Highly effective activation of aryl chlorides for Suzuki coupling in aqueous media using a ferrocene-based Pd(II)–diimine catalyst

The Suzuki coupling of aryl chlorides with boronic acids using a ferrocene-containing Pd(II)–diimine complex as catalyst, in aqueous media, under microwave heating is reported. A small amount of the catalyst (0.1%) was found to be highly effective for coupling unactivated aryl chlorides with boronic acids to form sterically hindered ortho-substituted biaryls. The same catalyst also enabled the coupling of aryl bromides and iodides with various boronic acids in very high yields. The catalyst is air stable and the catalytic reaction can be completed in 15 min.     

General and highly efficient fluorinated-N-heterocyclic carbene–based catalysts for the palladium-catalyzed Suzuki–Miyaura reaction

A general and highly efficient trifluoromethylated-N-heterocyclic carbene (NHC)-based catalyst for the palladium-catalyzed Suzuki–Miyaura reaction was reported. In the presence of the catalyst, reactions of non-activated aryl chlorides and triflates with aryl boronic acids occurred at room temperature with good to excellent yields (63–98%). In addition, catalysts generated from a combination of Pd(OAc)₂/imidazolium salt 6a is not only effective for the coupling of heteroaryl boronic acid with aryl halides and heteroaryl halides, but also efficient for coupling of other heteroaryl halides and heteroaryl boronic acids. Finally, the catalyst is highly effective for Suzuki–Miyaura reaction of aryl bromides and chlorides with 0.01–0.1 mol % loading if the temperature was raised at refluxed THF/H₂O.     

Eumelanin as a support for efficient palladium nanoparticle catalyst for Suzuki coupling reaction of aryl chlorides in water

Eumelanin-supported palladium (Pd) nanoparticle (NP) catalysts was found to exhibit excellent catalytic activities with high turnover number (TON, 2000) and turnover frequency (TOF, 1000 h^?1) for Suzuki cross coupling reaction of aryl chlorides in water. We propose that the amphiphilic property of the eumelanin support helps Pd NPs to catalyse the C–C coupling reaction in water through hydrophobic effect.     

微波辅助的聚氯乙烯-三乙撑四胺负载钯配合物对Suzuki反应的催化性能

探讨了在微波作用下, 聚氯乙烯-三乙撑四胺负载钯配合物(PVC-TETA-Pd)对四苯硼钠与卤代苯的Suzuki反应的催化性能. 实验发现: 在微波功率为200 W时, 在Na₂CO₃, NaF, KF, NaHCO₃等多种碱的存在下, 以DMF的水溶液(V∶V＝5∶3)为溶剂, 在无惰性气体保护下, PVC-TETA-Pd催化四苯硼钠与碘代苯在20 min内即可定量反应, 与常规加热方式相比, 节省了大量时间; 同时也证明了四苯硼钠的四个苯基均可参与Suzuki偶联反应; 该催化剂回收再利用3次后, 仍具有较高的催化活性.     

Thermal and catalytic degradation of pyrolytic oil from pyrolysis of municipal plastic wastes

Thermal and catalytic degradation of pyrolytic oil obtained from the commercial rotary kiln pyrolysis plant for municipal plastic waste was studied by using fluid catalytic cracking (FCC) catalyst in a bench scale reactor. The characteristics of raw pyrolytic oil and also thermal and catalytic degradation of pyrolytic oil using FCC catalyst (fresh and spent FCC catalyst) under rising temperature programming was examined. The experiments were conducted by temperature programming with 10 °C/min of heating rate up to 420 °C and then holding time of 5 h. During this programming, the sampling of product oil was conducted at a different degradation temperature and also different holding time. The raw pyrolytic oil showed a wide retention time distribution in GC analysis, from 5 of carbon number to about 25, and also different product characteristics with a comparison of those of commercial oils (gasoline, kerosene and diesel). In thermal degradation, the characteristics of product oils obtained were influenced by reaction temperature under temperature programming and holding time in the reactor at 420 °C. The addition of FCC catalyst in degradation process showed the improvement of liquid and gas yield, and also high fraction of heavy hydrocarbons in oil product due to more cracking of residue. Moreover, the characteristic of oil product in catalytic degradation using both spent and fresh FCC catalysts were similar, but a relatively good effect of spent FCC catalyst was observed.     

