Nirmala Sikder

Synthesis, characterisation, thermal and explosive properties of 4,6-dinitrobenzofuroxan salts

Two new initiatory molecules, e.g. rubidium and cesium salts of 4,6-dinitrobenzofuroxan (DNBF) have been prepared by reacting sodium salt of 4,6-dinitrobenzofuroxan (DNBF) with rubidium nitrate and cesium nitrate, respectively, at 60 degrees C in aqueous medium. The characterisation of compounds by IR, (1)H-NMR, elemental analysis and metal content is described along with some of the evaluated thermal and explosive properties. The results indicate that cesium salt of DNBF (Cs-DNBF) appears promising initiatory and may suitably replace potassium salt of DNBF (K-DNBF), being used currently in initiatory compositions.

Nitroanilinodinitrobenzofuroxans—synthesis, characterisation, thermal stability and explosive properties

Three new derivatives of 4,6-dinitrobenzofuroxan: 7-(4-nitrophenylamino)-4,6-dinitrobenzofuroxan, 7-(3,5-dinitrophenylamino)-4,6-dinitrobenzofuroxan and 7-(2,4,6-trinitrophenylamino)-4,6-dinitrobenzofuroxan, have been synthesised by condensing 4-nitroaniline, 3,5-dinitroaniline and 2,4,6-trinitroaniline with 7-chloro-4,6-dinitrobenzofuroxan, respectively. The characterisation of the compounds by IR, 1H-NMR, mass spectrometry and elemental analysis is described along with some of the evaluated preliminary explosive properties. The compounds were found to exhibit acceptable hazards properties. Furthermore, the thermal stability measurements indicated acceptable stability.

Synthesis, characterization and explosives properties of 7-(1h -1,2,4-triazol-3-amino)-4,6-dinitrobenzofuroxan (TADNB) and 7-(1h-1,2,3,4-tetrazol-5-amino)-4,6-dinitrobenzofuroxan (TEADNBF)

Abstract 7-(1H -1,2,4-triazol-3-amino)-4,6-dinitrobenzofuroxan(TADNB)and 7-(1H-1,2,3,4-tetrazol-5-amino)-4,6-dinitrobenzofuroxan(TeADNBF) have been prepared by condensing 7-chloro-4,6-dinitro benzofuroxan with 3-amino-1,2,4-triazole and 5-amino-1,2, 3,4-tetrazole respectively. The compounds have been characterized by spectral data and elemental analysis. Furthermore, some of the explosive properties of these compounds have also been investigated and reported herein.

Synthesis, characterization and thermal studies of 2-oxo-1,3,5-trinitro-1,3,5-triazacyclohexane (Keto-RDX or K-6)

2-Oxo-1,3,5-trinitro-1,3,5-triazacyclohexane (Keto-RDX or K-6), the most powerful energetic material among nitrourea explosives, has been prepared and scaled up at laboratory level. The identity and purity of the product are tested by elemental analysis, IR, NMR, mass and HPLC techniques. Thermal response and sensitivity experiments on K-6 are also described. The data on sensitivity shows that K-6 can be utilised practically only in phlegmatized form.

Synthesis, Characterization, and Thermal and Explosive Properties of Alkali Metal Salts of 5,7-Diamino-4,6-Dinitrobenzofuroxan (CL-14)

Potassium, rubidium, and cesium salts of 5,7-diamino-4,6-dinitrobenzofuroxan (CL-14) have been prepared by reacting sodium salt of 5,7-diamino-4,6-dinitrobenzofuroxan with alkali metal nitrate in an aqueous medium. The structure of the compounds was unequivocally confirmed by spectra data, elemental analyses, and estimation of metal content. Further, the compounds have been evaluated for explosive and thermal properties and found more suitable as compared to alkali metal salts of 4,6-dinitrobenzofuroxan (DNBF).

