Mixture Of Perchlorate Research Articles

Lithium coordination and mobility in gel electrolytes based on an acrylate polymer with ethylene oxide side chains

Multinuclear NMR has been used to investigate the structure and mobility of a series of polymer gel electrolytes. The co-polymers used as matrixes in the gels have acrylate backbones and side chains of ethylene oxide, where the length of the side chains has been varied, while the ratio of acrylate to ethylene oxide has been kept constant. The electrolyte is a mixture of lithium perchlorate and two solvents, ethylene carbonate and gamma butyrolactone. 13C spectra of the different gel electrolytes shows that both solvents interact with the salt, and that the strength of the interaction increases with decreasing length of the polymer side chains. It also appears that the lithium ions show no selectivity between the two types of solvent. Furthermore, the lithium chemical shift moves progressively upfield with increasing length of the side chains, showing a gradual change in interaction from lithium–solvent to lithium–(ethylene oxide).

Model of Impact Initiation of Composite Explosive Solid Systems

A model of mechanical initiation of solid explosives, applicable for analysis of sensitivity of individual substances and composite explosives, is developed. The model includes a system of equations of work softening of a high explosive charge under an impact, resulting dissipative heating, and heat release due to chemical reactions between the components of the explosive mixture. The critical parameters and reaction kinetics were numerically calculated for initiation of charges consisting of a mixture of ammonium perchlorate and polymethylmethacrylate. The results are compared to experimental data on sensitivity of this mixture to the impact. Key words: high explosive, impact, explosion, impact sensitivity.

Do Perchlorate and Triflate Anions Bind to the Uranyl Cation in an Acidic Aqueous Medium? A Combined EXAFS and Quantum Mechanical Investigation

Structural properties of uranyl cations in acidic aqueous perchlorate and triflate solutions were investigated using uranium LIII -edge extended X-ray absorption fine-structure spectroscopy (EXAFS) in conjunction with quantum mechanical calculations of gas-phase model complexes. EXAFS spectra were measured in aqueous solutions of up to 10 M triflic and 11.5 M perchloric acid, as well as mixtures of perchloric acid and sodium perchlorate. In no case is the perchlorate anion coordinated to UO2(2+). The number of equatorial water molecules bound to UO2(2+) is always about five. In the case of the 10 M CF3SO3H solution, an inner-sphere complexation of the triflate is observed with a U-S radial distance of 3.62 Å. These results are in qualitative agreement with quantum mechanical calculations of model uranyl complexes, according to which the interaction energies of anions follow the order perchlorate<triflate<<nitrate.

Thioacetalization of aldehydes and ketones in the presence of hydroxo complexes of platinum(II): An example of Lewis acid catalytic activity

The complex [(dppb)Pt(µ-OH)]2(BF4)2 displays high catalytic activity in the thioacetalization of a variety of aldehydes and ketones with mercaptoethanol under very mild conditions. The reaction rate is greatly enhanced by the addition to the reaction mixture of magnesium perchlorate as drying agent and molar turnovers as high as 9700 can be observed. The effect of different desiccating agents is also reported. The reactivity pattern observed, the similarity with other reactions and NMR spectroscopic investigations confirm the possible role of the complex as Lewis acid catalyst in promoting the reaction.Key words: thioacetalization, catalysis, aldehydes, ketones, platinum complex.

Approximate Method for Calculating the Impact Sensitivity Indices of Solid Explosive Mixtures

An approximate method is proposed to calculate the impact sensitivity indices (critical initiation pressure and critical charge thickness) for solid explosive mixtures (explosive compositions and mixtures of an oxidizer with a fuel). The calculation is based on some model concepts of the physicochemical and explosive properties of reactive mixtures. Test calculations of the sensitivity indices were performed for mixtures of HMX and TNT and mixtures of ammonium perchlorate with polymethylmethacrylate (PMMA) and TNT, and the results are compared with data of laboratory experiments on an impactor.