Green Synthesis of Some Calix[4]Resorcinarene Under Microwave Irradiation

A green synthetic procedure for the preparation of some calix[4]resorcinarenes using a household microwave oven has been carried out. This method represents a very rapid heating alternative to the conventional method that involves very long time of reactions (from 20-24 h in conventional heating to 5-8 min in microwave irradiation). C-4-hydroxy–3-methoxycalix[4]resorcinarene (CHMPCR), C-4-methoxyphenylcalix[4]resorcinarene (CMPCR) and C-2–phenylethenilcalix[4]resorcinarene (CPECR) was achieved by placed of resorcinol, an aldehyde, HCl and ethanol inside a household microwave oven. The product was recrystallized by methanol and analyzed by spectral analysis (FTIR, H-NMR and MS). Optimization of reaction was carried out in variation of microwave power, reaction times and reactant composition. The result shows that optimum condition of synthesis of C-4-hydroxy-3–methoxycalix[4]resorcinarene (CHMPCR) with microwave irradiation were at microwave power 332 W, reaction time 8 min and the mole ratio of resorcinol and 4-hydroxy-3-methoxyphenylbenzaldehyde 1:1. This parameter gave product in 97.8% (53.7% after recrystallization). The CPECR synthesis using resorcinol and cynnamaldehyde (1:1) at microwave power 332 W for 5 min afforded the product in 97.3% (44.5% after recrystallization). Whereas the reaction of resorcinol and 4-methoxyphenylbenzaldehyde (1:1.2) at microwave power 264 W for 5 min gave CMPCR in 99.5% (68.6% after recrystallization).     

Selective production of propylene from methanol over high-silica mesoporous ZSM-5 zeolites treated with NaOH and NaOH/tetrapropylammonium hydroxide

The influence of alkaline treatments with NaOH and NaOH/TPAOH mixtures on the physicochemical properties and catalytic performance of high-silica ZSM-5 zeolites (Si/Al = 175) during the methanol-to-propylene (MTP) reaction have been investigated. It was found that alkaline treatment in an NaOH/TPAOH solution with TPAOH/(NaOH + TPAOH) = 0.4 ensures the formation of narrow and uniform intracrystalline mesoporosity without severely damaging the crystal structure and the intrinsic acidity of the zeolite, leading to the best catalytic performance, including the highest propylene selectivity (47.2) and P/E ratio (4.97) as well as the longest catalyst lifetime (80 h).     

Catalytic vapor-phase oxidation of 2,2,2-trifluoroethanol

The synthesis of trifluoroacetaldehyde by vapor-phase oxidation of 2,2,2-trifluoroethanol using supported vanadium catalysts was studied. Significant differences were observed in the reaction outcomes resulting from different types of catalysts. The ZrO₂- and Al₂O₃-supported catalyst demonstrated both high catalytic activity and selectivity. The addition of co-catalysts such as MoO₃ or SnO₂ improved catalytic performance (Selectivity: up to 91%; S.T.Y.: >200 g L⁻¹ h⁻¹). The experimental results on catalyst lifetime showed a marked decrease in the activity of the Al₂O₃-supported catalyst within tens of hours, while the ZrO₂-supported catalyst showed little, if any, performance alterations for 2000 h.     

Microwave-assisted organic synthesis versus conventional heating. A comparative study for Fisher glycosidation of monosaccharides

The Fisher glycosidation of monosaccharides (d-glucose and d-mannose) with fatty alcohols was studied under microwave irradiation and conventional heating with strict internal temperature control using a fiber optic sensor. Surfactants were obtained in only 3 minutes under microwave at maximum power of 5 W to avoid overshoot and products decomposition. In contrast with the typical reported glycosidation methods, the reaction under conventional heating can be carried out at the same time and temperature with high conversion.     

