Presence Of Zinc Chloride Research Articles

Nitrogen-doped porous carbon from biomass with superior catalytic performance for acetylene hydrochlorination.

Acetylene hydrochlorination is an important aspect of the industrial synthesis of polyvinyl chloride, but it requires a toxic mercury chloride catalyst. Here we report a green, highly efficient and low cost nitrogen-doped soybean meal carbon (SBMC) catalyst obtained from the simple carbonization of biomass soybean meal (SBM) in the presence of zinc chloride. This material exhibits excellent catalytic performance during acetylene hydrochlorination, with an initial acetylene conversion greater than 99% and 98% selectivity for vinyl chloride at 200 °C over 110 h. Analyses by X-ray photoelectron spectroscopy and temperature programmed desorption as well as catalytic activity evaluations show that pyridinic species are the active sites for hydrogen chloride, while pyrrolic N species are the main active sites for acetylene. An analysis of charge calculations based on model catalysts further indicates that the activity of pyrrolic N species essentially determines the performance of the SBMC catalyst. This investigation of the mechanism of acetylene hydrochlorination over SBMC confirms that such nitrogen-doped catalysts have two different active sites for the adsorption and activation of hydrogen chloride and acetylene molecules. This mechanism is different from that associated with metal chloride catalysts such as HgCl2. This SBMC catalyst is a potential alternative to HgCl2@AC catalysts for vinyl chloride synthesis and suggests a new means of designing carbon catalysts with basic surfaces for acetylene hydrochlorination.

Novel Approach for Rapid and Efficient Synthesis of 2‐(3‐(4‐Aryl)‐1‐isonicotinoyl‐4,5‐dihydro‐1H‐pyrazol‐4‐yl)‐3‐phenylthiazolidin‐4‐one Derivatives and Screened Their Antimicrobial Activity

A series of compounds, viz. 2‐(3‐(4‐aryl)‐1‐isonicotinoyl‐4,5‐dihydro‐1H‐pyrazol‐4‐yl)‐3‐phenylthiazolidin‐4‐one 4 (a–n), have been synthesized by reaction of 3 (a–n) with thioglycolic acid in the presence of zinc chloride. Compounds 3 (a–n) have been synthesized by amination of formylated pyrazoles 2 (A–B), which were synthesized by formylation of 1 (A–B) by Vilsmeier–Haack reagent (POCl3/DMF). Compounds 1 (A–B) were synthesized by condensation of hydrazide and substituted acetophenones under conventional method and microwave irradiation method. These compounds were identified on the basis of melting point range, Rf values, infrared, 1H NMR, and mass spectral analysis. These compounds were evaluated for their in vitro antimicrobial activity, and their minimum inhibitory concentration was determined. Among them, compound 4b and compound 4l possess appreciable antimicrobial and antifungal activities. Antibacterial activity results showed that compounds containing electron‐withdrawing groups were more active than compounds containing electron‐releasing groups.

Synthesis and Study of some Heterocyclic Compounds from Schiff Base of Pinacolone

In this work, the synthesis of some heterocyclic compound of four, five and seven membered rings were done. On oxidation of the pinacole alcohol using concentrated sulphuric acid pinacolone were obtained and used as a precursor for the synthesis of three new Schiffs base through the reaction with para substituted anilines compounds. These imines were allowed to react with chloroacetyl chloride in dry dioxane to give the azetadine -2- one compounds. Also some thiazoldinone compounds were synthesized from the reaction of the corresponding imines with thioglycolic acid in the presence of zinc chloride in dry benzene and 1,3-oxazepine-4,7-diones, were obtained from the reaction of imines with maleic and phythalic anhydries in dry benzene. The synthesized compounds were characterized by IR spectroscopy and physical paramrters.

Zinc chloride catalyzed multicomponent synthesis of pyrazolopyridocoumarin scaffolds

An efficient synthesis of a series of pyrazolopyridocoumarins is reported by condensation of 4-hydroxycoumarin, benzaldehydes and 1-alkyl-5-amino-pyrazoles in the presence of 10 mol% zinc chloride in ethanol under reflux conditions through one-pot reaction. The significant attraction of this protocol is being a simple procedure, mild reaction condition, and excellent yield. The molecular structure of the compound (4e) is established by single crystal X-ray structure determination. A facile and an efficient protocol for the synthesis of novel pyrazolopyridocoumarins have been developed via a one-pot reaction of 4-hydroxycoumarin, benzaldehydes and 1-alkyl-5-amino-pyrazoles in the presence of zinc chloride in ethanol at reflux temperature. The present approach offers the advantages of simple methodology, high atom-economy, mild conditions, short reaction times, low environmental impact and high yield. The molecular structure of the compound (4e) is established by single crystal X-ray structure determination.

