Nitric Acid Esters Research Articles

Energetic Coordination Compounds: Investigation of Aliphatic Ligands and Development of Prototype Detonators.

In this work, energetic coordination compounds (ECCs) of transition metals (Fe, Ni, Cu, Zn) containing aliphatic amines as ligands were synthesized: ethylenediamine; 1,3-diaminopropane; tris(2-aminoethyl)amine; tris(3-aminopropyl)amine. The compounds were investigated in terms of ignition/explosion temperature, friction and impact sensitivity. For selected compounds, structural characterisation was presented (IR-ATR spectroscopy, Raman spectroscopy) and their morphology was determined (SEM, powder XRD). They were also investigated by differential scanning calorimetry (DSC). In order to assess the potential application of selected ECCs in detonators, underwater explosion tests were carried out, determining energetic performance. The results achieved for detonators containing ECCs were compared with those for reference detonators (containing pentaerythritol tetranitrate, PETN), indicating their potential use as a "green" alternative to nitric acid esters.

Synthesis of cellulose nitrates from Miscanthus × giganteus var. KAMIS cellulose obtained under pilot production conditions

The work is devoted to the study of a novel national raw material resource Miscanthus × Giganteus var. KAMIS, which is positioned as one of the most promising natural sources for obtaining high-quality cellulose for the purpose of its further chemical functionalisation. A batch of technical cellulose isolated from raw materials under pilot production conditions using the nitric acid method having a cellulose content of 50.2% was characterized by high α-cellulose mass fraction (92.8%) and degree of polymerisation (1200) values. On the basis of the pilot batch of technical cellulose, a sample of cellulose nitrates offering basic functional properties was obtained: mass fraction of nitrogen – 11.18%; viscosity – 48 MPa·s; solubility – 94%. The synthesised sample is characterized by extremely high solubility in acetone, confirming the production of cellulose nitric acid esters, and a high yield of 150%. IR-Fourier spectroscopy was used to identify the main functional groups in the experimental batch of technical cellulose (3384, 2902, 1639, 1428, 1370, 1319, 1161, 700–500 cm-1) and in a sample of cellulose nitrates (1659, 1278, 834, 746, 683 cm-1). Acorresponding affiliation to cellulose and cellulose nitric acid esters was established. The structural and morphological features of the fibres of the experimental batch of technical cellulose and a sample of cellulose nitrates were characterised using scanning electron microscopy. Combined methods of thermogravimetric and differential thermal analyses were used to establish high initial temperature (197 °C) and specific heat of decomposition (6.92 kJ/g) values at the beginning of intensive decomposition. The obtained results substantiate the possibility to chemically functionalise cellulose isolated from a new alternative source into cellulose nitric acid esters with satisfactory functional properties.

INVESTIGATION OF REACTIONS OF INTERACTION OF CELLULOSE NITRIC ESTERS WITH CARBOXYLIC ACID CHLORIDES

The chemical interaction of high-nitrogen cellulose ether with acetic, propionic, butyric and isobutyric acids has been studied. The general laws and features of the electrophilic substitution of functional groups of cellulose nitroesters are revealed. The preferred directions of the chemical interaction of cellulose nitrate with carboxylic acid chlorides are established: O-acylation of nitrate and hydroxyl groups; O-acylation of the glucopyranose ring; O-acylation of the ether bond with depolymerization of the chain of an SC molecule; hydrolysis of nitrate groups; destruction of the chain of a macromolecule of nitric acid ester with the formation of water-soluble organic compounds. The structure, properties and possibilities of using synthesized mixed cellulose ethers were studied. Effective methods have been developed for the chemical modification of cellulose nitrates with carboxylic acid chlorides. The probable directions of the reaction of the interaction of cellulose nitrates with electrophilic reagents are predicted based on quantum-chemical calculations of point charges on the atoms of the reacting molecules. The reactivity of highly substituted cellulose nitrates in reactions with carboxylic acid chlorides has been established. The optimal conditions for the interaction of cellulose nitrates with carboxylic acid chlorides have been identified and a mathematical model of the reaction kinetics has been constructed. The possibility of a directed change in the composition of chemically modified cellulose nitrates depending on the synthesis conditions has been established. As a result of the combined use of physicochemical research methods, the chemical composition was determined and the structure of the synthesized compounds was determined: cellulose acetyl nitrates, cellulose propionyl nitrates, cellulose butyryl nitrates, and cellulose isobutyryl nitrates. Using gel chromatography, it was found that the molecular weight characteristics of the synthesized samples are directly dependent on the conditions of their synthesis. It was found that electrophilic substitution of the functional groups of cellulose nitrate proceeds more intensively in the pyridine medium.

