Showing papers on "Hydrazine published in 2008"
TL;DR: Results show that the proposed electrode displays better electrocatalytic activity compared to the previously reported palladium modified electrodes towards oxidation of hydrazine.
156 citations
TL;DR: The mechanism and structure sensitivity of the electrocatalytic oxidation of hydrazine on platinum in alkaline solutions were investigated using cyclic voltammetry, steady-state current measurements, and on-line electrochemical mass spectrometry as mentioned in this paper.
140 citations
TL;DR: The method has been applied for the determination of hydrazine in boiler feed water and the resulting yellow colored product is stable in acidic medium and has a maximum absorption at 458 nm.
135 citations
TL;DR: Determination of hydrazine in river and drinking water samples was successfully performed andHydrazine vapor sensing by the proposed method was also reported.
108 citations
TL;DR: An efficient method has been developed for the reduction of carbon-carbon double bonds with diimide, catalytically generated in situ from hydrazine hydrate, and are a valuable alternative when metal-catalyzed hydrogenations are problematic.
Abstract: An efficient method has been developed for the reduction of carbon-carbon double bonds with diimide, catalytically generated in situ from hydrazine hydrate. The employed catalyst is prepared in one step from riboflavin (vitamin B(2)). Reactions are carried out in air and are a valuable alternative when metal-catalyzed hydrogenations are problematic.
101 citations
TL;DR: A mechanistic model is proposed in which hydrazine is suggested to be continuously produced from ammonium and hydroxylamine and subsequently oxidized to N2, and the proposed mechanism was verified by a mathematical model which could explain and predict most of the experimental data.
Abstract: Anaerobic ammonium oxidation is a recent addition to the microbial nitrogen cycle, and its metabolic pathway, including the production and conversion of its intermediate hydrazine, is not well understood. Therefore, the effect of hydroxylamine addition on the hydrazine metabolism of anaerobic ammonium-oxidizing (anammox) bacteria was studied both experimentally and by mathematical modeling. It was observed that hydroxylamine was disproportionated biologically in the absence of nitrite into dinitrogen gas and ammonium. Little hydrazine accumulated during this process; however, rapid hydrazine production was observed when nearly all hydroxylamine was consumed. A mechanistic model is proposed in which hydrazine is suggested to be continuously produced from ammonium and hydroxylamine (possibly via nitric oxide) and subsequently oxidized to N2. The electron acceptor for hydrazine oxidation is hydroxylamine, which is reduced to ammonium. A decrease in the hydroxylamine reduction rate, therefore, leads to a decrease in the hydrazine oxidation rate, resulting in the observed hydrazine accumulation. The proposed mechanism was verified by a mathematical model which could explain and predict most of the experimental data.
85 citations
TL;DR: In this article, a simple reduction method using TiO(2)-NTs as support was used to obtain Pd nanoparticles with a size range from 6 to 13 nm.
80 citations
TL;DR: In this paper, a modified hydrazine reduction route without any surfactant introduced was used to synthesize well dispersed nickel nanoparticles with uniform size, which were characterized by XRD, FESEM, TEM and TG.
79 citations
TL;DR: In this paper, a simple microwave-assisted solution phase approach was used to synthesize ZnO nanorods using hydrazine hydrate precursor, which is used as a mineralizer instead of sodium hydroxide.
Abstract: ZnO nanorods have been successfully synthesized by a simple microwave-assisted solution phase approach. Hydrazine hydrate has been used as a mineralizer instead of sodium hydroxide. XRD and FESEM have been used to characterize the product. The FESEM images show that the diameter of the nanorods fall in the range of about 25–75 nm and length in the range of 500–1,500 nm with an aspect ratio of about 20–50. UV–VIS and photoluminescence spectra of the nanorods in solution have been taken to study their optical properties. A mechanism for microwave synthesis of the ZnO nanorods using hydrazine hydrate precursor has also been proposed.
75 citations
TL;DR: The catalytic role of unsupported gold nanoparticles on the luminol-hydrazine reaction is investigated and the proposed method was successfully applied to the determination of hydrazine in boiler feed water samples.
