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An improved palladium-catalyzed system is established for the synthesis of 3,4-dihydro-3-oxo-2 H -1,4-benzoxazines from less reactive ethyl 2-(2-chlorophenoxy)alkanoates and aryl amines under controlled microwave heating, employing 2-dicyclohexylphosphino-2′,4′,6′-triisopropylbiphenyl (XPhos) as the ligand. Moreover, a high-yielding, three-component reaction protocol is disclosed for the efficient one-pot synthesis of 3,4-dihydro-3-oxo-2 H -1,4-benzoxazines from 2-halophenols, ethyl 2-bromoalkanoates, and aryl amines. Microwave heating at high temperature is necessary to achieve high yields with 2-chlorophenol. A wide range of substrates is tolerated affording the desired products in good to excellent yields.

The mechanisms of nitrogen- and phosphorus-centered nucleophile promoted thiol–vinylsulfone Michael addition reactions have been studied by theoretical calculations. It is found that the trimethylamine-promoted thiol–vinylsulfone Michael addition proceeds by the base-catalyzed mechanism, in which the attack of the methanethiolate–trimethylammonium ion pair at divinylsulfone is the rate-limiting step. Comparison of different types of nitrogen-centered nucleophiles suggests that the aliphatic amine-promoted reactions undergo the base-catalyzed mechanism whereas the aza-aromatic compound-promoted reactions undergo the nucleophile-initiated mechanism. The trimethylphosphine-promoted thiol–vinylsulfone Michael addition is found to proceed via the nucleophile-initiated mechanism, in which the attack of trimethylphosphine at divinylsulfone is the rate-limiting step. An amine is superior to an organophosphine for the base-catalyzed mechanism because of its stronger basicity. On the other hand, an organophosphine tends to undergo the nucleophile-initiated mechanism more easily than an amine because phosphorus can stabilize the charged intermediates.

Crystalline mesoporous γ-Al2O3 has been successfully synthesized under high temperature hydrothermal conditions and used as an excellent support for Pd(OAc)2. The resulting γ-Al2O3–Pd showed excellent catalytic activity for Suzuki–Miyaura cross-coupling reaction. As low as 0.2 mol% loading of Pd was needed to obtain cross-coupling products in good to excellent yields in aqueous DMF under microwave irradiation. Moreover, the novel catalyst can be easily recovered by filtration and reused without any diminishing observable activity after five runs.

The novel solid acidic ionic liquid polymer has been synthesized through the copolymerization of acidic ionic liquid oligomers and divinylbenzene (DVB). The catalytic activities were investigated through the biodiesel synthesis from waste oils. The results showed that the PIL was very efficient for both the transesterification of triglycerides and esterification of free fatty acids with the yield of 99.0%. The procedure was quite simple with just one-step to complete both the reactions under mild reaction conditions. The high hydrophobic BET surface, high catalytic activities and high stability were the key properties of the PIL.

Cyclization is an important chemical reaction for the dipeptides containing N-alkyl groups. The cyclization mechanism has been examined by theoretical calculations. Our calculation results indicate that the most favorable mechanism is the piperidine-catalyzed stepwise mechanism, in which piperidine acts as a proton shuttle. The attack of the N-terminal amino nitrogen at the C-terminal carbonyl carbon along with the proton transfer is the rate-limiting step. The effect of the alkyl substituent on the amide N on the cyclization reaction was then examined. Finally, the influence of the solvation effect, electronic effect and steric effect on the cyclization was investigated. It is found that all of these effects contribute to the cyclization.

Palladium-catalyzed Hiyama-type cross-coupling reactions of various arenesulfinates with organosilanes were achieved in good to excellent yields under aerobic conditions at 70 °C. Fluoride is essential, and tetrabutylammonium fluoride (TBAF) was shown to be the most efficient additive for these cross-coupling reactions. These cross-coupling reactions of the arenesulfinates provide high yields and show wide functional group tolerance, making them attractive alternative transformations to traditional cross-coupling approaches for carbon-carbon bond construction.

