Reaction Of Benzyl Alcohol Research Articles

Endorsing Organic Porous Polymers in Regioselective and Unusual Oxidative C═C Bond Cleavage of Styrenes into Aldehydes and Anaerobic Benzyl Alcohol Oxidation via Hydride Elimination.

Oxidative cleavage of styrene C═C double bond is accomplished by employing a nitrogen-rich triazine-based microporous organic polymer as an organocatalyst. We report this regioselective reaction as first of its kind with no metal add-ons to afford benzaldehydes up to 92% selectivity via an unusual Wacker-type C═C bond cleavage. Such a reaction pathway is generally observed in the presence of a metal catalyst. This polymer further shows high catalytic efficiency in an anaerobic oxidation reaction of benzyl alcohols into benzaldehydes. The reaction is mediated by a base via the in situ generation of hydride ions. This study is supported by experiments and computational analyses for a free-radical transformation reaction of oxidative C═C bond cleavage of styrenes and a hydride elimination mechanism for the anaerobic oxidation reaction. Essentially, the study unveils protruding applications of metal-free nitrogen-rich porous polymers in organic transformation reactions.

Iridium and copper supported on silicon dioxide as chemoselective catalysts for dehydrogenation and borrowing hydrogen reactions

• Iridium and copper supported on silicon dioxide. • Iridium –catalyzed reaction of tert -butanesulfinamide with benzyl alcohol. • Selective synthesis of unsaturated carbonyl compounds. High active ligand usually plays an important role during catalysis and synthesis chemistry. A new and efficient benzotriazole-pyridinyl-silane ligand (BPS) was designed, and the corresponding iridium and copper catalysts were synthesized and thoroughly characterized by means of EDS, TEM, and XPS. The resulting iridium composite revealed excellent catalytic activity for the reaction of tert-butanesulfinamide with benzyl alcohols, while copper catalyst could realize the synthesis of unsaturated carbonyl compounds through the reaction of benzyl alcohols with ketones. This provided an efficient method for selective synthesis of unsaturated carbonyl compounds from benzyl alcohols and ketones in high yields with good recovery performance.

Metallic oxide\u2013graphene composites as a catalyst for gas-phase oxidation of benzyl alcohol to benzaldehyde

A new catalyst (FAG) composed of Fe, Al, and graphene (G) was prepared for catalyzing the reaction of benzyl alcohol (BA) to benzaldehyde (BD). The catalyst was characterized by XRD, XPS, SEM, and BET analyses. The catalytic performance of FAG for oxidation of BA to BD was studied by comparing with the catalysts ferrous oxide (Fe), ferrous oxide doped with aluminum (FA), and ferrous oxide doped with graphene (FG). The effects of amount of graphene additive, temperature, and ratio of Fe and Al were also studied. The results show that the catalyst FAG has a great specific surface area of 80.40 m2 g−1 and an excellent catalytic performance for the reaction of BA to BD: the conversion of BA and yield of BD significantly increased, and the selectivity of BD reached 87.38%.

Ultrasonic Synthesis and Characterization of Organic–Inorganic Nafion/Layered Double Hydroxide Nanohybrids and the Application in Ritter Reaction

It is desired to develop a catalytic system for Ritter reaction with the green and fast method, this work designed and synthesized intercalated nafion in layered double hydroxide (LDH) by the ultrasonic method and applied for Ritter reaction of benzyl alcohols with nitriles in water as a green solvent under ultrasonic condition.

