Solvent-free allylic oxidation of cycloolefins over mesoporous CrMCM-41 molecular sieve catalyst at 1 atm dioxygen

Oxidation of cycloolefins was effectively performed under aerobic (1 atm dioxygen) and mild solvent-free conditions using mesoporous CrMCM-41 molecular sieve catalyst. For instance, Cycloolefins (C₅–C₇) were selectively oxidized to the corresponding α,β-unsaturated ketones (for example, cyclohexene – 52.2% conversion and 71.2% selectivity) and cycloolefins (C₈–C₁₂) were oxidized to epoxides (for example, cis-cyclooctene – 50% conversion and >99% selectivity) at 323–353 K for 24 h. The catalytic activity over recycled catalyst remains nearly same.     

Ruthenium-catalyzed cross-coupling reactions between ketones and primary amines

Ketones react with primary amines in dioxane at 180 °C in the presence of a catalytic amount of a ruthenium catalyst to give the corresponding α-alkylated ketones in moderate to good yields. With alkyl(methyl) ketones, the alkylation takes place exclusively at less-hindered methyl position over α-methylene.     

NiFe2O4@SiO2–PPA Nanoparticle: A Green Nanocatalyst for the Synthesis of β-Acetamido Ketones

ABSTRACT

In this work, silica coated magnetic nanoparticles of modified polyphosphoric acid (NiFe₂O₄@SiO₂–PPA deigned as NFS–PPA) represent as a reusable and green catalyst for one-pot four-component synthesis of β-acetamido ketones at room temperature under solvent-free conditions. This catalyst was synthesized and characterized by X-ray diffractions, transmission electron microscopy, scanning electron microscopy and vibrating sample magnetometry. The magnetic catalyst can be easily removed by a simple magnet and reused up to five times without any loss of its high catalytic activity. In addition to facility, this protocol enhances product purity and promises economic and also environmental profits.     

Effects of the preparation methods on the performance of the Cu–Cr–Fe/γ-Al2O3 catalysts for the synthesis of 2-methylpiperazine

Co-precipitation, impregnation and ultrasonic sol–gel (USG) methods have been used to prepare Cu–Cr–Fe/γ-Al₂O₃ catalysts, which were further used to synthesize 2-methylpiperazine. The catalysts were characterized by XRD, XPS, TG/DSC, BET, TPR, AAS and TEM. It is found that preparation method can greatly impact the catalytic performance of the catalysts, the Cu–Cr–Fe/γ-Al₂O₃ catalyst prepared by the ultrasonic sol–gel method proved to be the most active and stable for this reaction. The dispersion and stabilization of Cu⁰ in the reduced catalysts are attributed to the existence of CuCr₂O₄ and Fe₂O₃. A surprising copper migration was detected by XPS analysis for the Cu–Cr–Fe/γ-Al₂O₃-USG catalyst after the calcination process, which may be crucial to the high activity and stability of this catalyst.     

Conversion of biomass to fuel: Transesterification of vegetable oil to biodiesel using KF loaded nano-γ-Al2O3 as catalyst

KF-impregnated nanoparticles of γ-Al₂O₃ were calcinated and used as heterogeneous catalysts for the transesterification of vegetable oil with methanol for the synthesis of biodiesel (fatty acid methyl esters, FAME). The ratio of KF to nano-γ-Al₂O₃, calcination temperature, molar ratio of methanol/oil, transesterification reaction temperature and time, and the concentration of the catalyst were used as the parameters of the study. A methyl ester yield of 97.7 ± 2.14% was obtained under the catalyst preparation and transesterification conditions of KF loading of 15 wt%, calcination temperature of 773 K, 8 h of reaction time at 338 K, and using 3 wt% catalysts and molar ratio of methanol/oil of 15:1. This relatively high conversion of vegetable oil to biodiesel is considered to be associated with the achieved relatively high basicity of the catalyst surface (1.68 mmol/g) and the high surface to volume ratio of the nanoparticles of γ-Al₂O₃.     

Properties and performance of Pd based catalysts for catalytic oxidation of volatile organic compounds

Catalytic oxidations of volatile organic compounds (VOCs) (benzene, toluene and o-xylene) over 1 wt% Pd/γ-Al₂O₃ catalyst were carried out to assess the properties and performance of the Pd based catalyst. The properties of the prepared catalysts were characterized by the Brunauer Emmett Teller (BET) surface area, H₂ chemisorption, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and transmission electron microscopy (TEM) analyses. The experimental results revealed a significant increase in VOCs conversion with the lapse of the reaction time at certain reaction temperatures. On the other hand, the hydrogen pretreated 1 wt% Pd/γ-Al₂O₃ catalyst, whose shape of conversion curve is similar to the non pretreated catalyst, led the conversion curves for the total oxidation of VOCs to be shifted to lower temperature. It was also found that such increases in VOCs conversion were highly dependent on the oxidation state of Pd and the growth of Pd particles in the catalyst. In addition, in the case of the catalyst consisting of the same oxidation state (PdO/Pd²⁺ or Pd⁰), the particle sizes possibly play a more important role in the catalytic activity. The activity order of 1 wt% Pd/γ-Al₂O₃ catalyst with respect to the VOC molecule was o-xylene > toluene > benzene.     