Pearl shells are the main waste of the pearl industry, which discards millions of tons of pearl shells each year in China. To date, the use of pearl shells in the complete oxidation of volatile organic compounds (VOCs) has not been reported. In this paper, shell powder (SP) was used as a carrier for ceria and Pd catalysts for the complete oxidation of benzene. The influence of the ceria promoter on the texture/structure and catalytic performance of Pd/SP was investigated. The results show that adding ceria into the SP support increased the BET surface area and total pore volume and decreased the sinterability of SP. The catalytic activity and H 2 temperature-programmed reduction (H 2 -TPR) results show that adding ceria can greatly improve the oxidation properties of Pd/SP catalysts and enhance the catalytic activity for the complete oxidation of benzene. The improvement in the catalytic activity is mainly due to the optimization of the catalyst texture/structure and redox properties by the strong interaction of Pd and ceria and the addition of ceria.

In this study, polyethylene glycol (PEG) with different molecular weight, polyvinyl pyrrolidone (PVP), and polyvinyl alcohol (PVA), are chosen as porogens for preparing chitosan base porous microsphere supported palladium catalyst for coupling reactions. The pore structure of the microspheres was controlled by the compatibility of chitosan and counterpart polymers. The prepared porous chitosan microspheres supported palladium heterogeneous catalysts have been evaluated using the well-established Ullmann reductive homocoupling and the Heck cross-coupling reactions. The activities, stabilities and recyclability of the porous chitosan microspheres supported palladium catalysts are not only highly dependent upon the surface areas of the solid supports, but also upon the chemical properties of the water-soluble polymers. The degradation of the prepared heterogeneous palladium catalysts is mainly caused by a combination of the palladium leaching and the morphological transformation of the palladium species from the amorphous into the crystals.

In this study, a heterogeneous catalyst including palladium nanoparticles supported on nitrogen-doped mesoporous carbon (Pd@N-C) is synthesized from palladium salts as palladium precursor, colloidal silica as template, and chitosan as carbon source. N2 sorption isotherm results show that the prepared Pd@N-C had a high BET surface area (640m(2)g(-1)) with large porosity. The prepared Pd@N-C is high nitrogen-rich as characterized with element analysis. X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HR-TEM), and Raman spectroscopy characterization of the catalyst shows that the palladium species with different chemical states are well dispersed on the nitrogen-containing mesoporous carbon. The Pd@N-C is high active and shows excellent stability as applied in Heck coupling reactions. This work supplies a successful method to prepare Pd heterogeneous catalysts with high performance from bulk biopolymer/Pd to high porous nitrogen-doped carbon supported palladium catalytic materials.

A simple and efficient protocol has been developed for the synthesis of various symmetrical biaryls in good to excellent yields from the homocoupling reactions of arenediazonium salts with ferrous salt in carbon tetrachloride solution under mild reaction conditions. Moreover, the novel homocoupling has been demonstrated to proceed via an electron transfer reaction mechanism.

A SO3H-bearing nanofiber mat was synthesized and investigated as a novel heterogeneous acid catalyst. Preoxidated polyacrylonitrile nanofiber mat was prepared via electrospinning and heat treatment, and then reacted with chlorosulfuric acid to introduce the sulfonic groups. The nanofiber mat owned high acidity of 2.99 mmol/g. The preoxidation and sulfonation were examined by FT-IR spectroscopy, elemental analysis and X-ray diffraction spectroscopy (XRD). The fiber morphologies were characterized by scanning electron microscopy (SEM). The catalytic activities and reuse of the prepared nanofiber mat solid acid catalyst have been evaluated for the acetalization and esterification. The regular fiber mat structure could significantly facilitate the recovery and reuse of the catalyst. The excellent catalytic performance and easy recycling made the novel fiber mat solid acid hold great potential for the green chemical processes.

Mesoporous polydivinylbenzene (PDVB) based solid acid of PDVB-SO 3 H- x s have been successfully synthesized from sulfonation of superhydrophobic PDVB. Characterizations including FT-IR spectra, N 2 isotherms and element analysis showed that PDVB-SO 3 H -x s had high BET surface areas and adjustable contents of active site. Liquid-adsorption tests showed that PDVB-SO 3 H -x s exhibited much higher adsorption capacities for various organic compounds than those of H 3 PO 40 W 12 , S-ZrO 2 , SBA-15-SO 3 H and Amberlyst 15. Interestingly, PDVB-SO 3 H -x s showed better catalytic activities and recyclability towards transesterification to biodiesel than those of Amberlyst 15, Nafion NR50 and SBA-15-SO 3 H, which will be potentially important for their widely applications for producing of biodiesel in industry.

