An empirical method for predicting detonation pressure of CHNOFCl explosives

This paper describes a new method for prediction of the Chapman-Jouguet detonation pressures of CHNOFCl explosives using the heat of detonation, Q_det, the number of moles of gaseous products of detonation per gram of explosive, α, and the average molecular weight of gaseous products, M. The equation has the form: P_CJ=15.88α(MQ_det)^1/2ρ₀²−11.17, where P_CJ is the Chapman-Jouguet detonation pressure and ρ₀ the loading density. Calculated P_CJ by this procedure show good result with respect to measured detonation pressure for any pure or mixture of ideal and some of less ideal CHNOFCl explosives at ρ₀>0.8 g/cm³.     

Ultra‐Trace Silver Determination in Biological and Water Samples by Electrothermal Atomic Absorption Spectrometry after Electrodeposition on a Graphite Probe

A rapid and simple procedure was developed for selective and sensitive determination of ultra‐trace silver in biological and environmental samples using the electrodeposition on a graphite probe modified with palladium followed by electrothermal atomic absorption spectrometry. Several experimental parameters for the electrodeposition, such as deposition potential, electrolyte concentration, pH of solution and deposition time were optimized. The calibration graph after preconcentration was linear in the range of 10‐250 ngL^?1 with correlation coefficient of 0.9989 under the optimum conditions for procedure. The limits of detection (LOD) and quantification (LOQ) base on (3σ) and (10σ) were 2.8 ngL^?1 and 9.4 ngL^?1 respectively. Related standard deviation (RSD) for eight replicate measurements of 100 ngL^?1 silver was 4.3%. Samples were digested completely in a closed microwave digestion system using only perchloric acid, and interference owing to various cations was also investigated. The proposed procedure was successfully applied to determine silver in blood, urine and some environmental samples with satisfactory analytical results.     

Ionic Liquid Iodinating Reagent for Mild and Efficient Iodination of Aromatic and Heteroaromatic Amines and Terminal Alkynes

Hexamethylene bis(N-methylimidazolium) bis(dichloroiodate) (HMBMIBDCI), an ionic liquid iodinating reagent, have been prepared and characterized. Its ability to perform iodination reactions with a variety of substrates has been explored. In general, iodination reactions of aromatic and heteroaromatic amines proceed with good yields in the absence of solvent. Reactions of terminal alkynes in the presence of 1,8-diazabicyclo [5.4.O] undec-7-ene and tetrahydrofuran have been investigated as well.

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

Magnetic solid-phase extraction using Schiff base ligand supported on magnetic nanoparticles as sorbent combined with dispersive liquid-liquid microextraction for the extraction of phenols from water samples

ABSTRACT

In this work, the magnetic sorbent was developed by covalent binding of a Schiff base ligand, N,N’-bis(3-salicyliden aminopropyl)amine (salpr), on the surface of silica coated magnetic nanoparticles (Salpr@SCMNPs). The core-shell nanoparticle was applied for the magnetic solid-phase extraction (MSPE) combined with dispersive liquid-liquid microextraction (DLLME) of phenolic compounds from water samples prior to gas chromatography-flame ionisation detector (GC?FID). Characterisation of the Salpr@SCMNPs was performed with different physicochemical methods such as Fourier transform infrared (FT-IR), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). Variables affecting the performance of both extraction steps such as pH of the water sample, the sorbent amount, the desorption conditions, the extraction time; and extraction solvent were studied. Under the optimised conditions, the analytical performances were determined with a linear range of 0.01–100 ng mL^?1 and a limit of detection at 0.003–0.02 ng mL^?1 for all of the analytes studied. The intra-day (n = 5) and inter-day (n = 3) relative standard deviations (RSD%) of three replicates were each demonstrated in the range of 6.9–8.9% and 7.3–10.1%, respectively. The proposed method was executed for the analysis of real water samples, whereby recoveries in the range of 92.9–99.0% and RSD% lower than 6.1% were attained.     

Syntheses,crystal structures and solvatochromic properties of dinuclear oxalato-bridged copper(II) complexes

Three dinuclear copper(II) complexes, [Cu₂(L¹)₂(μ-ox)](ClO₄)₂?2(CH₃CN), [Cu₂(L²)₂(μ-ox)](ClO₄)₂?H₂O, and [Cu₂(L³)₂(μ-ox)](ClO₄)₂ where ox = oxalato; L = N,N-dimethyl,N′-benzylethane-1,2-diamine, L¹, N,N-diethyl,N′-benzylethane-1,2-diamine, L², N,N-diisoprophyl,N′-benzylethane-1,2-diamine, L³, were prepared and characterized by elemental analyses, spectral (IR, UV–Vis) data and molar conductance measurements. The crystal structures of [Cu₂(L¹)₂(μ-ox)](ClO₄)₂?2(CH₃CN) and [Cu₂(L³)₂(μ-ox)](ClO₄)₂ have been determined by single-crystal X-ray analysis. Solvatochromic behaviors were investigated in various solvents, showing positive solvatochromism. The effect of steric hindrance around the copper ion imposed by N-alkyl groups of the diamine chelates on the solvatochromism property of the complexes is discussed. Solvatochromism was also studied with different solvent parameter models using stepwise multiple linear regression method.     