Solid-State and Gas-Phase Structures and Energetic Properties of the Dangerous Methyl and Fluoromethyl Nitrates.

An improved synthesis of the simplest nitric acid ester, methyl nitrate, and a new synthesis of fluoromethyl nitrate use the metathesis of the corresponding iodomethanes with silver nitrate. Both compounds were identified by spectroscopy and the structures determined for in situ grown crystals by X‐ray diffraction as well as in the gas phase by electron diffraction. Fluorination leads to structures with shorter C−O and N−O bonds, has an energetically destabilizing effect and increases friction sensitivity, but decreases detonation performance.

Synthesis of (3-Hydroxyadamantan-1-yl)methanols

A convenient procedure has been developed for the synthesis of (3-hydroxyadamantan-1-yl)-methanols on the basis of nitroxylation of adamantan-1-ylmethanols with fuming nitring acid and subsequent reduction of intermediate nitric acid esters with hydrazine hydrate. The title diols have also been obtained by the reduction of 1-nitroxy-3-(nitroxymethyl)adamantanes. The nitroxylation process is accompanied by oxidation with the formation of substituted adamantane-1-carboxylic acids.

Blast Wave Parameters of Liquid Esters of Nitric Acid: Propane-1,2,3-triyl trinitrate, Propane-1,2-diyl Dinitrate, Ethane-1,2-diyl Dinitrate and Methyl Nitrate

Blast Wave Parameters of Liquid Esters of Nitric Acid: Propane-1,2,3-triyl trinitrate, Propane-1,2-diyl Dinitrate, Ethane-1,2-diyl Dinitrate and Methyl Nitrate

The Reagent‐depending Nitration of 1,3‐Dihydroxyacetone Dimer

Two highly energetic nitric acid esters were synthesized from the dimer of dihydroxyacetone. 1,3‐Dinitratoacetone (1) and its dimer 2,5‐bis(nitratomethyl‐2,5‐nitrato)‐1,4‐dioxane (2) were characterized by single‐crystal X‐ray diffraction, vibrational spectroscopy (IR and Raman), multinuclear NMR spectroscopy, and elemental analysis. The thermal behavior was investigated with DTA measurements. Although showing the same atomic stoichiometry, dimer 2 shows significantly higher sensitivities measured by BAM methods (drophammer and friction tester). Due to the high oxygen content of 62.2 %, 1 and 2 were evaluated as potential high energy dense oxidizers.

Mechanistic study of secondary organic aerosol components formed from nucleophilic addition reactions of methacrylic acid epoxide

