Benzyl Alcohol In Water Research Articles

A Ru-Based Complex for Sustainable One-Pot Tandem Aerobic Oxidation-Knoevenagel Condensation Reactions

Our novel binuclear complex-anchored Ru(III) catalyst, designed and assembled by sonicating 2,2′-(4,6-dihydroxy-1,3-phenylene)bis(1H-benzo[d]imidazole-4-carboxylic acid), Ru(DMSO)4Cl2 and 4-methylpyridine, demonstrates remarkable efficiency and selectivity. It promotes one-pot reactions, including active methylenes and benzyl alcohols in water, via a tandem aerobic oxidation/Knoevenagel condensation process, yielding benzylidene malononitrile in excellent yields. The catalyst’s ability to oxidize benzyl alcohols to aldehydes, which then undergo Knoevenagel condensation with active methylenes, makes it a multifunctional catalyst. Notably, the catalyst can be successfully retrieved and recycled for five successive rounds with no significant decrease in catalytic efficiency. The ICP study showed that no catalyst leaching was observed, indicating that the designed catalyst is indeed heterogeneous. The Ru catalyst outperformed other documented catalysts in terms of lower dose, shorter duration, decreased working temperature, and the absence of dangerous additives. This demonstrates the catalyst’s robustness and sustainability, making it a promising candidate for future organic conversions and industrial uses.

Water enhanced photo-oxidation of alcohols on colloidal quantum dots

CdS QDs were used as photocatalysts for the oxidation of benzyl alcohol in water. The combined experimental and theoretical calculation results reveal a unique phenomenon in which water acts as an “accelerator” for the oxidation reaction.

Catalysis via bimetallic Pd-Sn nanoparticles: green oxidation of secondary benzyl alcohol in water in the absence of base

Catalysis via bimetallic Pd-Sn nanoparticles: green oxidation of secondary benzyl alcohol in water in the absence of base

Pyrene-Based Covalent Organic Frameworks for Photocatalytic Hydrogen Peroxide Production.

Four highly porous covalent organic frameworks (COFs) containing pyrene units were prepared and explored for photocatalytic H2 O2 production. The experimental studies are complemented by density functional theory calculations, proving that the pyrene unit is more active for H2 O2 production than the bipyridine and (diarylamino)benzene units reported previously. H2 O2 decomposition experiments verified that the distribution of pyrene units over a large surface area of COFs plays an important role in catalytic performance. The Py-Py-COF though contains more pyrene units than other COFs which induces a high H2 O2 decomposition due to a dense concentration of pyrene in close proximity over a limited surface area. Therefore, a two-phase reaction system (water-benzyl alcohol) was employed to inhibit H2 O2 decomposition. This is the first report on applying pyrene-based COFs in a two-phase system for photocatalytic H2 O2 generation.

Highly efficient synthesis of benzyl benzoate directly from self-coupling of benzyl alcohol in water

Benzyl benzoate (BB), an important ester, still demands for green synthesis routes. In this work, by size regulation and proper functionalization of carbon nanotubes (CNTs) as the support of gold catalyst, this ester can be synthesized very efficiently directly from benzyl alcohol via oxidative coupling. More attractively, the reaction is performed using water as green solvent and molecular oxygen as green oxidant. Simultaneously, very high selectivity to BB can be obtained near full conversion within very short reaction time (just 0.5 h), while the low-value benzoic acid byproduct is negligible. This is very different from many reported gold catalysts that yield much benzoic acid and/or benzaldehyde in water. The results show that, besides the size of CNTs (length and diameter), the functionalization of CNTs is also critical for improving both conversion and the selectivity to BB. In addition, the reaction mechanism for forming BB ester is put forward as well.

Weakly Hydrophilic Imine-Linked Covalent Benzene-Acetylene Frameworks for Photocatalytic H2O2 Production in the Two-Phase System.

Conversing oxygen (O2) to hydrogen peroxide (H2O2) driven by solar energy is a promising H2O2 onsite production route but often short of efficient and durable photocatalysts. Herein, strong π-π conjugate polycyclic aromatic benzene and acetylene units have been constructed into new covalent organic frameworks (COFs) linked by imine C═N bonding. These COFs demonstrated two-dimensional hexagonal crystalline frameworks with higher crystallinity and larger surface area (>600 m2 g-1). Covalent benzene-acetylene frameworks possessed appropriate visible light-responsive band structure and the suppressed charge recombination rate. The -OH groups on their frameworks enable them to be weakly hydrophilic. As a result, it served as high-performance but durable photocatalysts for H2O2 production in the water-benzyl alcohol (BA) two-phase system. It delivered a H2O2 production rate of 1240 μmol h-1 gcat-1 and durable catalytic efficiency within 60 h, comparable to the best COF-based catalysts. This study provides an efficient two-phase photocatalytic system for H2O2 production based on weakly hydrophilic imine-linked benzene-acetylene organic photocatalysts.

