乙酸正丁酯绿色化合成的研究

文章采用732型强酸性阳离子交换树脂替代腐蚀性很强的硫酸,作为乙酸正丁酯合成的催化剂,对有机化学实验中乙酸正丁酯的合成方法进行绿色化改进。考察了催化剂用量、乙酸与正丁醇摩尔比及反应时间对乙酸正丁酯收率的影响,并对催化剂的重复使用情况进行了研究。优化的实验条件为:冰醋酸15 mL(0.263 mol),正丁醇48 mL(0.526 mol),催化剂用量2.5 g,反应时间45 min。乙酸正丁酯产率可达82.6%。

碳酸丙烯酯合成的工艺绿色化进展

以碳酸丙烯酯的合成为例,概要地介绍了这种化学品合成工艺的绿色化进展,其中包括各种合成方法采用的原始材料、催化剂选择和制备、副产物的生成、过程的原子经济性等。另外还介绍了以含叔胺基和季铵盐基团的大孔离子交换树脂和季铵化壳聚糖为多相催化剂由环氧丙烷和二氧化碳在超临界条件下合成碳酸丙烯酯过程中各自的一些工艺试验参数、影响因素、收率和选择性等。

Preparation of Ni(HCO_3)_2 and its catalytic performance in synthesis of benzoin ethyl ether

Ni（HCO3）2 with unique phase and high crystallinity was synthesized with urea hydrolysis. The as-prepared samples were well characterized in detail. N2 adsorption and desorption result manifests a high surface area of 99.03 m2/g with a pore size of 7.8 nm. Scanning electron microscopy （SEM） and particle size distribution reveal that the diameters of the formed pellets are uniform. Thermogravimetry （TG） analysis result shows that 500 ℃ could be the appropriate temperature for converting Ni（HCO3）2 precursors into NiO via a thermal decomposition process. CO2 and NH3 temperature-programmed desorption results show that Ni（HCO3）2 has explicit acid-base sites. Transmission electron microscopy （TEM） results vividly indicate that the pellets are aggregated by hexagonal platelets and possess porous structures. Ni（HCO3）2 can efficiently catalyze the one-step synthesis of benzoin ethyl ether from benzaldehyde and ethanol, with the conversion ofbenzaldehyde up to 57.5% and nearly 100% selectivity of benzoin ethyl ether.

Sustainable synthesis of supported metal nanocatalysts for electrochemical hydrogen evolution

Among the various types of heterogeneous catalysts,supported metal nanocatalysts(SMNCs)have attracted widespread interest in chemistry and materials science,due to their advantageous features,such as high efficiency,stability,and reusability for catalytic reactions.However,to obtain well-defined SMNCs and inhibit nanoparticle aggregation,traditional approaches generally involve numerous organic reagents,complex steps,and specialized equipment,thus hindering the practical and large-scale synthesis of SMNCs.In this review,we summarize green and sustainable synthetic methodologies for the assembly of SMNCs,including low temperature pyrolysis and solid-state,surfactant-and reductant-free,and ionic liquid assisted syntheses.The conventional application of SMNCs for electrochemical hydrogen evolution and the corresponding achievements are subsequently discussed.Finally,future perspectives toward the sustainable production of SMNCs are presented.

Biomolecule-assisted, cost-effective synthesis of a Zn_(0.9)Cd_(0.1)S solid solution for efficient photocatalytic hydrogen production under visible light

A series of alloyed Zn‐Cd‐S solid solutions with a cubic zinc blende structure were fabricated hydrothermally with the assistance of L‐cystine under mild conditions.The products were characterized by XRD,TEM,HRTEM,XPS,UV‐vis,and BET techniques,and the photocatalytic performance for the reduction of water to H2on the solid solutions was evaluated in the presence of S2?/SO32?as hole scavengers under visible light illumination.Among all the samples,the highest photocatalytic activity was achieved over Zn0.9Cd0.1S with a rate of4.4mmol h?1g?1,even without a co‐catalyst,which far exceeded that of CdS.Moreover,Zn0.9Cd0.1S displayed excellent anti‐photocorrosion properties during the photoreduction of water into H2.The enhancement in the photocatalytic performance was mainly attributed to the efficient charge transfer in the Zn0.9Cd0.1alloyed structure and the high surface area.This work provides a simple,cost‐effective and green technique,which can be generalized as a rational preparation route for the large‐scale fabrication of metal sulfide photocatalysts.