Abstract. Recently, methacrylic acid epoxide (MAE) has been proposed as a precursor to an important class of isoprene-derived compounds found in secondary organic aerosol (SOA): 2-methylglyceric acid (2-MG) and a set of oligomers, nitric acid esters, and sulfuric acid esters related to 2-MG. However, the specific chemical mechanisms by which MAE could form these compounds have not been previously studied with experimental methods. In order to determine the relevance of these processes to atmospheric aerosol, MAE and 2-MG have been synthesized and a series of bulk solution-phase experiments aimed at studying the reactivity of MAE using nuclear magnetic resonance (NMR) spectroscopy have been performed. The present results indicate that the acid-catalyzed MAE reaction is more than 600 times slower than a similar reaction of an important isoprene-derived epoxide, but is still expected to be kinetically feasible in the atmosphere on more acidic SOA. The specific mechanism by which MAE leads to oligomers was identified, and the reactions of MAE with a number of atmospherically relevant nucleophiles were also investigated. Because the nucleophilic strengths of water, sulfate, alcohols (including 2-MG), and acids (including MAE and 2-MG) in their reactions with MAE were found to be of similar magnitudes, it is expected that a diverse variety of MAE + nucleophile product species may be formed on ambient SOA. Thus, the results indicate that epoxide chain reaction oligomerization will be limited by the presence of high concentrations of non-epoxide nucleophiles (such as water); this finding is consistent with previous environmental chamber investigations of the relative humidity dependence of 2-MG-derived oligomerization processes and suggests that extensive oligomerization may not be likely on ambient SOA because of other competitive MAE reaction mechanisms.

Predicting the Shelf-Life of Single Base Propellants

Ammunitions stored in war fields have lifespans that are related to the single base propellants, as Nitrocellulose (NC), the main component of propelling gunpowder, decomposes naturally into an unstable substance, similar to other nitric acid esters. Decomposition is inevitable; however a decomposition product (NO2, NO3, and HNO3) and tranquillizer DPA (Diphenylamine), which have high reactivity, can be added to a propellant to restrain the induction of automatic catalysis by a decomposition product. The decay rate of the tranquillizer is also affected by the production rate of the decomposition product of NC. Thus, as the storage period of single base propellants lengthens, the reduction rate of the tranquillizer content increases. This paper presents a new methodology based on data mining and regression analysis for estimating the shelf-life of single base propellants using data from the ASRP to 105mm HE (KM1 and M1).

Synthesis of nitric acid esters from alcohols in a dinitrogen pentoxide/carbon dioxide liquid system

Organic nitric acid esters have been prepared in 89–98% yield by the nitration of the corresponding alcohols and polyols with N2O5 in liquid CO2.

Synthesis of Some Novel Organic Nitrates and Comparative in Vitro Study of Their Vasodilator Profile

Synthesis and structural characterization of the 4-phenylbutane-1,2-diyl dinitrate and of the erythro and threo diastereoisomers of 4-phenylbutane-1,2,3-triyl trinitrate as well as the HPLC chiral separation of the corresponding racemic mixtures are reported. Vasodilator activity of the single enantiomers of these products, of 4-phenylbutyl nitrate, and of the previously described phenylpropyl analogues were assessed on rat aorta strips precontracted with phenylephrine. The compounds were able to relax the contracted tissue in a concentration dependent manner. In the couples of antipodes, a complete lack of enantioselectivity was observed as far as the vasodilator potency is concerned. The concentration response curves of the products, with the exception of those of all the trinitrooxy substituted models, were rightward shifted in the presence of ALDH-2 inhibitors. Mono and dinitrates, but not trinitrates, displayed in vitro cross-tolerance with GTN. This new series of nitric acid esters is an interesting tool that can help to shed light on the unresolved puzzle of nitrate pharmacology. Selected members are worthy of additional study as potential drugs.

Synthesis and properties of poly-isocyanate energetic curing agent

Two tetrafunctional poly-isocyanate energetic curing agents with different molecular weight (EO03-1 and EO03-3) were synthesized via reaction of azido polyether polyol with hexamethylene diisocyanate (HDI). The reaction conditions and post processing steps were investigated. There was an exothermic peak at 252.89 °C referring to the thermal decomposition of azido group in differential scanning calorimetry (DSC) plot of EO03-3 and the glass transition temperature (Tg) was found at -47.13 °C. Thermal decomposition peak of GAP/EO03-3 elastomer was found to be at 254.56 °C and the Tg was found at -45.78 °C. To estimate the potential utility of EO03 in solid rocket propellants, an nitric acid ester, triethylene glycol dinitrate (TEGDN), was added to GAP/EO03-3 system as an energetic plasticizer. It was homogeneous even as the amount of TEGDN was equal to GAP/EO03-3 system and Tg of GAP/EO03-3/50%TEGDN was found at -69.08 °C. Mechanical properties of GAP/EO03 and GAP/EO03-3/chain extender were also studied.

