Replication of SMSI via ALD: TiO<Subscript>2</Subscript> Overcoats Increase Pt-Catalyzed Acrolein Hydrogenation Selectivity

The effects of sub-nanometer atomic layer deposition films of titania and alumina are compared for the acrolein hydrogenation selectivity of Pt/SrTiO₃ catalysts. The titania-overcoated catalyst is similar to strong metal-support interaction catalysts formed by high temperature reduction, with a thin titania film on top of the supported Pt nanoparticles and an increase in allyl alcohol selectivity, neither of which are observed for the alumina-overcoated catalyst.

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Reaction Profiles of High Silica MOR Zeolite Catalyzed Friedel–Crafts Acylation of Anisole Using Acetic Anhydride in Acetic Acid

Friedel–Crafts reaction of anisole over high silica mordenite zeolite was investigated. Detailed reaction profiles were obtained using various reaction conditions. In particular, the behavior of acetic anhydride during the reaction and the effect on the hydrophilicity of the mordenite zeolite catalyst were investigated.

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Increased Dispersion of Nickel Particles Supported on Activated Carbon by Treating with Methyl Iodide

A novel method dispersing nickel in fine particles on activated carbon (AC) was proposed in this study. The nickel particles with 2.2 nm average diameter supported on AC were obtained through re-dispersing the nickel particles by treating with methyl iodide under atmospheric pressure. High dispersion of nickel particles promoted the activity for methanol vapor-phase carbonylation over Ni/AC catalyst.

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Hen Egg White Lysozyme Catalyzed Efficient Synthesis of 3-Indolyl-3-hydroxy Oxindole in Aqueous Ethanol

A green synthesis of 3-indolyl-3-hydroxy oxindoles was reported using hen egg white lysozyme (HEWL) in an aqueous ethanol. The HEWL promotes this reaction efficiently from various isatins and indoles under mild reaction conditions with yields up to 98% bearing good adaptability to varied substrates in the reaction. This conversion has provided a new strategy to synthesize 3-indolyl-3-hydroxy oxindole derivatives employing biocatalytic promiscuity of less explored lysozyme. Based on the experimental studies, the plausible reaction mechanism is proposed.

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Gold Nanoparticles-Decorated Dithiocarbamate Nanocomposite: An Efficient Heterogeneous Catalyst for the Green A<Superscript>3</Superscript>-Coupling Synthesis of Propargylamines

Gold nanoparticles decorated magnetic dithiocarbamate nanocomposite (Au@CS₂–AP@Fe₃O₄) led to a suitable catalyst for the propargylamines synthesis via A³-coupling reaction in water. The prepared catalyst was characterized by Fourier-transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, atomic absorption spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy measurements.

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Early Transition Metal Doped Tungstite as an Effective Catalyst for Glucose Upgrading to 5-Hydroxymethylfurfural

Glucose valorization to 5-hydroxymethylfurfural (HMF) remains challenging in the transition towards renewable chemistry. Lewis acidic tungstite is a viable, moderately active catalyst for glucose dehydration to HMF. Literature reports a multistep mechanism involving Lewis acid catalyzed isomerization to fructose, which is then dehydrated to HMF by Brønsted acid sites. Doping tungstite with titanium and niobium improves activity by optimizing the ratio between Lewis and Brønsted acid sites.

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β-Cyclodextrin Based Nanosponge as a Biodegradable Porous Three-Dimensional Nanocatalyst in the One-Pot Synthesis of N- Containing Organic Scaffolds

The motivation behind the present study was to develop an application of β-cyclodextrin-based nanosponges with the tiny mesh-like structure as porous three-dimensional nanocatalyst in the one-pot three component condensations of various aromatic aldehydes with activated methylene compounds such as dimedone, thiobarbituric acid, 4-hydroxycoumarin, 4-hydroxy-6-methyl-2-pyrone and nucleophiles including indole and amines. This nanosponge catalyst afforded the privileged N- containing organic scaffolds as key intermediates in pharmaceutical chemistry in very short reaction times.

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PhI-Catalyzed Intramolecular Oxidative Coupling Toward Synthesis of 2-Amino-1,3,4-Thiadizoles

A highly efficient method for the synthesis of thiadiazole derivatives via intramolecular oxidative coupling of thiosemicarbazide, using the in situ generated hypervalent iodine(III) reagents is developed. The protocol can be carried out smoothly and provides a variety of thiadiazole derivatives in moderate to excellent yields.

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A highly efficient method for the synthesis of thiadiazole derivatives via PhI-catalyzed intramolecular oxidative coupling of thiosemicarbazide has been developed.

