A novel method for risk assessment of electrostatic sensitivity of nitroaromatics through their activation energies of thermal decomposition

This study presents a novel relationship between electric spark sensitivity of nitroaromatic energetic compounds and their activation energies of thermal decomposition. The new correlation can help to elucidate the mechanism of initiation of energetic materials by electric spark. It can be used to predict the magnitude of electric spark sensitivity of new nitroaromatics, which is difficult to measure. The methodology assumes that electric spark sensitivity of a nitroaromatic energetic compound with general formula C_aH_bN_cO_d can be expressed as a function of its activation energy of thermal decomposition as well as optimized elemental composition and the contribution of specific molecular structural parameters. The new correlation has the root mean square and the average deviations of 1.43 and 1.17 J, respectively, for 22 nitroaromatic energetic compounds with different molecular structures. The proposed new method is also tested for eight nitroaromatic energetic compounds, which have complex molecular structures, e.g., 1,3,7,9-tetranitrophenoxazine, 2,4,6-tris(2,4,6-trinitrophenyl)-1,3,5-triazine, and 1-(2,4,6-trinitrophenyl)-5,7-dinitrobenzotriazole.     

A unique path to reach thermostable polypyrrole/Pd microfibers via chemical oxidative polymerization

Polypyrrole/palladium (PPy/Pd) nanocomposites, labeled by PPy/Pd-2/1-0, PPy/Pd-2/1-25, and PPy/Pd-3/1-0, are synthesized via a direct redox reaction between pyrrole monomer and PdCl₂ in the presence of sodium dodecyl sulfate (SDS) stabilizer in chloroform (CHCl₃)/acetonitrile (CH₃CN) binary organic solvents with 2:1 and 3:1 volume ratios at two temperatures involving 0 and 25 °C. A Pd-unloaded polypyrrole (PPy-2/1-0) is also synthesized similarly using iron(III) chloride (FeCl₃) oxidant for comparison purposes. The volume ratio of the solvents used as well as the temperature at which the oxidative polymerization takes place affects significantly the thermostability of the resulting nanocomposites. According to the thermogravimetric analyses, the stability order towards heat is found to be PPy/Pd-2/1-25?>?PPy/Pd-2/1-0?>?PPy/Pd-3/1-0?>?PPy-2/1-0. The nanocomposite PPy/Pd-2/1-25 shows clearly more thermostability compared to PPy/Pd-2/1-0 analog at temperatures above 400 °C. Furthermore, whereas three discrete maxima can be obviously found in the differential thermal analysis (DTA) thermogram of PPy-2/1-0 pure sample, no distinctive exothermic peak is observed in the curves of the three Pd-loaded nanocomposites.     

Thermodynamic Consistency Test of Vapor–liquid Equilibrium Data of Binary Systems Including Carbon Dioxide (CO 2 ) and Ionic Liquids Using the Generic Redlich–Kwong Equation of State

The thermodynamic consistency test of solubility P–T–x data for binary mixtures including carbon dioxide (CO2) + a room temperature ionic liquid has been investigated. Experimental solubility data taken from the open literature for 32 binary mixtures of CO2/RTILs contains 80 isotherms. The applied consistency test is based on the fundamental Gibbs–Duhem equation with use of the generic Redlich–Kwong (GRK) equation of state (EoS) coupled with the van der Waals–Berthelot (GRK/vdWB) mixing rule. The optimum parameters were obtained by minimizing the summation of per cent relative deviations between modeled and experimental data, based on the bubble pressure algorithm. Modeling was found acceptable for all isotherms, which demonstrated the usability of the GRK equation of state. Results of the thermodynamic consistency test showed that 36 of the isothermal data sets were thermodynamically consistent, 37 were not fully consistent, 6 were thermodynamically inconsistent and only one data set was found to need another model.     

Green synthesis of bis-coumarin derivatives using Fe(SD)3 as a catalyst and investigation of their biological activities

A convenient, practical, green, and environmentally friendly method was developed for the synthesis of biscoumarins and corresponding tetrakis products from the reaction of 4-hydroxycoumarin and various aldehydes. The bis-coumarins were synthesized in high yield under mild reaction conditions. Products were obtained in the presence of in situ prepared Fe(SD)₃ [Iron(III) dodecyl sulfate] as a combined Lewis acid–surfactant catalyst (LASC) in water in short reaction times. Also, the antibacterial activity of compounds was screened against Pseudomonas aeruginosa and Escherichia coli as Gram-negative bacteria and Micrococcus luteus and Staphylococcus aureus as Gram-positive bacterial strains. Products 3g , 3k–l were most active than cefotaxime against E. coli and also compounds 3c and 3g were most active than cefotaxime against S. aureus.     