Endothelial protection by pentaerithrityl trinitrate: bilirubin and carbon monoxide as possible mediators.

Pentaerithrityl tetranitrate (PETN) is a long-acting donor of nitric oxide (NO) and has recently been characterized as an antianginal agent that, in contrast with other nitric acid esters, does not induce oxidative stress and is therefore free of tolerance. Moreover, animal experiments have revealed that PETN actively reduces oxygen radical formation in vivoand specifically prevents atherogenesis and endothelial dysfunction. Because heme oxygenase-1 (HO-1) has been described as an antiatherogenic and cytoprotective gene in the endothelium, our aim was to investigate the effect of the active PETN metabolite pentaerithrityl trinitrate (PETriN) on HO-1 expression and catalytic activity in endothelial cells. Endothelial cells derived from human umbilical vein were incubated with PETriN (0.01-1 mM) for 8 hr. PETriN increased HO-1 mRNA and protein levels in a concentration-dependent fashion up to 3-fold over basal levels. Elevation of HO-1 protein was accompanied by a marked increase in catalytic activity of the enzyme as reflected by enhanced formation of both carbon monoxide and the endogenous antioxidant, bilirubin. Pretreatment of endothelial cells with PETriN or bilirubin at low micromolar concentrations protected endothelial cells from hydrogen peroxide-mediated toxicity. HO-1 induction and endothelial protection by PETriN were not mimicked by isosorbide dinitrate, another long-acting nitrate. The present study demonstrates that the active PETN metabolite, PETriN, stimulates mRNA and protein expression as well as enzymatic activity of the antioxidant defense protein, HO-1, in endothelial cells. Increased HO-1 expression and ensuing formation of bilirubin and carbon monoxide may contribute to and explain the specific antioxidant and antiatherogenic actions of PETN.

Thermal ageing of rocket propellant formulations containing ε-HNIW (ε-CL20) investigated by heat generation rate and mass loss

New types of rocket propellant batches have been formulated with the objective of achieving higher burning rates. The main ingredients are (1) the energetic plasticizers glycidyl azide polymer-α,ω-diazide (GAP)-A (short chain GAP with azide end groups), trimethylolethane trinitrate (TMETN) and 1,2,4-butanetriol trinitrate (BTTN), (2) the energetic substances ammonium perchlorate (AP) and ε-CL20 (ε-HNIW, hexanitrohexazaisowurtzitane, crystallised in ε-phase). The binder is GAP (glycidyl azide polymer, diol component) cured with the polyisocyanate Desmodur™ N100. From the point of view of stability and ageing, the interesting fact is that the formulations contain none of the typical stabilisers for the nitric acid ester components TMETN and BTTN, although their contents range up to 21 mass%. One reason for doing so is to increase the content of the high energy ingredients. Seven formulations were examined in more detail. To assess basic stability the autoignition temperature test, Dutch mass loss test and vacuum stability test were used. To investigate ageing, two measurement quantities are applied: heat generation rate (heat flow) as function of time at 70, 80 and 89 °C and mass loss as function of time at the temperatures of 70, 80 and 90 °C. The evaluation of the measurements was done with reaction kinetic models. One batch (#189) containing BTTN shows significantly lower activation energy and pre-exponential factor. From mass loss one gets as activation energy for #189 of 101 kJ mol −1 in comparison to the range of 126–135 kJ mol −1 for the six other batches. But, based on the ageing caused by chemical decomposition reactions, all seven batches showed a good ageing behaviour. A use time period of up to 20 years of use seems realistic.

Nitric oxide releasing morpholine derivatives as hypolipidemic and antioxidant agents.

