Non-isothermal kinetic studies on thermal decomposition of energetic materials

Thermal stability and decomposition kinetics for two energetic materials, potassium nitroform (KNF) and 5-Nitro-2,4-dihydro-3H-1,2,4-triazol-3-one (NTO), were investigated to obtain information on their safety for handling, storage, and use. Differential scanning calorimetry (DSC) and simultaneous thermogravimetry-differential thermal analysis (TG-DTA) techniques have been used to study thermal behavior of these energetic compounds. The results of TG analysis revealed that the main thermal degradation for the KNF occurs during two temperature ranges of 270?C330 and 360?C430?°C. Meanwhile, NTO decomposes completely in temperature range of 250?C300 °C. TG-DTA analysis of KNF indicates that this energetic compound dehydrated (at about 108?°C) before its decomposition. However, NTO is thermally stable until its decomposition. The decomposition kinetic of energetic materials was studied by non-isothermal DSC under various heating rates. Kinetic parameters such as activation energy and frequency factor for thermal decomposition of energetic compounds were obtained via the methods proposed by ASTM E696 and Starink. Also, thermodynamic parameters correspond to the activation of thermal decomposition and critical ignition temperatures of the compounds were obtained.     

Waste-grass-mediated green synthesis of silver nanoparticles and evaluation of their anticancer,antifungal and antibacterial activity

Grass waste was used for transform an inexpensive waste into health. Silver nanoparticles (AgNPs) have been synthesized using waste material (dried grass). The average size of silver nanoparticles observed in transmission electron images was estimated to be about 15?nm. The anticancer, antifungal and antibacterial effect of AgNPs were studied in vitro. The minimum inhibitory concentration of AgNPs against Pseudomonas aeruginosa and Acinetobacter baumannii was calculated about 3?µg/ml. The highest level of inhibitory effect of AgNPs against Fusarium solani was close to 90% at a concentration of 20?μg/ml of AgNPs. An inhibitory effect on the cancer cell growth is reach, by increasing the concentration of AgNPs to 5?µg/ml; the cancer cells’ survival decreases about 30%. Western results showed that the expression of Cyclin D1 protein of MCF-7 cell line decreased after treatment with the effective concentration of AgNPs.     

An Efficient and Selective Solid State Oxidation of Thiols to Disulfides with Quinolinium Fluorochromate on Silica Gel

Summary. Various kinds of aliphatic (cyclic and acyclic), aromatic, and heterocyclic thiols are converted into the corresponding disulfides by quinolinium fluorochromate (QFC) on silica-gel in excellent yields. Selective oxidation of thiols in the presence of sulfides is also achieved under solid phase conditions.     

Aromatization of Various 1,4‐Dihydropyridines by Tetrabutylphosphonium Dichromate (TBPDC) under Conventional Heating and Microwave Irradiation

Tetrabutylphosphonium dichromate (TBPDC) has been found an efficient oxidizing agent for the aromatization of various 1,4‐dihydropyridines to their pyridine derivatives in refluxing acetonitrile and also under microwave irradiation. Short reaction times and clean workup are the advantages of this method.     

Mild and Efficient Synthesis of Benzoxazoles, Benzothiazoles, Benzimidazoles, and Oxazolo[4,5-b]pyridines Catalyzed by Bi(III) Salts Under Solvent-Free Conditions

Summary. A series of benzoxazoles, benzothiazoles, benzimidazoles, and oxazolo[4,5-b]pyridines was efficiently synthesized from the reactions of o-aminophenols, o-aminothiophenol, o-phenylenediamines, and 2-amino-3-hydroxypyridine with orthoesters in the presence of catalytic amounts of Bi(III) salts, such as Bi(TFA)₃, Bi(OTf)₃, and BiOClO₄ · xH₂O under solvent-free conditions. The remarkable features of this new protocol are high conversion, very short reaction times, cleaner reaction profiles under solvent-free conditions, straightforward procedure, and use of relatively non-toxic catalysts.     

Rapid and Efficient Synthesis of Imidazolines and Bisimidazolines Under Microwave and Ultrasonic Irradiation

Summary. Small assemblies of 2-imidazolines and bisimidazolines from appropriate nitriles and ethylenediamine with catalytic amounts of P₂S₅ employing a microwave assisted protocol were prepared. Sonication of this system also led to successful synthesis of 2-imidazolines and bisimidazolines. Another advantage of these systems is the ability to carry out large scale reactions.     

Electron‐deficient vanadium(IV) tetraphenylporphyrin: A new,highly efficient and reusable catalyst for chemoselective trimethylsilylation of alcohols and phenols with hexamethyldisilazane

In the present work, the application of electron‐deficient tetraphenylporphyrinatovanadium(IV) trifluoromethanesulfonate, [V^IV(TPP)(OTf)₂], in the trimethylsilylation of alcohols and phenols with hexamethydisilazane (HMDS) is reported. This new V(IV) catalyst was used as an efficient catalyst for silylation of not only primary alcohols but also sterically hindered secondary and tertiary alcohols with HMDS. Trimethylsilylation of phenols with HMDS was also performed to afford the desired Trimethylsilyl ethers (TMS) ethers. The chemoselectivity of this method was also investigated. This catalyst can be reused several times without loss of its activity. Copyright © 2011 John Wiley & Sons, Ltd.     

Developing an electro-thermal model to determine heat generation and thermal properties in a lithium-ion battery

Journal of Thermal Analysis and Calorimetry - Lithium-ion batteries should continuously be operated at the optimum temperature range $$\left( {15 \sim 40 \,^\circ C} \right)$$ for the best...     

Carbon–carbon coupling reactions catalyzed by supported Pd porphyrins

The tetrakis(4‐N‐methylpyridinium)porphyrinatopalladium(II) iodide, [Pd(TMPyP)]I₄, supported on Dowex 50WX8 and Amberlite IR‐120 ion‐exchange resins, was used as heterogeneous, recyclable and active catalyst for the Suzuki–Miyaura and Heck cross‐coupling reactions. These catalysts were applied to coupling of various aryl halides with phenylboronic acid and styrene in Suzuki and Heck reactions, respectively, and the corresponding products were obtained in excellent yields and short reaction times. The catalysts could be recovered easily by simple filtration and reused several times without significant loss of their catalytic activity. The catalysts were characterized by diffuse‐reflectance UV–visible spectroscopy and scanning electron microscopy, and their stability was confirmed by TGA. Copyright © 2014 John Wiley & Sons, Ltd.     

Ultrasound promoted selective synthesis of 2-aryl-5,6-dihydro-4H-1,3-oxazines catalyzed by K-10 and KSF montmorillonite clays: A practical procedure under mild and solvent-free conditions

Montmorillonite K-10 and KSF were found to be highly efficient, environmentally friendly and recyclable heterogeneous catalysts for the selective synthesis of a variety of 2-aryl-5,6-dihydro-4H-1,3-oxazines from arylnitriles and 3-amino-1-propanol under ultrasound irradiation. This new methodology provides excellent yields in short reaction times (10–25 min). The reaction work-up is very simple and the catalysts can be easily separated from the reaction mixture and reused several times in subsequent reactions. This catalytic system also exhibits excellent chemoselectivity in the synthesis of mono-oxazines from dinitriles.