Selective photoelectrocatalytic tuning of benzyl alcohol to benzaldehyde for enhanced hydrogen production

Hydrogen production can be promoted by replacing sluggish oxygen evolution reaction (OER) with a thermodynamically more favorable reaction, the primary oxidation reaction of benzyl alcohol to benzaldehyde. On a Bi2MoO6@TiO2NTA photocathode, the conversion of benzyl alcohol to benzaldehyde is realized with the selectivity of 100 %. This is originated from enhanced adsorption and activation of benzyl alcohol on this photoanode, as confirmed from tested by in situ FTIR techniques. The electrons generated during such a controllable and selective primary oxidation reaction is then utilized as the source for synergistical hydrogen production. The amount of generated hydrogen is then 5.5 times higher than that when OER is used. The efficiency for such hydrogen production is as high as 85 %. The proposed strategy combines solar energy and biomass for the efficient production of the valuable raw material - benzaldehyde as well as green energy source - hydrogen.

Ultrasound-assisted construction of a Z-scheme heterojunction with g-C3N4 nanosheets and flower-like Bi2WO6 microspheres and the photocatalytic activity in the coupling reaction between alcohols and amines under visible light irradiation

Flower-like Bi2WO6 microspheres and bulk g-C3N4 were prepared by the hydrothermal method and high-temperature calcining method, respectively. A new method based on the combination of ultrasonic stripping and mechanical stirring was used to obtain uniform composite x-Bi2WO6/g-C3N4 (x is the Bi2WO6 mass ratio) photocatalysts with a Z-scheme heterojunction. In the reaction of benzyl alcohol and aniline to form imine, the optimal composite, 30%-Bi2WO6/g-C3N4, showed a conversion rate of 87.6%, which is much higher than that of pure Bi2WO6 and g-C3N4. Characterization by SEM and TEM showed that the ultrasonically stripped g-C3N4 significantly reduced the radial dimension compared to bulk g-C3N4. A uniformly dispersed photocatalytic material was formed, and it maintained a flower-like microsphere structure. Materials characterized by N2 adsorption–desorption isotherms (BET) showed that the specific surface area of the g-C3N4 nanosheets increased by approximately ten times after ultrasonic stripping. The photostability of the composite was verified by cyclic experiments. Under visible light irradiation, the activation energy of the coupling reaction between benzyl alcohol and aniline was found to be decreased by 29.8 kJ mol−1. A capture experiment was used to verify the active species in the photocatalytic system, with the reaction found to be mainly completed through the synergistic action of h+, e− and •O2−.

A Highly Efficient Bifunctional Catalyst CoOx/tri-g-C3N4 for One-Pot Aerobic Oxidation–Knoevenagel Condensation Reaction

A highly efficient bifunctional catalyst of an s-triazine-based carbon-nitride-supported cobalt oxide is developed for the aerobic oxidation–Knoevenagel condensation tandem reaction of benzyl alcohol and malononitrile, whereby 96.4% benzyl alcohol conversion with nearly 100% selectivity towards benzylmalononitrile can be obtained in 6 h at 80 °C. The excellent catalytic performance derives from the high basicity of carbon nitride and strong redox ability of Co species induced by carbon nitride. The catalyst is also quite stable and can be reused without any regeneration treatment, whose product yield is only an 11.5% reduction after four runs.

Rational Optimization of Lewis‐Acid Catalysts for the Direct Amination of Alcohols, Part 1 – Activity Descriptors for Metal Triflates and Triflimides

Herein we report a comparison of Lewis acidity indicators (affinity scales, electronegativity, Fukui functions, global electrophilicity index) with a new in silico Beckett–Childs descriptor based on the build‐up of partial charge, computed by DFT, on phosphine oxide coordinated to a Lewis acid. When applied to a broad series of triflate and triflimide salts, the last descriptor allowed a qualitative description of catalytic activity trends for the model amination reaction of benzyl alcohol with aniline. A high activity for titanium triflimide was predicted and experimentally confirmed.

