Pd(0)-guanidine@MCM-41: a very effective catalyst for rapid production of bis (pyrazolyl)methanes

In this research, a rapid, green and efficient protocol for synthesis of bis (pyrazolyl)methane derivatives in the presence of Pd(0)-guanidine@MCM-41 catalysts under solvent-free conditions by the following two methods has been reported: (i) via the one-pot pseudo five-component reaction among phenylhydrazine (2 equivalents), ethyl acetoacetate (2 equivalents) and aromatic aldehydes (1 equivalent); and (ii) the one-pot pseudo three-component reaction between 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one (2 equivalents) and aromatic aldehydes (1 equivalent). Some advantages of this protocol include: green conditions, extremely short times, high efficiency, proper one-pot operation, generality of method, easy work-up and recyclability, and reusability of the catalyst up to five times without significant loss in catalytic activity.     

Silver chloride supported on Vitamin B1 -Organometallic magnetic catalyst: synthesis,density functional theory study and application in A3-coupling reactions

A highly efficient Fe₃O₄@VitB₁–Ag(I) magnetic catalyst has been obtained using surface modification of Fe₃O₄. To this end, silver chloride was immobilized on Fe₃O₄ nanoparticles via vitamin B₁ biomolecules. The synthesized biocompatible magnetic catalyst was applied in an A³-coupling reaction in the presence of aldehyde, amine and phenyl acetylene under solvent-free conditions and afforded the desired products in excellent yields. Also, interactions between metal and ligand in the Fe₃O₄@VitB₁–Ag(I) were studied using theoretical calculations.     

Novel synthesis of silica-coated magnetic nano-particles based on acidic ionic liquid,as a highly efficient catalyst for three component system leads to furans derivatives

In this work, thiocarbohydrazide doped iron nanoparticles as a novel, green, heterogeneous, and inexpensive catalyst is reported. This catalyzed the three components reaction of dialkylacetylenedicarboxylate with aromatic aldehydes and aromatic amines to yield the corresponding furan derivatives EtOH. An indispensable part of green chemistry is to be able to recover and reuse catalysts without any notable drop in catalytic activity. The analysis of catalyst and application of that for the synthesis of title compounds in high yields reveal this property. The formation, size of the metal ions present in the material is confirmed by powdered X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA).     

Mo (CO)6‐assisted Pd‐supported magnetic graphene oxide‐catalyzed carbonylation‐cyclization as an efficient way for the synthesis of 4(3H)‐quinazolinones

In this paper, a novel catalyst is introduced based on the immobilization of palladium on modified magnetic graphene oxide nanoparticles. The catalyst is characterized by several methods, including transmission electron microscopy, scanning electron microscopy, X‐ray fluorescence, vibrating‐sample magnetometer, Fourier transform‐infrared and dynamic light scattering (DLS) analysis. The activity of the catalyst was investigated in the synthesis of 4(3H)‐quinazolinones via Pd‐catalyzed carbonylation‐cyclization of N‐(2‐bromoaryl) benzimidamides by Mo (CO)₆. The Mo (CO)₆ is used as a carbon monoxide source for performing the reaction under mild conditions. The catalyst showed good reusability, and no change in activity was observed after 10 cycles of recovery.     

Evaluating impacts of fish stock enhancement and biodiversity conservation actions on the livelihoods of small‐scale fishers on the Beijiang River,China

Inappropriate development and overexploitation have seriously degraded aquatic resources in China. Stakeholders identified three fish stock enhancement and biodiversity conservation scenarios for the Beijiang River: S1, increased fish restocking; S2, no fishing season and habitat conservation; and S3, strict pollution control. Potential impacts of these actions on the livelihoods of fishers were evaluated using applied economic modeling. Baseline costs and benefits came from logbooks from 30 fishers and a survey of 90 households in three villages. The financial net benefit for a household was US$1583 (￥11,160) annually, representing a 142% and 387% return on capital and operating costs, respectively. Larger catches associated with S1 and S2 generated a net benefit of US$1651 and US$1822, respectively. Strict pollution control resulting in higher catches (+20%) and lower operating costs (?20%) would increase the net benefit by 15.9% to US$1835 annually. Pollution control would benefit other resource users and is a prerequisite for ecological restoration. Recommendations for Resource Managers

• Stringent pollution control measures are essential to conserve aquatic biodiversity and enhance the livelihoods of fishers but will require considerable public and private sector investment.
• Enhanced fish stocks in the Beijiang River could benefit poor livelihoods but may not be sufficient to lift households out of poverty, aged fishers require government assistance to diversify their livelihoods, access alternative urban employment, and survive with dignity.
• Adopting the economic modeling approach presented here could enable responsible authorities to simultaneously evaluate fish stock enhancement and biodiversity conservation options.
• Broader application of the approach presented here could help ensure small‐scale inland fisheries are managed sustainably and aquatic ecosystems are restored and protected by 2020, in line with Target 6 of the United Nations’ Convention on Biological Diversity Strategic Plan for Biodiversity.