新型钻相前体制备耐硫变换催化剂及其表征

在室温下用等孔容离子交换共浸渍法制备了球型CoO-MoO₃-K₂O/γ-Al₂O₃宽温耐硫变换催化剂HB-3Q。考察了载体、钻铂前驱盐、竟争剂、金属离子负载量、浸演液pH值等对催化剂物化性能的影响, 用XRD、DTA等分析手段表征了活性组分在载体γ-Al₂O₃上的微观分散状态。表明用新型低廉的钻和铂前驱盐, 可获得与常规氨配合法相同变换活性和颗粒抗压碎强度的耐硫变换催化剂, 而成本却大幅下降。     

Coral-like nanostructured α-Mn2O3 nanaocrystals for catalytic combustion of methane: Part I. Preparation and characterization

Coral-like nanostructured α-Mn₂O₃ nanocrystals were prepared by oxidative decomposition of MnCO₃, exhibiting tremendous activity in the catalytic combustion of methane. This prepared α-Mn₂O₃ nanocrystals showed ultra-high stability during reaction while the structure feature was unaffected. The ultra-stable structure of the α-Mn₂O₃ catalyst has been demonstrated by characterization of SEM, XPS, XRD, Raman spectroscopy. The performance of the α-Mn₂O₃ nanocrystals has proven reproducible and potentially to be an applied catalyst for methane combustion.     

A highly stable and efficient catalyst for direct synthesis of LPG from syngas

Liquefied petroleum gas (LPG) fuel was directly synthesized from syngas over a hybrid catalyst which contained a methanol synthesis catalyst and zeolite. The new hybrid catalyst composed of (Pd–Ca/SiO₂) and β-zeolite, showed a high activity and selectivity for LPG production. X-ray diffraction (XRD) characterization of the catalyst was used to analyze the deactivation of (Pd–Ca/SiO₂)/β-zeolite.     

Efficient hydrotalcite-based catalyst for acetone condensation to α-isophorone—scale up aspects and process development

It is previously known that the thermal decomposition of Mg/Al hydrotalcite precursor results in a catalyst that yields the highest ratio of isophorone/mesityl oxide during aldol condensation of acetone. This work describes the catalyst scale up and process development starting from the Mg/Al precursor aimed at maximizing the α-isophorone production and minimizing feed loss to heavies. Selectivity to isophorone was shown to be inversely proportional to the catalyst particle size. A compromise between smaller desired particle size and the associated increase in pressure drop was achieved by adding macroporous diatomaceous earth to the extrudates. Addition of up to 40% macroporous diatomaceous earth improved the α-isophorone selectivity of the extruded catalyst. Intermediate products, such as mesityl oxide and β-isophorone, could be successfully recycled to further increase the α-isophorone yield.     

Design,Synthesis and Evaluation of Novel Derivatives of Curcuminoids with Cytotoxicity

Curcumin and curcuminoids have been discussed frequently due to their promising functional groups (such as scaffolds of α,β-unsaturated β-diketone, α,β-unsaturated ketone and β′-hydroxy-α,β-unsaturated ketone connected with aromatic rings on both sides) that play an important role in various bioactivities, including antioxidant, anti-inflammatory, anti-proliferation and anticancer activity. A series of novel curcuminoid derivatives (a total of 55 new compounds) and three reference compounds were synthesized with good yields using three-step organic synthesis. The anti-proliferative activities of curcumin derivatives were examined for six human cancer cell lines: HeLaS3, KBvin, MCF-7, HepG2, NCI-H460 and NCI-H460/MX20. Compared to the IC₅₀ values of all the synthesized derivatives, most α,β-unsaturated ketones displayed potent anti-proliferative effects against all six human cancer cell lines, whereas β′-hydroxy-α,β-unsaturated ketones and α,β-unsaturated β-diketones presented moderate anti-proliferative effects. Two potent curcuminoid derivatives were found among all the novel derivatives and reference compounds: (E)-5-hydroxy-7-phenyl-1-(3,4,5-trimethoxyphenyl)hept-1-en-3-one (compound 3) and (1E,4E)-1,7-bis(3,4,5-trimethoxyphenyl)hepta-1,4-dien-3-one (compound MD12a). These were selected for further analysis after the evaluation of their anti-proliferative effects against all human cancer cell lines. The results of apoptosis assays revealed that the number of dead cells was increased in early apoptosis and late apoptosis, while cell proliferation was also decreased after applying various concentrations of (E)-5-hydroxy-7-phenyl-1-(3,4,5-trimethoxyphenyl)hept-1-en-3-one (compound 3) and (1E,4E)-1,7-bis(3,4,5-trimethoxyphenyl)hepta-1,4-dien-3-one (compound MD12a) to MCF-7 and HpeG2 cancer cells. Analysis of the gene expression arrays showed that three genes (GADD45B, SESN2 and BBC3) were correlated with the p53 pathway. From the quantitative PCR analysis, it was seen that (1E,4E)-1,7-bis(3,4,5-trimethoxyphenyl)hepta-1,4-dien-3-one (compound MD12a) effectively induced the up-regulated expression of GADD45B, leading to the suppression of MCF-7 cancer cell formation and cell death. Molecular docking analysis was used to predict and sketch the interactions of the GADD45B-α,β-unsaturated ketone complex for help in drug design.     