Thioacetalization of aldehydes and ketones in the presence of hydroxo complexes of platinum(II): An example of Lewis acid catalytic activity

The complex [(dppb)Pt(µ-OH)]2(BF4)2 displays high catalytic activity in the thioacetalization of a variety of aldehydes and ketones with mercaptoethanol under very mild conditions. The reaction rate is greatly enhanced by the addition to the reaction mixture of magnesium perchlorate as drying agent and molar turnovers as high as 9700 can be observed. The effect of different desiccating agents is also reported. The reactivity pattern observed, the similarity with other reactions and NMR spectroscopic investigations confirm the possible role of the complex as Lewis acid catalyst in promoting the reaction.Key words: thioacetalization, catalysis, aldehydes, ketones, platinum complex.

Rapid and Simple Method for the Determination of Vanadium in Beer by ICP AES with Ultrasonic Nebulization

An accurate and reproducible method for the direct determination of vanadium in beer using inductively coupled plasma atomic emission spectrometry (ICP AES) with an ultrasonic nebulization system is described. The analytical conditions were optimized in order to achieve the appropriate sensitivity. Samples were digested with a 1 : 1 nitric acid–perchloric mixture. The analytical detection limit was 0.4 μg/L, and the relative standard deviation was 2.8% at the 10 ng/mL V levels. The method was applied to determine vanadium (15.9–244.3 μg/L) in 11 different samples of beer widely consumed in the Argentine Republic.

Experimental verification of the recoil force versus burning-rate dependence

Experimental results on the recoil-force dependence on the burning rate for composite propellants based on stoichiometric mixtures of ammonium perchlorate (AP) and polymethylmethacrylate (PMMA) are presented. Propellants with additions of Al or Al2O3 were also tested to investigate dispersion phenomena. Changes in the initial temperature, pressure, and external radiation allowed variations of the burning rate. Thus, to deduce the burning rate from the recoil force, the parameters of the fitting law must be determined for each propellant composition under a particular set of external conditions.

One Pot Synthesis of Alpha-Aminonitrile and Alpha-Amino Acid From Schiff Bases

Addition of Potassium cyanide to a mixture of Schiff base and lithium perchlorate afforded a-aminonitriles in high yields. Addition of potassium cyanide to a methanolic solution of Schiff base and phosphoric acid afforded a-aminonitriles. When the reaction mixture was refluxed it gave a-amino acids in high yields.

Dissociation Constant, Ka, and Stability Constant, K(HA2-), of the 1:1 Homoconjugate of Sulfuric and Nitric Acids in Acetonitrile at 298.1 K. Revised Values

Previously reported values of pKa and K(HA2-) of sulfuric (first step) and nitric acids in acetonitrile derived from spectrophotometric indicator data have been revised. The revised values are 8.04, 2.7 × 103 mol-1 dm3 and 10.59, 1.2 × 103 mol-1 dm3, respectively. Both Ka and K(HA2-) of sulfuric acid are some 1.7 times smaller than those reported from potentiometric glass electrode data. An estimate of KaK(HA2-) of sulfuric acid was made from simultaneous spectrophotometric nitroaniline indicator and electrolytic conductivity measurements in solutions allowed to stand for various times. The glass electrode was used in mixtures of nitric acid and tetraethylammonium nitrate, pKa and K(HA2-) being 10.53 and 1.15 × 103 mol-1 dm3, respectively. The homoconjugation constant was verified from the increase in solubility of sodium nitrate in the presence of nitric acid. The protonation constant of aniline, 1010.57 mol-1 dm3, was determined spectrophotometrically in aniline−anilinium perchlorate mixtures with p,p‘-dimethylaminoazobenzene and found to be in excellent agreement with the literature value.

Smooth ascent

Once a solid-fuel rocket has been lit, it's like an enormous firework — it can be neither stopped nor controlled. Typically, the solid fuel is a mixture of aluminium powder and ammonium perchlorate and, to make a more controllable fuel, DREADCO chemists are replacing these ingredients with fine aluminium wire and a water-based gel, respectively.

