Preparation and Characterization of Binder for Inorganic Composites Made from Amorphous Mineral Raw Material

The preparation and characterization of a composite binder made through a sol-gel route from an amorphous mineral raw material has been studied. The amorphous mineral raw material is alumino-silicate based but contains also alkaline earth and some transition metal oxides. A stable sol can be prepared by dissolving the raw materials in formic acid. The drying and heat treatment of the subsequent gel has been studied by thermogravimetry, nuclear magnetic resonance, infrared spectroscopy as well as X-ray diffraction studies. The different constituents of the raw material have shown to play a major role during the drying and heat treatment of the gels. The binding effect of the binder was evaluated to be good by studying paper-binder composites as well as wetting properties.     

A new,convenient and expeditious synthesis of 4-alkyl-5-methyl-1H-pyrazol-3-ols in water through a multicomponent reaction

A new, simple and efficient synthesis of 4-alkyl-5-methyl-1H-pyrazol-3-ols in water by a two-pot four component reaction of ethyl acetoacetate, hydrazine hydrate, aldehyde and ketone in presence K₂CO₃ as the catalyst is described. Use of water as the reaction medium, operational simplicity, mild reaction conditions, application of a cost-effective, nontoxic and easily available catalyst with auto-tandem catalysis, wide substrate scope, easy workup and purification process make the protocol highly attractive.     

p-TSA-catalyzed facile and efficient one-pot eco-friendly synthesis of novel isoxazolyl amino furo[3,2-c]quinolinone derivatives in aqueous medium

A green and operationally simple approach for the synthesis of novel isoxazolyl amino furo[3,2-c]quinolinone derivatives by a one-pot three-component reaction of 4-amino-3-methyl-5 styrylisoxazoles, aryl glyoxal monohydrates and 4-hydroxy-1-methyl-2-quinolinone using p-TSA as the catalyst in aqueous medium was developed. The protocol proves to be an efficient and an environmentally benign in terms of high yields, operational simplicity, clean reaction profile, compatibility with wide range of substrates, water as a solvent and easy purification.     

Electrocatalytic Hydrogenation and Oxidation in Aqueous Conditions†

Water molecule contains one oxygen and two hydrogen atoms, making it a potential oxygen and hydrogen source. Electrocatalytic organic reduction and oxidation using water as oxygen and/or hydrogen donors provide an environmentally friendly and sustainable strategy to replace traditional chemical‐driven stoichiometric reactions that use sacrificial reagents. Furthermore, the development of electrochemical synthesis provides a potential application for low tension photoelectricity, which is not cost‐effective during boosted voltage and application. In the last decade, electrocatalytic redox reactions of organic molecules in aqueous media had shown progress owing to the development of electrode materials and water‐splitting technology. This paper highlights several electrocatalytic systems and corresponding mechanisms for both hydrogenation and oxidative transformation of representative compounds. The activation process of protons and water on the working electrode surface has received special focus. Furthermore, paired electrolysis using water as the oxygen and hydrogen source has been demonstrated. This paired system combines hydrogenation and oxidation half‐reactions in one cell using water as the hydrogen and oxygen source, resulting in high atomic and electron utilization rates.     

A Simple,Efficient and Green Procedure for Knoevenagel Condensation in Water or under Solvent‐free Conditions

1,4‐Diazabicyclo[2.2.2]octane was used as an efficient catalyst in the Knoevenagel condensation reaction of various kinds of aromatic/aliphatic/heterocyclic/αβ‐unsaturated aldehydes and ketones with active methylene compounds. This is a convenient and rapid method for Knoevenagel condensation, which affords the corresponding substituted electrophilic alkenes in excellent yields. The reaction condition is mild and the method is operationally simple. The products, only E‐isomers were detected, did not need to be purified. The use of water as the reaction medium makes the process environmentally benign. The catalysts can be recycled six times without activity loss.     

The application of clean production in organic synthesis

Clean production,as an important part of green chemistry,has received great atte ntion and considerable development in recent years.In this perspective article,we summarized some examples of(nearly)quantitative synthesis,clean separation and purification to emphasize clean production.These reactions were carried out by using eco-friendly solvents and the pure products could be easily obtained through clean procedures.     