Cu2O-catalyzed Ullmann-type reaction of vinyl bromides with imidazole and benzimidazole

Cu₂O was found to be an efficient and economical metal catalyst in the Ullmann cross-coupling reaction of vinyl bromides with imidazole or benzimidazole. The system Cu₂O/ethyl 2-oxocyclohexanecarboxylate showed high catalytic activity in MeCN at 80–90 °C. The reaction gave the corresponding coupling products in good to excellent yields.     

Syngas production from ethanol dry reforming over Rh/CeO2 catalyst

Carbon dioxide reforming of ethanol over Rh/CeO₂ catalyst was deeply investigated at different reaction temperatures of 450–700 °C and reactant ratios (CO₂/ethanol from 1 to 3) under atmospheric pressure. The obtained results indicated that Rh/CeO₂ catalyst presented a promising activity and stability for syngas production from renewable bio-ethanol instead of conventional methane. Typically, CO₂-rich conditions (CO₂/ethanol = 3) were favorable for reaction process and dynamic coke cleaning, which led to remarkably stable performance over 65 h on stream. The strong redox capacity of CeO₂ support might also accelerate CO₂ activation and prevent the carbon accumulation over the catalyst surface. Additionally, tunable H₂/CO ratios were available by changing the CO₂/ethanol ratios. The results from characterization of samples before and after catalytic tests allowed to establish the relationship between textural properties and catalytic performance.     

Palladium-catalyzed cross-couplings of functionalized 2-bromobenzofurans for atom-economic synthesis of 2-arylbenzofurans using triarylbismuth reagents

The palladium catalyzed, atom-economic synthesis of various functionalized 2-arylbenzofurans was achieved through cross-coupling reaction of 2-bromobenzofurans with triarylbismuth reagents. The palladium catalytic protocol is very efficient to furnish various cross-coupled functionalized 2-arylbenzofurnas in high yields using triarylbismuth reagents with three aryl couplings as multi-coupling organometallic nucleophiles in one-pot operation. All the coupling reactions were completed in 1 h short reaction time involving three couplings from triarylbismuths under heating condition.     

Facile synthesis of aryl(het)cyclopropane catalyzed by palladacycle

Sphos (2-dicyclohexylphosphino-2′,6′-dimethoxy-1,1′-biphenyl) adduct of cyclopalladated ferrocenylimine (IIe) exhibited highly catalytic activity for the Suzuki cross-coupling reaction of cyclopropylboronic acid with aryl(het) halides with 1 mol % catalyst loading. This process was applied to both of aryl and heteroaryl halides (Br and Cl), and made the various arylcyclopropane and heteroarylcyclopropane to be easily synthesized. A variety of substituents on the aryl halides, such as alkyl, acetyl, benzoyl, ether, formyl, carboxylate, methoxy, nitro and cyano were tolerated.     

Impact of reforming catalyst on the anodic polarisation resistance in single-chamber SOFC fed by methane

This paper emphasises the electrochemical and catalytic properties of a Ni–10% GDC (10% gadolinium-doped ceria) cermet anode of a single-chamber solid oxide fuel cell (SC-SOFC). Innovative coupling of electrochemical impedance spectroscopy with gas chromatography measurements was carried out to characterise the anode material using an operando approach. The experiments were conducted in a symmetric anode/electrolyte/anode cell prepared by slurry coating resulting in 100 μm-thick anode layers. The electrochemical performance was assessed using a two-electrode arrangement between 400 °C and 650 °C, in a methane-rich atmosphere containing CH₄, O₂ and H₂O in a 14:2:6 volumetric ratio. The insertion of a Pt–CeO₂ based catalyst with high specific surface area inside the cermet layer was found to promote hydrogen production from the Water Gas Shift reaction and consequently to improve the electrochemical performances. Indeed, a promising polarisation resistance value of 12 Ω cm² was achieved at 600 °C with a catalytic loading of only 15 wt.%.     