This article present results on the preparation, characterization, and application of fibrous polymer mat–supported Fe(III) mesotetraphenylporphyrin (FeTPP)/TiO2 photocatalysts for the photodegradation of azo-dyes. Scanning electron microscope results showed that the mean diameters of FeTPP/TiO2/polymer mats were in the range of 246.0–305.6 nm. Photocatalytic activities of these hybrid nanofibers were evaluated by the photocatalytic degradation of methyl orange in an aqueous environment under the visible light irradiation. Results showed that chlorinated polyvinyl chloride and poly(styrene) (PS) fibrous mats were the two best supporting materials for the FeTPP/TiO2 photocatalyst. PS fibrous mats supported the fact that the FeTPP/TiO2 photocatalyst (FeTPP/TiO2/PS mat) could degrade methyl orange up to 98.5% in 5 h. Furthermore, the FeTPP/TiO2/PS mat also exhibited high and stable photocatalytic activity toward four other azo-dyes. The FeTPP/TiO2/PS mat might find application in the preparation of ...

Mesoporous titanium dioxide with crystalline mesopore walls (M-TiO2-ns) have been successfully synthesized through the self-assembly of poly 4-Vinylpyridine template and tetrabutyl titanate precursor based on their complex bond interaction under high temperature (180 °C) hydrothermal conditions. X-ray diffraction shows that M-TiO2-ns have highly crystalline mesopore walls with anatase phase characters; N2 sorption–desorption isotherms, SEM and TEM images show that M-TiO2-ns have high BET surface areas (85 and 120 m2/g, respectively), large pore volumes (0.32 and 0.34 cm3/g, respectively) and crystalline mesopore walls, which exhibit monolithic morphology with crystal sizes around 3–5 μm. Interestingly, M-TiO2-ns exhibit much higher catalytic activities and good recyclability in both induced reduction of decabromodiphenyl and oxidation of Rhodamine B under UV light than those of nonporous crystalline TiO2 and M-TiO2 templated by hydrocarbon surfactant of F127, which is even comparable with that of commercial P25. Combination of the unique characters such as crystallinity, stable mesostructure, large BET surface areas and superior photo catalytic activities make M-TiO2-ns a kind of potentially important material for removing of organic pollutions in environment through green photo irradiation processes.

Electrospinning has been employed to fabricate uniform polyacrylonitrile and polyacrylonitrile copolymer nanofiber mats supporting metalloporphyrins (MTPP; M: Zn(II), Cu(II), Ni(II), Co(II), Fe(III) and Pd(II); TPP: meso-tetraphenylporphyrin). The nanofiber mat-supported metalloporphyrins are shown as efficient photocatalysts for the degradation of various azo-dyes in aqueous solutions under visible light irradiation. The effect of transition metals on azo-dye photodegradation has been examined. The nanofiber mat-supported copper–porphyrin and iron–porphyrin complexes are among the most effective photocatalysts for azo-dye degradation. Immobilization of the metalloporphyrins onto the nanofiber mats greatly facilitates the recovery and reuse of the expensive and toxic photocatalysts. Most interestingly, there are no significant degradations of the photocatalytic activities of the recycled photocatalysts. © 2012 Society of Chemical Industry

Novel solid acid based on carbon/silica composites are synthesized through one-pot hydrothermal carbonization of hydroxyethylsulfonic acid, sucrose and tetraethyl orthosilicate (TEOS). The novel solid acid owned the acidity of 2 $\boldsymbol{\cdot}$ 0 mmol/g, much higher than that of the traditional solid acids such as Nafion and Amberlyst-15 (0 $\boldsymbol{\cdot}$ 8 mmol/g). The catalytic activities of the solid acid are investigated through acetalization. The results showed that the novel solid acid was very efficient for the reactions. The high acidity and catalytic activities made the novel carbon/silica composites based solid acid hold great potential for the green chemical processes.

Magnetically active and SO3H-functionalized ordered mesoporous resin and carbon (MOMR-SO3H, MOMC-SO3H) were successfully prepared by high-temperature hydrothermal synthesis from resol, copolymer surfactant, and iron cations at 180 °C, followed by sulfonation from sulfuric acid fuming. X-ray diffraction patterns show that MOMR-SO3H and MOMC-SO3H have ordered hexagonal mesoporous symmetry. N2 isotherms indicate that these samples have uniform and opened mesopores, high surface areas (335–591 m2/g), and large pore volumes (0.34–0.35 cm3/g). Transmission electron microscopy shows that iron nanoparticles, which are superparamagnetic in nature, are highly dispersed in MOMC-SO3H sample. Catalytic tests show that MOMC-SO3H is highly active and excellently recyclable in esterification of acetic acid with butanol, esterification of acetic acid with cyclohexanol, and condensation of benzaldehyde with ethylene glycol. More interestingly, MOMC-SO3H catalyst is magnetically active, showing potential applications for separating catalysts by a magnetic field in the future.