Oxidation behavior of N-hydroxyphthalimide (NHPI) and its electrocatalytic ability toward benzyl alcohol: Proton acceptor effect

The effect of proton acceptor on the electrochemistry of proton-coupled electron transfer reagents is always worthy of attention. Formal potentials of NHPI with different proton acceptors have been measured by cyclic voltammetry and were used to discriminate hydrogen bonding and deprotonation engaging in the oxidation of NHPI. With the negative shifting of formal potentials, the formation of hydrogen bonding complex was suggested when adding water into NHPI acetonitrile solution, a new wave caused by the addition of one pyridine base may be caused by a deprotonation process followed by a single electron transfer step. In addition, electrooxidation reactions of benzyl alcohol mediated by hydrogen bonding or deprotonation modified NHPI have been addressed and significant findings have been reported.

A new heterofunctional support for enzyme immobilization: PEI functionalized Fe3O4 MNPs activated with divinyl sulfone. Application in the immobilization of lipase from Thermomyces lanuginosus

Lipase from Thermomyces lanuginosus (TLL) was immobilized onto a novel heterofunctional support, divinyl sulfone (DVS) superparamagnetic nanoparticles (SPMNs) functionalized with polyethyleneimine (PEI). Particle size and zeta potential measurements, elemental analysis, X-ray powder diffraction, magnetic measurements, and infrared spectroscopy analysis were used to characterize the TLL preparations. At pH 10, it was possible to achieve 100 % of immobilization yield in 1 h. The immobilization pH gives TLL preparations with different stabilities; indeed the TLL preparation immobilized at pH 5.0 was the most stable during the thermal inactivation at all pH values. For the hydrolysis of racemic methyl mandelate, the nanobiocatalysts immobilized at pH 5.0 and blocked with ethylenediamine (EDA) and ethanolamine (ETA) obtained good enantioselectivities (68 % and 72 %, respectively) with high catalytic activities in the reaction medium at pH 7.0. The operational stability of the systems was evaluated in the esterification reaction of benzyl alcohol, obtaining up to 61 % conversion after the seventh reaction cycle. These results show that SPMN@PEI-DVS support is a robust strategy for the easy and rapid recovery of the nanobiocatalyst by applying a magnetic field, showing great potential for industrial applications.

An Efficient Vanadia Supported SrTiO3 Nanocatalyst for the Selective Oxidation of Benzylalcohol to Benzaldehyde

AbstractIn the present study, SrTiO3 (STO) was synthesized using oxalate method. A series of V2O5 nanoparticles supported on SrTiO3 (V2O5 / STO) with the vanadia content ranging from 0.5 to 2 wt. % was synthesized by wet impregnation method. Physicochemical properties of the synthesized catalysts were determined by X‐ray diffraction, Fourier transform infrared spectroscopy, Transmission electron microscopy, N2 physisorption and X‐ray photoelectron spectroscopy and acidity by pyridine adsorption method. XPS studies of the catalysts reveal that vanadium is in +5 oxidation state. Particle size of the catalysts calculated from TEM image analysis was found to be in the range of 86–92 nm. Pyridine adsorption studies reveals presence of Lewis acidity in the catalysts and the number of Lewis acid sites increase with vanadium content of the catalysts. Their catalytic activity was evaluated for the liquid phase oxidation of benzyl alcohol to benzaldehyde. STO is found to be least active and highly selective for the formation of benzaldehyde product where as V2O5/STO catalysts were found to be highly active and selective for the oxidation of benzyl alcohol reaction. Among all the catalysts the one with 1 wt. % loading of vanadia contains a greater number of active sites is found to be highly efficient heterogeneous catalyst system for selective oxidation of benzyl alcohol with 100 % benzaldehyde selectivity. The catalytic activity of the catalysts was correlated with the physico‐chemical properties of the catalysts.

