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International audience; Investigating the possibility of a straightforward formation of tetrazoline or tetrazolidine structures, the reactivity of a tetrazole derivative towards reducing conditions has been studied. The catalytic hydrogenation of 1,1’-dimethylbistetrazole (DMBT) was carried out using various catalysts (Pd/C, Pt/C, Rh/C, Pd/Pt/C, Lindlar, PtO2 and Raney Ni) over a wide range of hydrogen pressure (35–150 bar) and a temperature range from 20 to 60 °C. This exhaustive study enabled to find the optimal conditions for DMBT hydrogenation and to suggest a plausible reaction mechanism. The chemical reduction of DMBT was conducted using several hydrides (BH3, NaBH4, DIBAL and LiAlH4). The reduction products were identified subsequently to conditions optimizing. The suggested reaction mechanism, featuring a retro-[3 + 2]-cycloaddition, was validated by both experimental and theoretical approaches.

In this paper, we describe a new strategy developed for the synthesis of MMH using the Raschig process. For the first time, it consists in synthesizing chloramine under stoichiometric conditions which leads to a more economical process because it avoids the additional steps of extraction due to the presence of excess reagents. However, monochloramine is not very stable and, therefore, it is necessary to study its stability. The various batch tests show that the reaction must be strictly controlled. As shown from DSC analyses on stoichiometric chloramine solutions, a risk of decomposition is present from 36 °C. Thus, controlling the temperature rise requires efficient cooling in the synthesis reactor or synthesis at low temperature, in order to avoid any sudden decomposition of the synthesis solution.

International audience; A new strategy for the development of monomethylhydrazine (MMH) using the Raschig process is discussed in this publication. The determination of optimal conditions for the synthesis of MMH required the development of a kinetic model. In order to validate the results of the calculation, a device for synthesis under pressure (13 bar) by direct injection of the stoichiometric monochloramine, synthesized using microreactor technology, into monomethylamine (MMA) was developed. The experimental data, in accordance with the theoretical results of the kinetic model, make it possible to establish a new process for the synthesis of monomethylhydrazine.

After having established in a previous paper that the synthesis of stoichiometric monochloramine is hazardous due to the high exothermicity of the reaction and the risk of decomposition of the solution from 36 °C, it appeared that the best solution for this synthesis is to use microreactor technology. A series of experiments carried out using a Doehlert experimental design provided access to a mathematical model describing, for an initial fixed composition ratio [NH4+]0/[OCl−]0, the evolution of the yield as a function of temperature, the flow rate of the reagents and the number of sodium hydroxide equivalent. Thus, the optimal conditions for the synthesis of stoichiometric chloramine using microreactor technology were established.

The catalytic hydrogenation of both 1 and 2-pyrazoline was studied in order to obtain the pyrazolidine. Among the studied catalysts, the Pd/C type catalyst permitted to hydrogenate the 1-pyrazoline but did not hydrogenate 2-pyrazoline. A slow hydrogenation of 2-pyrazoline occurred with a Pt/C and a mixed Pd/Pt/C catalyst. We demonstrated that catalyst poisoning occurred, which is due to the presence of the NH link of the 2-pyrazoline, blocking the active centers of the catalyst. At least, the Rh/C catalyst permitted to hydrogenate the mixture of 1 and 2-pyrazolines with a quantitative yield. The experiments showed that it was possible to reduce the reaction time by using catalysts having different specific areas. The Raney nickel catalyst also gave good results but its use requires much more precautions. Two process schemes were then established, taking into account both the synthesis of the 1 and 2-pyrazolines and their hydrogenation.

Another route to obtain pyrazolidine was developed. It consists of a three step mechanism, which involves, first, the sequential formation of N,N′-dichloro-1,3-diaminopropane starting from 1,3-diaminopropane and sodium hypochlorite, second, a dehydrohalogenation of the dichloro derivative leading to 1-pyrazoline and 2-pyrazoline and finally, the hydrogenation of these two derivatives in order to obtain the compound of interest. In this paper, our study was focused on the kinetics of the formation of 1-pyrazoline and 2-pyrazoline. A kinetic model was proposed and then validated by experimental results. A quantum calculation (Gaussian09/CBS-QB3) was performed in order to determine the stability of the 1 and 2-pyrazolines. It showed that the 2-pyrazoline is more stable than the 1-pyrazoline. This process has been validated on the ISOCHEM production site.

The present study describes a new way of preparing pyrazolidine by intramolecular Raschig amination using 1,3-diaminopropane and sodium hypochlorite. A global process has been developed, involving the characterization of the reaction mechanisms, kinetic studies and the optimization of the synthesis parameters. The rates were determined as a function of the reagent concentrations, pH and temperature. The overall reaction, of the first order with respect to both reagents, is the result of two successive mechanisms: the first being pH independent, the second accelerated by increasing pH. The bimolecular rate was simulated as a function of hydroxide ion activity. The activation enthalpy and entropy of the molecular process were established at 25 °C. A kinetic model is proposed and then validated by the experimental results. Finally, it was found that the yield of pyrazolidine essentially depends on the ratio p ([1,3-diaminopropane]0/[sodium hypochlorite]0) of the initial molar concentrations and the ratio of the rates k2/k1 (k1: rate of the N,N-dichloro-1,3-diaminopropane formation and k2: rate of N-chloro-1,3 diaminopropane formation).