Reactions in Water – A Greener Approach Using Ruthenium Catalysts

Reactions using transition metals as catalysts have emerged as an efficient method in the recent times. However, the selection of solvent plays a crucial role in this regard. Several solvents used traditionally suffer majorly with problems of toxicity; high boiling point etc. leading to drastic reaction conditions. Water being a non‐toxic, non‐inflammable and environmentally benign can replace the hazardous organic solvents in laboratory as well as industry. Maintaining a minimum catalyst loading percentage we can advantageously avail high levels of selectivity. Water was found to be a good solvent medium for several metal catalysed reactions. An intramolecular deprotonation mechanism is followed by the ruthenium (II) catalysts in water; thereby, facilitating the catalytic action of the metal. These studies can help the industrial chemists to utilize water as a solvent for their reactions towards improvement of their waste management procedure. This review mainly focuses on the several recent developments in the above direction.     

Rapid four-component reactions in water: synthesis of pyranopyrazoles

An environmentally benign four-component reaction in aqueous medium at room temperature has been developed for the synthesis of 6-amino-5-cyano-3-methyl-4-aryl/heteroaryl-2H,4H-dihydropyrano[2,3-c]pyrazoles.     

Sol-Gel Derived Binder for Inorganic Composites

A new low cost inorganic binder system for large volume products like fiber insulation, building materials, etc. has been developed based on sol-gel technology. The precursor for the binder system is an amorphous mineral raw material containing silica as the major component. The sol was prepared by dissolving the amorphous mineral material in formic acid and the mineral was dissolved in a few hours dependent on the molarity of the formic acid. The sol stability was dependent on the solids content and the pH. The gel formation was studied using light scattering and NMR. The results show a growing particle size of particles mainly consisting of silica while the other cations were dissolved in the pore liquid. During the drying of the wet gels, salts of these cations were crystallized in the pores and further decomposed during heating. The derived binder shows good wetting properties to mineral fiber surfaces and a good strength of paper-binder composites. The new binder system applicable to approximately 800°C has a great potential as a substitute for some traditional organic systems.     

Water-acetic acid mediated an efficient and eco-friendly protocol for the one-pot synthesis of bis-isoxazolyl amino dihydro-1H-indol-4(5H)-ones under mild reaction conditions

A cost-effective and eco-friendly straightforward synthesis of new bis-isoxazolyl amino dihydro-1H-indol-4(5H)-ones is successfully achieved via one-pot three-component reaction of N-isoxazolyl enaminone, aryl glyoxal monohydrates and 4-amino-3-methyl-5-styrylisoxazoles by using water as a reaction medium and acetic acid (AcOH) as cheap and green promoter. The protocol proves to be an efficient and environmentally benign in terms of high yields, low reaction time, operational simplicity, metal-free and wide substrates scope. Most important of all, this reaction process is green.     

Synthesis in Water and Antimicrobial Activity of 5-Trichloromethyl-4,5-dihydroisoxazoles

Two series of 5-trichloromethylisoxazoles were synthesized from the cyclocondensation of 1,1,1-trichloro-4-methoxy-3-alken-2-ones [Cl₃CC(O)C(R²) = C(R¹)OMe, where R¹ = H, Me, Et, Pr, iso-Pr, cyclo-Pr, Bu, terc-Bu, CH₂Br, CHBr₂, CH(Me)SMe, (CH₂)₂Ph, and Ph, and R² = H; R¹ = H and R² = Me and Et; R¹ and R² = -(CH₂)₄- and -(CH₂)₅-; and R¹ = Et and Ph and R² = Me] with hydroxylamine hydrochloride through a rapid one-pot reaction in water. The 5-trichloromethyl-4,5-dihydroisoxazoles were aromatized by reaction with concentrated sulfuric acid to obtain the respective 5-trichloromethylisoxazoles. Their structures were confirmed by elemental analysis, ¹H/¹³C nuclear magnetic resonance, and electron impact mass spectroscopy. Crystal structure analysis for 5-triclhoromethyl-5-hydroxy-3-propyl-4,5-dihydroisoxazole (2d) and 5-trichloromethyl-5-hydroxy-3,4-hexamethylene-4,5-dihydroisoxazole (2o) is presented. The antimicrobial activities of the 5-trichloromethyl-4,5-dihydroisoxazole derivatives were examined using the standard twofold dilution method against Gram-positive bacteria (Staphylococcus aureus), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), and yeasts (Candida spp. and Cryptococcus neoformans). All of the tested 5-trichloromethyldihydroisoxazoles exhibited antibacterial and antifungal activities at the tested concentrations.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