Green synthesis of pure and doped semiconductor nanoparticles of ZnS and CdS

Nanoparticles of pure and Cu/Ag-doped CdS and ZnS have been synthesized via chemical bath deposition without using any capping or toxic reagents.The synthesis was carried out through a simple and less expensive green method.The XRD result shows that both pure CdS and ZnS and their doped derivatives are of high crystalline with hexagonal packing structure.The average crystalline size of all nanoparticles was calculated using Debye-Scherrer formula.The crystalline size of nanoparticles of pure samples varied with that of the doped sample.The average crystalline sizes of all nanoparticles are found to be in the range of 5.5-2.2 nm for CdS（from pure to doped） and 4.3-3.4 nm for ZnS,respectively.The band gap values obtained from UV-visible spectra are in the range of 3.5-2.1 e V for CdS and 3.3-2.7 e V for ZnS derivatives,respectively.The FTIR spectral data give characteristic peaks for Cd—S,Cu—S,Ag—S and Zn—S bonds and confirm the formation of respective nanoparticles.The peaks corresponding to the microstructural formation are also observed.The FE-SEM images show the granular morphological structure for all the samples.The agglomeration size of the samples in the range of 10-50 nm for CdS：Cu and 50-100 nm for ZnS：Cu is observed.

Synthesis and physico-chemical properties of new green electrolyte 1-butyl-3-methylimidazolium perchlorate

1-butyl-3-methylimidazolium perchlorate([BMIM]ClO4) was synthesized by two steps with N-methylimidazolium.Some physico-chemical properties,such as density,surface tension,viscosity,electrical conductivity as well as electrochemical window,were investigated and solvent performance was also studied.The results show that this kind of ionic liquid is an excellent electrolyte with low viscosity,high electrical conductivity and wide electrochemical window.In addition,[BMIM]ClO4 is soluble in most conventional solvents and some metal oxides have high solubility in it,which lays the foundation of direct electrolysis of metal oxides in this ionic liquid.

Green Synthesis of RuO2 Electrode for Electrochemical Water Treatment

Nowadays, the electrochemical water treatments are very important methods used for the removal of organic and inorganic impurities from fresh, drinking water and wastewater. The method consists of carrying out the oxidation reaction at the anode where pollutants are transferred into non-toxic substances, by decomposing into simpler compounds or transferring into oxidation form. RuO2-based Dimensional Stable Anode （DSA） is a technologically good and important electrode for water treatment because of its unique characteristics such as high thermal and chemical stability, low resistivity and low overpotential. This paper reviews the methods for fabricating RuO2-based electrodes that can be used in electrochemical water treatment. Depending on the different fabrication routes, RuO2 electrodes will possess the different electro-catalytic property and stability.

Enhanced Property of Thin Cuprous Oxide Film Prepared through Green Synthetic Route

Thin cuprous oxide films have been prepared by chemical vapor deposition(pulsed spray evaporation-chemical vapor deposition)method without post-treatment.The synthesis of cuprous oxide was produced by applying a water strategy effect.Then,the effect of water on the morphology,topology,structure,optical properties and surface composition of the obtained films has been comprehensively investigated.The results reveal that a pure phase of Cu2O was obtained.The introduction of a small quantity of water in the liquid feedstock lowers the band gap energy from 2.16 eV to 2.04 eV.This finding was mainly related to the decrease of crystallite size due to the effect of water.The topology analyses,by using atomic force microscope,also revealed that surface roughness decreases with water addition,namely more uniform covered surface.Moreover,theoretical calculations based on density functional theory method were performed to understand the adsorption and reaction behaviors of water and ethanol on the Cu2O thin film surface.Formation mechanism of the Cu2O thin film was also suggested and discussed.

A Simplified Green Chemistry Approach to the Synthesis of Carbon-Carbon Double Bonds Via Knoevenagel Condensation Catalyzed with ZrOCl2.8H2O

A green and simplified room-temperature procedure was reported for the synthesis of carbon-carbon double bonds by Knoevenagel condensation of various aldehydes with malononitrile and ethyl cyanoacetate in the presence of catalytic amount of ZrOCl2·8H2O in aqueous media.