1,1,4,4-Tetramethyl-2-tetrazene (TMTZ) is considered as a prospective replacement for toxic hydrazines used in liquid rocket propulsion. The heat of formation of TMTZ was computed and measured, giving values well above those of the hydrazines commonly used in propulsion. This led to a predicted maximum Isp of 337 s for TMTZ/N2 O4 mixtures, which is a value comparable to that of monomethylhydrazine. We found that TMTZ has a vapor pressure well below that of liquid hydrazines, and it is far less toxic. Finally, an improved synthesis is proposed, which is compatible with existing industrial production facilities after minor changes. TMTZ is thus an attractive liquid propellant candidate, with a performance comparable to hydrazines but a lower vapor pressure and toxicity.

This report is a summary of our work on energetic materials. Herein, triazole-, tetrazole-, 2-tetrazene- and hydrazine-based energetic compounds are described. An overview of the synthetic methods and of the problematic around the quest of new explosives is given. Hydrogen-bonding formation and alkylation (methylation) reactions were studied as a mean to decrease the sensitivities towards classical stimuli and increase their thermal and chemical stability. 15N NMR spectroscopy is a valuable tool for the assignment of the methylation site in keeping with the results of the crystal structure analysis. Lastly, the thermal/chemical stability, sensitivity data and energetic performance of the compounds is described.

N-aminopiperidine (NAPP) belongs to a large family of compounds, namely the cyclic alkylhydrazines, used as precursors for different targets in fine chemicals, such as pharmaceuticals and cosmetics. The formation of NAPP via the Raschig process by reacting piperidine (C5H10NH, PP) with monochloramine (NH2Cl) involves many side-reactions because of the reactivity of the latter. An exhaustive kinetic model, which reflects the rate of NAPP formation and that of side-reactions occurring during the synthesis of NAPP, was established. Additionally, a comparative study of theoretical and experimental concentration-time curves permitted to verify the accuracy of the model in a diluted medium. Moreover, the established kinetic model allowed to define the optimal conditions for NAPP synthesis in a concentrated medium, by varying the reactants concentrations, [PP]/[NH2Cl] ratio, pH and temperature. Hence, the application of the kinetic model enabled to optimize the reaction in view of its transfer to a continuous process.

Formation of N-aminopiperidine (NAPP) in the reaction of monochloramine with piperidine was studied by varying the reagents concentrations, pH and temperature. The study was carried out in diluted solutions, recording simultaneously monochloramine concentration by UV spectrophotometry at 243 nm and hydrazine concentration at 237 nm after treatment with formaldehyde. The presence of two competitive reactions: formation of NAPP and a complex parallel reaction limiting the yield of hydrazine, was established. Reaction products were characterized by GC/MS analysis. The rate constant of NAPP formation and activation parameters were determined, k 1 = 56 × 10−3 M−1 s−1 (25°C) and k 1 = 9.3 × 106 exp(−46.5/RT) M−1 s−1, respectively.

This study relates to a determination of liquid–liquid ternary system water–sodium hydroxide-1,3-diaminopropane to optimize the conditions of the isolation of hydrazine by liquid–liquid extraction, generated by the addition of solid sodium hydroxide. Three isotherms were established at 293, 313, and 323 K by Isoplethic Thermal Analysis, method developed in our laboratory and consists of the evolution of one or more physical properties of the system when its composition is modifying, and chemical titrations. The coordinates of the critical point were determined using the diameter method.

A new strategy for the synthesis of N-aminopiperidine (NAPP) was developed using hydroxylamine-O-sulfonic acid (HOSA). A systematic study of NAPP formation and degradation reactions was carried out in diluted medium, in order to identify products and to establish a kinetic modelling. Principal parameters have been defined, in particular, that obtaining high yields (>90%) requires non stoichiometric conditions. The extraction and purification processes were also studied. NAPP isolation and piperidine recycling were optimized after the establishment of the various solid-liquid-liquid and liquid-vapour implied phase diagrams. At least, a calorimetric study of solvatation and reaction enthalpies was undertaken in order to estimate reactor heating temperature in the case of anhydrous synthesis. The combination of our kinetic, thermodynamic and calorimetric data allows the establishment of two process schemes: one using pure piperidine, the other, a 66 w% titrating azeotropic solution in piperidine.

This work involves the study of the solid/liquid equilibrium in the NaCl–NaOH–H2O ternary system. The aim is to optimize the operating conditions of an evaporator–crystallizer used in a hydrazine extraction process. The latter is conducted at industrial scale using the Raschig method, a general method for preparing hydrazines for aerospace and pharmaceutical applications. The extraction process includes the use of a Kestner type evaporator–crystallizer to first isolate hydrazine and water by evaporation and then separate two salts: sodium hydroxide, recovered as an aqueous solution, and sodium chloride which crystallizes. However, problems related to the co-precipitation of NaCl–NaOH may be encountered in industry, leading to the clogging of installations. Therefore, it is necessary to ensure that only NaCl crystallizes while maintaining NaOH in liquid state. Knowledge of the equilibrium phases of the NaCl–NaOH–H2O ternary system is thus required, particularly the liquid/solid phase. Phase equilibrium experiments were performed by isoplethic thermal analysis (ITA) and chemical titrations over the temperature range of 313 to 353 K at atmospheric pressure. ITA is an isobaric and isothermal method developed in our laboratory and based on the measurement of the thermal effects associated with transformations in a system (appearance or disappearance of a phase) when its composition is changed. The NaCl crystallization domain was fully determined and the operating parameters of the device were defined precisely as a function of temperature and composition of the Kestner loop.