ZnO nanoparticles: An efficient nanocatalyst for the synthesis of β-acetamido ketones/esters via a multi-component reaction

A convenient one-pot multi-component reaction of aromatic aldehydes, enolizable ketones or β-keto esters and acetonitrile in the presence of acetyl chloride and 10 mol% ZnO nanoparticles for the synthesis of β-acetamido ketones/esters at room temperature is described.     

An Eco-Friendly Ultrasound-Assisted Synthesis of Novel Fluorinated Pyridinium Salts-Based Hydrazones and Antimicrobial and Antitumor Screening

The present work reports an efficient synthesis of fluorinated pyridinium salts-based hydrazones under both conventional and eco-friendly ultrasound procedures. The synthetic approach first involves the preparation of halogenated pyridinium salts through the condensation of isonicotinic acid hydrazide (1) with p-fluorobenzaldehyde (2) followed by the nucleophilic alkylation of the resulting N-(4-fluorobenzylidene)isonicotinohydrazide (3) with a different alkyl iodide. The iodide counteranion of 5–10 was subjected to an anion exchange metathesis reaction in the presence of an excess of the appropriate metal salts to afford a new series of fluorinated pyridinium salts tethering a hydrazone linkage 11–40. Ultrasound irradiation led to higher yields in considerably less time than the conventional methods. The newly synthesized ILs were well-characterized with FT-IR, ¹H NMR, ¹³C NMR, ¹¹B, ¹⁹F, ³¹P and mass spectral analyses. The ILs were also screened for their antimicrobial and antitumor activities. Within the series, the salts tethering fluorinated counter anions 11–13, 21–23, 31–33 and 36–38 were found to be more potent against all bacterial and fungal strains at MIC 4–8 µg/mL. The in vitro antiproliferative activity was also investigated against four tumor cell lines (human ductal breast epithelial tumor T47D, human breast adenocarcinoma MCF-7, human epithelial carcinoma HeLa and human epithelial colorectal adenocarcinoma Caco-2) using the MTT assay, which revealed that promising antitumor activity was exhibited by compounds 5, 12 and 14.     

Hydrogenation of CO2 to formic acid on supported ruthenium catalysts

We report on the preparation and application of novel heterogeneous supported ruthenium catalysts. The catalysts are active in the synthesis of formic acid from the hydrogenation of carbon dioxide and are characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray powder diffraction analysis and transmission electron microscopy. Abundant hydroxyl groups, which interact with the ruthenium components, play an important role in the catalytic reactions. Highly dispersed ruthenium hydroxide species enhance the hydrogenation of CO₂, while crystalline RuO₂ species, which are formed from the relatively high ruthenium content or the pH of the solution during preparation of the catalyst, restrict the production of formic acid. Optimal activity of ruthenium hydroxide as a catalyst for the hydrogenation of CO₂ to formic acid is achieved over a γ-Al₂O₃ supported 2.0 wt% ruthenium catalyst, which is prepared in a solution of pH 12.8 with NH₃·H₂O as a titration solvent. A possible hydrogenation mechanism for the hydroxide ruthenium catalyst is proposed.     

功能化离子液体在室温下催化醛(酮)与二元醇的缩合反应

采用功能化离子液体1-甲基-3-丙磺酸基咪唑盐作为溶剂/催化剂双功能体系,通过探针反应,固定原料环己酮与离子液体催化剂的摩尔比为50∶1进行工艺参数的优化,得到优化工艺条件为:n(环己酮)∶n(1,2-丙二醇)=1∶1.5,在20℃条件下反应0.1 h可以得到缩合产物,转化率大于97%.研究了该催化剂对其他醛(酮)与二元醇的缩合反应的催化性能,结果表明,该工艺无需有机溶剂及脱水剂,反应结束产物与催化体系分层,通过倾析便可得到产物,简化了分离过程且离子液体可以循环使用.     

