Catalytic Preparation Research Articles

FSM-16/AEPC-SO3H: Synthesis, Characterization and Its Application for the Catalytic Preparation of 1,8-Dioxo-octahydroxanthene and Tetrahydrobenzo[b]pyran Derivatives

A new acidic mesoporous catalyst (FSM-16/AEPC-SO3H) was successfully synthesized and characterized by FT-IR, TGA, XRD, SEM, TEM, EDS and BET techniques. The FSM-16/AEPC-SO3H showed excellent catalytic activity for the synthesis of 1,8-dioxo-octahydroxanthene and tetrahydrobenzo[b]pyran derivatives. The synthesized catalyst can also be recycled.

Catalytic Preparation of Si3N4-Bonded SiC Refractories and Their High-Temperature Properties

Effects of Cr2O3 nanoparticles (NPs) on the catalytic nitridation of Si powders were investigated, and the results showed that the Cr2O3 NP catalysts enhanced the nitridation of Si powders and promoted the formation of Si3N4 whiskers. The complete conversion of Si was achieved at [1473 K (1200 °C)] for 3 hours with the addition of 3 wt pct Cr2O3 NPs. First-principle calculations suggested that the electron transfer from Cr2O3 to N2 molecules facilitates the Si nitridation. Moreover, Si3N4-bonded SiC refractories were also prepared using in-situ formed Cr2O3 NPs as catalysts, and the hot modulus of rupture at [1673 K (1400 °C)] of as-prepared refractories was about three times higher than that of samples without catalysts; the corrosion resistance against molten cryolite of the former was remarkably lower than that of the latter. The improvement was attributed to the catalytic effects of Cr2O3 NPs for in-situ formation of a fund of Si3N4 whiskers, which formed a network structure in the samples.

First Organocatalytic Asymmetric Synthesis of 1-Benzamido-1,4-Dihydropyridine Derivatives.

Preliminary results concerning the first asymmetric synthesis of highly functionalized 1-benzamido-1,4-dihydropyridine derivatives via the reaction of hydrazones with alkylidenemalononitriles in the presence of β-isocupreidine catalyst are reported. The moderate, but promising, enantioselectivity observed (40–54% ee), opens the door to a new area of research for the asymmetric construction of new chiral 1,4-dihydropyridine derivatives, whose enantioselective catalytic preparation are still very limited. Moreover, the use of hydrazones for the enantioselective construction of chiral 1,4-dihydropyridines has been overlooked in the literature so far. Therefore, our research represents a pivotal example in this field which remains still unexplored.

Synthesis of chiral \u03b1-trifluoromethyl alcohols and ethers via enantioselective Hiyama cross-couplings of bisfunctionalized electrophiles

Methods for synthesis of chiral organic compounds bearing trifluoromethyl-substituted stereocenters are of great interest for agrochemical and pharmaceutical labs and industries in their search for new bioactive materials. We report on employment of bisfunctionalized electrophiles, bearing both a trifluoromethyl and a functional group as direct substituents of the reactive center, in cross-coupling reactions. We exemplify this concept in the asymmetric synthesis of enantioenriched α-trifluoromethyl- and perfluoroalkyl-containing benzylic and allylic ethers and alcohols by nickel-catalyzed stereoconvergent Hiyama cross-coupling reaction. Substrate electrophiles are conveniently prepared in few steps from trifluoroacetic acid. The method represents a conceptually different approach to chiral CF3-substituted alcohols and ethers and allows for a rapid catalytic preparation of a wide range of these valuable compounds in high yields and enantioselectivity.

Efficient and stereodivergent synthesis of unsaturated acyclic fragments bearing contiguous stereogenic elements.