Evaluation on the Activity of Surfactant Immobilized and Metal Cation Exchanged Impregnated Montmorillonite Nanoclays on Oxidation of Benzyl Alcohol

Nanoclay minerals received considerable importance in the field of material applications and organic synthesis because of natural occurrence, greater surface area, good selectivity, ion exchange properties, economical, functional simplicity, easy modification, and environmental acceptability. The eco-friendly liquid-phase oxidation reaction of benzyl alcohol over modified nanoclays such as metal cation exchanged impregnated nanoclays and surfactant immobilized with oxyanions of Cr(VI) and Mn(VII) yields benzaldehyde. Surfactant immobilized (HDTMA-Cr(VI)/Mn(VII)-MMT-nanoclays) and impregnated Mn+-MMT-Cr(VI)/Mn(VII)-nanoclays were prepared and the activity of modified nanoclays were studied. The oxidation reactions were carried out by varying the molar mass of the modified nanoclays with active species, reaction period and amount of catalyst on the yield of benzaldehyde. Surfactant immobilized nanoclays were found to be more active than impregnated nanoclays. The percentage yield of the product was calculated using 2,4-dinitrophenylhydrazine derivative. The materials used for this analysis were examined under different characterization techniques like XRD, SEM and TGA. From the XRD spectra was observed that the interlamellar spacing of montmorillonite nanoclay, Al3+-MMT-nanoclay, HDTMA-Cr(VI)-MMT-nanoclay and HDTMA-Mn(VII)-MMT-nanoclay were 9.81A, 9.931 A, 27.6 A and 28.0 A respectively. The superficial area of montmorillonite nanoclay has higher than modified nanoclay which was confirmed by SEM images. The TGA analysis stated that the used nanomaterial is thermally stable. The product obtained, benzaldehyde was indicated by TLC and confirmed by spectral studies like FTIR, 1H NMR and GC–MS. The activity of regenerated modified nanoclays was studied under standard experimental conditions up to the fourth generation. The result of different solvents on the yield of aldehyde was determined. The materials used are naturally occurring, safe to handle, environmentally friendly and reusable.

Screening of the Au:Pt Atomic Ratio Supported in SrCO3: Effects on the Performance of the Solvent-Free Oxidation of Benzyl Alcohol

We have prepared, by a sol-immobilization method, bimetallic catalysts with different Au:Pt atomic ratios supported on commercial SrCO3. The catalytic performance for the oxidation reaction of benzyl alcohol of such materials was compared to the monometallic counterparts, aiming at the obtaining of the best composition of the material. It was found that the Au:Pt atomic ratio presents a remarkable effect on the system performance, i.e., Pt-rich systems are more selective; however, less active. Thus, an equilibrium related to the activity and selectivity of the system was obtained by considering the yield of the system. Also, some density functional theory (DFT) insights were obtained by using a cluster of 14 atoms of Au and 1 or 2 atoms of Pt. X-ray photoelectron spectroscopy, elemental mapping in scanning transmission electron microscopy before and after catalyst usage, flame atomic absorption spectroscopy, Rietveld refinement, among other techniques, were used and associated to the experimental data, which allowed us to propose a catalytic mechanism for the system, which was important since SrCO3 has not been considered before as catalyst support for alcohol oxidation reactions.

Photo-induced generation of size controlled Au nanoparticles on pure siliceous ordered mesoporous silica for catalytic applications

Abstract A versatile in situ photochemical reduction approach was used to generate a composite of gold nanoparticles and pure siliceous SBA-15 silica support with regular mesopores. The mesoporous silica support was first synthesized and, after calcination, was suspended in a solution of gold bromide (EtOH or H2O) containing a free radical generator activated by UV irradiation and used for the photochemical reduction of gold precursor. The influence of gold precursor concentration, light intensity and nature of the solvents on the formation and properties of gold nanoparticles (size, dispersion, stability) on the mesoporous SBA-15 support have been studied with the aim of optimizing the dispersion of the gold nanoparticles in the mesoporous network and their chemical stability. The catalytic activity of the resulting AuNPs@SBA-15 nanocomposite was successfully evaluated for the oxidation of benzyl alcohol reaction in liquid-phase.