In present work, adsorption/desorption and catalytic oxidation of three common volatile organic compounds on Na-montmorillonite, Al and AlCe pillared clays supported Pd catalysts, were investigated. The results showed that after pillaring, S BET , V micro and V meso of clays were obviously increased, which then improved the Pd dispersion. Catalysts with suitable amount and strength of acidity are fit for VOC adsorption and deep oxidation. VOC adsorption/desorption and catalytic activity results showed that catalysts with high S BET , large pore volume and suitable acidity can adsorb more VOCs, and exhibit better catalytic activity for VOC deep oxidation.

Porous chitosan microspheres (PCMS) were prepared from crosslinking chitosan/polyethylene glycol (PEG) interpenetrating microspheres through selective dissolution of the water-soluble PEG component for the immobilization of palladium catalyst. The resultant Pd/PCMS supported palladium has been demonstrated as a highly active and easily recyclable heterogeneous catalyst for the Ullmann-type reductive homocoupling of aromatic halides and the Heck cross-coupling of aromatic halides with acrylates. Most interestingly, the prepared Pd/PCMS heterogeneous palladium catalyst can also be employed in the environmentally-benign aqueous solution due to the highly hydrophilic hydroxyl and amino functional groups of chitosan. The large size of the microsphere structure can greatly facilitate separation and recycling of the expensive and toxic palladium catalysts from the reaction mixture and the recovered Pd/PCMS catalyst can preserve the catalytic activity and selectivity for the Heck reaction without any observable degradation over ten recycling times. The high activity and stability of the Pd/PCMS catalyst have been attributed to a combination of the high specific surface area of the porous structure as well as the strong chelation of palladium species with the abundant chitosan surface hydroxyl, amino and carbonyl functional groups.

Density function calculations were carried out to investigate the mechanism of the Ni-catalyzed N-butenyl-substituted imidazolium salt annulation reaction. The results indicate that the reaction proceeds along the proposed oxidative addition–insertion-reductive elimination mechanism while some steps could be combined in specific pathways. The most favored pathway starts with oxidative addition, followed by coordination of the C C double bond to Ni(II), and finishes by direct reductive elimination to generate the 5-membered fused-ring product. The direct reductive elimination step is rate limiting. The origin of the regioselectivity is attributed to the coordination of the C C double bond to Ni(II) after oxidative addition which is the initial key divergence to give different products. The intermediate ready for insertion and reductive elimination to form the 6-membered fused-ring product has a significantly higher energy than that ready for direct reductive elimination to form the 5-membered ring, leading to the lack of the necessary intermediate for the formation of the 6-memebered ring product.

Novel excellent hydrophobic- mesoporous- polymer-based solid acid catalysts have been successfully synthesized by copolymerization of divinylbenzene (DVB) with sodium p-styrene sulfonate (H-PDVB-x-SO3H's) under solvothermal conditions. N2 isotherms and TEM images showed that H-PDVB-x-SO3H's have high BET surface areas, large pore volumes, and abundant mesoporosity; CHNS element analysis and acid–base titration technology showed that H-PDVB-x-SO3H's have adjustable sulfur contents (0.31–2.36 mmol/g) and acidic concentrations (0.26–1.86 mmol/g); TG curves showed that H-PDVB-x-SO3H's exhibited much higher stability of the active site (372 °C) than that of the acidic resin of Amberlyst 15 (312 °C); contact angle and water adsorption tests showed that H-PDVB-x-SO3H's exhibited excellent hydrophobic properties. Catalytic tests in esterification of acetic acid with cyclohexanol, esterification of acetic acid with 1-butanol, and condensation of benzaldehyde with ethylene glycol showed that H-PDVB-x-SO3H's were mo...

Iodides are most suitable as substrates if the ester side chain bears an active methylene group.