Oxidation of benzyl alcohol catalyzed by ligand-stabilized Au nanoparticles in the presence of weak bases

Ligand-stabilized gold nanoparticles (tetrakis(hydroxymethyl)phosphonium chloride-Au, citrate-Au, cetrimonium bromide-Au) were synthesized and mixed with several weak-base solids (barium carbonate, Amberlite IRA-900) and acidic solid (Dowex 50WX2 resin). Those catalysts were applied for the oxidation of benzyl alcohol in water at 80 oC. Almost ligand-stabilized Au nanoparticles/weak-base solids showed good conversion of benzyl alcohol and high selectivity of benzoic acid, whereas ligand-stabilized Au nanoparticles/acidic solid were catalytically inactive. Nanoparticles were characterized by transmission electron microscopy, zetapotential measurement, and dynamic light scattering. The catalytic activity and product selectivity were determined by using a gas chromatography coupled with a mass selective detector. Our study suggests that the oxidation reaction in water could be catalyzed by gold with the presence of weak-base solids.

Ionic Liquid Hydrogels Based on Poly(2-acrylamido-2-methyl-1-propanesulfonic Acid -co-1-vinylimidazole): A Green and Efficient Catalyst Carrier for Ag Nanoparticles in Oxidation and Adsorption of Benzyl Alcohol in Water

Ionic Liquid Hydrogels Based on Poly(2-acrylamido-2-methyl-1-propanesulfonic Acid -co-1-vinylimidazole): A Green and Efficient Catalyst Carrier for Ag Nanoparticles in Oxidation and Adsorption of Benzyl Alcohol in Water

Minimalist De Novo Design of an Artificial Enzyme.

We employed a reductionist approach in designing the first heterochiral tripeptide that forms a robust heterogeneous short peptide catalyst similar to the “histidine brace” active site of lytic polysaccharide monooxygenases. The histidine brace is a conserved divalent copper ion-binding motif that comprises two histidine side chains and an amino group to create the T-shaped 3N geometry at the reaction center. The geometry parameters, including a large twist angle (73°) between the two imidazole rings of the model complex, are identical to those of native lytic polysaccharide monooxygenases (72.61°). The complex was synthesized and characterized as a structural and functional mimic of the histidine brace. UV–vis, vis-circular dichroism, Raman, and electron paramagnetic resonance spectroscopic analyses suggest a distorted square-pyramidal geometry with a 3N coordination at pH 7. Solution- and solid-state NMR results further confirm the 3N coordination in the copper center of the complex. The complex is pH-dependent and could catalyze the oxidation of benzyl alcohol in water to benzaldehyde with yields up to 82% in 3 h at pH 7 and above at 40 °C. The catalyst achieved 100% selectivity for benzaldehyde compared to conventional copper catalysis. The design of such a minimalist building block for functional soft materials with a pH switch can be a stepping stone in addressing needs for a cleaner and sustainable future catalyst.

Base-free selective oxidation of benzyl alcohol in water over palladium catalyst supported on titanium niobate nano sheets

BackgroundExploring catalysts with high-efficiency, stability and mild reaction conditions for oxidation of alcohols is an urgent task. In this work, a simple and efficient nanostructured catalyst system is developed, comprising homogenously dispersed Pd nanoparticles (NPs) with the average sized of 2.84 nm supported on titanoniobate nano sheets. MethodsThe metal precursors are deposited onto the exfoliated TiNbO5 nano sheets through the electrostatic interaction and then reduced to nanoparticles by the UV irradiation. Selective oxidation of benzyl alcohol in ultrapure water was achieved with the as-prepared Pd-TNO under conditions of the base-free and atmospheric pressure with using air as an oxidant. Significant FindingsThe results demonstrate that the catalyst exhibits excellent catalytic activity and selectivity in the aerobic oxidation of benzyl alcohol to benzaldehyde. Furthermore, the catalyst can be reused to five times without significant loss of performance. The nanostructure obtained with the exfoliation/restacking process favors the mass transfer and provides a unique nano reactor during the reaction.

