Solid Hydrazine Research Articles

A visible-light-sensitive siloxene-based composite material with enhanced photocatalytic activity

A novel layer-stacking approach that produces a layered composite of siloxene and reduced graphene oxide (RGO) sheets is presented. This method is based on the assembly of siloxene and graphene oxide sheets, followed by reduction at low temperature using solid hydrazine. High-resolution transmission electron microscopy reveals that the resulting siloxene-RGO composite has a layered structure with sheets that appear to be alternately stacked in a face-to-face fashion. This composite exhibits excellent photocatalytic activity under visible-light irradiation, with a photocurrent density that is about 40 times higher than that of the siloxene sheets alone. It is evident that the RGO sheets stacked on the siloxene surfaces are the key elements that increase the photocatalytic activity of the layered composite. This layer-stacking approach enhances siloxene properties in many ways, rendering ample opportunities for the development of new siloxene-based composite materials with novel functionalities.

Facile solid-state synthesis of oxidation-resistant metal nanoparticles at ambient conditions

A simple and scalable method for the synthesis of metal nanoparticles in the solid-state was developed, which can produce nanoparticles in the absence of solvents. Nanoparticles of coinage metals were synthesized by grinding solid hydrazine and the metal precursors in their acetates and oxides at 25 °C. The silver and gold acetates converted completely within 6 min into Ag and Au nanoparticles, respectively, while complete conversion of the copper acetate to the Cu sub-micrometer particles took about 2 h. Metal oxide precursors were also converted into metal nanoparticles by grinding alone. The resulting particles exhibit distinctive crystalline lattice fringes, indicating the formation of highly crystalline phases. The Cu sub-micrometer particles are better resistant to oxidation and exhibit higher conductivity compared to conventional Cu nanoparticles. This solid-state method was also applied for the synthesis of platinum group metals and intermetallic Cu3Au, which can be further extended to synthesize other metal nanoparticles.

Crystal structure prediction and hydrogen-bond symmetrization of solid hydrazine under high pressure: a first-principles study

In this article, the crystal structure of solid hydrazine under pressure has been extensively investigated using ab initio evolutionary simulation methods. Calculations indicate that hydrazine remains both insulating and stable up to at least 300 GPa at low temperatures. A structure with P2₁ symmetry is found for the first time through theoretical prediction in the pressure range 0-99 GPa and it is consistent with previous experimental results. Two novel structures are also proposed, in the space groups Cc and C2/c, postulated to be stable in the range 99-235 GPa and above 235 GPa, respectively. Below 3.5 GPa, C2 symmetry is found originally, but it becomes unstable after adding the van der Waals interactions. The P2₁→Cc transition is first order, with a volume discontinuity of 2.4%, while the Cc→C2/c transition is second order with a continuous volume change. Pressure-induced hydrogen-bond symmetrization occurs at 235 GPa during the Cc→C2/c transition. The underlying mechanism of hydrogen-bond symmetrization has also been investigated by analysis of electron localization functions and vibrational Raman/IR spectra.

Hydrogen Bond in Compressed Solid Hydrazine

The high-pressure behavior of hydrazine has been investigated by in situ Raman spectroscopy and synchrotron X-ray diffraction experiments under pressure up to 46.5 and 33.0 GPa, respectively. It is found that the liquid hydrazine solidifies into phase I at about 1.2 GPa. The symmetry of phase I is confirmed to be space group P21 by the peak assignment, group theory analysis, and Rietveld refinement of XRD patterns. A solid–solid transition from phase I to phase II is observed in both Raman spectroscopy and XRD experiments at about 2.4 GPa, which is ascribed to the formation of new hydrogen bonds between hydrazine molecules. At 18.4 GPa, an isostructural transition from phase II to the final phase III is observed. The pressure-induced adjustment of bifurcated hydrogen bond is first researched and regarded as the origin of the isostructural transition. Above 20.6 GPa, a clear softening behavior occurs in the NH2 symmetric stretching mode. The coupling of optical vibrations derived from enhancement of the hydrogen bond is proposed as a crucial role in this softening process.

Large scale production of highly conductive reduced graphene oxide sheets by a solvent-free low temperature reduction

A novel one-pot process that can produce freestanding reduced graphene oxide (RGO) sheets in large scale through a mechanochemical method is presented, which is based on a 1:1 adduct of hydrazine and carbon dioxide (H3N+NHCO2−, solid hydrazine). We were able to synthesize RGO sheets by grinding solid hydrazine with graphene oxide (GO), followed by storing the mixed powder at 50°C for 10min. No solvents, nor large vessels, nor post-annealing at high temperatures are required. The resulting RGO sample was characterized by elemental analysis, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, Brunauer–Emmett–Teller measurement, thermo gravimetric analysis, Fourier transform infrared spectroscopy, solid state nuclear magnetic resonance spectroscopy, and conductivity measurement. It exhibits excellent conductivity and possesses a high specific surface area. This reduction method was successfully applied for the fabrication of inkjet-printed RGO devices on a flexible substrate.