Synthetic organic strategies that enable the catalytic and rapid assembly of a large array of organic compounds possessing multiple stereocenters in acyclic systems are somewhat rare, especially when it comes to reaching today’s high standards of efficiency and selectivity. In particular, the catalytic preparation of a three-dimensional molecular layout of a simple acyclic hydrocarbon skeleton possessing several stereocenters from simple and readily available reagents still represents a vastly uncharted domain. Here, we report a rapid, modular, stereodivergent and diversity-oriented unified strategy to construct acyclic molecular frameworks bearing up to four contiguous and congested stereogenic elements, with remarkably high levels of stereocontrol and in only three catalytic steps from commercially available alkynes. A regio- and diastereoselective catalytic Heck migratory insertion reaction of alkenylcyclopropyl carbinols merging selective C–C bond cleavage of a cyclopropane represents the key step.

Tire-derived carbon for catalytic preparation of biofuels from feedstocks containing free fatty acids

The utilization of waste feedstocks rich in free fatty acids (FFAs) improves biofuel production on the basis of economics and sustainability. However, converting these feedstocks to usable biofuel poses inherent problems in terms of the FFA to biofuel conversion yield and the catalyst lifetime. Here, we report novel ferric sulfate impregnated carbon derived from waste tires as highly active catalysts for FFA to biofuel conversion. Our approach takes advantage of facile synthesis methods involving sonication and dehydration processes to create materials that are useful for the efficient catalytic conversion of FFAs to advanced biofuels. Esterification of FFAs to fatty acid methyl esters was achieved at 65 °C and atmospheric pressure with >98% yield even in the presence of triglycerides. These catalysts maintained similar activity after four successive uses, which indicates that the active catalytic sites are effectively supported by the three-dimensional meso/microporous architecture of the tire-derived carbon.

Metal silicates: efficient catalysts for the three-component preparation of 2-amino-5-oxo-4-aryl-4,5-dihydroindeno[1,2-b]pyran-3-carbonitrile derivatives

Abstract A highly efficient catalytic preparation of 2-amino-5-oxo-4-aryl-4,5-dihydroindeno[1,2-b]pyran-3-carbonitrile derivatives using different metal silicates was developed through a three-component reaction of malononitrile, aromatic aldehydes, and 1,3-indandione in high yields.

Inspired Preparation of Zinc Oxide Nanocatalyst and the Photocatalytic Activity in the Treatment of Methyl Orange Dye and Paraquat Herbicide

As the need to use green chemistry routes increases, environmentally friendly catalytic processes are a demand. One of the most important and abundant naturally occurring catalysts is chlorophyll. Chlorophyll is the first recognized catalyst; it is a reducing agent due to its electron-rich structure. The effects of spinach on the preparation of zinc oxide nanoparticles and the photocatalytic degradation of methyl orange and paraquat in sunlight and under a UV lamp and photocatalytic degradation in sunlight were studied. Different parameters of the catalytic preparation process and photocatalytic degradation process were studied. Characterization of differently prepared samples was carried out using different analytical techniques such as XRD, SEM, and EDX and finally the photocatalytic activity towards decomposition of methyl orange and paraquat.

Catalytic preparation of graphitic carbon spheres for Al2O3-SiC-C castables

Graphitic carbon spheres (GCS) with diameters of 0.37–0.39 µm were prepared via hydrothermal carbonization combined with catalytic graphitization using glucose and Ni nanoparticles (NPs) as respectively a carbon source and a catalyst. They were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The optimal conditions for graphitization of amorphous carbon spheres produced from hydrothermal carbonization of glucose were 3 h firing at 1200 °C with 1.0 wt% of Ni catalyst. Three model types of Al2O3-SiC-C castables using ball pitch, GCS and graphite flake were prepared and tested. Compared with that in the case of using ball pitch or flake graphite, the water demand in the case of using GCS was lower, the bulk density, modulus of rupture and crushing strength were higher, and the thermal shock resistance was better (owing to the high graphitization degree and high thermal conductivity of GCS).