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[Zn(<Emphasis Type="SmallCaps">l</Emphasis>-proline)<Subscript>2</Subscript>] Catalyzed One-Pot Synthesis of Propargylamines Under Solvent-Free Conditions

A simple, one-pot, three-component, green synthesis of a wide range of propargylamines is reported by A³-coupling (aldehyde, alkyne and amine) via C–H activation of alkynes using [Zn(l-proline)₂] as an efficient and reusable heterogeneous catalyst. High catalytic activity was achieved in comparatively low temperature under solvent-free conditions. All reactions were carried out in an open atmosphere without the use of any co-catalyst/additive.

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Strontium Doped MCM-41: A Highly Efficient,Recyclable and Heterogeneous Catalyst for the Synthesis of Phenoxy Pyrazolyl Pyrazolines

Strontium doped MCM-41 (Sr-MCM-41) has been synthesized as an efficient, heterogeneous and recyclable catalyst. The catalyst, Sr-MCM-41 is characterized by various techniques such as FTIR, SEM, EDX, elemental Mapping, TEM, TGA, BET, XRD, XPS and ICP-AES analyses. The catalytic activity of the catalyst (Sr-MCM-41) has been explored by synthesizing a library of phenoxy pyrazolyl pyrazoline derivatives in excellent yield (96–98%) under microwave irradiation (3–5 min) using ethanol as solvent. The catalyst could be recycled upto five cycles.

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A Comparative Study of the Photoconduction,Photocatalytic and Electrocatalytic Performance of g-C<Subscript>3</Subscript>N<Subscript>4</Subscript>/ZnS/CuS Heterojunctions with Different Morphologies

Ternary heterojunctions g-C₃N₄/ZnS/CuS with different morphologies were constructed. The g-C₃N₄/ZnS/CuS (hexagonal-nanosheets) exhibited the largest photocurrent, the best photocatalytic and electrochemical activity, which revealed the influence discipline of different morphologies on photoconductivity, photo/electro-catalytic activity. It indicated that this heterojunction can be used as an excellent photoconductor device, a high-efficiency photo/electro-catalyst.

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Magnetic Nanoparticle-Supported Cu–NHC Complex as an Efficient and Recoverable Catalyst for Nitrile Hydration

Magnetic nanoparticles supported N-heterocyclic carbene–Cu complex was prepared and authenticated by FT-IR, SEM, EDX, VSM, powder-XRD. The catalytic activity of these magnetically retrievable NPs was investigated for hydration of nitriles as the simplest route for the synthesis of amides in an atom-economical manner. A wide range of nitriles containing various functional groups such as olefin, aldehyde, nitro, carboxylic acid was examined in this transformation to generate their corresponding amides in the aqueous medium. The immobilized catalyst was easily recovered using an external magnet and reused for six times without significant loss of its catalytic activity.

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Zr-Modified SBA-15 Supported Ni Catalysts with Excellent Catalytic Performance of CO Selective Methanation in H<Subscript>2</Subscript>-Rich Fuels

CO selective methanation is a promising route for the purification of CO in H₂-rich gas for on-board H₂-based fuel cells. Herein, we synthesized a Zr-modified SBA-15 supported Ni catalyst, which exhibits both high catalytic performance, deep-removing CO concentration to below 10 ppm with a selectivity higher than 50% in a very low-temperature range (170–220 °C), and long-term stability. The results of XRD, XPS, TPR, TPD and TEM characterizations reveal that the doping of Zr not only improves the dispersion of Ni species, enhances the CO adsorption, but also suppresses the CO₂ adsorption, resulting in the prominent catalytic performance.

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Higher Alcohol Synthesis Over Rh Catalysts: Conditioning of Rh/N-CNTs by Co and Mn Entrapped in the Support

Abstract

Rh nanoparticles supported on commercial non-purified N-doped CNTs (NCNTs) containing residual CNT growth catalyst have been studied in hydrogenation of CO to higher alcohols. It has been found that Co and Mn residues in NCNTs are not inert, but change the catalyst under reaction conditions and efficiently promote the catalyst resulting in both increasing activity and selectivity to C₂₊ alcohols with time on stream.

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Biomimetic Cleavage of Aryl–Nitrogen Bonds in <Emphasis Type="Italic">N</Emphasis>-Arylazoles Catalyzed by Metalloporphyrins

The cleavage of C–N single bonds of N-containing compounds provides either an excellent nitrogen source or an excellent carbon source. In this study, an efficient metalloporphyrins/H₂O₂ cleavage of C–N bonds of arylpyrazoles was investigated. The effects of different factors, including different catalysts, catalyst dosages, H₂O₂ dosages, reaction temperature and reaction time were studied. The experimental results showed that the optimal catalyst was FeTPPCl, and the yield of pyrazole derivatives could reach up to 12.3%, which was fourfold higher than hemin catalyzed reaction and closed to ceric ammonium nitrate catalyzed reaction, respectively. Compared with transition-metal-catalyzed and strong-oxidization cleavage of C–N bonds, this protocol is characterized by environmentally-friendly, stable, mild reaction conditions and simplified operation procedures.