     

Facile preparation and synergy study of DMC/ZnGA composite catalyst for the synthesis of oligo (propylene‐carbonate) diols

To overcome the weak carbon dioxide (CO₂) conversion ability of Zn‐Co double metal cyanide (DMC) catalyst, zinc glutarate (ZnGA) catalyst was introduced into the DMC catalytic system and applied for the synthesis of oligo (propylene‐carbonate) diols. The DMC/ZnGA composite catalyst (mass ratio = 10:1) exhibited an excellent synergistic effect which had enhanced CO₂ activation ability, high yield and good selectivity. In copolymerization process, ZnGA catalyst not only provided activated CO₂ for DMC catalyst, but also transferred the propagating chain with more alternating structures to DMC catalyst. Both of the two effects increased the carbonate content in the final products. Overall, DMC catalyst dedicated to the polymer chain growth, while the increased CO₂ conversion mainly attributed to ZnGA catalyst. Oligo (propylene‐carbonate) diols with carbonate unit content of 45.1 mol%, Mn of 1228 g/mol, W_PC of 4.3 wt% and high yield of 1689 g/g _cat was obtained.     

Mesostructure organic‐inorganic hybrid ionic liquids based on heteropoly acids: Effect of linkage on the molecular structure and catalytic activity

The new inorganic–organic hybrids based on SO₃H‐functionalized ionic liquids (ILs) and Keggin‐type heteropoly acids (H₃PW₁₂O₄₀, H₃PMo₁₂O₄₀, and H₄SiW₁₂O₄₀; HPAs) are prepared and characterized by FT‐IR, NMR, XRD, CV, SEM/EDX, ICP‐OES, BJH and UV. Different molecular structures according to the different inorganic part were also proved. Potentiometric titration showed a good relationship between catalytic activity and acidity of the catalysts. Electrochemical aspects showed electron transfer ability of the compounds. For understanding catalytic activities of the HPA‐IL hybrids in N‐formylation reaction, effect of catalyst composition, substrate, and reaction conditions were studied. The best SO₃H‐functionalized ionic liquid catalyst was readily recovered and reused for four runs. Easy preparation of the catalyst, simple and easy work‐up, mild reaction conditions, low cost, excellent yields and short reaction times are the key features of this work.     

Microfunnel‐filter‐based emulsification microextraction followed by gas chromatography for simple determination of organophosphorus pesticides in environmental water samples

A simple and fast method named microfunnel‐filter‐based emulsification microextraction is introduced for an efficient determination of some organophosphorus pesticides including diazinon, malathion, and chlorpyrifos in the environmental samples including the river, sea, and well water. This method is based upon the dispersion of a low‐toxicity organic solvent (dihexyl ether), as the extractant, in a high volume of an aqueous sample solution (45 mL). It is implemented without a centrifugation step, and using a syringe filter and a micro‐funnel, the phase separation and transfer of the enriched analytes to the gas chromatograph are simply achieved. By filtration of the extractant phase, a suitable sample clean‐up is obtained, and the total extraction time is just a few minutes. The factors influencing the extraction efficiency are optimized, and under the optimal conditions, the proposed method provides a good linearity (in the range of 15–1500 ng/mL (R² > 0.996). A high enrichment factor is obtained (in the range of 306–342), and the method provides low limits of detection and quantification (in the ranges of 4–8 and 15–25 ng/mL, respectively).     

Supported dual‐acidic 1,3‐disulfoimidazolium chlorozincate@HZSM‐5 as a promising heterogeneous catalyst for synthesis of indole derivatives

HZSM‐5‐supported Brönsted and Lewis acidic ionic solid 1,3‐disulfoimidazolium chlorozincate materials ([dsim]₂[ZnCl₄]@HZSM‐5) were synthesized with various ratios (3, 6, 9, 17 and 50% w/w). The heterogeneous materials were characterized via a variety of spectroscopic techniques. Dual acidity of these materials was determined using specified techniques. These acidic solids were examined as stable heterogeneous catalysts for the Fischer indole reaction of equimolar amounts of phenylhydrazine hydrochloride and various aliphatic or aromatic ketones at 80–90°C in neat condition to produce substituted indole derivatives. The efficient 17% ionic salt‐loaded HZSM‐5 composite was easily reused for ten consecutive cycles with a slight loss of its activity. The recycled catalyst was further analysed using powder X‐ray diffraction and inductively coupled plasma optical emission spectrometric techniques.     

Multistrain edge‐based compartmental model on networks

Multistrain diseases, which are infected through individual contacts, pose severe public health threat nowadays. In this paper, we build competitive and mutative two‐strain edge‐based compartmental models using probability generation function (PGF) and pair approximation (PA). Both of them are ordinary differential equations. Their basic reproduction numbers and final size formulas are explicitly derived. We show that the formula gives a unique positive final epidemic size when the reproduction number is larger than unity. We further consider competitive and mutative multistrain diseases spreading models and compute their basic reproduction numbers. We perform numerical simulations that show some dynamical properties of the competitive and mutative two‐strain models.