Sulfuric acid catalyzed addition of β-dicarbonyl compounds to alcohols under conventional heating and microwave-assisted conditions

The highly efficient direct addition of β-dicarbonyl compounds to secondary alcohols has been achieved using one of the cheapest acids, H₂SO₄, as the catalyst. For a series of β-dicarbonyl compounds and various secondary alcohols, the addition reactions all complete in 5 min with high yields both under the conventional heating condition and under the microwave heating condition. The comparison of the results obtained from the microwave heating condition with those obtained from the conventional heating condition shows that no obvious specific or nonthermal microwave effects exist in the microwave-assisted addition reactions.     

Palladium-catalysed direct arylations of NH-free pyrrole and N-tosylpyrrole with aryl bromides

The palladium-catalysed direct coupling of aryl halides with pyrroles provides a greener access to arylated pyrroles than more classical couplings such as Suzuki, Stille or Negishi reactions. However, so far, NH-free pyrrole and N-tosylpyrrole gave disappointing results for such couplings either in terms of regioselectivity of the arylation, catalyst loading or substrate scope. The reactivity of both NH-free pyrrole and N-tosylpyrrole was studied, and the tosylated pyrrole led to higher yields of coupling products due to better conversions of the aryl bromides. A range of aryl bromides undergo regioselective coupling at C2 of N-tosylpyrrole in moderate to good yields using 1 mol % [Pd(Cl(C₃H₅)]₂ as the catalyst, KOAc as the base in DMAc.     

Ligand free,highly efficient synthesis of diaryl ether over copper fluorapatite as heterogeneous reusable catalyst

A novel ligand-free, highly efficient, and an inexpensive method has been developed by using ecofriendly, heterogeneous reusable copper fluorapatite (CuFAP) catalyst for the synthesis of diaryl ethers from the cross coupling reaction of the various substituted aryl halides (fluoride, chloride, bromide, and iodide) with the potassium salts of various substituted phenols in the presence of N-methyl 2-pyrrolidone (NMP) as a solvent at 120 °C. The protocol obtained the corresponding cross coupling products in good to excellent yield. The CuFAP catalyst was recovered by simple filtration from the reaction mixture and reused several times without the loss of catalytic activity.     

Oligomerization of Dicyclopentadiene Fraction Using Monosubstituted Titanium Chloride as a Catalyst

The purpose of this study is to investigate the dicyclopentadiene fraction of liquid pyrolysis product oligomerization with the use of the modified catalytic system based on titanium alkoxides. The choice of reaction catalyst is specified by searching the ways of obtaining petroleum resins with the improved performance characteristics and the possibility of low-temperature polymerization. The use of monosubstituted titanium chloride as a catalyst allows obtaining light resins, films on the base of which are smooth, glossy and have good technical characteristics: adhesion 1 point, resilience <1 mm, impact resistance >10 cm.     

Sulfonate group modified Ni catalyst for highly efficient liquid-phase selective hydrogenation of bio-derived furfural

A simple and highly efficient Ni catalyst was synthesized and showed excellent catalytic performance for selectively liquid-phase hydrogenation of furfural to furfuryl alcohol or tetrahydrofurfuryl alcohol.     

Microwave-assisted C–H bond activation using a commercial microwave oven for rapid deuterium exchange labeling (C–H → C–D) in carbohydrates

Studies have shown that facile hydrogen → deuterium exchange in two model carbohydrates via stereospecific C–H bond activation could be achieved using a pre-sonicated Raney Nickel^® catalyst and microwave irradiation. Using a simple commercial microwave oven and a silica-gel bath, monosaccharide and disaccharide samples underwent isotopic exchange using microwave irradiation for sequential 15 s intervals. The influence of chilling between irradiation intervals was examined. The results revealed increasing levels of ²H incorporation without either epimerization or concomitant decomposition seen earlier in non-optimized experiments.