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Palladium-Catalyzed Direct Ortho C–O bond construction of Azobenzenes with Iodobenzene diacetate via C–H Activation

Abstract

A method of direct synthesis of ortho-acyloxylated azoarenes via palladium-catalyzed C–H bond activation was developed. The reaction proceeded was smoothly at room temprature and have better yield in shorter times. The obtained ortho-acyloxylated azoarenes could be efficiently converted into 2-hydroxyazobenzenes in good yields through a hydrolysis process.

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Many various ortho-acyloxylated azoarenes were obtained in moderate to high yields by palladium-catalyzed direct C(sp²)-H acyloxylation of aromatic azo compounds with PhI(OAc)₂

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Improvement of Activity and Thermostability of Agar-Entrapped,Thermophilic, Haloalkaliphilic Amylase AmyD8

An extremophilic amylase from Alkalilimnicola sp. NM-DCM-1 was expressed and purified. The amylase, AmyD8, was extremophilic, with maximal activity at 55 °C, pH 10.5 and 2.4 M NaCl. AmyD8 had a broad substrate utilization spectrum, hydrolyzing branched and linear substrates. AmyD8 was stable and active in nonionic and anionic surfactants. AmyD8 was organic solvent resistant, retaining activity after incubation in benzene, methanol, ethanol and isopropanol. AmyD8 was entrapped in an agar–agar matrix with 89% entrapment yield and no loss in relative activity. Entrapped AmyD8 retained its extremophilic properties. Entrapment enhanced AmyD8’s thermal stability, the half-life of the entrapped enzyme nearly doubled after incubation at 50–65 °C. Entrapped AmyD8 had excellent recyclability, retaining 58% of initial activity after 16 hydrolysis cycles. These extreme properties give AmyD8 great economic feasibility.

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Promotional Influence of Hydroxyl Complexing Agent on Ethanol Synthesis from Syngas Over CuZnAl Catalysts Without Other Metal Promoters

Ternary CuZnAl catalysts promoted with three kinds of hydroxyl complexing agents were prepared by a complete liquid-phase method and tested for ethanol synthesis from syngas in a slurry bed reactor. The catalysts were characterized by XRD, H₂-TPR, NH₃-TPD, N₂ adsorption, XPS and TEM techniques. Activity results showed that ethanol selectivity enhanced significantly after the addition of hydroxyl complexing agents. Overall, the catalyst promoted by ethanolamine exhibited the best catalytic performance, with the concentration of ethanol and higher alcohols in the total alcohols reached up to 56.5% and 75.1%, respectively. The addition of hydroxyl complexing agents caused the reduction temperature of Cu⁺ shifted to be higher and the amount of weak acid sites to be decreased. It also favored the formation of AlOOH and Cu particles with larger particle size. These factors together contributed to the remarkable selectivity of ethanol and higher alcohols.

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Self-Oscillations During Ethylene Oxidation Over a Ni foil

Oscillatory behavior during ethylene oxidation over a Ni foil has been discovered in the temperature range of 600–800 °C. The oscillatory behavior occurred in C₂H₄ excess in contrast to the well-known oscillations during C₂H₄ oxidation over Pt and Rh. The periodic variation in oxygen imbalance together with in situ TGA measurements and the variation in color during the oscillations indicate that the oscillations are closely connected with reversible oxidation of Ni to NiO. The observation of oscillations in pulse supply mode prove also important role of periodic carbon deposition/removal. A characteristic feature of the oscillations during ethylene oxidation is high sensitivity of the oscillation waveform to the catalyst temperature. The oscillations were accompanied by propagation of the oxidation and reduction fronts which could be observed with the naked eye.

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Insight into Stereo-Induction by Minor Modification in the Ligand in DNA-Based Hybrid Catalysis

A pair of bisbenzimidazole derivatives as catalytic ligand was evaluated in DNA-based hybrid asymmetric reaction. Similar structure of both ligands induced entirely different stereoselectivity in Diels–Alder reaction and Friedel–Crafts alkylation. The binding mode of the two Cu²⁺ complexes to st-DNA was elaborated by circular dichroism, UV–vis, IR, Raman spectroscopy, and singular value decomposition analysis. The coordination mode of ligand to Cu²⁺ substantially impacted on dominant conformation of complex. The major binding mode depended on the steric chemistry of complex, directly regulating chiral microenvironment in hybrid catalytic system. Although the title ligand did not present considerable enantioselectivity in catalysis, the current research provided a feasible approach to insight into catalytic microenvironment of chiral scaffold. It will help to reveal the mechanism of stereo-induction in DNA-based hybrid asymmetric reaction.

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