Electrocatalytic activity of porous nanostructured Fe/Pt-Fe electrode for methanol electrooxidation in alkaline media

An electrochemical approach to fabricate a nanostructured Fe/Pt-Fe catalyst through electrodepo-sition followed by galvanic replacement is presented. An Fe/Pt-Fe nanostructured electrode was prepared by deposition of Fe-Zn onto a Fe electrode surface, followed by replacement of the Zn by Pt at open-circuit potential in a Pt-containing alkaline solution. Scanning electron microscopy and energy-dispersive X-ray techniques reveal that the Fe/Pt-Fe electrode is porous and contains Pt. The electrocatalytic activity of the Fe/Pt-Fe electrode for oxidation of methanol was examined by cyclic voltammetry and chronoamperometry. The electrooxidation current on the Fe/Pt-Fe catalyst is much higher than that on flat Pt and smooth Fe catalysts. The onset potential and peak potential on the Fe/Pt-Fe catalyst are more negative than those on flat Pt and smooth Fe electrodes for methanol electrooxidation. All results show that this nanostructured Fe/Pt-Fe electrode is very attractive for integrated fuel cell applications in alkaline media.     

Synthesis,characterization and crystal structures of new Zinc(II) and Nickel(II) complexes containing morpholine moiety and their antibacterial studies

The ligand 1,2-dimorpholinoethane (DME) was used to prepare Zn(II) and Ni(II) complexes of the general formulation MLX₂ (L = DME, X = Cl or NO₃). Zinc(II) complex exhibits spectral properties indicative of a distorted tetrahedral geometry, with DME coordinating through two nitrogen atoms and two chlorides completing the tetrahedron. This is in contrast to the six-coordinated, distorted octahedral geometry exhibited by nickel(II) complex of DME when NO₃ was used as counter ions. The X-ray diffraction confirms the structures of two complexes and shows that the ligand coordinates through two nitrogen atoms while the two ether linkages are not involved in complexation, which would have been the case if the morpholine rings were in the boat form. The ligand and related complexes have antibacterial activity against the five Gram-positive bacteria: Bacillus subtilis ATCC 6633, Staphylococcus aureus ATCC 6538, Bacillus cereus NRRL-B-3711, Enterococcus faecalis ATCC 29212 and Streptococcus pyogenes and also against the three Gram-negative bacteria: Escherichia coli ATCC 11230, Pseudomonas aeruginosa ATCC 15442 and Klebsiella pneumonia ATCC 70063. The results showed that in some cases the antibacterial activity of the complexes exceeded the one of sulfisoxazole used as a standard.     

Energy,Exergy, Exergoeconomic and Emergy-Based Exergoeconomic (Emergoeconomic) Analyses of a Biomass Combustion Waste Heat Recovery Organic Rankine Cycle

In recent decades, there has been an increasing trend toward the technical development of efficient energy system assessment tools owing to the growing energy demand and subsequent greenhouse gas emissions. Accordingly, in this paper, a comprehensive emergy-based exergoeconomic (emergoeconomic) method has been developed to study the biomass combustion waste heat recovery organic Rankine cycle (BCWHR-ORC), taking into account thermodynamics, economics, and sustainability aspects. To this end, the system was formulated in Engineering Equation Solver (EES) software, and then the exergy, exergoeconomic, and emergoeconomic analyses were conducted accordingly. The exergy analysis results revealed that the evaporator unit with 55.05 kilowatts and the turbine with 89.57% had the highest exergy destruction rate and exergy efficiency, respectively. Based on the exergoeconomic analysis, the cost per exergy unit (c), and the cost rate (C˙) of the output power of the system were calculated to be 24.13 USD/GJ and 14.19 USD/h, respectively. Next, by applying the emergoeconomic approach, the monetary emergy content of the system components and the flows were calculated to evaluate the system’s sustainability. Accordingly, the turbine was found to have the highest monetary emergy rate of capital investment, equal to 5.43×1012 sej/h, and an output power monetary emergy of 4.77×104 sej/J. Finally, a sensitivity analysis was performed to investigate the system’s overall performance characteristics from an exergoeconomic perspective, regarding the changes in the transformation coefficients (specific monetary emergy).     

A new rearranged tricyclic abietane diterpenoid from Salvia chloroleuca Rech. f. & Allen

Phytochemical investigation of the roots of Salvia chloroleuca led to the isolation and identification of a new rearranged abietane diterpenoid (1). Its structure was elucidated by interpretation of the 1D and 2D NMR spectra and completed by the analysis of the HR-ESI-MS data. Compound 1 is the secondly reported compound on a rearranged tricyclic abietane (4,5-seco-5,10-friedo-abietane) diterpenoid with a ketal functionality between C-2 and C-11. A plausible biosynthetic pathway of 1 was also proposed.