A novel polyacrylonitrile hybrid fiber mat supported solid acid catalyst was prepared by electrospinning, and its catalytic activities were carefully investigated through acetalization reactions. The results showed that this hybrid fiber mat exhibits high activity for the reactions, with average yields over 95%. Besides having catalytic activities similar to the solid acid, the heterogeneous solid acid/polyacrylonitrile mat can be reused in six runs without significant loss of catalytic activities. The large size of the hybrid fiber mat greatly facilitates recovery of the catalyst from the reaction mixture. The high and stable catalytic activities of the hybrid fiber mat hold great potential for green chemical processes and preparation of membrane reactors in the future. .

A Pd-catalysed cascade protocol, consisting of intermolecular O-alkylation and spontaneous intramolecular amidation, has been established for efficient synthesis of 2 H-1,4-benzoxazin-3-(4 H)-ones from o-halophenols and 2-chloroacetamides. A varity of substrates afford the desired products in good to excellent yields. It is particularly attractive for synthesis of a library of 2 H-1,4-benzoxazin-3-(4 H)-ones.

Nanoporous poly(vinyl alcohol) (PVA) nanofiber mats prepared by means of electrospinning have been used for the immobilization of palladium catalyst. Thermal treatment of the palladium-loaded PVA nanofiber mats results in the cross-linking of the matrix PVA molecules as well as the reduction of the divalent palladium (Pd2+) into zerovalent palladium (Pd0) species. The palladium oxidation states were examined by X-ray photoelectron spectroscopic (XPS) analysis. The PVA nanofiber morphology was characterized by scanning electron microscopy (SEM). The catalytic activity and recyclability of the prepared heterogeneous palladium catalysts have been evaluated for the Ullmann, Heck–Mizoroki and Sonogashira coupling reactions of aromatic halides. The large structure of the Pd/PVA nanofiber mats can greatly facilitate its separation and recycling, and the high catalytic activity and stability of the prepared Pd/PVA nanofiber mats have been attributed to the chelation of palladium species with the abundant hydroxyl functional groups on the PVA matrix surface area.

A concise first total synthesis of 4-epi-phomonol has been accomplished in 6 steps and 33% overall yield from (R)-1,2-epoxypentane. The key features of the synthesis include an application of protecting-group-free strategy, a prins cyclization to install the tetrahydropyran ring, and a substrate-controlled dihydroxylation to fix the stereocenters at the C3 and C4 positions.

An experimental approach was developed to determine the intrinsic thermolysis rate constants of the central carbon–carbon bond during the dl/meso isomerization of diethyl 2,3-dicyano-2,3-di(p-substituted phenyl)succinates (G=H, Me, OMe, Cl, and NO2) at temperatures ranging from 80 to 120 °C. The obtained rate constants are significantly affected by the polarity of the para substituents, in sharp contrast to their negligible effects on the dl/meso isomerization equilibrium constants. Moreover, the substituent effects on the activation enthalpies can be linearly correlated with the Hammett substituent resonance constants and the homolytic dissociation enthalpies (bond dissociation energies) of the benzylic C–H bonds of ethyl 2-cyano-2-(p-substituted phenyl)acetates. Copyright © 2011 John Wiley & Sons, Ltd.

Palladium and cerium oxide promoted Co/Al2O3 catalysts were prepared and used for oxidation of benzene. Influence of Pd, Ce and Co/Ce molar ratios on the properties and catalytic performance was investigated. The results indicated that addition of palladium and cerium oxide could provide active oxygen species to cobalt oxide and make Co3O4 particles better dispersed on Al2O3, thus enhancing oxidation ability of the catalyst. High catalyst activity is mainly attributed to better dispersed Co3O4 on Al2O3, smaller Co3O4 crystallites and larger CeO2 crystallites which can strengthen the interaction among PdO, CeO2 and Co3O4.

Palladium acetate [Pd(OAc)(2)]-catalyzed Hiyama cross-coupling of arenediazonium salts with organosilanes was found to generate biaryl products in high yields in alcoholic solutions. The simple and efficient protocol does not require any bases, ligands, or air/moisture. The transformation can tolerate either electron-donating or electron-withdrawing functional groups. Theoretical studies show that the transmetalation is the rate-limiting step for the cross-coupling reaction and both acetate and tetrafluoroborate anions may be involved in the direct reaction with the silicon atom.