Attempts to design porous carbon monoliths using porous concrete as a template - Part II: Some aspects of the pore formation mechanism

Abstract Porous concrete has been proven as a promising template to prepare porous carbon monoliths because it can easily be formed to any geometric shape. To optimize the pore size distribution the template-assisted route can be combined with steps of the classical carbon activation such as the carbonization in the presence of zinc chloride. For the rational designing of such routes, profound knowledge of the pore-formation process is necessary. This is however complicated because the pore formation is the result of a complex interplay of different sub-processes. Here, we present approaches to estimate the contributions of these sub-processes to the overall porosity in a quantitative way. For that, the role of the template, the gasification reactions as well as the activating agent has been elucidated by elaborate analysis of nitrogen adsorption data.

Facile synthesis of monolithic hierarchical porous carbon materials via molten salt method

Hierarchical porous carbon materials (HPCMs) have attracted promising potential in the fields of catalyst supports, adsorbents, and electrochemical electrodes. However, traditional templating methods suffer from complicated synthesis processes as well as the difficulty of removing templates. In this work, HPCMs were successfully synthesized by direct polymerization of resorcinol and furfural in the presence of zinc chloride. Zinc chloride is served as dehydration and porogen, which plays a key role in the formation of HPCMs and could be removed easily with deionized water, thus inorganic template and hazardous chemicals could be avoided. Carbonization temperature and the molar ratio of raw materials have significant effect on the textural properties of HPCMs. When the molar ratios of isopropanol/resorcinol and zinc chloride/resorcinol were chosen as 6.0 and 4.0, respectively, in the carbonization temperature of 900 °C, HPCMs containing interconnected micro-, meso-, and macropores are obtained, whose density is down to 0.16 g/cm3 and specific surface area is up to 935.9 m2/g.

ZnCo2O4 nanorods as a novel class of high-performance adsorbent for removal of methyl blue

Spinel ZnCo2O4 nanorods were synthesized by a simple template-free hydrothermal method in the presence of zinc chloride, cobalt chloride, glucose, and urea. The phase structure, morphology and chemical composition have been characterized by X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and the corresponding selected area electron diffraction (SAED). The results showed that the typically porous and poly-crystalline structure was successfully grown on the surface of ZnCo2O4 nanorods. The ZnCo2O4 nanorods were further applied to remove methyl blue (MB), which was used as a model of organic pollutants in aqueous solution. In particular, the maximum equilibrium adsorption capacity of MB in ZnCo2O4 nanorods reaches up to 2400 mg/g, which is higher than that of most adsorbents. The adsorption isotherms and kinetics followed standard Langmuir and pseudo-second-order models, respectively. MB adsorption decreased with increasing solution pH at pH > 7 implying that MB adsorption on ZnCo2O4 nanorods may via chemisorption between negatively charged MB molecular and positively charged adsorption sites on the surface of ZnCo2O4 nanorods. This study provides great promise of using ZnCo2O4 nanorods as adsorbent for removal of pollutant dyes.

Preparation of valuable products from cleaned carbon of fuel ash

This work provides a method to use waste carbon of fuel ash left after steam generation in power stations in Egypt to prepare valuable products such as activated carbon and alumina-dolomite-carbon bricks. Carbon content in ash as received amounts to 41.22%, S to 7.2% and others to 11.36% compared to 80%, 4.2% and 2.55% after cleaning respectively. Impurities (21 wt%) in carbon were decreased to 4.78% by sulphuric acid leaching, and carbon content in ash amounts to 95.22%, S to 4.35% and others to 0.36%. Activated carbon (AC) with surface area of 1050 m2/g was prepared by steam gasification at ≤800 °C in presence of zinc chloride. The activation process has ∆E value of 82.6 kJ/mol. The AC quality was tested by adsorption of hexa-valent Cr6+ from waste tannery solution. It adsorbed 124 mg Cr6+/g C equivalent to 94% of the present Cr6+. Alumina-dolomite-carbon bricks were made by hot mixing Al2O3, dolomite, C with coal tar pitch. The green bricks were baked at 1000 °C, multi-impregnated with molten coal tar pitch followed by charring at 750 °C to seal the porous system of the fired bricks.The prepared brick samples have high density value, good thermal and chemical stability, an outstanding resistance against hydration (>60 days). Brick body is a heterogeneous composite of dolomite and carbon particles that possess different physico-chemical properties.

Surface tension, electrical conductivity and viscosity of the LiCl-NaCl-ZnCl2 molten system

Three physicochemical properties have been investigated for LiCl-NaCl-ZnCl2 molten system in restricted concentration range up to xZnCl2=0.20. Surface tension, electrical conductivity and viscosity have been determined using maximum bubble pressure method, method based on the principle of phase shift measurement and torsion pendulum method. Concentration dependencies of these properties have been calculated for 923, 973 a 1023K and plotted for 973K. Results have shown that the presence of zinc chloride does not significantly influence determined physico-chemical properties and their change is gradual.