Green,rapid, and highly efficient syntheses of α,α′-bis[(aryl or allyl)idene]cycloalkanones and 2-[(aryl or allyl)idene]-1-indanones as potentially biologic compounds via solvent-free microwave-assisted Claisen–Schmidt condensation catalyzed by MoCl5

A new, green, and highly efficient protocol for the expeditious preparation of some α,α′-bis[(aryl or allyl)idene]cycloalkanones and 2-[(aryl or allyl)idene]-1-indanones via a simple microwave-assisted Claisen–Schmidt condensation reaction catalyzed by MoCl₅ was successfully developed. Outstanding features of the current methodology include the use of solvent-free conditions, simple operation, use of a very inexpensive and available catalyst, low catalyst loading, short reaction times, high yields of the pure products, no harmful by-products, easy workup, and also the applicability of microwave irradiation as a clean source of energy. Furthermore, a gram-scale reaction was successfully conducted, proving the scalability of this current Claisen–Schmidt condensation reaction.     

Assessment of Thermal Stability and Detonation Performance of 4-Amino-1,2,4-triazolium Nitrate as compared to 2,4,6-Trinitrotoluene for Melt-cast Explosives

4-Amino-1,2,4-triazolium nitrate (4-ATN) is an energetic and non-sensitive ionic liquid, which was introduced as a good candidate in previous works for the replacement of 2,4,6-trinitrotoluene (TNT) in melt-cast explosives. Since previous studies used pure nitric acid for nitration of 4-ATN, the effect of the use of low price industrial nitric acids (50 %, 70 % and 98 %) is investigated on the percent yields of 4-ATN. The thermogravimetric and differential scanning calorimetry (TGA/DSC) are done on the synthesized 4-ATN with impure nitric acid at a heating rate of 10 K · min^–1 by the vacuum system. The obtained TGA/DSC curves confirm decomposition of 4-ATN involving melting and dissociation. Derivative thermogravimetric (DTG) curves of 4-ATN at various heating rates are applied to obtain activation energy of thermolysis by several model-free techniques. The calculated activation energies are in the range 78.7–87.7 kJ · mol^–1, which are about 10 kJ · mol^–1 more than the reported activation energy of industrial TNT (purity 98.2 %), i.e. 66–70 kJ · mol^–1. Assessments of detonation performance of 4-ATN are also compared with TNT, which show higher detonation performance of 4-ATN. Thus, 4-ATN can be used with nitramine compounds as melt-cast explosives with higher thermal stability and detonation performance than corresponding nitramine compound/TNT explosives.     

One-pot synthesis of 2H-indazolo[2,1-b]phthalazine-triones via nano γ-Al2O3/BF3/Fe3O4 as an efficient catalyst and theoretical DFT study on them

Experimental and computational studies were carried out for the synthesis of 2H-indazolo[2,1-b]phthalazine-triones using γ-Al₂O₃/BF₃/Fe₃O₄ as a nanocatalyst in optimized and solvent-free conditions. The most significant features of the existing protocol are easy preparation of the catalyst, short reaction times, environmentally benign, and milder reaction conditions. The analysis data were reported using the experimental results of this investigation, such as: H-NMR, FT-IR (Fourier-transform infrared spectroscopy), X-ray diffraction, vibrating-sample magnetometer, Thermal gravimetric analysis (TG-DTG), nitrogen adsorption isotherm, Field Emission Scanning Electron Microscopy, and Transmission electron microscopy images of nanocatalyst. In this study, 2H-indazolo[2,1-b]phthalazine-triones have also been theoretically investigated using DFT-B3LYP/6-31G method. Also, some of the physical chemistry properties have examined for conformers of products, which there was good agreement between the computational results and obtained experimental for the products.     

Trimesic acid is a suitable building block in triple four-component Ugi reaction: access to unique trivalent compounds

Monatshefte für Chemie - Chemical Monthly - A triple four-component Ugi reaction of isocyanide, amine, aldehyde, and trimesic acid as the acid component with three acidic functional groups in...     

A simple,rapid and effective protocol for synthesis of bis(pyrazolyl)methanes using nickel–guanidine complex immobilized on MCM-41

Research on Chemical Intermediates - In this paper, a rapid, easy and very efficient method for the synthesis of bis(pyrazolyl)methanes has been reported in the presence of nickel–guanidine...     

Synthesis and antibacterial evaluation of diaminomaleonitrile-based azo-Schiff bases and 8,9-dihydro-7H-purine-6-carboxamides

Research on Chemical Intermediates - Some new DAMN-based Schiff base 6a–6g were synthesized via a condensation reaction of the corresponding azo dyes with...