Performance and CO Production of a Non-Azide Airbag Propellant in a Pre-Pressurized Gas Generator

This paper presents a numerical study of the transient operation of a pre-pressurized (augmented) airbag inflator. Augmented inflators dilute hot gaseous products of propellant combustion with ambient temperature, high-pressure stored gas before discharging the mixture into the airbag. The solid propellant selected for this study is a non-azide propellant composed of a mixture of azodicarbonirnide, potassium perchlorate, and cupric oxide, Predicted performance of the inflator is presented in terms of pressure, temperature and mass flow rate profiles in the inflator and discharge tank which is used to simulate an airbag. This work also predicts first-order estimates of gas-phase species exit concentrations and characteristic residence times in the inflator. Carbon monoxide. produced as a product of combustion from the high flame temperature propellant, is partially converted to COz as it flows from an internal combustionchamber to the pressurized plenum before being discharged into the airbag, Specifically. the production/destruction of CO is tracked using three different gas-phase reaction models: I) chemically frozen. 2) local (shifting) equilibrium. and 3) finite-rate elementary kinetics. Results presented in this paper demonstrate the necessity of an airbag combustion program that includes finite-rate, gas-phase kinetics. Results from the finite-rate CO chemistry model are qualitatively consistent with experimental results reported by others for the same propellant formulation in a similar operating environment.

Analysis of Inorganic Anions by Capillary Zone Electrophoresis.

Determination of inorganic anions by capillary zone electrophoresis is reported in this study. An anions mixture of bromide, chloride, fluoride, nitrite, sulfite, sulfate, perchlorate, chlorate and chlorite was separated by a capillary column and detected by indirect UV method. The running buffer contained 5mM ammonium dichromate, 10mM ammonium acetate, 20mM diethylenetriamine, and in 10% methanol solution at pH 9.3. A potential of 15kV at the cathode(reversed polarity) was utilized for the separation of inorganic anions. A complete separation of anions was achieved in less than 10 min and the applicabilities of the method were demonstrated for forensic evidences. We performed analysis of inorganic anions in toluene inhaled human's urine and in postmortem bloods by capillary zone electrophoresis and ion chromatography

Preparation of a Macrocyclic Polyamine-bonded Column for the Electrophoretic Separation of Inorganic and Organic Anions

A 24-membered macrocyclic polyamine based on the propylene-1,3-diamine unit that was able to form polyprotonated, highly charged species in the neutral pH region was selected to act as an anion complexone. It was synthesized and incorporated in a fused-silica capillary for the electrophoretic separation of inorganic and organic anions. This complexing agent can selectively modulate the mobility of anions by forming anion complexes with varying degrees of stability. Parameters which influence capillary electrophoretic separations such as applied voltage, choice of electrolyte anion, electrolyte pH and electrolyte concentration were investigated. A mixture of thiosulfate, chloride, sulfate, selenate, perchlorate, tungstate, carbonate and selenite could be separated in 5 mM sodium chromate at pH 10.0 within 13 min. A mixture of bromide, oxalate, malate, citrate, tartrate, maleate, succinate, acetate, lactate, butyrate, p-hydroxybenzoate, salicylate and octanesulfonate could be separated in 10 mM phthalate at pH 5.0 within 11 mins. Under the same conditions, even geometric isomers or mixtures of polycarboxylates and polyphosphates, such as ATP and ADP, could be well separated. The experimental results indicated that incorporating the chelating functional group in the inner wall of the capillary markedly enhances the selectivity of the system.

Dinuclear iron(III)–metal(II) complexes as structural core models for purple acid phosphatases †