1,1,1-Trimethylhydrazinium iodide ([(CH(3))(3)N-NH(2)]I, 1) was reacted with a silver salt to form the corresponding nitrate ([(CH(3))(3)N-NH(2)][NO(3)], 2), perchlorate ([(CH(3))(3)N-NH(2)][ClO(4)], 3), azide ([(CH(3))(3)N-NH(2)][N(3)], 4), 5-amino-1H-tetrazolate ([(CH(3))(3)N-NH(2)][H(2)N-CN(4)], 5), and sulfate ([(CH(3))(3)N-NH(2)](2)[SO(4)]·2H(2)O, 6·2H(2)O) salts. The metathesis reaction of compound 6·2H(2)O with barium salts led to the formation of the corresponding picrate ([(CH(3))(3)N-NH(2)][(NO(2))(3)Ph-O], 7), dinitramide ([(CH(3))(3)N-NH(2)][N(NO(2))(2)], 8), 5-nitrotetrazolate ([(CH(3))(3)N-NH(2)][O(2)N-CN(4)], 9), and nitroformiate ([(CH(3))(3)N-NH(2)][C(NO(2))(3)], 10) salts. Compounds 1-10 were characterized by elemental analysis, mass spectrometry, infrared/Raman spectroscopy, and multinuclear NMR spectroscopy ((1)H, (13)C, and (15)N). Additionally, compounds 1, 6, and 7 were also characterized by low-temperature X-ray diffraction techniques (XRD). Ba(NH(4))(NT)(3) (NT=5-nitrotetrazole anion) was accidentally obtained during the synthesis of the 5-nitrotetrazole salt 9 and was also characterized by low-temperature XRD. Furthermore, the structure of the [(CH(3))(3)N-NH(2)](+) cation was optimized using the B3LYP method and used to calculate its vibrational frequencies, NBO charges, and electronic energy. Differential scanning calorimetry (DSC) was used to assess the thermal stabilities of salts 2-5 and 7-10, and the sensitivities of the materials towards classical stimuli were estimated by submitting the compounds to standard (BAM) tests. Lastly, we computed the performance parameters (detonation pressures/velocities and specific impulses) and the decomposition gases of compounds 2-5 and 7-10 and those of their oxygen-balanced mixtures with an oxidizer.

Oxidation of 1,1-dimethylhydrazine leads to the formation of (E)-1,1,4,4-tetramethyl-2-tetrazene (1). Compound 1 undergoes oxidative addition with chloramine (Cl–NH2) to form the (E)-1-aminomethylidene-1,4,4-trimethyl-2-tetrazenium cation (TAT+) as its chloride salt 2. Metathesis reactions of salt 2 with energetic anion-transfer reagents lead to the formation of ionic compounds based on the TAT+ cation and the following anions: nitrate 3, perchlorate 4, 5,5′-azobis(tetrazolate) 5·6H2O, picrate 6, and azide 7. The water of crystallization in compound 5·6H2O can be removed to form the anhydrous material 5. All compounds were characterized by analytical and spectroscopic methods, and the solid-state structures of salts 2, 3, 4, 5·6H2O, and 6 were determined by low-temperature X-ray crystallography. We used preliminary energetic testing to gain insight into the sensitivities of the materials towards impact and friction and we assessed their thermal stability by differential scanning calorimetry (DSC) measurements. Additionally, the heats of formation of the energetic compounds were computed by using quantum mechanical methods (CBS-4M) and these values were used to determine some performance parameters of interest for the pure compounds and for their formulations with an oxidizer. Lastly, we calculated the expected decomposition gases of the pure compounds as well as those of the mixtures with an oxidizer.

1,1-Dimethylhydrazine can be readily alkylated with bromoacetonitrile to form 1-cyanomethyl-1,1-dimethylhydrazinium bromide ([(CH(3))(2)N(CH(2)CN)NH(2)]Br, 1). The metathesis reaction of compound 1 led to the formation of a new family of energetic salts based on the [(CH(3))(2)N(CH(2)CN)NH(2)](+) cation and nitrate (2), perchlorate (3), azide (4), 5-aminotetrazolate ([H(2)N-CN(4)](-), 5), 5,5'-azobistetrazolate ([N(4)C-N=N-CN(4)](2-), 7), and picrate (8) anions. The new materials were characterized by elemental analysis, mass spectrometry, and (multinuclear) NMR and vibrational (infrared and Raman) spectroscopies. Additionally, the molecular structure of the [(CH(3))(2)N(CH(2)CN)NH(2)](+) cation in compounds 1, 3, and 8 and that of sodium 5,5'-azobistetrazolate octahydrate (NaZT·8H(2)O) were solved by X-ray diffraction techniques. The hydrogen-bonding networks found in the structure of salts 1, 3, 8, and NaZT·8H(2)O are described using graph-set analysis. The melting and decomposition points of the new compounds were determined by differential scanning calorimetry, and insight into their sensitivity towards impact, friction, and electrostatics was gained by submitting the materials to standard tests. Furthermore, we estimated some performance parameters of interest and predicted the decomposition gases formed upon decomposition of salts 2-8 and of mixtures with an oxidizer. The interesting thermal, sensitivity, and performance properties of some of the compounds described in this work make them attractive towards a prospective energetic application.