Oxygen vacancies-enriched Ta-doped Bi2WO6 with Pt as cocatalyst for boosting the dehydrogenation of benzyl alcohol in water

Selective photocatalytic oxidation of alcohols into value-added aldehydes or ketones is a promising alternative for alcohol oxidation concerning the mild reaction conditions and the controllable selectivity. To increase the activity, defective Bi2WO6 with abundant oxygen vacancies (OVs) was synthesized via substitution of W by Ta. The resulting Ta-doped Bi2WO6 loaded with Pt nanoparticles as co-catalyst efficiently converted aromatic and aliphatic alcohols into the corresponding carbonyl compounds with high selectivity (>99%) in aqueous solution under visible-light irradiation and anaerobic conditions, with equivalent H2 as a coupled product. The optimal amount of benzyl alcohol converted by the Ta-doped catalyst was two times higher than that of the undoped catalyst. Surface OVs were found to favor the dissociative adsorption of the alcohols and to prolong the life time of the charge carriers. More importantly, isotopic labelling experiments confirmed that over Pt-loaded pristine undoped Bi2WO6, the coupled H2 product results from water reduction, while over Pt-loaded Ta-doped Bi2WO6, the produced H2 originates from benzyl alcohol, implying that benzyl alcohol can be photo-oxidized via a complete dehydrogenation pathway. Thus, enriched surface OVs in photocatalysts can activate α-C-H bonds in alcohols, boosting the photocatalytic oxidation performance.

Highly dispersive Pd nanoparticles decorated strontium niobate nanosheets: Efficient and recyclable catalyst for base-free aerobic oxidation of benzyl alcohols in water

2D perovskite Sr2Nb3O10 (SNO) nanosheets were synthesized by cation exchange-assisted liquid exfoliation and applied as supports for the immobilization of palladium (Pd) nanoparticles through the electrostatic assembly with Pd(NH3)42+ precursors and successive in-situ photoreduction. Pd nanoparticles with an average diameter of 9.22 nm are uniformly dispersed on the surface of strontium niobate nanosheets. The obtained nanohybrid Pd-SNO could serve as an efficient heterogeneous catalyst for the atmospheric pressure oxidation of benzyl alcohol to benzaldehyde by using air as an oxidizing agent and water as the sole solvent at low temperature (80 °C). Furthermore, the catalyst could be easily separated from the reaction mixture by simple centrifugation and reused five times without significant degradation in catalytic activity under the investigated conditions. We believe that the synthetic strategy described in this work is a feasible means of developing effective noble metal/layered transition metal oxide hybrid catalysts for organic reactions.

Hierarchical CeO2@N-C Ultrathin Nanosheets for Efficient Selective Oxidation of Benzylic Alcohols in Water.

A monodisperse CeO2@N-C ultrathin nanosheet self-assembled hierarchical structure (USHR) has been prepared by metal-organic framework template methods. The uniform coating of nitrogen-doped carbon (N-C) layers could play an important role in the adsorption and activation of benzylic alcohol. The unique 3D hierarchical structure self-assembled by ultrathin nanosheets provided enough active sites for the catalytic reaction. Therefore, the CeO2@N-C USHR can afford excellent catalytic performance for selective oxidation of benzylic alcohols in water.

Visible-Light-Induced Preparation of Quinazolinones by Oxidation of Benzyl Alcohols in Water

Visible-Light-Induced Preparation of Quinazolinones by Oxidation of Benzyl Alcohols in Water

Dual Stimuli-Responsive Copper Nanoparticles Decorated SBA-15: A Highly Efficient Catalyst for the Oxidation of Alcohols in Water

In the present work, a temperature and pH-responsive hybrid catalytic system using copolymer-capped mesoporous silica particles with metal nanoparticles is proposed. The poly(2-(dimethylamino)ethyl methacrylate)(DMAEMA)-co-N-tert-butyl acrylamide) (TBA)) shell on mesoporous silica SBA-15 was obtained through free radical polymerization. Then, copper nanoparticles (CuNPs) decorated SBA-15/copolymer hybrid materials were synthesized using the NaBH4 reduction method. SBA-15 was functionalized with trimethoxylsilylpropyl methacrylate (TMSPM) and named TSBA. It was found that the CuNPs were uniformly dispersed in the mesoporous channels of SBA-15, and the hybrid catalyst exhibited excellent catalytic performance for the selective oxidation of different substituted benzyl alcohols in water using H2O2 as an oxidant at room temperature. The dual (temperature and pH-) responsive behaviors of the CuNPs/p(DMAEMA-co-TBA)/TSBA catalyst were investigated using the dynamic light scattering technique. The conversion of catalytic products and selectivity were calculated using gas chromatographic techniques, whereas the molecular structure of the products was identified using 1H and 13C nuclear magnetic resonance (NMR) spectroscopy. The catalyst showed excellent catalytic activity toward the oxidation of alcohol to aldehyde in an aqueous medium below the lower critical solution temperature (LCST) and pKa values (7–7.5) of the copolymer. The main advantages of the hybrid catalyst, as compared to the existing catalysts, are outstanding alcohol conversion (up to 99%) for a short reaction time (1 h), small amount of the catalyst (5 mg), and good recyclability equal to at least five times.