Catalytic Preparation of Cyclic Carbonates from CO2 and Epoxides by Metal–Porphyrin and −Corrole Complexes: Insight into Effects of Cocatalyst and meso-Substitution

Extensive DFT calculations have been performed to elucidate the plausible mechanisms and effects of the cocatalyst and meso-substitution of the macro ring on the coupling reaction of CO2 with epoxide catalyzed by metal prophyrin and corrole complexes. Here the catalytic generation of cyclic carbonate from CO2 and epoxide by the Al–, Mg–, and Zn–porphyrin catalysts is predicted to follow a similar multistep mechanism, in which the ring-opening and -closure steps experience relatively high free energy barriers, while the CO2 insertion is facile. The computational results lend support to the remarkable catalytic role of a quaternary ammonium salt cocatalyst in the order PPNCl > PPNBr > PPNI. Introduction of the aryl and chlorinated aryl substituents on the porphyrin ligand reduces the electrophilicity of an aluminum center to some extent but remarkably enhances binding interactions among catalyst, cocatalyst, and reactant, which may facilitate the initial reaction. The ring-closure step is less influenced by...

Asymmetric Catalytic Preparation of Polysubstituted Cyclopropanol and Cyclopropylamine Derivatives

AbstractThe catalytic asymmetric carbometalation of cyclopropenes followed by either an electrophilic oxidation or amination reaction provides a unique approach to the formation of diastereomerically pure and enantiomerically enriched cyclopropanol and cyclopropylamine derivatives, respectively.

Asymmetric Catalytic Preparation of Polysubstituted Cyclopropanol and Cyclopropylamine Derivatives.

The catalytic asymmetric carbometalation of cyclopropenes followed by either an electrophilic oxidation or amination reaction provides a unique approach to the formation of diastereomerically pure and enantiomerically enriched cyclopropanol and cyclopropylamine derivatives, respectively.

Heat capacity and thermodynamic functions of silica-doped γ-Al2O3

Abstract Alumina can exist in a variety of structural phases, including the more common alpha and gamma phases. The gamma phase is particularly useful as a support material for catalysts, but compared to the alpha phase there is little thermodynamic data reported for it. Even less data are available for alumina prepared with dopants such as silica. These materials have improved thermal stability over their un-doped counterparts. This makes them especially useful in high temperature catalytic applications, and while they have been, in many regards, well characterized, gaps still exist in the available thermodynamic data. Additionally, water from synthesis conditions or catalytic preparation tends to bind to gamma phase alumina, further complicating thermodynamic data collection and analysis. We collected heat capacity data for a set of silica-doped alumina samples calcined at 300 °C (chemical formula Al2O3 0.089 SiO2 1.190 H2O), 600 °C (Al2O3 0.089 SiO2 1.027 H2O), 900 °C (Al2O3 0.089 SiO2 0.321 H2O), and 1100 °C (Al2O3 0.089 SiO2 0.187 H2O) using a Quantum Design Physical Properties Measurement System (PPMS). The data were fit to mathematical functions, and from these fits entropy, enthalpy, and Gibbs energy functions were calculated. The standard molar entropies for silica-doped alumina calcined at 300 °C, 600 °C, 900 °C, and 1100 °C are 101.69 J K−1 mol−1, 90.206 J·K−1·mol−1, 73.758 J·K−1·mol−1, and 66.444 J·K−1·mol−1 respectively.

In-situ catalytic preparation and characterization of SiC nanofiber coated graphite flake with improved water-wettability

Abstract SiC nanofiber coated graphite flake was fabricated at a relatively low temperature via a novel in-situ catalytic reaction route using Fe(NO 3 ) 3 ·9H 2 O as a catalyst precursor. The effects of catalyst content, firing temperature, and graphite/Si ratio on the formation of SiC nanofiber and water wettability of modified graphite were investigated. The in-situ formed Fe catalyst facilitated the formation of SiC nanofiber, and its optimal content was found to be 0.6–0.8 wt%. Single-crystalline SiC nanofibers with diameter in-situ Fe catalyst could be attributed to the increased bond length and weakened bond strength in CO (g) and SiO (g) molecules upon their adsorption onto the Fe catalyst. The water contact angle of SiC nanofiber-coated graphite could be reduced to as low as 6° within just 2.3 s contact time, indicating its substantially improved water wettability.

Cobalt-Catalyzed Silylcarbonylation of Unactivated Secondary Alkyl Tosylates at Low Pressure.