A new route to synthesize N-aminopiperidine (NAPP) from hydroxylamine-O-sulfonique acid (HOSA) and piperidine was described. Kinetics of the reaction was investigated to optimize the conditions of the synthesis. Since the reaction is fast, this study was carried out in a diluted medium (10−3 to 10−2 mol/l). To determine the concentration of the reaction product, NAPP was allowed to react with formaldehyde and the product was analysed by UV and HPLC techniques. The formation of NAPP is consistent with the first-order reaction to two reagents, governed by the nucleophilic substitution via SN2 mechanism. Oxidation of NAPP by HOSA was identified as the main secondary reaction which consistently reduced the yield of NAPP. A number of differential equations were elaborated and solution of these equations serves to predict the behavior of the system as a function of the reagent concentrations, pH and temperature. From the corresponding mathematical treatment a unique implicit expression was derived that characterizes the reaction medium. It was found that the [PP]0/[HOSA]0 molar ratio (p), the initial concentrations of [PP]0 and [HOSA]0, the ratio of rate constants k 2/k 1 and temperature are the only parameters that affect the yield of NAPP from HOSA. The results calculated from this model are in good agreement with the experimental data and they can be used to determine the optimal conditions of the reaction.

N,N′-Dimethylhydrazine and several of its salts with energetic anions were synthesized and fully characterized by elemental analysis, DSC, mass spectrometry, multinuclear NMR (1H, 13C, and 15N) spectroscopy, and vibrational (Raman, IR) spectroscopy. According to the DSC measurements, the compounds exhibit good thermal stabilities, and the nitrate (2) and dicyanamide (4) salts belong to the ionic-liquid type (i.e., Tm < 100 °C). Additionally, the solid-state crystal structure of the nitrate [2: triclinic, P, a = 5.360(2) A, b = 5.806(2) A, c = 6.866(2) A, α = 113.73(2)°, β = 92.44(2)°, γ = 90.08(2)°, V = 195.4(1) A3], perchlorate [3: orthorhombic, Pbca, a = 11.774(2) A, b = 11.072(3) A, c = 14.050(3) A, V = 1831.6(7) A3], sulfate [5: monoclinic, P21/n, a = 5.913(1) A, b = 9.509(1) A, c = 10.351(1) A, β = 90.29(1)°, V = 582.0(1) A3], monopicrate [6b: monoclinic, P21/c, a = 10.910(1) A, b = 6.7436(1) A, c = 16.442(2) A, β = 103.40(1)°, V = 1176.7(2) A3], and dipicrate dihydrate [6·2H2O: monoclinic, P21/n, a = 8.230(1) A, b = 13.024(1) A, c = 10.642(1) A, β = 104.43(1)°, V = 1104.7(2) A3] salts were determined. Furthermore, a natural bond orbital (NBO) analysis of the structure of the [MeNH2–NH2Me]2+ cation was performed. Standard tests were used to examine the sensitivity of the compounds towards impact, friction, and electrostatic discharge. Lastly, the heats of formation of the compounds were calculated by means of quantum chemical calculations and used to determine the detonation parameters and specific impulses of the compounds and those of mixtures with an oxidizer.

Sodium and potassium methyl(nitroso)amide (M[CH3N2O], M = Na (1), K (2)) were prepared by the reaction of monomethylhydrazine with iso-pentyl nitrite or n-butyl nitrite and a suitable metal ethoxide (M[CH3CH2O], M = Na, K) in an ethanol-ether mixture. The reaction of monomethylhydrazine with a small excess of iso-pentyl nitrite or n-butyl nitrite and in the absence of a metal ethoxide led to the formation of N-nitroso-N-methylhydrazine (CH3(NO)N–NH2, (3)). Alternatively, compound 3 was prepared by the amination reaction of 1 or 2 using the sodium salt of HOSA in ethanol solution. Compounds 1–3 were characterized using elemental analysis, differential scanning calorimetry, mass spectrometry, vibrational (infrared and Raman) and UV spectroscopy and multinuclear (1H, 13C and 15N) NMR spectroscopy. For compounds 1–3, several physical and chemical properties of interest and sensitivity data were measured and for compound 3 thermodynamic and explosive properties are also given. Additionally, the solid-state structure of compound 3 was determined by single-crystal X-ray analysis and the structures of the cis- and trans-[CH3N2O]– anions and that of 3 were optimized using DFT calculations and used to calculate the NBO charges.

1-Isopropylidene-2-methylhydrazine (1), 1-isopropylidene-2-hydroxyethylhydrazine (2) and 1-isopropylidene-2-formylhydrazine (3) were synthesized by reaction of the corresponding hydrazine with an excess of acetone in the presence of a drying agent (anhydrous sodium sulfate or barium oxide). All compounds 1–3 were characterized by elemental analysis, coupled gas chromatography-mass spectrometry (GC–MS), multinuclear NMR spectroscopy (1H, 13C and 15N) and vibrational spectroscopy (infrared and Raman). Compounds 1 and 2 are liquid at room conditions and their density was measured by means of a picnometer, however, (at room conditions) compound 3 is a solid and its crystal density and structure were determined by low temperature X-ray diffraction techniques (monoclinic, P21/n, Z = 4, a = 5.666(1) A, b = 6.254(1) A, c = 15.277(4) A, β = 91.30(2)°, V = 541.2(2) A3). The structure of hydrazone 3 is discussed in detail and compared to that of monoformylhydrazine. Finally, the (gas phase) structure of compound 3 was optimized using DFT calculations (B3LYP/6-31+G(d, p)) and its NBO charges are reported.