Fast oxidation of secondary alcohols by the bromate-bromide system using cyclic microwave heating in acidic water

We report an improved, gentle, cyclic microwave activation technique for the oxidation of secondary alcohols using nonhazardous hypobromous acid (BrOH) as the reagent in acidic water. Several aliphatic and aromatic secondary alcohols were successfully oxidized to the corresponding ketones using this technique in high yields and with only minor amounts of side products.     

钒酸铋黄色颜料的制备——推荐一个无机化学教学实验

该实验以Bi(NO_3)_3和NH_4VO_3为原料,采用液相沉淀法,制备钒酸铋黄色颜料。学生通过控制反应物初始浓度、溶液pH、温度与时间等条件制备分散性良好、颗粒细小、组成均匀的钒酸铋。实验涉及溶液配制、加热搅拌、简易回流、控温、调pH、检验、抽滤、洗涤、干燥等操作。钒酸铋是一种绿色环保的黄色颜料,且具有降解污染物的光催化性能,因此,该实验不仅对于提高学生无机制备实验能力具有很好的教学效果,还在实验教学中渗透了环保理念。     

官能化硅胶负载Pd—Cu催化剂的制备及催化芳香氯化物水相脱氯作用

将聚乙烯吡烷酮（PVP）与双金属Pd^2 、Cu^2 配位后,再负载于用平均分子量为600的聚乙二醇（PEG）官能化的硅胶上（SiO2-PEG600),制成一种新型双负载双金属催化剂PVP-PdCl2-CuCl2/SiO2-PEG600,将其用于催化难溶于水的芳香卤化物水相脱卤,在无需加入任何有机溶剂的情况下,对芳香氯化物呈现出高的脱氯活性和选择性,并具有良好的重复使用性能。通过IR、TEM、比表面积测定等手段,探讨了催化剂各组分在催化脱卤中的作用及可能的催化脱卤机理。     

Water as a green solvent combined with different techniques for extraction of essential oil from lavender flowers

Using water as a green solvent with a variable geometry makes use of physical and chemical phenomena that are fundamentally different from those applied in conventional extraction techniques such as hydro-distillation, steam distillation or solvent extraction. Advantages and drawbacks of using water as a solvent with different physical and chemical states have been compared. A total of ten extraction techniques: hydro-distillation (HD), steam distillation (SD), turbo-hydro-distillation (THD), salt-hydro-distillation (NaCL-HD), enzyme-hydro-distillation (Enzyme-HD), micelle-hydro-distillation (Micelle-HD), ultrasound-hydro-distillation (US-HD) or subcritical water-hydro-distillation (SW-HD), solvent-free microwave extraction (SFME) and microwave steam distillation (MSD) were used to extract the essential oil from lavender (Lavandula L.) and their results were compared. The quantity was measured by the yield of essential oil and the quality was evaluated using the oil composition especially the content of linalyl acetate, linalool and terpin-4-ol compared with the corresponding control sample: Hydro-distillation. For environmentally friendly of the process: extraction time, total energy consumption and CO₂ emission were considered and compared with conventional hydro-distillation. The mechanism explaining the linalyl acetate degradation has been resolved by using COSMO-RS software. Based on the present experimental conditions, it is recommended that lavender oil may be produced preferably by steam distillation assisted by microwave extraction to reduce the by-product formation by various chemical reactions and to get better oil recoveries.     