Novel polypyrrole based acid catalyst has been synthesized through the neutralization reaction of polypyrrole and sulfuric acid. The polypyrrole based acid owned the acidity as high as 6.0 mmol/g, which was much higher than that of the traditional solid acids such as Nafion and Amberlyst-15 (0.8 mmol/g). The catalytic activities of the novel solid acid were investigated through the acetalization. The results showed that the novel solid acid held high activities for the reactions. Furthermore, the recycled activities of the catalyst indicated that the solid acid owned high stability during the catalytic process and little acid sites dropped from polypyrrole. The high acidity and stability made the novel polypyrrole based acid hold great potential for the green chemical processes.

The novel carbon-based strong acid catalyst has been synthesized through the simple heat treatment of 2-hydroxyethylsulfonic acid and starch. The novel solid acid owned the high acidity of 2.6 mmol/g, much higher than that of the traditional solid acids such as Nafion and Amberlyst-15 (0.8 mmol/g). The catalytic activities of the novel carbon-based acid were investigated through the acetalization reactions. The results showed that the novel solid acid was very efficient for the reactions with high yields. The high acidity and catalytic activities made the novel solid acid hold great potential for the green chemical processes.

Pyrrolo[1,2-a]imidazole and pyrrolo[2,1-b]thiazole derivatives were synthesized in a one-pot procedure by [3 + 2] cycloaddition reactions of the corresponding imidazolium ylides and thiazolium ylides with an alkene followed by oxidative aromatization of the primary cycloadducts under the action of the mild oxidant tetrakispyridinecobalt(II) dichromate. Antiproliferative activity of 14 new bicyclic N-fused heterocycles against the human hepatocellular liver carcinoma (Hep-G2) cell line were examined by the MTT method. Some of the compounds showed favorable antiproliferative activity, especially compound 3i displayed potent antiproliferative activities with an IC50 value of 0.36 μg/cm3.

Novel biodegradable three-dimensional (3D) composites with good mechanical properties have been prepared by coagulation of a chitosan/polyvinyl pyrrolidone (CS/PVP) solution in NaOH. For example, the strength and modulus of CS/PVP (1/1) were 82.5 MPa and 1.86 GPa, increasing 237% and 644% compared with CS, respectively. Scanning electron microscopy and Fourier transform infrared analysis suggest that the PVP component did not dissolve during the preparation process. The nonsolution of the composites is attributed to the extremely strong hydrogen bonding formed between the CS and PVP macromolecules. It was also found that there are synergistic effects between the formation of hydrogen bonding with PVP and cross-linking with glutaraldehyde (GA) for the improvement in the mechanical properties of CS. The mechanism of strength improvement has been discussed thoroughly from the aspects of free volume.

The novel ionic liquid with both Lewis and Bronsted acid sites has been synthesized and its catalytic activities for acetalization and Michael addition were investigated carefully. The novel ionic liquid was stable to water and could be used in aqueous solution. Furthermore, the molar ratio of the Lewis and Bronsted acid sites could be adjusted according to different reactions. The results showed that the novel ionic liquid was very efficient for the traditional acid-catalyzed reactions with good to excellent yields in short time.

Nanometer sized (mean size: 433.9 nm) pearl shell particles (SP) were prepared with a ball mill. Thermal analysis and Fourier transform infrared (FTIR) results proved that the SP contained mainly CaCO3 (about 95%) and a small organic phase (about 5%). Novel biodegradable composites based upon chitosan (CS) and SPs were prepared using an in situ precipitation method. The organic components of SP are highly compatible with both CS and glutaraldehyde (GA). The strength and modulus of CS gel rods, prepared by coagulation of a CS/SP/GA solution in NaOH, in both the dry and wet state, were improved remarkably with addition of appropriate amounts of SP together with GA. For example, with a composition of 3% SP and 0.3% GA added, the strength and modulus were 42.9 MPa and 1.41 GPa, increasing 75 and 464% compared with CS alone, respectively. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) results showed that GA acts as not only a crosslinking agent for CS, but also a compatibilizer for CS and SP. I...

