An Efficient Zinc‐Catalyzed Dehydration of Primary Amides to Nitriles

In the present study, the zinc‐catalyzed dehydration of a variety of amides with N‐methyl‐N‐(trimethylsilyl)trifluoroacetamide (MSTFA) as a dehydration reagent into the corresponding nitriles has been examined in detail. With the straightforward and commercially available zinc(II)triflate as the precatalyst and MSTFA, an excellent system has been established to afford nitriles in excellent yields and chemoselectivities. After investigation of reaction conditions and the scope and limitations, several efforts were carried out to understand the reaction mechanism.     

Microwave-Assisted,Rapid, Solvent-Free Aza-Michael Reaction by Perchloric Acid Impregnated on Silica Gel

Highly efficient solvent-free aza-Michael additions of a variety of amines to α,β-unsaturated carbonyl compounds under microwave-irradiation conditions catalyzed by perchloric acid impregnated on silica gel (HClO₄/SiO₂) is reported. The reactions are completed within 2–7 min in a microwave oven to produce the corresponding adducts in excellent yields, and the catalyst can be recovered and reused.     

Zinc Chloride–Catalyzed Expeditious Route to Nitriles

Zinc chloride has been found to be an excellent catalyst for a one-pot synthesis of nitriles from araldehydes and hydroxylammonium chloride under solvent-free conditions. The features of the present method are short reaction time, easy workup procedure, and good yields of the nitriles.     

The Structures of ZnCl2-Ethanol Mixtures,a Spectroscopic and Quantum Chemical Calculation Study

We report in this article the structural properties, spectral behavior and heterogeneity of ZnCl₂-ethanol (EtOH) mixtures in a wide-composition range (1:3 to 1:14 in molar ratios), using ATR-FTIR spectroscopy and quantum chemical calculations. To improve the resolution of the initial IR spectra, excess spectroscopy and two-dimensional correlation spectroscopy were employed. The transformation process was suggested to be from EtOH trimer and EtOH tetramer to EtOH monomer, EtOH dimer and ZnCl₂-3EtOH complex upon mixing. The theoretical findings showed that increasing the content of EtOH was accompanied with the flow of negative charge to ZnCl₂. This led to reinforcement of the Zn←O coordination bonds, increase of the ionic character of Zn‒Cl bond and weakening and even dissociation of the Zn‒Cl bond. It was found that in some of the ZnCl₂-EtOH complexes optimized at the gas phase or under the solvent effect, there existed hydroxyls with a very special interactive array in the form of Cl‒Zn⁺←O‒H^…Cl⁻, which incredibly red-shifted to wavenumbers <3000 cm⁻¹. This in-depth study shows the physical insights of the respective electrolyte alcoholic solutions, particularly the solvation process of the salt, help to rationalize the reported experimental results, and may shed light on understanding the properties of the deep eutectic solvents formed from ZnCl₂ and an alcohol.     

Montmorillonite K10/ZnCl2 Catalyzed Alkyl Disulfide Substitution Reactions: Preparation of Thiomethyl Derivatives for the Synthesis of Organic Conducting Materials

Experiments are described detailing a method for the direct introduction of thiomethyl groups into activated benzenes, thiophene and benzo[b]thiophene using an activated mesoporous clay to promote thiomethyl substitution. Elaboration of 2,3-dithiomethylbenzo[b]thiophene, a product of the clay-catalyzed reaction of benzo[b]thiophene with dimethyl disulfide, to a tetrathiafulvalene derivative is described.     

One-Pot Synthesis of 2-Amino-5,10-dihydro-5,10-dioxo-4-phenyl-4H-benzo[g]chromene Derivatives Catalyzed by ZnCl2

An efficient one-pot synthesis of 2-amino-5,10-dihydro-5,10-dioxo-4-phenyl-4H-benzo[g]chromene derivatives has been achieved by the reaction of 2-hydroxynaphthalene-1,4-dione, cyanothioacetamide, and aromaticaldehyde in EtOH at room temperature catalyzed by ZnCl₂. The structures of the products were characterized by infrared, ¹H NMR, mass, and elemental analysis.