A series of mixed-valent iron and mixed-metal FeIII–MII (M = Zn, Cu, Ni or Co) complexes of the phenolate-hinged dinucleating ligand 2,6-bis{[bis(2-pyridylmethyl)amino]methyl}-4-tert-butylphenolato(1–), bpbp– have been prepared and characterized. Both exogenous bidentate bridging groups and different terminal ligands bound to each different metal ion at the exogenous site were identified. The structure of the mixed-valence complex [(bpbp)Fe2(F)2(H2O)2][BF4]2 confirms that it is a rare example of a dimetallic complex of a single-atom hinged acyclic dinucleating ligand with a ‘non-bridged’ arrangement at the exogenous bridging site. Mössbauer spectroscopy indicates valence trapping in this complex with the parameters, ΔEQ 3.242 mm s–1, δ 1.169 mm s–1 and ΔEQ 0.221 mm s–1, δ 0.460 mm s–1, respectively for the high spin Fe2+ and high spin Fe3+ ions. Crystals of [(bpbp)Fe2(F)2(H2O)2][BF4]2·4H2O are triclinic, space group P (no. 2), with a = 12.695(1), b = 19.197(2), c = 10.202(1) Å, α = 102.95(1), β = 97.61(1), γ = 93.76(1)°, Z = 2. The structure was refined to R = 0.1009 on F using 4338 reflections with I > 2σ(I) (wR2 on all data and F 2 = 0.3522). The FeII and FeIII atoms are bridged asymmetrically by the phenolic oxygen atom of bpbp– with FeII–O 2.175(6) Å and FeIII–O 2.033(6) Å with a FeIII · · · FeII distance of 3.726(2) Å. The two terminal fluoride ions are bound to the FeIII atom and strongly hydrogen bonded to two water molecules bound to the adjacent FeII atom. This complex may model the mode in which fluoride ions bind to the active site of the purple acid phosphatases (PAPs) thereby inhibiting the activity of these enzymes. Tetrahedral oxo anions are known also to inhibit PAPs and to mimic this inhibition a FeIII–ZnII complex incorporating molybdate bridging groups was prepared. Crystals of [(bpbp)FeZn(MoO4)2]·C3H7OH· 2H2O are monoclinic, space group P21/n with a = 11.773(13), b = 21.394(7), c = 17.001(11) Å and β = 90.98(7)°, Z = 4. The structure was refined to R = 0.0434 on F using 3758 reflections with I > 2σ(I) (wR2 on all data and F 2 = 0.1339). The FeIII · · · ZnII distance is 3.819(4) Å. A series of acetate-bridged complexes were prepared by the novel method of diffusing ethyl acetate or isopropyl acetate into mixtures of Hbpbp and iron perchlorate in the presence and absence of a second type of metal ion. The acetate bridging groups are the result of the hydrolysis of the alkyl acetate. These complexes have the general formulation [(bpbp)FeM(CH3CO2)2][ClO4]2. Crystals of [(bpbp)FeCu(CH3CO2)2][ClO4]2·0.5CH3OH are monoclinic, space group P21/n

96/03487 Determination of forms of organic sulfur in coal by step-wise oxidation with perchloric acid-ferric perchlorate mixture

Sr geochemistry in coal has been studied on the basis of its distribution in 457 samples of coal, coaly shales and mineral interlayers from several Bulgarian coal deposits. Model experiments were also carried out. The analysed Sr contents are lower than the average values for coals. Only the Burgas deposit is enriched in Sr due to marine influence. The coal lithotypes liptain, vitrain, xylain and fusain are usually enriched in Sr as compared to the whole samples from which they were separated.Sr occurs in both organic (Srorg) and inorganic (Srinorg) forms. The relation to organic matter is demonstrated by: (1) Sr enrichment in low-ash coals and in lighter specific gravity fractions; (2) leaching of Sr bound to humic acids by treatment with 2% NaOH; (3) sorption experiments on xylain at pH 4-5.5 - up to 92% of Sr in solution was taken up by the sorbents; a mechanism of cation exchange as well as formation of metallo-organic complexes is proposed. Host minerals of Srinorg are aragonite, gypsum, calcite and feldspar. The highest Srinorg content is related to aragonite.

Determination of forms of organic sulfur in coal by step-wise oxidation with perchloric acid-ferric perchlorate mixture

Differentiation of organic sulfur forms in coal by step-wise oxidation with a mixture of perchloric acid (HClO4) and ferric perchlorate (Fe(ClO4)3) was studied. Various organic sulfur compounds were oxidized with HClO4 solution containing Fe(ClO4)3, and the amounts of sulfate formed during reaction were measured. The compounds can be grouped into three categories according to their reactivities as follows: (1) easily oxidized ones, i.e. disulfides, for which almost all of the sulfur was converted to sulfate after oxidation, (2) less reactive ones including aliphatic sulfides, aliphatic and aromatic thiols (20–30% of sulfur in these compounds was oxidized to sulfate), and (3) relatively stable ones, i.e. thiophenes and aromatic sulfides, from which no sulfate was formed. Samples of Illinois No. 6 and Bevier coals were also reacted with HClO4 solutions containing increasing concentration of Fe(ClO4)3. The organic sulfur in these coals could be differentiated into various groups according to their reactivities.