Volatile organic compounds (VOCs) are considered as a major pollutant in indoor and outdoor air. More stringent environmental regulations have been implemented in order to reduce the VOC emissions. One of the techniques available for destructive removal of VOCs is catalytic oxidation. In the present work, Al/Rare Earths (REE: Y, Ce, La, Pr and Nd) pillared clays (PILCs) were used to support 0.2 wt.% of palladium for the complete oxidation of low concentration of benzene. The supports and catalysts were characterized by XRD, N 2 adsorption/desorption, FTIR spectroscopy, HRTEM and H 2 -TPR techniques. The results indicated that after Al and Al/REE pillaring, the basal spacing, S BET , A mic and V mic of Al and AlREE-PILC had a considerable increase compared with those of Na-mmt. Activity tests of deep oxidation of benzene showed that the catalytic activity of Pd catalysts supported on Al and AlREE-PILC were much higher than that on initial clays, which was due to the fact that optimized structure of PILCs, such as large basal spacing, high S BET and porosity, improved Pd dispersion and increased the active sites of Pd. Especially for Pd/AlCe-PILC, the temperature of complete oxidation was about 280 °C, exhibiting the highest catalytic activity.

An efficient and recyclable ligand-free heterogeneous catalyst has been prepared by the immobilization of palladium onto ground pearl shell powders (Pd/shell powders, Pd/SP). The catalytic activity and recyclability of the prepared Pd/SP along with the charcoal and calcium carbonate supported palladium (Pd/C and Pd/CaCO3) catalysts have been evaluated using the reductive homocoupling of aromatic halides. Pd/SP not only has higher catalytic activity, but also exhibits much stronger stability than Pd/C and Pd/CaCO3. The remarkable Pd/SP stability has been attributed to the chelation of palladium species with the surface chitin and protein molecules of the supported pearl shell powders. The X-ray photoelectron spectroscopy (XPS) studies show that the reductive Pd0 species can be regenerated in situ from the oxidative Pd2+ species for the Pd/SP catalyzed reductive homocoupling of aromatic halides in ethanol/DMSO solution, suggesting that the heterogeneous and homogeneous palladium catalysis proceeds through a similar Pd0/Pd2+ cycle catalytic mechanism.

Novel biodegradable three-dimensional composites with a porous structure have been prepared by coagulation of a chitosan (CS)/poly ethylene glycol (PEG) solution in NaOH. It is confirmed that PEG acts not only as a modifier to improve the mechanical properties, but also as a porogen for the CS matrix to induce porous structure. The porous structure and mechanical properties of the composites can be tailored with the amount of PEG and glutaraldehyde (GA). The addition of GA can improve the interaction strength and compatibility between the PEG phase and CS matrix. The resulting composites have smaller pore size, lower porosity, and better mechanical properties.

TiO2/PS, Fe(III) tetraphenylporphyrin (FeTPP)/PS and TiO2/FeTPP/PS nanofibers were prepared by electrospinning a mixture solution of corresponding compounds in N, N-dimethylformamide (DMF). The absorbance of FeTPP was characterized by UV-vis spectroscopy. The surface morphologies of these electrospun mats were evaluated with scanning electron microscope (SEM). Their photocatalytic activities were examined with the photodegradation reaction of methyl orange in aqueous solution under the irradiation of visible light. The result shows that the photocatalytic activity of TiO2/FeTPP/PS mat is higher than that of FeTPP/PS mats, which in turn is better than that of TiO2/PS mats in the photodegradation of methyl orange. The degradation percent of methyl orange could be up to 97.8% in 3 h by the FeTPP/TiO2/PS mat photocatalyst.

The novel efficient procedure has been developed for the conjugate addition of amines to electron deficient alkenes using the novel SO3H functionalized ionic liquid as catalyst. The results showed that the novel catalyst owned high activities for the reactions with excellent yields within several minutes. Various amines and electron deficient alkenes were successfully transformed to the corresponding products in the catalytic system. Operational simplicity, without need of any solvent, low cost of the catalyst used, room temperature, high yields, reusability, excellent chemoselectivity and wide applicability are the key features of this methodology.

Cyanate ester (CE) resin was blended with epoxy resin (EP) at different mass ratios (CE/EP: 100/0, 90/10, 70/30, 50/50, 30/70, 10/90, and 0/100). The curing process of the blend system was characterized by Fourier transform infrared spectrometry (FTIR) and differential scanning calorimetry (DSC). Examination of the mechanical properties, thermal stability, and morphology of the blend systems showed that addition of epoxy resin resulted in improved toughness but a little sacrifice in thermal stability when compared with neat CE. The free volume size of the blend system determined by positron annihilation lifetime spectroscopy (PALS) decreased with the epoxy resin content, which is consistent with the chemical structure changes for the copolymerization between CE and EP. The crosslinking units of curing products (oxazoline, oxazolidinone, and polyether network) of the blends are all smaller in size than those of triazine ring structure from neat CE. Therefore, the free volume size of the blends decreases with increase of EP content. The correlations between the free volume properties and other physical properties (thermal stability and mechanical properties) have also been discussed.