Hydrogenation of Methyl Benzoate over Mn/Al Catalysts: Comparison among Catalyst Preparation Routes

Mn/Al catalysts for hydrogenation of methyl benzoate to benzaldehyde were prepared by different methods. The catalyst prepared from hydrotalcite-like precursor, the mesoporous MSU-γ supported Mn catalyst and the Mn-incorporated MSU-γ catalyst are more active than conventional Mn/γ-Al₂O₃ catalyst. The reaction temperature for the same yield level can be reduced by 20–60 °C. High specific surface area, high dispersion of manganese oxide species and strong interaction of manganese oxide species with γ-Al₂O₃ are of benefit to the reaction.     

Hydrogenation of methyl propionate over Ru–Pt/AlOOH catalyst: Effect of surface hydroxyl groups on support and solvent

A ruthenium–platinum bimetallic catalyst supported on boehmite was prepared by co-impregnation and hydrothermal reduction and characterized by XRD, TEM and TG–DTG. Reduction time of the catalyst affected the conversion of γ-Al₂O₃ to boehmite and the specific surface area of the catalyst, and consequently influenced the catalytic performance of the catalyst. Under the same conditions, the Ru–Pt/AlOOH catalyst showed much higher activity and selectivity than the Ru–Pt/γ-Al₂O₃ in aqueous hydrogenation of methyl propionate. The selectivity to 1-propanol of 97.8% could be obtained at methyl propionate conversion of 89.1% over Ru–Pt/AlOOH at 453 K under 5 MPa of H₂ for 6 h. It is postulated that the high performance of this novel catalyst is related to the cooperation of the hydroxyl groups of support surface and water solvent.     

Isomerization of n-hexane over Platinum loaded zeolite catalysts

The isomerization of n-hexane over Pt-loaded Hβ, H-ZSM-5 and H-dealuminated mordenite was studied at temperatures lower than 573 K under atmospheric pressure. It was found that Pt loaded H β showed the highest activity and selectivity of these three catalysts. Namely, the conversion of hexane was 76 C-% and selectivities to dimethylbutanes, methylpentanes and cracking products were 19.4, 76.2 and 4.4 C-%, respectively, under the following conditions: reaction temperature, 548 K; W/ F, 5 g h mol⁻¹; molar ratio of hydrogen to n-hexane, 4. Pt/Hβ catalyst showed a good stability, because Hβ has acid sites with medium strength and three-dimensional large pores. We can adjust the balance between metallic sites and acid sites to obtain right catalyst which has the highest activity and the highest selectivity for the isomerization of hexane.     

Photo-Fenton degradation of 17β-estradiol in presence of α-FeOOHR and H2O2

A novel photocatalyst, α-FeOOH-coated resin (α-FeOOHR), was prepared and applied for the photodegradation of natural estrogen 17β-estradiol (E2) in presence of H₂O₂ under the relatively weak UV irradiation. The continuing loading of ferric oxide on resin was achieved by in situ hydrolysis of Fe³⁺ in alkaline solution. The effects of initial pH, catalyst loading, oxidant concentration and iron leaching on the photodegradation of E2 were investigated. The batch photodegradation experiment showed that high removal efficiency of E2 and fairly good mechanic stability could be obtained by the spherical photocatalyst α-FeOOHR in aqueous solutions. The photodegradation efficiencies slightly decreased with the increase of initial pH in the wide pH range of 3–11. Increase of oxidant and catalyst will enhance photodegradation efficiencies thus lead to increase the Ferric leaching. Neglected iron leaching showed the stability of the loaded α-FeOOH withstanding the oxidation. X-ray photoelectron spectrum (XPS) shed light on the surface activity change of photocatalyst and heterogeneous catalytic essence of this process.     

Wet 2,4,6-trichloro[1,3,5]triazine (TCT) an efficient catalyst for synthesis of -bis(substituted-benzylidene) cycloalkanones under solvent-free conditions

An array of aromatic aldehydes undergo crossed aldol condensation with ketones in the presence of catalytic amounts of wet-TCT under solvent-free conditions to afford the corresponding α,α^′-bis(substituted-benzylidene) cycloalkanones in excellent yields. Contrary to the existing methods, which use classical Lewis acids a new catalyst (TCT) is employed. This method is also general with respect to all types of aromatic aldehydes and is an eco friendly procedure.