74 citations
TL;DR: In this article, the authors irradiated solid ammonia (NH3) in the temperature range of 10-60 K with high-energy electrons to simulate the processing of ammonia-bearing ices in the interstellar medium and in the solar system.
Abstract: We irradiated solid ammonia (NH3) in the temperature range of 10-60 K with high-energy electrons to simulate the processing of ammonia-bearing ices in the interstellar medium and in the solar system. By monitoring the newly formed molecules online and in situ, the synthesis of hydrazine (N2H4), diazene (N2H2 isomers), hydrogen azide (HN3), the amino radical (NH2), molecular hydrogen (H2), and molecular nitrogen (N2) has been confirmed. Our results show that the production rates of hydrazine, diazene, hydrogen azide, molecular hydrogen, and molecular nitrogen are higher in amorphous ammonia than those in crystalline ammonia; this behavior is similar to the production of molecular hydrogen, molecular oxygen, and hydrogen peroxide found in electron-irradiated water ices. However, the formation of hydrazine in crystalline ammonia does not show any temperature dependence. Our experimental results give hints to the origin of molecular nitrogen in the Saturnian system and possibly in the atmospheres of proto-Earth and Titan; our research may also guide the search of hitherto unobserved nitrogen-bearing molecules in the interstellar medium and in our solar system.
TL;DR: Ethyl imidate hydrochlorides 1 and 2 were prepared by passing HCl gas through solutions of substituted benzyl cyanides and absolute ethanol and their chemical structures were confirmed by means of IR, 1H- and 13C-NMR data and by elemental analysis.
Abstract: Ethyl imidate hydrochlorides 1 were prepared by passing HCl gas through solutions of substituted benzyl cyanides and absolute ethanol. Ethoxycarbonylhydrazones 2 were synthesized from the reaction of compounds 1 with ethyl carbazate. Treatment of 2 with hydrazine hydrate leads to the formation of substituted 4-amino-4,5-dihydro-1H-1,2,4-triazole-5-ones 3. Isatin and 5-chloroisatin were added to 3 to form Schiff bases 4 and N-Mannich bases 5 of these compounds were synthesized by reacting with formaldehyde and piperidine. Their chemical structures were confirmed by means of IR, 1H- and 13C-NMR data and by elemental analysis.
TL;DR: In this paper, a methyl 2-(thiazol-2-yl carbamoyl)acetate was synthesized and used as starting material for the synthesis of Schiff bases and imides.
Abstract: Methyl 2-(thiazol-2-ylcarbamoyl)acetate was synthesized and used as starting material. It was treated with hydrazine hydrate to afford the hydrazide, which was reacted with nitromethane and formaldehyde to give the saturated nitropyrimidine. The hydrazide was reacted with phenyl isothiocyanate to afford the thiosemicarbazide, which was cyclized with ethyl bromoacetate, sodium hydroxide, or sulfuric acid to afford N-phenylthiazolidinone, N-phenyltriazole, and thiadiazolyl derivatives. The methyl 2-(thiazol-2-ylcarbamoyl)acetate was coupled with diazonium salts of aniline, 4-chloroaniline, 4-bromoaniline, or 4-aminobenzenesulfonamide to afford the carbamoyl acetates, which were reacted with 2-aminobenzimidazole, 1,2,4,5-tetrachlorophthalic anhydride, and hydrazine hydrate to afford the corresponding thiazolylmalonamide, tetrachloroisoindolylimide, and tri-azole derivatives. Schiff bases and imides are newly synthesized candidates obtained via simple condensation of the hydrazide with aldehydes, 2,3-pyridinedicarboxylic anhydride, or 1,8-naphthalenedicarboxylic anhydride. The pharmacological screening showed that many of these compounds have good antihypertensive α-blocking activity and low toxicity.
TL;DR: 3,6-Dichloropyridazine undergoes a smooth metallation using (tmp)2Zn.2MgCl2.2LiCl, leading to highly substituted pyrazolo[3,4-c]pyridazines derivatives and bis-organozinc species react with various electrophiles.
