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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.

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.

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

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

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

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

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

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.

The formation of 3-azabicyclo[3,3,0]oct-2-ene in the course of the synthesis of N-amino-3-azabicyclo[3,3,0]octane using the Raschig process results from the following two consecutive reactions: chlorine transfer between the monochloramine and the 3-azabicyclo[3,3,0]octane followed by a dehydrohalogenation of the substituted haloamine. The kinetics of the reaction were studied by HPLC and UV as a function of temperature (15 to 44°C), and the concentrations of NaOH (0.1 to 1 M) and the chlorinated derivative (1 to 4×10−3 M). The reaction is bimolecular (k=103×10−6 M−1 s−1; ΔH0#=89 kJ mol−1; and ΔS0#=−33.6 J mol−1 K−1) and has an E2 mechanism. The spectral data of 3-azabicyclo[3,3,0]oct-2-ene were determined. IR, NMR, and ES/MS analysis show dimerization of the water-soluble monomer into a white insoluble dimer. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet: 30: 129–136, 1998.