(1E,2E)-2,2′-dipyridylglyoxime (1) was synthesized by a literature method involving the reaction of 2,2′-pyridyl with an excess of hydroxylammonium chloride and sodium hydroxide in distilled water. 1 was characterized by elemental analysis, melting point, mass spectrometry, and NMR (1H and 13C) spectroscopy. In addition, the crystal structure of 1 was determined by low temperature X-ray analysis. 1 crystallizes in the monoclinic space group P21/n with four formula units in the unit cell and the following unit cell parameters: a = 6.269(1) A, b = 10.258(1) A, c = 9.132(1) A, β = 107.59(1)°, and V = 559.7(1) A3. Strong OċN hydrogen bonds link the molecules of 1, forming three-dimensional hydrogen-bonded networks; whereas the unclassical CċO hydrogen bonds result in the formation of C1,1(9) and C2,2(18) infinite chains and dimmer pairs with the graph-set descriptor R2,2(16). Lastly, the structure of 1 was fully optimized using DFT calculations (B3LYP/6-31+G(d,p)) and the NBO and Mulliken charges were calculated at the same level of theory. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 23:59–65, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20752

The Raschig synthesis of hydroxyethylhydrazine (HEH) is studied, that is, the reaction of monochloramine on ethanolamine. The formation of HEH is monitored by UV spectrometry, and the influence of temperature and pH is studied. The primary reaction is an SN2-type mechanism, whereas the main secondary reaction is the oxidation of HEH by monochloramine. This reaction is also monitored by UV spectrometry, and the oxidation product is identified by GC–MS analysis, showing the formation of hydroxyethylhydrazone. The reaction mechanisms and the rate constants were determined, and the results permit establishing the main reactions occurring during HEH synthesis. These reactions were validated in a concentrated medium, with the systematic study of the influence of the molar ratio p ([HEH]0/[NH2Cl]0) and the final sodium hydroxide concentration and temperature. A comparison is made with the other synthesis process already published, that is, the alkylation of hydrazine by either chloroethanol or epoxide. © 2011 Wiley Peiodicals, Inc. Int J Chem Kinet 43: 331–344, 2011

The reduction of N-chloro-3-azabicyclo[3.3.0]octane with sodium borohydride at different pH values and variable concentrations of the haloamine and reducing agent was studied. The reaction was found to be second order and exhibited a specific acid catalysis. The enthalpy and entropy of activation were determined at pH 12.89. A mathematical treatment of the kinetic data allowed a complete characterization of the final state and the determination of percentage of haloamine reduced as a function of temperature, [NaBH4]/[haloamine] ratio, arid pH. A reaction mechanism is proposed.

The study deals with the direct oxidation kinetics of micronic cobalt metal particles and its simulation for the complete transition from metal to ceramic. The simulation was also experimentally verified. All the three possible interfaces, Co/CoO, CoO/Co3O4 and Co3O4/O2 (air), have been taken into consideration for the simulation. The complete oxidation kinetics has been investigated from the thermogravimetric studies under isothermal conditions in the temperatures 973–1173 K. A quantitative interpretation based on the diffusion of Co or oxygen ions through the grown oxide layer has been proposed. The activation energy for the oxidation kinetics calculated from the Arrhenius law was 161 ± 20 kJ mol−1.

Three isothermal sections of the isobaric ternary system H2O–NaOH–C5H10NH were determined by Isoplethic Thermal Analysis at 293, 313, and 323 K. Miscibility gaps were completely delimited and each critical point was calculated. This system is then characterized by a prevalent miscibility gap, three crystallization domains and two triphasic invariant domains. The relevant exploitation of this diagram so permits us to deduce the demixing temperature leading to the optimal transfer of the organic compounds in the light phase and also the composition of the organic phase recovered after this second step of extraction. Moreover, the addition of calculated quantities of sodium hydroxide aqueous solution allows to be in optimized conditions for the next distillation operations.

International audience; The study deals with the direct-oxidation kinetics of micronic-cobalt metal particles and its simulation for the complete transition from metal to ceramic. The simulation was also experimentally verified. All the three possible interfaces, Co/CoO, CoO/Co3O4 and Co3O4/O2 (air), have been taken into consideration for the simulation. The complete oxidation kinetics has been investigated from the thermogravimetric studies under isothermal conditions in the temperatures 973–1173 K. A quantitative interpretation based on the diffusion of Co or oxygen ions through the grown oxide layer has been proposed. The activation energy for the oxidation kinetics calculated from the Arrhenius law was 161 ± 20 kJ mol−1.

The oxidation of methylhydrazine (monomethylhydrazine MMH) is studied in a strictly single-phase gaseous medium, in a reconstituted surrounding atmosphere. In order to work under such conditions, a specific apparatus was assembled to monitor the evolution of the reactants through time. The reaction kinetics was studied at 50°C to avoid condensation of the water formed and for O2/MMH mole ratios between 1 and 4. Under these conditions, the partial pressures of O2 were between 0.05 and 0.18 bar (4% MMH per volume). The main reaction products were monitored through time and identified by gas chromatography coupled with mass spectrometry (GC/MS). The products were: N2, CH4, CH3-NH-N=CH2 (formaldehyde monomethylhydrazone), NH3, H2O, CH3OH, and CH2=N-N=N-CH3 (2,3,4-triazapenta-1,3-diene). The formation of nitrosamines was not observed under these experimental conditions. The rate laws related to the disappearance of the reagents were clearly established and can be described by 2 consecutive parallel reactions of order 2 whose rate constants are: k1 = 7.57 × 10−2 bar−1 min−1 and k2 = 0.5 bar−1 min−1. Analysis of the products permitted establishing an approximated balance of the global reaction.