Rapid Normal Raman Spectroscopy of Sub-Ppm Oxy-Anion Solutions: The Role of Electrophoretic Preconcentration

Normal Raman spectroscopy is used as an on-line detector for capillary electrophoresis (CE) to detect sub-ppm mixtures of nitrate and perchlorate in water. Field-amplified injection, a form of sample stacking, into a running electrolyte of 0.1 M KCl increases the analyte concentration at the detection window by up to 1800 times its starting value. Raman bands of nitrate (1047 cm−1) and perchlorate (934 cm−1) are measured in a total separation time of less than 3 min, with only 1-s integration times. The Raman spectroscopy of solutions originally 1 × 10−5 M nitrate (620 ppb) and perchlorate (1 ppm) is demonstrated.

Nickel and vanadium in air particulates at Dhahran (Saudi Arabia) during and after the Kuwait oil fires

Abstract Air particulates, both the total suspended (TSP) and inhalable (PM 10 , smaller than 10 microns in size), were collected during and after the Kuwait oil fires (from March 1991 to July 1992) using Hi-Vol samplers. These samples were wet-digested at 120°C in an aqua regia and perchloric acids mixture for 3 h. Air particulate samples collected in 1982 at the same location were prepared similarly. Concentrations of nickel and vanadium were determined in the aliquot samples using an inductively coupled argon plasma analyser (ICAP). The monthly mean concentrations of nickel and vanadium, on volume basis, increased rapidly from March to June and decreased sharply during July–August in 1991. The minimum mean concentrations of these elements were found in the particulate samples collected in December 1991 which gradually increased through May 1992. Like 1991, nickel and vanadium concentrations in the air particulates spiked in June and decreased again in July 1992. This distribution pattern of nickel and vanadium concentrations was similar to that of the predominant wind from the north (Kuwait). In general, concentrations of these elements were higher in the air particulates collected during April–July 1991 as compared with those collected in 1992 during the same period. The TSPs contained higher concentrations of nickel and vanadium than those found in the PM 10 samples. However, this trend was reversed when concentrations of nickel and vanadium, on were expressed on particulate weight basis. The monthly mean concentrations of nickel and vanadium, on weight basis, decreased gradually through 1991 and increased slightly from March to July 1992. Concentrations of these elements were significantly higher in the air particulate samples collected in 1991 than those samples collected during 1982 at the same location. The data of this study suggest a contribution of the Kuwait oil fires in elevating nickel and vanadium concentrations in the air particulates at Dhahran during April–July 1991. Concentrations of these elements were largely below their proposed limits in the ambient air (for nickel-50 μg m −3 , air; for vanadium—1 μg m −3 air). It is, therefore, anticipated that concentrations of nickel and vanadium in the air particulate samples were not a health concern during Kuwait oil fires at Dhahran, Saudi Arabia.

Ultrasonic Agitation Accelerates cis-Glycosylation with Heterogeneous Promoters

Ultrasonic agitation increases the yield of glycosylations with donors such as 3,4,6-tri-O-acetyl-2-azido-2-deoxy-α-D-galactopyranosyl chloride using the heterogeneous promoters silver zeolite, cadmium zeolite or a mixture of silver perchlorate and silver carbonate on celite. The stereospecificity of the glycosylation depends on the nature of the alcohol to be glycosylated, the nature of the solid support and the solvent. Glycosylation catalyzed by silver zeolite in toluene solutions of the donor 3,4,6-tri-O-acetyl-2-deoxy-2-phtalimido-β-D-glucopyranosyl bromide, that usually produce trans-β-glycosides, yield cis-glycosides with unreactive alcohols. In these unreactive alcohols, e.g. methyl 2-O-benzoyl-4,6-O-benzilidene-β-D-galactopyranoside and benzyl 3,4,6-tri-O-benzyl-α-D-mannopyranoside, the hydroxyls to be glycosylated are hydrogen-bonded to a cis vicinal oxygen. This feature was evident in their AM1 minimized conformations and was indicated by the solution J(OH,CH) 1H NMR coupling constants.