Synthesis of polymeric ionic liquids mircrospheres/Pd nanoparticles/CeO2 core-shell structure catalyst for catalytic oxidation of benzyl alcohol

New catalysts based on polymeric ionic liquids were synthesized and applied into selective oxidation of benzyl alcohol. Polymeric ionic liquid microspheres (PILM) were prepared by radical polymerization, and then the cations in the imidazole ring were exchanged with the metal anions. After that, the metal anions were reduced to Pd nanoparticles that was supported on the surface of PILM. This metal loading method favored the maximum amount of supported Pd nanoparticles that were uniformly distributed on the surface of PILM. In addition, the introduction of CeO2 prevented the aggregation of Pd nanoparticles and finally formed PILM/Pd/CeO2 catalysts with a core-shell structure. The performance of the PILM/Pd/CeO2 catalysts was evaluated by changing the [K2CO3] : [alcohol] molar ratio, reaction temperature and oxygen flow rate in the oxidation reaction of benzyl alcohol. The conversion and selectivity under the optimal reaction conditions reached 48% and 98% respectively The catalysts were effective and reusable after 5 cycles of experiments. In the end, a mechanism underlying the reaction pathway in benzyl alcohol oxidation was put forward.

Production of benzylamine by tandem dehydrogenation/amination/reduction over Cu and Au catalysts

The feasibility of continuous synthesis of benzylamine from benzyl alcohol by tandem dehydrogenation/amination/reduction has been demonstrated over Cu/SiO2 and Au/TiO2. Both catalysts exhibited an equivalent metal particle size range (1−6 nm) and mean (3.1–3.2 nm, from STEM). Hydrogen chemisorption measurements revealed (five-fold) higher uptake on Au/TiO2 than Cu/SiO2 under reaction conditions. Reductive amination of benzaldehyde over Cu/SiO2 generated a 99 % yield of dibenzylamine with no detectable benzylamine. Reaction of benzyl alcohol with NH3 (in N2) over Cu/SiO2 established utilisation of reactive hydrogen from alcohol dehydrogenation to convert intermediate imines to amines. Benzonitrile was the principal product due to the limited hydrogenation capacity of Cu. Inclusion of Au/TiO2 with Cu/SiO2 as a physical mixture promoted benzylamine formation and inhibited condensation-hydrogenation of benzylamine with benzaldehyde. Incorporation of H2 at low partial pressure (PH2= 0.04 atm) in the feed and a lower reaction temperature (498 K → 448 K) enhanced benzylamine production.

Synthesis of N-benzylated cobalt phthalocyaninetetrasulfonamide and its application in oxidative desulfurization catalysis

The FeCl2/K2CO3 catalyst system was used successfully for the synthesis of oil soluble N-benzylated cobalt phthalocyaninetetrasulfonamide by the reaction of benzyl alcohol on water-soluble cobalt phthalocyaninetetrasulfonamide via heating at 135 °C for 20 h under N2. The new oil-soluble peripherally N-benzylated phthalocyanine was characterized by elemental analysis, FT-IR, UV–vis, TG and mass spectrometry. The catalytic activity of this new cobalt complex for oxidation of dibenzothiophene (DBT) was evaluated in n-dodecane (a middle distillate model compound) using H2O2 as an oxidant. The acetonitrile was taken as an extracting solvent for further extracting DBT sulfoxide and sulfone. The novel peripherally substituted cobalt(II) complex showed better oxidative desulfurization catalytic activity than cobalt phthalocyanine and cobalt phthalocyaninetetrasulfonamide. DBT oxidation kinetics were evaluated by lumped nth- and first-order kinetic models. The maximum removal of the DBT was found to be 85% at the optimized dose and experimental conditions.