Solid-state and solvent-free synthesis of azines, pyrazoles, and pyridazinones using solid hydrazine

Azines, pyrazoles, and pyridazinones were isolated as the sole products in high yields (>97%) by grinding solid hydrazine (H3N+NHCO2−) with di-carbonyl compounds or by their reaction in the absence of solvent. Neither catalysts nor additives were needed to promote the reactions. The solid-state and solvent-free reactions proceeded under ambient conditions and did not produce any wastes other than water and carbon dioxide. They are operationally easy, environmentally safe, and readily scalable, allowing for highly selective synthesis of compounds containing the hydrazine motif.

From ‘Solid Hydrazine' to Solid-State Azines

From ‘Solid Hydrazine' to Solid-State Azines

ChemInform Abstract: Synthesis of Azines in Solid State: Reactivity of Solid Hydrazine with Aldehydes and Ketones.

AbstractThe reaction proceeds by solid state grinding of a hydrazine and aldehydes or ketones to afford the conjugated azines with < 97% yield.

Synthesis of Azines in Solid State: Reactivity of Solid Hydrazine with Aldehydes and Ketones

Highly conjugated azines were prepared by solid state grinding of solid hydrazine and carbonyl compounds such as aldehydes and ketones, using a mortar and a pestle. Complete conversion to the azine product is generally achieved at room temperature within 24 h, without using solvents or additives. The solid-state reactions afford azines as the sole products with greater than 97% yield, producing only water and carbon dioxide as waste.

Catalytic hydrolysis of hydrazine borane for chemical hydrogen storage: Highly efficient and fast hydrogen generation system at room temperature

There has been rapidly growing interest for materials suitable to store hydrogen in solid state for transportation of hydrogen that requires materials with high volumetric and gravimetric storage capacity. B-N compounds such as ammonia-triborane, ammonia-borane and amine-borane adducts are well suited for this purpose due to their light weight, high gravimetric hydrogen storage capacity and inclination for bearing protic (N-H) and hydridic (B-H) hydrogens. In addition to them, more recent study [26] has showed that hydrazine borane with a gravimetric hydrogen storage capacity of 15.4% wt needs to be considered as another B-N compound that can be used for the storage of hydrogen. Herein we report for the first time, metal catalyzed hydrolysis of hydrazine borane (N 2H 4BH 3, HB) under air at room temperature. Among the catalyst systems tested, rhodium(III) chloride was found to provide the highest catalytic activity in this reaction. In the presence of rhodium(III) chloride, the aqueous solution of hydrazine borane undergoes fast hydrolysis to release nearly 3.0 equivalent of H 2 at room temperature with previously unprecedented H 2 generation rate TOF = 12000 h −1. More importantly, it was found that in the catalytic hydrolysis of hydrazine borane the reaction between hydrazine borane and water proceeds almost in stoichiometric proportion indicating that the efficient hydrogen generation can be achieved even from the highly concentrated solution of hydrazine borane or in the solid state when water added to the solid hydrazine borane. This finding is crucial especially for on-board application of the existing system. The work reported here also includes ( i) finding the solubility of hydrazine borane plus its stability against self-hydrolysis in water, ( ii) the definition of reaction stoichiometry and the identification of reaction products for the catalytic hydrolysis of hydrazine borane, ( iii) the collection of wealthy kinetic data to demonstrate the effect of substrate and catalyst concentrations on the hydrogen generation rate and to determine the rate law for the catalytic hydrolysis of hydrazine borane, ( iv) the investigation of the effect of temperature on the rate of hydrogen generation and determination of activation parameters ( E a, ΔH #, and ΔS #) for the catalytic hydrolysis of hydrazine borane.

Isolation and structural characterization of the elusive 1 : 1 adduct of hydrazine and carbon dioxide

A solid hydrazine was isolated as a crystalline powder by reacting aqueous hydrazine with supercritical CO(2). Its structure determined by single crystal X-ray diffraction shows a zwitterionic form of NH(3)(+)NHCO(2)(-). The solid hydrazine is remarkably stable but is as reactive as liquid hydrazine even in the absence of solvents.

A new advanced method for heterogeneous catalysed dechlorination of 1,2,3-, 1,2,4-, and 1,3,5-trichlorobenzenes in hydrocarbon solvent

A new advanced method for dechlorination of 1,2,3-, 1,2,4-, and 1,3,5-trichlorobenzenes in organic solvent catalysed by palladium on carbon support and solid hydrazine hydrochloride yields benzene in short reaction times. The catalyst system can be efficiently reused for several cycles. Ultrasound radiation of the heterogeneous catalyst reaction increases remarkably the rate of dechlorination.

A new advanced method for heterogeneous catalysed dechlorination of polychlorinated biphenyls (PCBs) in hydrocarbon solvent

The dechlorination of PCBs with solid hydrazine hydrochloride catalysed by palladium, in an organic solvent, yields biphenyl in short reaction times. The catalyst system can be efficiently reused for several cycles. Ultrasonication of the heterogeneous catalysed reaction increases the dechlorination rate remarkably. The reactivity of the CCl bond on the PCB ring are in the order meta> para≫ ortho.