微波辐照方式对CdS和Bi2S3纳米粒子结晶度的影响

The effect of traveling microwave irradiation on the crystallinities of CdS nanoparticles and Bi₂S₃ nanorods was studied. Results showed that as compared with stationary microwave irradiation the crystallinities and the crystal growth of sulfide nanoparticles were improved. Traveling microwave irradiation can supply narrower frequency distribution and stronger power density of irradiation， CdS nanoparticles and Bi₂S₃ nanorods obtained are better in crystallinities and larger in size than under stationary microwave irradiation.     

Organic Reactions in Water: Transformation of Aldehydes to Nitriles using NBS under Mild Conditions

Aliphatic, aromatic, heterocyclic, conjugated, and polyhydroxy aldehydes gave corresponding nitriles in high yields at 0°C using NBS and ammonia in water.     

Ternary mutual diffusion coefficients of ZnCl2−KCl−H2O at 25°C by Rayleigh interferometry

Mutual diffusion coefficients and densities were measured for aqueous ZnCl₂–KCl mixtures at 25° by using free-diffusion Rayleigh interferometry and pycnometry, respectively. The ZnCl₂ concentrations were fixed at 1.5 mol-dm^–3, whereas those of KCl were 0.5, 1.25, 2.0, or 4.0 mol-dm^–3. This corresponds to a half charged zinc-chlorine storage battery at various suporting electrolyte concentrations. The main-term coefficient of ZnCl₂ only varies by 10% with KCl concentration, whereas that of KCl varies by about 22%. The ZnCl₂ cross-term coefficient remains small and positive; in contrast the KCl cross-term coefficient goes through a maximum and is negative at high and low KCl concentrations. At KCl concentrations of 0.5 and 4.0 mol-dm^–3, solutions with the KCl c0 are statically and dynamically (diffusively) unstable at the top and bottom of the boundary. Evaluation of the parameters of the non-linear least-squares solution to the diffusion equation is difficult for the 1.25 mol-dm^–3 KCl case, since this system has nearly equal eigenvalues in its diffusion coefficient matrix.     

Thermodynamic properties of transition metals in aqueous solution:4. The enthalpies of mixing aqueous solutions of CdCl2, CuCl2 and ZnCl2 with MgCl2 at varying ionic strength at 25°C

Enthalpies of mixing ΔH _m of aqueous solutions of CdCl₂, CuCl₂, and ZnCl₂ with MgCl₂ solutions were measured at ionic strengths of 1.0, 2.0, and 3.0 at 25°C. The excess enthalpy equations of Pitzer were then fitted to the resulting ΔH _m data. The resulting parameters are the temperature derivatives of the activity coefficient mixing parameters in the Pitzer system.     

A Rapid and Efficient Method for Dehydration of Primary Amides to Nitriles. Preparation of Acrylonitrile Derivatives

Chloromethylene iminium salts (Vilsmeier reagents) have a long history and thoroughly investigated chemistry⁽¹⁾. Chloro-N, N-dimethylforminium chloride 1 is most conveniently generated by the reaction of N, N-dimethylformamide (DMF) with oxalyl chloride⁽²⁾. The reagent has also been obtained usingthicnyl chloride at elevated temperature and a variety of acid chlorides^(1b). The literature describes several examples of the use of thionyl chloride in combination with DMF in which 1 or a related species is thought to function as the reactive intermediate in the transformation of amides to nitriles⁽³⁾.     

A one-pot chemoselective S-alkylation and acetylation of thiohydantoins using the alkyl orthoformate-ZnCl2-Ac2O reagent system

The chemoselective S-alkylation of 2-thiohydantoins is reported. The methodology involves the use of alkyl orthoformates (trimethyl and triethyl) as alkylating agents, which in the presence of Ac₂O and ZnCl₂ chemoselectively alkylate the thio group whilst other nucleophilic groups present in the thiohydantoins are acetylated simultaneously in moderate to high yields. A plausible mechanism for this reaction is delineated.     