The synthesis and evaluation of activity of some nitric acid esters of substituted morpholines are presented. All compounds inhibit lipid peroxidation and reduce cholesterol (20-63%) and triglyceride (37-85%) plasma levels. The more potent NO donors 14 and 17 specifically reduce low-density lipoprotein (LDL). These data indicate that proper structural modifications to the hypolipidemic and antioxidant morpholines enabling NO production, besides preserving or enhancing the above activities, offer a remarkable reduction of LDL, considered advantageous for antiatheromatic agents.

Simultaneous Derivatization and Quantification of the Nitric Oxide Metabolites Nitrite and Nitrate in Biological Fluids by Gas Chromatography/Mass Spectrometry

Simultaneous quantification of nitrite and nitrate, the major oxidative metabolites of L-arginine-derived nitric oxide (NO), in biological fluids by GC or GC/MS methods is currently impossible. The separate analysis of these anions is associated with severe methodological problems. Therefore, a GC/MS method was developed which allows, for the first time, simultaneous quantification of nitrite and nitrate in various biological fluids. The method involves a single derivatization procedure, by which endogenous nitrite and nitrate and their externally added 15N-labeled analogues are simultaneously converted in aqueous acetone by pentafluorobenzyl bromide to the nitro and nitric acid ester pentafluorobenzyl derivatives, respectively, and a single GC/MS analysis. Nitrite and nitrate concentrations measured in plasma and urine of humans by this method correlated excellently with those from quantification of nitrite and nitrate in these matrixes using a previously reported GC/MS method that, however, requires reduction of nitrate to nitrite. Also, the present method enables discrimination between S-nitro- and S-nitroso-glutathione, which have identical chromatographic and spectrophotometric properties. The method is very useful to routinely study metabolism and reactions of NO and its metabolites in vitro and in vivo. It is accurate, interference-free, sensitive-50 fmol of [15N]-nitrite and [15N]nitrate were detected at signal-to-noise ratios of 870:1 and 95:1, respectively-and should be a reference method for nitrite and nitrate measurements.

Determination of the kinetic data of the thermal decomposition of energetic plasticizers and binders by adiabatic self heating

The thermal decomposition behaviour of the following plasticizers and uncured binders (diols for PUR-type elastomer binders) was investigated in solutions of toluene (with 10 mass% contents) by adiabatic self heating with an `accelerating rate calorimeter' (ARC ™): uncured GAP (poly-glycidylazide) from two manufacturers, polyGLYN (poly-glycidylnitrate) mixture (58.8/41.2 in mass%) N-methyl-/ N-ethyl-NENA (NENA = N-(2-nitratoethyl)-nitramine), DANPE (1,5-diazido-3-nitraza-pentane), GAPA (short chain GAP but with azido end groups), EGBAA (ethylene glycol-bis-(α-azidoacetate), octylazide (not for use in explosives), GAP-AA-2000 (normal GAP, but OH-end groups as esters of α-azidoacetic acid), GAP-AA-500 (short chain GAP, but OH-end groups as esters of α-azidoacetic acid). Three types of energetic groups are represented with these compounds: the organic nitric acid ester group, the nitramine group and the organic azido group. The closed measuring system prevents the solutions from evaporating and gives a good adiabaticity. The amount of the solution weighed-in was about 6 g, the measuring cells used are made from titanium with one inch in diameter. All named energetic substances would deflagrate after a short period of controllable self heating with the weighed-in amount of energetic substance. The advantage of the investigation of the solutions is that the decomposition of the energetic substances can be followed in a fully controlled way. With the self heat rate curves one can distinguish the plasticizers and binders with respect to the decomposition temperature range, the heat generation and the heat generation rate. The Arrhenius parameters and the released heats of reaction have been determined from the self heat rate curves, which have been described well with reactions of first order. The self heat rate curves have been scaled to the thermal inertia equal to one, which corresponds to (1) the measurement on a solution without measuring cell and to (2) the measurement on the energetic substance alone without solvent and measuring cell. The procedures of the scaling and of the data evaluation are described.