Numerical analysis of a ram accelerator employing two-phase combustion

A numerical investigation is carried out of the flowfield around a ram accelerator projectile running through a tube filled with a detonating gas laden with reactive solid particles. First, a mathematical model for the two-phase, chemically reactive flow is proposed. A total variation diminishing numerical scheme is employed, based on the resolution of two Riemann problems: a classical one for the gas phase, and a nonconventional one for the dispersed phase. Results are presented, first for a ram projectile flying at 6.7 km/s through an H2/O2/He mixture, and compared with recent data. Then, computations are made for the same conditions, but with the addition of solid hydrazine nitrate particles. It appears that the existence of sufficiently small particles improve the performance of the ram accelerator.

Infrared spectroscopy of homogeneously nucleated hydrazine aerosols: Disordered and crystalline phases

Fourier Transform Infrared Spectroscopy has been used to study homogeneously nucleated hydrazine (N2H4) aerosols formed in a variable temperature flow cell. The spectra contain both resonant absorptions and Mie scattering features which allow detailed information to be obtained on the phase of the aerosol particles and the size distribution that is formed. In addition, the relative intensities of the absorption and scattering features can be used as a qualitative probe of the density of the particles. A disordered phase is observed at cell temperatures ranging from 230 to 180 K and a transition to a crystalline phase occurs over the temperature range 180–175 K. At lower temperatures the infrared spectra become progressively narrower, indicating that the quality of the crystals improves as the temperature is lowered. The result is previously unobserved details in the hydrazine N‐H stretch vibrations of the crystalline solid. The high quality of the spectra obtained under these conditions suggests that at the high condensation rates characteristic of the present experiments, self‐annealing yields highly crystalline particles. Mie calculations, based upon the complex refractive index data for amorphous solid hydrazine, are shown to have utility in modeling the infrared spectrum of the disordered phase, which we tentatively assign as a supercooled liquid.

Proton transport in solid hydrazine sulphate

Proton mobility has been established in solid hydrazine sulphate through coulometric, conductivity, NMR, IR, X-ray diffraction and Raman studies. Electrical conductivity measurement has been made on pressed pellets in the frequency range from 0.1 to 100 KHz in the temperature range 300 to 500 K. The frequency dependence of the conductivity has been explained on the basis of a ‘variable-potential-barrier’ model. A plausible mechanism for proton transport has also been suggested.

Fast-proton transport in hydrazine sulphate. I. Coulometric, conductivity and optical studies

Proton mobility has been established in solid hydrazine sulphate through coulometric, conductivity, IR, DSC and TGA studies. The electrical conductivity has been measured on pressed pellets in the frequency range from 100 Hz to 100 kHz in the temperature range 300-500K. The frequency dependence of the conductivity has been explained on the basis of a 'variable-potential-barrier' model. The DC conductivity has been estimated from the complex admittance (B-G) plots. The sigma against 1/T curves show a sudden increase in conductivity at about 480K which has been attributed to a structural phase transition. A possible mechanism for proton transport has also been suggested and discussed vis-a-vis NMR studies reported in part II of this paper.

Molecular structure and molecular motion of solid hydrazine

The crystal structure and molecular structure of solid hydrazine are discussed on the basis of a Zeeman study of the 14N NQR, proton spin-lattice relaxation measurement and some diffraction studies. The NQR data and the spin-lattice relaxation data support the space group C 2 2 rather than C 2 h 2. A model of the molecular motion that is governed by vacancy diffusion is proposed as a motion to which the relaxation mechanisms are due in the temperature range between 240 and 273 K. A calculation of T 1 is presented on the basis of the model, from which the correlation time τ is deduced to be 3 × 10 −4 seconds at 273 K.

Raman spectra of gases. XV: Hydrazine and hydrazine‐d4

AbstractThe Raman spectra of gaseous hydrazine and hydrazine‐d4 have been recorded from 40 to 3500 cm−1. For the ‘light’ molecule, strongly polarized lines at 3398, 3329 and 1076 cm−1 have been assigned to the NH antisymmetric stretch, NH symmetric stretch, and NN stretch, respectively. For the hydrazine‐d4 molecule, strongly polarized lines at 2442, 2422, 1031, 930 and 749 cm−1 have been assigned to the ND antisymmetric stretch, ND symmetric stretch, NN stretch, ND2 was and ND2 rock, respectively. The Raman spectra of both solid hydrazine and hydrazine‐d4 have been recorded and the splitting in the intramolecular fundamental region indicates that there are at least four molecules per primitie cell. In the lattice region of the spectra the optical translations and librations are assigned and the number of lattice modes rules out both of the space groups previously proposed for hydrazine from scattering studies.

Proton magnetic relaxation study of solid hydrazine

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