A catalytic preparation of silyl enol ethers from unactivated secondary alkyl tosylates is reported. An inexpensive cobalt catalyst is used under mild conditions with low pressures of carbon monoxide. Nucleophilic, anionic cobalt carbonyls facilitate the catalytic activation of a range of alkyl tosylates. The silylcarbonylation offers a practical approach to synthetically valuable silyl enol ethers from simple starting materials.

Polyhedral oligomeric silsesquioxane (POSS) containing sulfonic acid groups as a metal-free catalyst to prepare polycaprolactone

Organic-inorganic hybrid nano-building block of polyhedral oligomeric silsesquioxane (POSS) containing hyperbranched sulfonic acid groups was easily prepared within a day through oxidation reaction at room temperature. The desired product was fully characterized by 1H, 13C{1H} NMR, 29Si CP/MAS NMR, FT-IR spectroscopy, and TGA-DSC analysis, confirming the complete formation of sulphonic acids while retaining the cubic structure of silsesquioxanes cage. Furthermore, the proton exchange capacities of POSS catalyst were determined to be 5.39 meq of H+/g, much greater than any previous silicon-based materials, leading to the catalytic preparation of polycaprolactone with well-controlled polymerization under the metal-free system and without the addition of any co-catalysts and solvents.

Phosphonium salt and ZnX2–PPh3integrated hierarchical POPs: tailorable synthesis and highly efficient cooperative catalysis in CO2utilization

Phosphonium salt and ZnX2–PPh3integrated POPs have been successful synthesized and were employed in cooperative catalytic preparation of cyclic carbonates.

Atom Economic Ruthenium‐Catalyzed Synthesis of Bulky β‐Oxo Esters

AbstractRuthenium complexes with the formulae Ru(CO)2(PR3)2(O2CPh)2 [6a–h; R=n‐Bu, p‐MeO‐C6H4, p‐Me‐C6H4, Ph, p‐Cl‐C6H4, m‐Cl‐C6H4, p‐CF3‐C6H4, m,m′‐(CF3)2C6H3] were prepared by treatment of triruthenium dodecacarbonyl [Ru3(CO)12] with the respective phosphine and benzoic acid or by the conversion of Ru(CO)3(PR3)2 (8e–h) with benzoic acid. During the preparation of 8, ruthenium hydride complexes of type Ru(CO)(PR3)3(H)2 (9g, h) could be isolated as side products. The molecular structures of the newly synthesized complexes in the solid state are discussed. Compounds 6a–h were found to be highly effective catalysts in the addition of carboxylic acids to propargylic alcohols to give valuable β‐oxo esters. The catalyst screening revealed a considerably influence of the phosphine′s electronic nature on the resulting activities. The best performances were obtained with complexes 6g and 6h, featuring electron‐withdrawing phosphine ligands. Additionally, catalyst 6g is very active in the conversion of sterically demanding substrates, leading to a broad substrate scope. The catalytic preparation of simple as well as challenging substrates succeeds with catalyst 6g in yields that often exceed those of established literature systems. Furthermore, the reactions can be carried out with catalyst loadings down to 0.1 mol% and reaction temperatures down to 50 °C.magnified image

A Catalytic SE Ar Approach to Dibenzosiloles Functionalized at Both Benzene Cores.

A general procedure for the catalytic preparation of dibenzosiloles functionalized at one or both benzene rings starting from readily available ortho-silylated biphenyls is reported. This method provides rapid access to silole building blocks substituted with chlorine atoms at both phenylene groups, thereby allowing catalytic access to directly polymerizable dibenzosiloles. Moreover, it is shown that, despite the involvement of highly electrophilic intermediates, a considerable range of Lewis-basic, for example, oxygen- and nitrogen-containing, functional groups is tolerated. The mechanism of this intramolecular electrophilic aromatic substitution (SE Ar) proceeds through a sulfur-stabilized silicon cation, generated catalytically from the hydrosilane precursor.

ChemInform Abstract: Recent Advances in the Catalytic Preparation of Cyclic Organic Carbonates

AbstractReview: 101 refs.