Effect of Zinc Chloride in Ash in Oxidation Kinetics of Ni-Based and Fe-Based Alloys

Corrosion by molten phases leads to severe corrosion of heat exchangers in waste-to-energy plants. In addition, the presence of heavy metal chlorides in ash deposit increases degradation at low temperature due to the formation of highly corrosive molten phases. In this study, two heat exchanger materials, a low alloy steel (16Mo3) and a nickel based alloy (Inconel 625) were exposed in air to three different synthetic ashes, with various chloride contents, including ZnCl2 at isothermal temperatures of 450 and 650 °C in a muffle furnace. After the test, thickness and mass losses were evaluated on two separate samples, and metallographic cross sections of the specimens were characterized via SEM/EDX analyses. Both measurement results were in good agreement and showed that the corrosion observed on both materials was higher in the presence of zinc chloride in ash at 450 °C than in ashes without heavy metal chloride at 650 °C.

Synthesis and photoluminescence properties of star-shaped 2,3,6,7-tetrasubstituted benzo[1,2-b:4,5-b′]difurans

A new reaction of α-haloketones with hydroquinones leading to highly fluorescent star-shaped 2,3,6,7-tetrasubstituted benzodifurans is described. Thus 2,3,6,7-tetrakis(4-bromophenyl)-4,8-didecylbenzo[1,2-b:4,5-b′]difuran, the core of benzodifuran stars, was obtained from 1,2-bis(4-bromophenyl)-2-chloroethanone and 2,5-didecyhydroquinone in the presence of zinc chloride without a solvent. Elongated benzodifuran derivatives were obtained by the reaction of tetrabromobenzodifuran with aryl-, heteroaryl- or vinylboronic acid MIDA esters in the presence of Pd(dppf)Cl2 catalyst, and tripotassium phosphate as a base in 1,4-dioxane/water mixture. The star-shaped products, obtained in 37–99% yield, exhibit the UV–Vis fluorescence with high quantum yields, 69–100%. Due to the long-chained alkyl groups at positions 4 and 8, these highly π-conjugated products are soluble in many organic solvents.

Bio-oil production via catalytic supercritical liquefaction of Syrian mesquite (Prosopis farcta)

Supercritical liquefaction of Syrian mesquite (Prosopis farcta) stems was performed to produce bio-oil in methanol and acetone without and with (zinc chloride, sodium hydroxide) catalyst at three different temperatures (255, 275 and 295°C) using a high pressure (40MPa) autoclave reactor for 75min reaction time. The effects of process parameters including temperature, catalyst and solvent on liquefaction yields were investigated. The optimum conditions for liquefaction were provided with zinc chloride as catalyst and acetone as solvent at 295°C. According to the results, the highest conversion of 77.96% and liquid yield of 49.67% were obtained in acetone at 295°C in the presence of zinc chloride. The produced bio-oils were analyzed and characterized by the methods including elemental analysis (EA), Fourier transform infrared spectroscopy (FT-IR) and gas chromatography–mass spectrometry (GC–MS). EA indicated that the most of the raw material's energy was recovered in bio-oils with HHVs between 20 and 34MJ/kg. GC–MS showed the formation of diverse compounds including aliphatics, aromatics, oxygenated and nitrogenated compounds. Acetone bio-oils were enriched in aromatics, ketones and esters while methanol bio-oils contained sugars and carboxylic acids.

ChemInform Abstract: Reactivity of N‐Boc‐Protected Amino‐Ynones in the Presence of Zinc Chloride: Formation of Acetylenic Cyclic Imines and Their Palladium Complexes.

Amino-ynones can be seen as precursors of various heterocyclic rings. Although γ-amino-ynones have been used to prepare exocyclic vinylogous amides in the presence of Bronsted acids, we describe here the use of zinc chloride as a weak Lewis acid for their conversion into acetylenic cyclic imines. This reaction, which was attempted for a diverse range of γ-amino-ynones, proved to be robust and efficient in most cases and was easily extended to δ-amino-ynones to yield various acetylenic cyclic imines. Depending on the workup procedure, the latter compounds could be isolated either as free organic compounds or as zinc complexes. The ability of these cyclic imines to form complexes with palladium is also reported.

3,4-Bis(diethoxyphosphorylmethyl)furan in electrophilic substitution reactions

Procedure for preparation of 3,4-bis(diethoxyphosphorylmethyl)furan is developed and its behavior in the electrophilic substitution reactions is studied. Formylation according to Vilsmeier and acetylation with acetic anhydride in the presence of phosphoric acid lead to the formation of the corresponding 2-formyl and 2-acetyl derivatives. In the reaction with dimethylmethylenammonium chloride in acetonitrile 2-dimethylaminomethyl derivative is formed. The reaction with paraforemaldehyde and hydrogen chloride in the presence of zinc chloride gives exclusively 2,5-bis(chloromethyl)-3,4-bis(diethoxyphosphorylmethyl)furan. From this compound by means of the Michaelis–Becker reaction 2,3,4,5-tetrakis(diethoxyphosphorylmethyl)furan was synthesized. Coupling constants between phosphorus atoms in polyphosphonates obtained are evaluated.

