up to 200 °C) and is also stable under the oxidation reaction conditions. To our knowledge this work is the first example of the application of a palladium complex covalently anchored to silica for the aerobic oxidation of alcohols.

Dinitrogen Tetraoxide Complexes of Iron(III) and Copper(II) as Efficient and Mild Reagents for Oxidation of Hydroxy Compounds

Abstract Fe(NO3)3·1.5N2O4 is a highly efficient reagent for the oxidation of various classes of hydroxy compounds in dichloromethane at room temperature, or in the absence of solvent. Cu(NO3)2·N2O4 oxidizes different hydroxy compounds in refluxing carbon tetrachloride and is a highly selective reagent for oxidation of primary benzylic alcohols in refluxing EtOAc.