微波辐射促进ZnCl_2与Y分子筛固相反应的研究

采用XRD、IR和原子吸收光谱等手段对微波固相法制备的ZnCl2／Y催化剂进行了表征·微波辐射促进了ZnCl2在分子筛表面分散和固态离子交换，分散的ZnCl2可与分子筛表面氧原子发生较强的配住键合作用．当ZnCl2的负载量达到37．5％时，ZnCl2仍可完全分散于NaY分子筛表面，此时的固态离子交换度为84％．随着分子筛表面酸菌和区强度的增加，ZnCl2与分子筛的固态离子交换量减少．     

Amide Hydrolysis Reaction Catalyzed by KF/Al2O3 under Microwave Irradiation and Solvent Free Conditions

A microwave‐enhanced hydrolysis of amides utilizing KF/Al₂O₃ in the absence of solvents has been developed. Amines are produced in excellent yields along with the corresponding carboxylic acids.     

Diprotodecarboxylation Reactions of 3,4-Dialkoxythiophene-2,5-dicarboxylic Acids Mediated by Ag2CO3 and Microwaves

An efficient and rapid method is reported to obtain 3,4-dialkoxythiophenes from 3,4-dialkoxythiophene-2,5-dicarboxylic acids through a diprotodecarboxylation reaction with Ag₂CO₃/AcOH as a catalytic system and microwave heating in dimethylsulfoxide (DMSO) as solvent. This methodology lets us obtain for the first time good performance with thiophenes bearing strong electron-donating groups such as alkoxides. This methodology eliminates the usage of harmful quinoline as solvent, as well as the long reaction times typically used (12–18 h) to obtain the 3,4-dialkoxythiophenes. The reaction of 7 diacids showed good yields (60–89%) following 20 min of microwave heating in a temperature range of 120–150 °C.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

High-Surface-Area-Activated Carbon Derived from Mango Peels and Seeds Wastes via Microwave-Induced ZnCl2 Activation for Adsorption of Methylene Blue Dye Molecules: Statistical Optimization and Mechanism

In this study, Mango (Mangifera indica) seeds (MS) and peels (MP) seeds mixed fruit wastes were employed as a renewable precursor to synthesize high-surface-area-activated carbon (MSMPAC) by using microwave-induced ZnCl₂ activation. Thus, the applicability of MSMPAC was evaluated towards the removal of cationic dye (methylene blue, MB) from an aqueous environment. The key adsorption factors, namely A: MSMPAC dose (0.02–0.1 g), B: pH (4–10), and C: time (5–15 min), were inspected using the desirability function of the Box-Behnken design (BBD). Thus, the adsorption isotherm data were found to correspond well with the Langmuir model with a maximum adsorption capacity of (232.8 mg/g). Moreover, the adsorption kinetics were consistent with both pseudo-first-order and pseudo-second-order models. The spontaneous and endothermic nature of MB adsorption on the MSMPAC surface could be inferred from the negative ∆G° values and positive value of ∆H°, respectively. Various mechanisms namely electrostatic forces, pore filling, π-π stacking, and H-bonding govern MB adsorption by the MSMPAC. This study demonstrates the utility of MS and MP as renewable precursors to produce high-surface area MSMPAC with a potential application towards the removal of cationic organic dyes such as MB.     

离子层气相反应法(ILGAR)制备CuInS2薄膜的研究

CuInS₂ thin films have been prepared by ion layer gas reaction (ILGAR) using C₂H₅OH as solvent, CuCl and InCl₃ as reagents and H₂S gas as sulfuration source. The effects of cationic concentrations and numbers of cycle on the properties of CuInS₂ film were investigated. The chemical composition, crystalline structure, surface topography, deposited rate, optical and electronic properties of the films were characterized by X-ray diffractrometry (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), ultraviolet-visible spectrometry (UV-Vis) and Hall System. The results show that the crystalline of CuInS₂ thin films and the deposition rate have been improved with the increase of cationic concentration, while CuxS segregation phases appear with further increasing cationic concentration. The deposition rate is close to constant as cationic concentration is fixed. CuInS₂ thin film derived form lower cationic concentration is uniform, compact and good in adhesion to the substrates. The absorption coefficient of CuInS₂ thin films is larger than 10⁴ cm^-1, and the band gap E_g is in the range of 1.30～1.40 eV. The dark resisitivity of the thin film decreases from 50 to 10 Ω·cm and the carrier concentration ranges are over 10¹⁶ cm^-3.