Reactivity of N‐Boc‐Protected Amino‐Ynones in the Presence of Zinc Chloride: Formation of Acetylenic Cyclic Imines and Their Palladium Complexes

AbstractAmino‐ynones can be seen as precursors of various heterocyclic rings. Although γ‐amino‐ynones have been used to prepare exocyclic vinylogous amides in the presence of Brønsted acids, we describe here the use of zinc chloride as a weak Lewis acid for their conversion into acetylenic cyclic imines. This reaction, which was attempted for a diverse range of γ‐amino‐ynones, proved to be robust and efficient in most cases and was easily extended to δ‐amino‐ynones to yield various acetylenic cyclic imines. Depending on the workup procedure, the latter compounds could be isolated either as free organic compounds or as zinc complexes. The ability of these cyclic imines to form complexes with palladium is also reported.

Catalytic pyrolysis of Alcea pallida stems in a fixed-bed reactor for production of liquid bio-fuels

Pyrolysis of Alcea pallida stems was performed in a fixed-bed tubular reactor with and without catalyst at three different temperatures. The effects of pyrolysis parameters including temperature and catalyst on the product yields were investigated. It was found that higher temperature resulted in lower liquid (bio-oil) and solid (bio-char) yields and higher gas yields. Catalysts had different effects on product yields and composition of bio-oils. Liquid yields were increased in the presence of zinc chloride and alumina but decreased with calcium hydroxide, tincal and ulexite. The highest bio-oil yield (39.35%) by weight including aqueous phase was produced with alumina catalyst at 500°C. The yields of bio-char, bio-oil and gas produced, as well as the compositions of the resulting bio-oils were determined by elemental analysis, TGA, FT-IR and GC–MS. 160 different compounds were identified by GC–MS in the bio-oils obtained at 500°C.

Lewis acid promoted direct synthesis of tetraalkynylstannanes

This Letter presents a selective and efficient one-pot synthesis of tetraalkynylstannanes via direct interaction of terminal alkynes with tin tetrachloride in the presence of zinc chloride and amines. The influence of the nature and amount of Lewis acid and amine on the course of this transformation has been investigated. The proposed approach has the advantages of readily available reactants, high yields and atom economy. It is also applicable to a wide range of substrates with base-, and nucleophile-sensitive groups.

Heat resistant polymeric coatings based on triallylcyanurate

The possibility electro-copolymerization of triallyl cyanurate with vinyl acetate, acrylic acid, and 1-vinylimidazole in the presence of zinc chloride was considered. It was found that the complexed monomer was reduced at an electrode easier than free. On the basis of these monomers dense, uniform polymeric films were formed on the electrode surface.

ChemInform Abstract: Diastereoselective Synthesis of Functionalized Tetrahydropyrimidin‐2‐thiones via ZnCl2 Promoted One‐Pot Reactions.

In the presence of zinc chloride, the in situ generated β-enamino ester from the reaction of morpholine, piperidine and pyrrolidine with methyl propiolate reacted, with aromatic aldehydes and thiourea in ethanol resulting in the functionalized tetrahydropyrimidin-2-thiones in satisfactory yields and with good diastereoselectivity. When aromatic aldehydes bearing electron-withdrawing group were used in the reaction, the 4-hydroxytetrahydropyrimidin-2-thione derivatives were obtained as the main product.

Influence of the method of activation on the structural and sorption properties of the products of carbonization of sucrose

The comparative research of bulk carbonization of sucrose at different temperatures (Ar, 400–900°C) in the presence of activating agents (H3PO4 and ZnCl2) and water vapor was carried out. X-ray diffraction, nitrogen and hydrogen adsorption and IR spectroscopy were used for investigating of the structural and sorption characteristics of the obtained materials. It was shown that in conditions of non-catalytic bulk carbonization of sucrose homogeneous microporous carbons were formed; with the increasing of the temperature of carbonization micropore volume and adsorption of hydrogen (up to 1.48wt.%, 900°C) were increased. The essential effect of using an activating agent and/or catalytic agent on the porous structure of carbons: in the presence of phosphoric acid carbons with increased micro- and supermicropore volume were obtained. Mainly mesoporous carbons were formed in the presence of zinc chloride. It was established that thermal activation with steam at 800 and 850°C results in the significant increase of specific surface area of the carbons (SBET – up to 2287m2/g) and hydrogen adsorption – up to 1.88 and 1.99wt.% accordingly.