To optimize yields, the study of reaction kinetics related to the synthesis of 2-hydroxyethylhydrazine (HEH) obtained from the alkylation of N2H4 by 2-chloroethanol (CletOH) was carried out with and without sodium hydroxide. In both cases, the main reaction of HEH formation was followed by a consecutive, parallel reaction of HEH alkylation (or dialkylation of N2H4), leading to the formation of two isomers: 1,1-di(hydroxyethyl)hydrazine and 1,2-di(hydroxyethyl)hydrazine. In this study, hydrazine and hydroxyalkylhydrazine alkylations followed SN2 reactions triggered directly by CletOH or indirectly in the presence of a strong base by ethylene oxide, an intermediate compound. The kinetics was studied in diluted mediums by quantifying HEH and CletOH by gas chromatography and gas chromatography coupled with mass spectrometry (GC-MS). The activation parameters of each reaction and the influence of a strong base present in the medium on the reaction mechanisms were established. A global mathematical treatment was applied for each alternative. It allowed modeling the reactions as a function of reagent concentrations and temperature. In the case of direct alkylation by CletOH, simulation was established for semi-batch and batch syntheses and was confirmed in experiments for concentrated mediums (1.0 M ≤ [CletOH]0 ≤ 3.2 M and 15.7 M ≤ [N2H4]0 ≤ 18.8 M). Simulation therefore permits the prediction of the instantaneous concentration of reagents and products, in particular ethylene oxide concentration in the case of indirect alkylation, which must be as weak as possible. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 382–393, 2009

International audience; The kinetics of the oxidation of N-aminopiperidine with chloramine was studied at different temperatures, with variable concentrations of the two reactants and at a pH ranging between 12 and 13.5. The reaction showed to be involving two steps: the first corresponded to the formation of a diazene intermediate, the second to the evolution of this intermediate into numerous compounds within a complex reactional chain. The rate law of the first step was determined by the Ostwald method and found to be first order with respect to each reactant. The rate constant was determined at pH = 12.89 and T = 25°C: k2 = 1.15  105 exp(-39/RT) M-1 s-1 (E2 in kJ mol-1) With decreasing pH value, the first step exhibited acid catalysis phenomena, and diazene was converted into azopiperidine particularly faster. This created overlapping UV-absorptions between chloramine and azopiperidine, also observed in HPLC. GC/MS analyses were used to identify some of the numerous by-products formed. Their proportions are dependent of both pH and the reactants' concentrations ratio. A reaction mechanism taking this relationship into account, was suggested.

by Chaza Darwich*a), Mazen Elkhatibb), Georg Steinhauserc), and Henri Delalua) a) Laboratoire Hydrazines et Procedes, UMR 5179 UCBL-CNRS-ISOCHEM (groupe SNPE), Universite Claude Bernard Lyon 1, Bâtiment Berthollet, 22 Avenue Gaston Berger, F-69622 Villeurbanne Cedex (phone: þ 33-4-72431410; fax: þ 33-4-72431291; e-mail: chaza.darwich@univ-lyon1.fr) b) Laboratory of Applied Chemistry and Toxicology, Faculty of Sciences, Section 3, Department of Chemistry, P. O. Box 826, Tripoli, Lebanon c) Vienna University of Technology, Atominstitut der sterreichischen Universit ten, Stadionallee 2, A-1020 Vienna

After an exhaustive study of the system ammonia–dimethylchloramine in liquid ammonia, it was interesting to compare the reactivity of this system in liquid ammonia with the same system in an aqueous medium. Dimethylchloramine prepared in a pure state undergoes dehydrohalogenation in an alkaline medium: the principal products formed are N-methylmethanimine, 1,3,5-trimethylhexahydrotriazine, formaldehyde, and methylamine. The kinetics of this reaction was studied by UV, GC, and HPLC as a function of temperature, initial concentrations of sodium hydroxide, and chlorinated derivative. The reaction is of the second order and obeys an E2 mechanism (k1 = 4.2 × 10−5 M−1 s−1, ΔH○# = 82 kJ mol−1, ΔS○# = −59 J mol−1 K−1). The oxidation of unsymmetrical dimethylhydrazine by dimethylchloramine involves two consecutive processes. The first step follows a first-order law with respect to haloamine and hydrazine, leading to the formation of an aminonitrene intermediate (k2 = 150 × 10−5 M−1 s−1). The second step corresponds to the conversion of aminonitrene into formaldehyde dimethylhydrazone at pH 13). This reaction follows a first-order law (k3 = 23.5 × 10−5 s−1). The dimethylchloramine–ammonia interaction corresponds to a SN2 bimolecular mechanism (k4 = 0.9 × 10−5 M−1 s−1, pH 13, and T = 25°C). The kinetic model formulated on the basis of the above reactions shows that the formation of the hydrazine in an aqueous medium comes under strong competition from the dehydrohalogenation of dimethylchloramine and the oxidation of the hydrazine formed by the original chlorinated derivative. A global model that explains the mechanisms both in an anhydrous and in an aqueous medium was elaborated. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 340–351, 2008

International audience; The use of ab initio and DFT methods to calculate the enthalpies of formation of solid ionic compounds is described. The results obtained from the calculations are then compared with those from experimental measurements on nitrogen-rich salts of the 2,2-dimethyltriazanium cation (DMTZ) synthesized in our laboratory and on other nitrogen-rich ionic compounds. The importance of calculating accurate volumes and lattice enthalpies for the determination of heats of formation is also discussed. Furthermore, the crystal structure and hydrogen-bonding networks of the nitroformate salt of the DMTZ cation is described in detail. Lastly, the theoretical heats of formation were used to calculate the specific impulses (I-sp) of the salts of the DMTZ cation in view of a prospective application in propellant formulations.

