Simulating ion clustering in potassium thiocyanate aqueous solutions with various ion-water models

Using a molecular dynamics simulation technique,we compared several commonly used ion-water models to describe the microscopic structures and dynamics in KSCN aqueous solutions.Results are compared with observations of femtosecond infrared vibrational-energy transfer and anisotropy measurements.The Jorgensen/TIP4P model is found to provide the best reproduction of clustering properties such as percentage of clustered ions,cluster-size distribution,concentration dependence of the water,and ion-rotation time constants.     

Disordered kalsilite KAlSiO4

The X‐ray powder diffraction pattern that corresponds to the disordered state of kalsilite (potassium aluminium orthosilicate), KAlSiO₄, is investigated. The directionality of (Al,Si)O₄ tetrahedra within single six‐membered tetrahedral ring building units (S6R) could not be defined. With equal probability for the directionality of each tetrahedra within one S6R [free apex pointing up (U) or down (D)], an undefined sequence of U and D directionalities is needed to describe the S6R building units. The extinction conditions of disordered kalsilite are also different compared to ordered kalsilite within the space group P6₃. In disordered kalsilite, h0l and hhl reflections with l = 2n + 1 are systematically absent.     

Radiation induced polymerization of Vinylbenzoate–II. Study of the molecular weights of polymers

Abstract

In this study, the molecular weights of the polymer from vinyl benzoate has been reported for different dose rates and different temperatures. The mol.wt. remains around 4000. With increasing dose, the molecular weight increases to about 14,000. The degrees of polymerization and the kinetic chain lengths calculated from the experimentally determined G _R values have been compared which show that the kinetic chain length is larger than the D ^? Pn.

From a plot of the (D ^? Pn)^?1 vs. R _p , an intercept is obtained which is equal to 3.25 × 10^?2 which is higher than obtained in conventional polymerization. By examining the effect of temperature on mol.wt., the dependence of R _p on dose rate and the absence of induction period it has been concluded that chain transfer occurs to impurities that are generated during radiolysis.     

Rapid Synthesis of N-Acyl Ureas from Their Thio Analogues Using Wet Silica-Supported Permanganate Under Solvent-Free Conditions

A rapid method to N-acyl ureas from corresponding N-acyl thioureas is described. N-coumaroyl-N′-arylthioureas, which are easily prepared by the reaction of coumarin-3-carboxylic acid chloride with potassium thiocyanate and arylamines, can be expeditiously transformed into corresponding N-acyl ureas via r.t. grinding with wet silica supported potassium permanganate under solvent-free conditions in an excellent yield.     

Grafting of 4‐Vinyl Pyridine onto Nylon‐6 Initiated by Cu(III)

In this article, the graft copolymerization of 4‐vinyl pyridine (4VP) onto nylon‐6 (PA6) using potassium diperiodacuprate (III) (DPC)–PA6 redox system as initiator is investigated in an alkaline medium. The structure and the properties of graft copolymer are confirmed by Fourier transfer infrared spectroscopy (IR), X‐ray diffraction and thermogravimetric analysis (TGA). The mechanism is proposed to explain the generation of radicals and the initiation. The effects of reaction variables, such as the initiator concentration, ratio of 4VP to PA6, pH, as well as reaction temperature and time are investigated. Graft copolymers with high grafting efficiency (>95%) were obtained, which indicated that the DPC–PA6 redox system was an efficient initiator for this graft copolymerization. The quaternized PA6‐g‐P4VP (QPAVP) is proven to be an excellent adsorbent to heavy metal ions.     

Poly(3,5‐dichloroaniline) Doped with Different Sulfonic Acids

Poly(3,5‐dichloroaniline) was prepared by chemical oxidation in the presence of various sulfonic acids as doping agent, using potassium permanganate as oxidant. 1‐Naphtalene sulfonic acid, 2‐naphatalene sulphonic acid, 1,5‐naphtalene disulfonic acid, and p‐toluenesulfonic acid were the acids of choice. Infrared and UV‐Vis spectroscopy, utilized to characterize the polymers, revealed that the compounds exist in the emeraldine (conductive) oxidation state. The level of doping, conductivity, and morphology were determined as well. The presence of a sulfonic acid produces a morphological change, from granular to microtubule structures, which is responsible for the strong increase in the conductivity of the polymer.     

三个稀土-主族三金属Ln(III)-Sr(II)-K(I)配合物的结构与发光性质

用2,4,6-吡啶三甲酸和稀土钐、镝或钆的高氯酸盐溶液、碳酸锶、碳酸钾在180℃水热条件下进行反应,制备出3个含有3种金属离子的配位聚合物[LnSrK（ptc）₂（H₂O）]_n（Ln=Sm（1）、Dy（2）、Gd（3）,H₃ptc=2,4,6-吡啶三甲酸）。X射线单晶衍射分析表明三者具有相同的结构,属三斜晶系,P1空间群。配合物中配体2,4,6-吡啶三甲酸根以2种不同的配位方式与3种金属离子配位,一种方式中连接了7个金属离子,另一种方式中连接了8个金属离子。Ln（Ⅲ）为八配位,与羧基上的6个氧原子和2个吡啶环上的2个氮原子配位;Sr（Ⅱ）也是八配位,配位原子均为氧原子;K（I）与5个氧原子配位。荧光发射光谱表明,钐和镝的配合物在紫外光激发下均发射Sm（Ⅲ）和Dy（Ⅲ）两种离子的特征荧光,钆的配合物在紫外光激发下由于发生荷移跃迁而发射绿色荧光。     

One-Pot Synthesis of 3,5-Disubstituted 1,2,4-Oxadiazoles Directly from Nitrile and Hydroxylamine Hydrochloride Under Solvent-Free Conditions Using Potassium Fluoride as Catalyst and Solid Support

A one-pot synthesis of 3,5-disubstituted 1,2,4-oxadiazoles with two identical substituents directly from the reaction of nitriles and hydroxylamine hydrochloride in the presence of potassium fluoride as catalyst and solid support under solvent-free condition is described. Moreover, the formation of products has been discussed, and a plausible mechanism has been presented. Simplicity of the process, workup in aqueous media, and excellent yields are some advantages of this method.     

Mild and Efficient Procedure for Michael Addition of N-Heterocycles to α,β-Unsaturated Compounds Using Anhydrous K3PO4 as Catalyst

Imidazole, 1,2,4-triazole, indole, and benzotriazole undergo conjugate additions with α, β-unsaturated carbonyl compounds in the presence of anhydrous potassium phosphate at ambient temperature to afford the corresponding Michael adducts in excellent yields.     

Facile Synthesis of Benzotriazole Derivatives Using Nanoparticles of Organosilane-Based Nitrite Ionic Liquid Immobilized on Silica and Two Room-Temperature Nitrite Ionic Liquids

Nanoparticles of organosilane-based nitrite ionic liquid immobilized on silica, 1-butyl-3-methylimidazolium nitrite, and 1-(3-trimethoxysilylpropyl)-3-methylimidazolium nitrite were used as effective reagents for the preparation of benzotriazole derivatives from 1,2-diaminobenzenes at room temperature under mild solvent-free conditions. These ionic liquids play as nitrosonium sources in this procedure.1,2-Diaminobenzene derivatives have been treated with ionic liquids to give the related diaminobenzenes in very good to excellent yields in short reaction times.

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