TL;DR: Here it is found, besides being combustible hydrazine can also be used as a structure-directing agent and the ratio of zinc nitrate to hydrazin is found to control the morphology of ZnO.
TL;DR: The ability of zirconium dinitrogen compounds to participate in heterocumulene insertion chemistry is demonstrated and the regiochemistry of the N2 carboxylation is controlled by the ansa-cyclopentadienyl ligand.
Abstract: Addition of 2 equiv of carbon dioxide to the ansa-zirconocene dinitrogen complex resulted in selective insertion into each zirconium nitrogen bond, forming a C2 symmetric dicarboxylated diazenido compound. Treatment with excess Me3SiI furnished the ansa-zirconocene diiodide along with the N,N‘-dicarboxylated silylated hydrazine. New nitrogen−carbon bonds were also assembled by addition of methyl triflate. Tri- and tetrasubstituted hydrazines could be formed by treatment with water and Me3SiI, respectively. The regiochemistry of the N2 carboxylation is controlled by the ansa-cyclopentadienyl ligand where the sterically demanding tert-butyl substituents and the C2 symmetry of the dimer dictates the stereochemistry of CO2 insertion. These results demonstrate the ability of zirconium dinitrogen compounds to participate in heterocumulene insertion chemistry.
TL;DR: In this article, an Activated Carbon (AC) supported tungsten carbide was reported for the catalytic decomposition of hydrazine for the first time, and it was found that the WC x α /AC-H catalyst prepared by a carbothermal hydrogen reduction process exhibited excellent catalytic performances both in the microreactor and in a 1 Newton hydrazines microthruster.
Abstract: Activated carbon (AC) supported tungsten carbide was reported for the catalytic decomposition of hydrazine for the first time. It was found that the WC
x
/AC-H catalyst prepared by a carbothermal hydrogen reduction process exhibited excellent catalytic performances both in the microreactor and in a 1 Newton hydrazine microthruster. The XRD, TEM and microcalorimetry results suggest that the formation of well crystallized W2C phase, the restraining of the carbon deposition, as well as the prohibiting of the methanation should be responsible for the high activity and stability of the WC
x
/AC-H catalyst in the hydrazine decomposition reaction.
TL;DR: The results showed that HNTO has an insensitive nature as RDX and NTO, etc, and it makes a higher nitrogen content and lower acidity.
TL;DR: It is concluded that apparently further attention should be given to tri- and tetramethyl hydrazine and 1-formyl 2,2-dimethylhydrazine as well as to the hydrazones of formaldehyde and acetaldehyde as these five compounds may contribute to the overall environmental toxicity of residual rocket fuel and its transformation products.
Abstract: QSAR/QSTR modelling constitutes an attractive approach to preliminary assessment of the impact on environmental health by a primary pollutant and the suite of transformation products that may be persistent in and toxic to the environment. The present paper studies the impact on environmental health by residuals of the rocket fuel 1,1-dimethyl hydrazine (heptyl) and its transformation products. The transformation products, comprising a variety of nitrogen containing compounds are suggested all to possess a significant migration potential. In all cases the compounds were found being rapidly biodegradable. However, unexpected low microbial activity may cause significant changes. None of the studied compounds appear to be bioaccumulating.
Apart from substances with an intact hydrazine structure or hydrazone structure the transformation products in general display rather low environmental toxicities. Thus, it is concluded that apparently further attention should be given to tri- and tetramethyl hydrazine and 1-formyl 2,2-dimethyl hydrazine as well as to the hydrazones of formaldehyde and acetaldehyde as these five compounds may contribute to the overall environmental toxicity of residual rocket fuel and its transformation products.
TL;DR: The microwave-induced synthesis of pyrazolo[3,4d]pyrimidines 4 in the reaction of N4substituted-2,4-diamino-6-chloro-5-carbaldehydes 3 with hydrazine is described in this paper.
TL;DR: In this paper, the nanoAg/Ti electrode was evaluated using cyclic voltammetry (CV) and chronoamperometry (CA) for hydrazine oxidation.