Gas permeation characteristics of a hydrogen selective supported silica membrane

A highly hydrogen permeable silica membrane, referred to as Nanosil, was obtained by chemical vapor deposition of a thin SiO₂ layer on a porous Vycor glass support. This composite membrane showed good permeance (10⁻⁸ mol m⁻² s⁻¹ Pa⁻¹) for the small gas molecules (He, Ne, and H₂) at 873 K with high selectivity (10⁴) over other larger gas molecules (CO₂, CO, and CH₄). The characteristics of gas transport on the Vycor and Nanosil membrane were investigated with several gas diffusion models. The experimental gas permeation data on Vycor glass could be explained by the occurrence of Knudsen diffusion in parallel with surface diffusion. The permeance of the small gas molecules (He, Ne, and H₂) on the Nanosil membrane was activated, and increased as temperature increased. However, this permeance was limited at high temperature because of the limited permeance on the Vycor support. The gas permeance on the deposited silica layer was obtained by applying a series analysis of gas permeation on the combined silica layer and Vycor support composite system. The order of permeance through the silica layer was He>H₂>Ne which was the same as that through vitreous silica glass, but occurred with lower activation energies. The order of permeation of these small gas molecules did not follow either mass or molecular size but could be explained using a statistical gas permeance model.     

Correlation between crystal symmetry and the splitting of d orbital in the thiocyanate nickel(II) complexes

New [Ni(SCN)₂(L)_4/2] complexes, where L = py (1), γ-pic (2), pyCH₂OH (3), py(CH₂)₃OH (4) were synthesized in simple reactions of NiCl₂·6H₂O with ammonia thiocyanate and pyridine type ligands in methanol solutions. Blue crystals of [Ni(SCN)₂(py)₄] (1), [Ni(SCN)₂(pyCH₂OH)₂] (3) and [Ni(SCN)₂(py(CH₂)₃OH)₂] (4) crystallize in the monoclinic system, blue crystal of [Ni(SCN)₂(γ-pic)₄] (2) – in the tetragonal one, and red crystal of [Ni(SCN)₂(PPh₃)₂] (5) – in the triclinic one. The ligands of complexes (1) and (3) were indicated as rather strong π-acceptors while that of complex (4) one has some π-donor properties. When the aliphatic chain (CH₂) elongates in the sequence: (1), (3) and (4), an increase in the orbital contribution to the magnetic moment and a decrease in the 10Dq value of the d orbital splitting are related to the change of the point group symmetry from D_2h, via D_2v to C_2h.     

Performance of ion chromatography in the determination of anions and cations in various natural waters with elevated mineralization

The performance of ion chromatography in the determination of anions and cations in natural mineral waters of different composition and different total mineralization was evaluated. Up to 12 ions of the 20 usually included in extended chemical analysis of natural waters were successfully determined by ion chromatography alone. At least 98.60% and up to 99.96% of total cation composition of mineral waters was determined by ion chromatography. Hydrogen carbonate predominated in anion composition of mineral waters and was determined titrimetrically. The percentage of anions determined by ion chromatography in the remaining anion composition of mineral waters was between 98.90% and 99.96%. The agreement between total concentrations of anions and cations in individual mineral waters determined predominantly by ion chromatography is very good and the performance of ion chromatography for the basic and for the extended chemical analysis of highly mineralized water samples is very high. Method development was assisted by previously developed algorithms and appropriate experimental conditions are also discussed.     

"鸡尾酒"实验——无机元素化学实验中美育迁移作用的探索

以“美育”内涵中“培养发现美的能力”为契合点,借助大一新生在无机元素化学实验中发现美时获取的成就感,引导学生在追求“美丽”实验结果的过程中,自发地对基本操作进行训练和提高,由此发挥美育在无机化学实验教学过程中的迁移作用。以钴离子形成多色配合物为“点”,带动学生持续发现实验中更多的“美”,逐步培养细心、耐心和恒心的素养。同时,在新高考、新生源背景下,注重大一新生化学学习兴趣的提高,将直接影响到其对专业的认知及职业的认同,因而其积极作用是不容忽视且意义深远的。     

Reusable and Efficient Cul/TBAB‐Catalyzed Iodination of Terminal Alkynes in Water under Air

An environmentally‐friendly and operationally‐simple process for the synthesis of 1‐iodoalk‐1‐ynes under mild conditions catalyzed by CuI/TBAB in water under air was developed in this study. Catalyst loadings of CuI as low as 1–2 mol% gave 1‐iodoalk‐1‐ynes in good to high yields, and the residual aqueous solution after extraction with hexane could be reused for the next reaction without any treatment.