Green Synthesis and Physical and Chemical Characterization of Chitosans with a High Degree of Deacetylation, Produced by a Binary Enzyme System

Chitosan is a biopolymer obtained from chitin, where the N-acetylglucosamine monomer is in its deacetylated form; this polymer is useful for a wide variety of industrial applications. The properties and uses of chitosan depend on its physical and chemical characteristics, which result from the treatments used for its production. In this study, we report the preparation and characterization ofchitosan oligosaccharides by a green synthesis from crystalline shrimp chitin, using a sequential enzyme treatment by chitinase and chitin deacetylase. Chitinases were purified from grapes and used to rupture the crystalline shrimp chitin structure, modifying the crystallinity index from 57.6% to 15.9%. The resultant polymers were deacetylated using a recombinant chitin deacetylase from Saccharomyces cerevisiae, which was cloned and expressed in Pichia pastoris. The chitosans produced showed an estimated DA （degree of acetylation） of approximately 20%, and the molecular weights ranged from -7,600 to -3,700 after treatment in pH 3.0 and pH 6.0 for 10 min and 40 min, respectively. Physical and chemical characterization of the products indicated that enzyme fragmentation of chitin probably makes the acetamide groups more accessible to deacetylation, forming homogeneous polymers that are free of hazardous sub-products, have defined low molecular weights, and are highly deacetylated.

Design and synthesis by redox polymerization of a bio-based carboxylic elastomer for green tire

Poly(dibutyl itaconate-co-isoprene-co-methacrylic acid)(PDIM) elastomer was designed and synthesized by redox emulsion polymerization under mild conditions. PDIM has high molecular weight, relatively high yield, and low glass transition temperature(Tg). The structure of PDIM was determined by FTIR and NMR, and the carboxyl content was obtained by titration in a non-proton solvent. Tensile strength and elongation at break increased with increasing carboxyl content. In addition, the interaction between PDIM and silica was elucidated by rubber process analyzer(RPA) and TEM, and the results showed that the silica-PDIM interaction was strong, but the silica-silica interaction was weak.

Green synthesis of NiFe LDH/Ni foam at room temperature for highly efficient electrocatalytic oxygen evolution reaction

Clean energy technologies such as water splitting and fuel cells have been intensively pursued in the last decade for their free pollution. However, there is plenty of fossil energy consumed in the preparation of the catalysts,which results in a heavy pollution. Therefore, it is much desired but challenging to fabricate high-efficiency catalysts without extra energy input. Herein, we used a facile one-pot room-temperature method to synthesize a highly efficient electrocatalyst of nickel iron layered double hydroxide grown on Ni foam(NiFe LDH/NF) for oxygen evolution reaction(OER). The formation of the NiFe LDH follows a dissolutionprecipitation process, in which the acid conditions by hydrolysis of Fe^3+ combined with NO3^- could etch the NF to form Ni^2+. Then, the obtained Ni^2+ was co-precipitated with the hydrolysed Fe^3+ to in situ generate NiFe LDH on the NF. The NiFe LDH/NF exhibits excellent OER performance with a low potential of about 1.411 V vs. reversible hydrogen electrode(RHE) at a current density of 10 m A cm^-2, a small Tafel slope of 42.3 mV dec^-1 and a significantly low potential of ~1.452 V vs. RHE at 100 mA cm^-2 in 1 mol L^-1 KOH. Moreover, the material also keeps its original morphology and structure over 20 h. This energy-efficient strategy to synthesize NiFe LDH is highly promising for widespread application in OER catalyst industry.

Surface-gel-conversion synthesis of submicron-thick MFI zeolite membranes to expedite shape-selective separation of hexane isomers

Ultrathin zeolite membranes are of paramount importance in accelerating gas transport during membrane separation,and lowering down their membrane thicknesses to submicron scale is deemed to be very challenging.Herein,we develop an advanced approach of surface gel conversion for synthesis of submicron-thick pure silica MFI(silicalite-1)zeolite membranes.Viscous gel is prepared by finely adjusting the precursor composition,enabling its reduced wettability.The unfavorable wetting of the support surface can effectively prevent gel penetration into alumina support voids.Aided by the seeds,the surface gel is directly and fully crystallized into an MFI zeolite membrane with minimal water steam.A membrane with a thickness of 500 nm is successfully acquired and it is free of visible cracks.Additionally,the as-synthesized membranes exhibit rapid and selective separation of hexane isomers by virtue of unprecedentedly high n-hexane permeance of 24.5×10^−7 mol m^−2 s^−1 Pa^−1 and impressive separation factors of 13.3-22.6 for n-hexane over its isomers.This developed approach is of practical interest for sustainable synthesis of high-quality zeolite membranes.