Identification of alkyl dinitrates in ambient air of Central Europe

Bifunctional organic nitrates – organic esters of nitric acid – are part of the pool of components of odd nitrogen (NOY) in the atmosphere. In this paper, we report the identification of dinitrates in ambient air of Central Europe (Ulm, Germany). The organic nitrates were sampled by adsorptive high volume sampling of 100 m3 of air with 100 g precleaned silica. Sample preparation and group separation was performed by NP-HPLC. Separation and detection was done by HRGC/EI-MSD. We have extended the identification of dinitrates in ambient air to a number of 30, of which only five have been reported by other authors before. To our knowledge, this is the first time that 13 non-vicinal dinitrates and two branched dinitrates have been identified in ambient air. Four organic nitrates have never been reported before: the non-vicinal 1,3-dinitrooxy-pentane (1,3C5), the two branched 2-methyl-1,2-dinitrooxy-propane (2M1,2C3) and 2-methyl-2,3-dinitrooxy-butane (2M2,3C4), and one diastereomer of 3,4-dinitrooxy-hexane (RR/SS-3,4C6). We are also assigning the configuration of the two diastereomers of 2,4-dinitrooxy-pentane (2,4C5) found in air before using reference standards obtained by enantioselective synthesis.

The nitric oxide donor SIN-1 is free of tolerance and maintains its cyclic GMP stimulatory potency in nitrate-tolerant LLC-PK1 cells.

Using an established cell culture model, the present study investigates whether linsidomine (SIN-1), a spontaneous donor of nitric oxide and active metabolite of the antianginal drug molsidomine, induces tolerance to its own cyclic GMP stimulatory action or shows a diminished response after tolerance induction with glyceryl trinitrate. Incubations with nitric oxide donors were carried out in LLC-PK1 kidney epithelial cells. Intracellular levels of cyclic GMP, the vasodilatory second messenger of nitric oxide, were determined by radioimmunoassay. A 5-h preincubation with glyceryl trinitrate (0.01-100 microM) led to complete inhibition of a subsequent cyclic GMP stimulation by glyceryl trinitrate but left the cyclic GMP response to SIN-1 unaltered. Similarly, cyclic GMP elevations by the spontaneous nitric oxide donors sodium nitroprusside and spermine NONOate were not affected after pretreatment with glyceryl trinitrate. Moreover, pretreatment with SIN-1 (1-1000 microM) had no significant effect on SIN-1-dependent cyclic GMP stimulation. Our results show that in LLC-PK1 cells, SIN-1 is free of tolerance induction and not cross-tolerant to glyceryl trinitrate. This may be due to the spontaneous nitric oxide release from SIN-1, which in contrast to nitric acid esters does not require enzymatic bioactivation and may therefore be unaffected by nitrate tolerance.

Nitrate Tolerance Is Specific for Nitric Acid Esters and Its Recovery Requires an Intact Protein Synthesis

Using cultured LLC-PK1cells the present study investigates mechanisms leading to nitrate tolerance and its reversal. A 5-h pretreatment with glyceryl trinitrate (GTN, 0.01-100 μM) resulted in desensitization of the intracellular cyclic GMP response to a subsequent 10-min challenge with GTN (1 μM). The spontaneous donor of nitric oxide (NO) spermine NONOate, which releases NO independently of enzymatic catalysis, did not induce tolerance to its own cyclic GMP stimulatory effect and remained fully effective in GTN-tolerant cells. Tolerant cells regained sensitivity to GTN after a 30-h incubation in media. Recovery of the cyclic GMP response was blocked in the presence of cycloheximide (10 μM) suggesting that de novo protein synthesis is necessary for tolerance reversal. Our results demonstrate that nitrate tolerance is specific for nitric acid esters and possibly due to down-regulation of enzymes involved in bioactivation of, and NO generation from, organic nitrates.