Amination of 1,1-dimethylhydrazine with NH2 Cl or hydroxylamine-O-sulfonic acid yields 2,2-dimethyltriazanium (DMTZ) chloride (3) and sulphate (4), respectively. The DMTZ cation was paired with the nitrogen-rich anions 5-aminotetrazolate (5), 5-nitrotetrazolate (6), 5,5'-azobistetrazolate (7), and azide (8), yielding a new family of energetic salts. The synthesis was carried out by metathesis reactions of salts 3 or 4 and a suitable silver or barium salt. To minimize the risks involved when using heavy metal salts, we used electrodialysis for the synthesis of azide 8, which avoids the use of highly sensitive species. The DMTZ derivatives were characterized by IR and multinuclear NMR spectroscopy, elemental analysis, and X-ray diffraction. Thermal stabilities were measured using DSC analysis and their sensitivities towards classical stimuli were determined using standard tests. Lastly, the relationship between hydrogen bonding in the solid state and sensitivity is discussed.

(E)-1,1,4,4-tetramethyl-2-tetrazene (TMTZ) is formed from the oxidation of the unsymmetrical 1,1-dimethylhydrazine (UDMH) and is used as a storable liquid fuel which can be considered as a new potential propellant for space rocket propulsion. To better understand the toxicological behavior of the compound, an intraperitoneal administration of TMTZ was performed in mice to define its toxicokinetics and tissue distribution. A fully validated liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) assay was developed to determine TMTZ levels in biological samples. Determination of TMTZ was achieved using 50 μL of plasma or tissue solution. Precipitation with ammonium sulfate and acetonitrile was used for sample preparation. Liquid chromatography was performed on an Atlantis HILIC Silica column (Waters; 3 μm, 150 mm × 2.1 mm i.d.). Isocratic elution with a mixture of ammonium acetate buffer (pH 5, 100 mM)/water/acetonitrile (3:2:95, v/v/v) was used. The detection was conducted using an electrospray source in positive ion mode. TMTZ and (15)N2-TMTZ (internal standard) were quantitated in selected reaction monitoring mode using the transition m/z 117→72 and 119→74, respectively. Standard curves exhibited excellent linearity in the range of 10-500 ng/mL for plasma and 50-2000 ng/mL for all tissues (heart, liver, brain, kidney, and lung) analyzed, and acceptable precision and accuracy (

The rate of the oxidation of N-amino-3-azabicyclo[3.3.0]octane by chloramine has been studied by GC and HPLC between pH 10.5 and 13.5. The second-order reaction exhibits specific acid catalysis. The formation of N,N′-azo-3-azabicyclo[3.3.0]octane or 3,4-diazabicyclo[4.3.0]non-2-ene is pH, concentration, and temperature dependent. In alkaline media, the exclusive formation of 3,4-diazabicyclo[4.3.0]non-2-ene is observed. Kinetic studies show that the oxidation of N-amino-3-azabicyclo[3.3.0]octane by chloramine is a multistep process with the initial formation of a diazene-type intermediate, which is converted by hydroxide ions into 3,4-diazabicyclo[4.3.0]non-2-ene. Because it was not possible to follow the rate of change of the intermediate concentration, to determine the kinetics of 3,4-diazabicyclo[4.3.0]non-2-ene formation, a procedure based on the degeneration of the precursor process was adopted. An appropriate mathematical treatment allowed a quantitative interpretation of all the phenomena observed over the given pH interval. The activation parameters were determined. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 327–338, 2006

In the present work we have focus our care on the controversial intermediate salt: Ni(NO 3 ) 2 . 5.5 H 2 O. To prepare this phase, we have carried out, in the range 60-80°C, a controlled evaporation of a solution of nickel nitrate, hexahydrate resulting from the melting of a 100g Ni(NO 3 ) 2 .6H 2 O batch sample in an isothermal pilot reactor. The proof of its existence is given, for the first time, by powder x-ray diffraction data.

The liquid-vapour equilibria of the binary system water-ethylenediamine have been experimentally studied under isobaric conditions on the one hand at 100, 400 and 700 Torr, and on the other hand at 2,69 and 3,65 atm. The phase equilibrium modelling, as a function of temperature and pressure, has been carried out by means of the quasiideal model, according to both two fundamental assumptions: the basicity of EDA and the solvation of chemical species that constitute the solution. The thermodynamic analysis of experimental data leads mainly to the following results: - the hydrolysis enthalpy of EDA reaches around 50 kJ, - the global degree of solvation linearly varies with the logarithm of pressure, - the azeotropic phenomenon disappears above 180 kPa, - within the range of pressure studied, experimental data and calculation results are in very good agreement.