Effect of Si/Al Ratio on the Catalytic Activity of Two‐Dimensional MFI Nanosheets in Aromatic Alkylation and Alcohol Etherification

AbstractZeolite catalysts with pronounced two‐dimensional (2D) morphologies, specifically 2D MFI nanosheets composed of multilamellar stacks of MFI nanosheets, are hypothesized to offer accessibility advantages in catalytic reactions involving large, bulky molecules. The Si/Al ratio of zeolite catalysts is an important parameter determining their performance. However, the effect of Si/Al ratio on catalytic reactivity is not well understood in 2D zeolite catalysts. To provide further insight into this issue, the catalytic performance of 2D MFI nanosheet materials with different Si/Al ratios is compared using the liquid phase Friedel‐Crafts alkylation of mesitylene with benzyl alcohol & the self‐etherification of benzyl alcohol that occurs in parallel, both of which are catalyzed by Brønsted acid sites. The turnover frequency (TOF) of the catalysts is found to decrease with decreasing Si/Al ratio, with the etherification reaction being the main contributor to this trend. When the same reaction is carried out in the presence of a bulky poison, 2,6 di‐tert‐butylpyridine (DTBP), to selectively deactivate the external acid sites, only the etherification reaction of benzyl alcohol takes place in the micropores of the 2D MFI catalyst and the effectiveness factor is found to decrease with decreasing Si/Al ratio. The single component adsorption isotherms of benzyl alcohol show that the uptake normalized per acid site decreases with decreasing Si/Al ratio. Thus, increasing the density of acid sites in the micropores by decreasing the Si/Al ratio makes it more difficult for the reactant molecules to access them, as demonstrated by the decrease in TOF and the effectiveness factor. While the micropore reactions (benzene alkylation, alcohol etherification) showed a clear trend with Si/Al ratio, the reaction catalyzed on the external surface (mesitylene alkylation) did not, showing distinct differences in reactivity.

Lipase‐Catalyzed tert‐Butoxycarbonylation of Alcohols Using Boc2O

AbstractLipase‐catalyzed tert‐butoxycarbonylation of alcohols using di‐tert‐butyl dicarbonate (Boc2O) was developed. Aspergillus niger lipase, Burkholderia cepacia lipase, Pseudomonas fluorescens lipase, Candida rugosa lipase, and Candida antarctica lipase B were examined. The reaction of benzyl alcohol with Boc2O proceeded smoothly in the presence of Candida rugosa lipase in hexane to produce benzyl tert‐butyl carbonate in a good yield. Similarly, the tert‐butoxycarbonylation reactions of 4‐methylbenzyl alcohol, 4‐methoxybenzyl alcohol, 4‐chlorobenzyl alcohol, 4‐bromobenzyl alcohol, 4‐nitrobenzyl alcohol, 2‐phenylethanol, 3‐phenyl‐1‐propanol, cinnamyl alcohol, and 2‐naphthalene methanol using Boc2O in the presence of Candida rugosa lipase in hexane resulted in very good to‐excellent yields of the corresponding tert‐butoxycarbonylated alcohols.

Oxygen-vacancies-engaged efficient carrier utilization for the photocatalytic coupling reaction

Defects can greatly optimize the solar light harvesting capability and electronic structure of oxide materials. However, it remains challenging to achieve a defect engineering strategy under mild conditions. Meanwhile, the simultaneous exploitation of photogenerated holes (h+) and electrons (e−) to promote both photooxidation and photoreduction in a coupled system has rarely been reported. For the first time, we reveal an oxygen-vacancies-mediated photocatalytic strategy in which the electrons and holes are fully utilized for nitrobenzene reduction coupled with benzyl alcohol oxidation. The oxygen vacancies (OVs) generated in situ on the surface of TiO2 greatly extend light absorption into the visible region and promote the photogenerated electron transport for efficient photocatalysis. The experimental and theoretical results together indicate that chemisorption on the TiO2 surface decreases the oxidation potential of benzyl alcohol and causes an upward shift in its HOMO, which facilitates the oxidation reaction of benzyl alcohol to benzaldehyde. The in situ generated surface OVs also act as a bridge to enable the trapping and transferring of the photoinduced electrons to the nitrobenzene. This work provides a new perspective of utilizing the chemisorption between the reactant and catalyst to achieve a defect engineering strategy for synergetic photocatalysis.