A novel palladium catalyst supported on shell powder has been prepared, and its application to the Heck reaction of aryl iodides with olefins has been reported. The results showed that the novel catalyst had extremely high activities for the reactions with the average yield over 90%. Also, this catalyst showed excellent stability in Heck reactions, being reused three times. The catalyst was characterized by X-ray powder diffraction and field-emission scanned electron microscopy images, and the energy dispersive X-ray analyzer. Copyright © 2010 John Wiley & Sons, Ltd.

Acid catalysts are very important in the production of many industrial chemicals. The novel polythiourethane-based solid acid has been synthesized via two steps. The copolymerization of tolylenediisocyanate (TDI) and 1,2-bis[(2-mercaptoethyl)thio]-3-mercapto-propane (MR) was carried out as the first step, and the amount of free mercarpto groups in the polythiourethane was controlled by adjusting the molar ratio of TDI and MR. The second step was the formation of the sulfonic acid groups by oxidation of the free mercapto groups. Possible catalytic activity was investigated through the traditional acid-catalyzed reactions including acetylation and synthesis of Schiff base. The results showed that this novel catalyst was very efficient for these reactions and produced high yields. Use of this catalyst simplifies process operations by not requiring any solvent, plus low usage amounts and low cost of the catalyst used with high yields, in particular, wide applicability and reusability are key features. The novel solid acid catalyst also has great potential for more environmental-friendly processes as it can be recycled and reused (easily separated) without any loss of activity. © 2010 Curtin University of Technology and John Wiley & Sons, Ltd.

In this paper, the results showed that the addition of an appropriate amount of reactive rubbers ((ie: carboxyl randomized butadiene-acrylonitrile rubber (CRBN) and hydroxyl terminated butadiene-acrylonitrile rubber (HTBN)) to epoxy resin/cyanate ester resin (EP/CE) (70/30) improved both the mechanical properties and thermal stability of the resulting blends. CRBN and HTBN have different reactive activity and dispersion state in EP/CE/rubbers. No drop in the thermal stability of the EP/CE network with addition of these two rubber component is related to the low rubber concentrate and the reactions between the rubbers and EP or CE.

The novel biacidic carbon has been synthesized via one-step hydrothermal carbonization of glucose, citric acid, and hydroxyethylsulfonic acid at 180 °C for only 4 h. The novel carbon had an acidity of 1.7 mmol/g with the carbonyl to sulfonic acid groups molar ratio of 1:3, which was confirmed by IR, XPS, TPD, SEM, and BET analyses. The catalytic activities of the carbon were investigated through esterification and oxathioketalization. The results showed that the carbon owned the comparable activities to sulfuric acid, which indicated that the carbon holds great potential for the green processes.

The novel acid carbon has been synthesized successfully via one-step hydrothermal carbonization. The acid carbon owned the morphologies of the spheres with smooth surfaces and the acidity of 2.4 mmol/g. The catalytic activities of the novel acid carbon were investigated through oxathioacetalization. The results showed that the acid carbon owned high activity for the reactions with the average yields over 95%. The advantages of high activity, stability, reusability, low cost for the simple synthetic procedure and wide application to various carbonyl compounds made the acid carbon one of the best choices for the reactions.

A novel carbon-based strong acid catalyst was synthesized through the one-step hydrothermal carbonization of furaldehyde and p-toluenesulfonic acid (PTSA) in aqueous solution at 180 °C for only 4 h. The novel carbon-based solid acid possessed high acidity, and the catalytic activities were investigated by esterification and oxathioketalization. The results showed that the novel catalyst demonstrated much greater activity than the traditional solid acids and was comparable to sulfuric acid. The one-step method provides an efficient procedure for the synthesis of various functionalized carbons by one-step hydrothermal carbonization.

Carbon functionalized with sulfonic acid groups has been synthesized using the one-step hydrothermal carbonization of furaldehyde and hydroxyethylsulfonic acid aqueous solution at 180 °C for 4 h. The carbon exhibited high acidity and comparable activities to sulfuric acid for the traditional acid-catalyzed reactions, which indicated that it has great potential for environment-friendly processes. The copolymerization method provides an efficient procedure for the synthesis of various functionalized carbons by one-step hydrothermal carbonization.