Front Cover: A Borrowing Hydrogen Strategy for Dehydrative Coupling of Aminoisoquinolines with Benzyl Alcohols in Water (Eur. J. Org. Chem. 5/2020)

Front Cover: A Borrowing Hydrogen Strategy for Dehydrative Coupling of Aminoisoquinolines with Benzyl Alcohols in Water (Eur. J. Org. Chem. 5/2020)

Ligand-tuned cobalt-containing coordination polymers and applications in water

Co-CIA could realize the alkylation of ketones and alcohols, alcohols and alcohols without extra bases and organic solvents, while Co-NCIA was effective for the synthesis of 1-benzyl-2-aryl-1H-benzo[d]imidazoles from various phenylenediamine and benzyl alcohols in water.

A Borrowing Hydrogen Strategy for Dehydrative Coupling of Aminoisoquinolines with Benzyl Alcohols in Water

We report a borrowing hydrogen strategy for a palladium‐catalyzed dehydrative coupling of aminoisoquinolines with benzylic alcohols in water. This cascade reaction using the π‐benzylpalladium system can be achieved in an atom‐economic process without the need for base or other additives, furnishing the N‐benzylated aminoisoquinolines in moderate to excellent yields along with water as the sole co‐product. The crossover experiment using [D7]benzyl alcohol and 4‐methoxybenzyl alcohol afforded H/D scrambled products. KIE experiments showed that benzylic C–H bond cleavage of benzyl alcohol was involved in the turnover limiting step (KIE = 4.4). The coupling reaction was found to be first order in benzyl alcohol with a kinetic solvent isotope effect (KSIE) of 1.6. These experimental results are consistent with a borrowing hydrogen mechanism in water. Notably, the water‐soluble Pd0/TPPMS system can be applied to the more challenging catalytic benzylic amination with aminoisoquinoline nucleophiles despite the possible deactivation of PdII species.

Surfactant - Alcohol interactions: An ultrasonic, UV and FTIR analysis

The study focuses on the density, viscosity and ultrasonic velocity of non-ionic surfactant sorbitan sesquioleate with alcohols. Sorbitan sesquioleate dissolves in water-anisyl alcohol, water-benzyl alcohol and water-cinnamyl alcohol. Different concentrations of these mixtures are determined in order to view the Critical Micelle Concentration (CMC). To study the molecular interaction of the mixture of surfactant and alcohols, various acoustical parameters such as adiabatic compressibility (β), intermolecular free length (Lf), internal pressure (πi), Rao's constant (Ra), absorption coefficient (α/f2), free volume (Vf), cohesive energy (CE), relaxation time (τ), acoustical impedance (Za) and solvation number (Sn) have been calculated. The trends in the variation of these parameters are used to discuss the molecular interactions present among the mixtures. UV and FTIR analysis confirm this interaction of the mixture of surfactant and alcohols.

Gold(III)-Catalyzed Decarboxylative C3-Benzylation of Indole-3-carboxylic Acids with Benzylic Alcohols in Water.

A strategy for the gold(III)-catalyzed decarboxylative coupling reaction of indole-3-carboxylic acids with benzylic alcohols has been developed. This cascade reaction is devised as a straightforward and efficient synthetic route for 3-benzylindoles in moderate to excellent yields (50-93%). A Hammett study of the protodecarboxylation gives a negative ρ value, suggesting that there is a buildup of positive charge on the indole ring in the transition state. Furthermore, comparison of initial rates in H2O and in D2O reveals an observed kinetic solvent isotope effect (KSIE = 2.7). This simple protocol, which affords the desired products with CO2 and water as the coproducts, can be achieved under mild conditions without the need for base or other additives in water.