The synthesis of 1-amino-2-methylindoline by the Raschig process was undertaken in aqueous solution. The principal side reaction that occurs in the medium is the oxidation of 1-amino-2-methylindoline formed by chloramine. To increase the yield of 1-amino-2-methylindoline, its oxidation by chloramine was studied by GC and HPLC at various concentrations of reactants and for a pH interval ranging between 9.9 and 13.5. The reaction is bimolecular and exhibits a specific acid catalysis. In alkaline medium, 1-amino-2-methylindole is the principal product. The enthalpy and entropy of activation were determined at pH 12.89. In unbuffered solution, the interaction was autocatalyzed by the ammonium ions formed, which indicates a competitive oxidation of neutral and ionic forms of 1-amino-2-methylindoline by chloramine. A mathematical treatment based on one implicit equation allows a quantitative interpretation of all the phenomena observed over the above pH interval. It takes both acid–base dissociation equilibrium and alkaline hydrolysis of chloramine into account. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 515–523, 2002

The reduction of chloramine, methylchloramine, dimethylchloramine and N-chloro-3-azabicyclo­[3.3.0]octane by sodium borohydride was studied according to pH, temperature and concentrations of haloamine and reducing agent. The interaction is bimolecular and exhibits a specific acid catalysis. The enthalpy and entropy of activation were determined at pH 12.89. A mathematical treatment of the reaction kinetics allows the complete characterization of the final state and determination of the percentage of reduced haloamine in terms of [NaBH4]/[R1R2NCl] ratio, pH and temperature. A reaction mechanism is proposed. Copyright © 2002 John Wiley & Sons, Ltd.

The reaction between chloramine and 2-methylindoline was studied at pH 12.89, T = 40°C, and for different initial concentrations of reactants. The interaction includes two concurrent bimolecular mechanisms leading to 1-amino-2-methylindoline and 2-methylindole. The rate laws were determined at the first moments of the reaction by using a differential method. By considering the totality of the reactions that occur in the medium, an appropriate mathematical model was developed. It permits to follow the evolution of the system over time and to calculate the final yields of reaction products. An optimization in terms of the initial contents of 2-methylindoline and chloramine was performed. It indicated that the maximum yield of 1-amino-2-methylindoline does not exceed 56%. The results show the limit of the Raschig process for the synthesis of indolic hydrazines in aqueous medium. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 575–584, 2002

We synthesized nitrosamines (R2N-NO) with R = iPr (1), nPr (2), nBu (3), and hydroxyethyl (4) from the amine using sodium nitrite/p-toluenesulfonic acid in CH2Cl2. The rate of formation of 1-4 increases in the direction iPr

This report is a summary of our work on energetic materials. Herein, triazole-, tetrazole-, 2-tetrazene- and hydrazine-based energetic compounds are described. An overview of the synthetic methods and of the problematic around the quest of new explosives is given. Hydrogen-bonding formation and alkylation (methylation) reactions were studied as a mean to decrease the sensitivities towards classical stimuli and increase their thermal and chemical stability. 15N NMR spectroscopy is a valuable tool for the assignment of the methylation site in keeping with the results of the crystal structure analysis. Lastly, the thermal/chemical stability, sensitivity data and energetic performance of the compounds is described.

Direct α-addition of azido groups on methyltetrazene backbones had never been described in the literature. We report herein the one-step α-azidonation of 1,1’,4,4’tetramethyl-2-tetrazene (TMTZ) that leads to 1-azidomethyl-1’,4,4’-trimethyl-2-tetrazene (MATMTZ) and 1,4-di(azidomethyl)-1’,4’-dimethyl-2-tetrazene (DADMTZ): two nitrogenrich tetrazene derivatives with promising energetic interest. These compounds were synthesized using azidoiodinane reagents such as the iodosylbenzene/trimethylsilyl azide couple or azidobenziodoxolone, while neither chloration reagents nor sodium azide allowed the introduction of azido groups on the α-carbon of tetramethyltetrazene. The α-azidonation reaction of TMTZ was optimized in order to predominantly form either monoor diazidomethyltetrazene derivative, which were characterized by H, C and N NMR. Moreover, the theoretical heats of formation of the two azidoderivatives were computed using Density Functional Theory (B3LYP) and composite methods (CBS-QB3). Propulsion performance parameters such as density and specific impulse were calculated using, respectively, Molecular Mechanics (MM) and OPHELIE code, which is a variant of the CEA code of NASA.

The synthesis of high-grade chloramine was studied starting from sodium hypochlorite solutions containing 25% in NaOCl. The reagents at 100 chlorometric degrees are relatively stable and lose approximately 1.4° by 24 h at 17°C. They present a temperature of crystallization of 14.2°C (precipitation of NaOCl·5H2O) but it is possible to use them at −20°C in undercooling state. To obtain quantitative yields, it is necessary to neutralize the totality of hydroxide ions generated by the reaction and to operate below −10°C in order to limit oxidation of chloramine by the hypochlorite ions. The addition of an acceptor soluble salt is the most appropriate solution because it regenerates ammonia as soon as it is consumed and stabilizes chloramine by maintaining the pH around 10. The ammoniacal combinations NH4NO3–NH4Cl–NH3–H2O and NH4NO3–NH3–H2O are compatible and allow to operate in monophasic medium until −30°C. The yields are close to 95% with a titre in NH2Cl of 2.3 M (11.4%). Experiments carried out in continuous rating lead to a monochloramine solution of 2 M.

3-Azabicyclo[3.3.0]octane has been determined in dilute aqueous solution (10 mg l −1 ) by ultraviolet spectrophotometry after derivatization with hypochlorite ion. The reaction has been carried in the presence of an excess of hypochlorite (10–50%) in buffer solutions of pH ranging between 10 and 13. Formed N -chloro-3-azabicyclo[3.3.0]octane exhibits an absorption band at λ =257 nm ( ϵ =358 M −1 cm −1 ). This method has the advantage of operating in alkaline medium and for low contents of amine. It is particularly well adapted to the study of phases equilibria in the liquid–liquid ternary system RR′NH–NaOH–H 2 O and to the determination of amines contents in aqueous solutions.