Direct determination of zirconium and silicon in zircon by flame atomic absorption spectrometry using two rapid decomposition methods

Analysis of zircon for its zirconia and silica content is important as part of quality control. Due to its exceptional thermal and chemical stability, decomposition is difficult under ordinary conditions. Two relatively rapid and accurate decomposition methods using alkali fusion and hydrofluoric acid have been described. In the present work, zircon has been fused with molten sodium hydroxide in 1u2006:u20066 mole ratio in an open vessel at 550 °C to give acid soluble sodium zirconate and water soluble sodium ortho silicate. The acid soluble zirconate and water soluble silicates were separated and analysed by flame atomic absorption spectrometry (FAAS) for zirconia and silica content. The effects of zircon to alkali ratio and decomposition temperature on degree of decomposition have been studied. The acid decomposition method was developed using hydrofluoric (HF) acid at elevated temperatures in closed microwave (MW) digestion system. The MW digested samples containing water soluble fluoride compounds of Zr and Si were directly analysed by FAAS. Several temperature profiles of MW system were studied for acid strengths of 40% and 48% and optimised conditions were achieved to investigate the effect of strength on the extent of decomposition and decomposition temperature. Complete digestion was observed at 225 °C (48%) and 250 °C (40%). MW acid digestion decomposes samples with a very short heating time of 20 min with small amount of reagents (∼10 mL) as compared to conventional methods. For increasing absorption for Zr in FAAS, all solutions were analysed in presence of 0.5 M HF + Al salt. The proposed MW digestion method using HF has also been applied successfully for analyzing zirconium carbide and is well suited for other refractory zirconium compounds.

Rapid determination of impurity of boron nitride in amorphous boron powder using inductively coupled plasma-atomic emission spectrometry (ICP-AES) and ion chromatography (IC)

Ever-increasing use of amorphous boron powder (ABP) in high-energy materials (HEMs) and allied compositions has created frequent demand for the analysis of boron (B). The presence of nitrogen in inert gas (Ar) used during the synthesis of ABP or from trapped air during the process results in the formation of boron nitride in a significant quantity (up to 4%), and hence an adequate analytical method for the selective estimation of nitride content has been established. Conventionally, ABP is analyzed by fusion with sodium carbonate followed by total B-content estimation from inductively coupled plasma-atomic emission spectrometry (ICP-AES). This method of B estimation using ICP-AES is not sufficient alone to differentiate B from ABP and BN, and an alternative new analytical method was developed for the rapid and direct estimation of BN in ABP. Due to its substantial chemical inertness, decomposition of BN is extremely difficult, and therefore the digestion was attempted with several acids and acid mixtures using microwave digestion in a closed vessel at various temperatures. H2SO4 (98%), HNO3 (68–70%), HF (40%) + H2SO4, HF (40%) + HNO3, HF (40%) and HF (48%) were tried, and complete digestion of pure BN into ammonium fluoroborate (NH4BF4) was observed only with HF and HF + HNO3. The results were then compared with those obtained with alkaline carbonate (Na2CO3) fusion. Digestion with HF alone using microwaves is suitable for the direct estimation of BN as a minor ingredient or impurity in ABP and other B-based materials using ion chromatography (IC). Microwave-acid digestion decomposed samples at elevated temperatures (∼200 °C) with a short heating time (∼10 min) with a small quantity of reagents (∼3 ml) compared with conventional methods. The extent of the decompositions at different temperatures was monitored and studied by estimating B through ICP-AES and ammonium ions by IC. The proposed microwave digestion method using HF followed by ICP-AES/IC analysis is equally applicable for analyzing BN as a major component, and has also been applied successfully for analyzing boron carbide (B4C) and is well suited for other refractory compounds.

Synthesis and characterization of some new styphnyl-bis-ß-alanine derivatives

A new series of N,N–dinitro-styphnyl-bis-ß-alanine derivatives have been prepared, characterised and evaluated for its preliminary explosives properties in order to find its suitability to explosives and propellants formulations.