Abstract: Silver nanoparticles were directly deposited on the surface of titanium by the hydrothermal method using polyethylene glycol as the reduction agent. The electrocatalytic activity of the prepared titanium-supported nanoAg/Ti electrode towards hydrazine oxidation in alkaline solutions was evaluated using cyclic voltammetry (CV) and chronoamperometry (CA). The CV results show that the nanoAg/Ti electrode is electrochemically active towards hydrazine oxidation with oxidation potentials ranging between −0 . 6 and 0.6 V vs. SCE. The onset potential of ca. −0.6 V vs. SCE for the hydrazine oxidation was recorded. A sharp increment in the current density of hydrazine oxidation with the increase of the hydrazine concentration was observed. CA results show stable steady-state current densities ( i ss ) for the hydrazine oxidation. For the anodic potential holding at 0.1 V, the CA measurement delivered the i ss value of over 0.58 mA cm −2 mM −1 in the presence of 20 mM hydrazine. A linear dependence of the i ss upon the hydrazine concentration was found in the range of 0–60 mM hydrazine. Results imply that the nanoAg/Ti electrode presents stable and significantly high electroactivity for the hydrazine oxidation.
TL;DR: The synergistic effect between Ni and Ag led to improvement of dispersion and reactivity of nickel in the presence silver for precipitated catalysts, which could be explained by the mechanism of metal reduction in the hydrazine media.
TL;DR: Pyrazolidine dihydrochloride can be used in the acceleration of Biginelli reactions between urea, ethyl acetoacetate and various aldehydes to provide DHPMs in good to excellent yields.
TL;DR: In this article, a series of alumina supported ruthenium catalysts, which were prepared by hydrogen treatment or hydrazine reduction, were characterized by N2 adsorption, X-ray diffraction (XRD), XRF, CO chemisorption and temperature-programmed desorption of hydrogen (H2-TPD).
Abstract: A series of alumina supported ruthenium catalysts, which prepared by hydrogen treatment or hydrazine reduction, were characterized by N2 adsorption, X-ray diffraction (XRD), X-ray fluorescence (XRF), CO chemisorption, and Temperature-programmed desorption of hydrogen (H2-TPD). In contrast to the samples with conventional hydrogen reduction, there was almost no residual chlorine in the samples using RuCl3 as precursor with hydrazine treatment. Furthermore, the dissolved aluminum could be removed much more easily in basic solution, which led to the higher BET surface and pore volume of hydrazine-reduction catalysts. Therefore, the active phase (Ru metal) would not be contaminated. Three main peaks, which occurred at about 150, 375, and 650 °C, respectively, were observed in the H2-TPD profiles of Ru/Al2O3 catalysts with a high amount of residual chlorine. A new peak of desorption hydrogen centering at 240 °C, which was completely suppressed by the high amount of residual chlorine, might appear in the profiles of the samples with the washing procedure following hydrogen reduction or hydrazine treatment. The peaks with the desorption temperature lower than 500 °C were relative with dissociatively adsorbed hydrogen and spillover hydrogen simultaneity, and the peak at above 500 °C was caused by spillover hydrogen and would be stabilized by hydroxyl groups on alumina surface.
TL;DR: A carbon paste electrode modified with cobalt phthalocyanine (CPECoPc) was developed and applied to the determination of hydrazine [N2H4] in industrial boiler feed water as mentioned in this paper.
Abstract: A carbon paste electrode modified with cobalt phthalocyanine (CPECoPc) was developed and applied to the determination of hydrazine [N2H4] in industrial boiler feed water. The CPECoPc exhibited good electrocatalytical activity for hydrazine oxidation at pH 13. A linear correlation was obtained between anodic peak current (Iap) and hydrazine concentration in the range of 1.25 × 10−4 to 9.80 × 10−4 mol L−1, fit by the equation Iap = 1.47 + 4.90 × 105 [N2H4] with a correlation coefficient of 0.9967. A detection limit of 7.35 × 10−5 mol L−1 was obtained. Recovery of hydrazine from three samples ranged between 99.0% and 102.9%. The modified electrode showed no interference by cations commonly present in boiler water, such as K+, Na+, Ca2+, Mg2+, Al3+, Pb2+, and Zn2+. The results obtained for hydrazine in boiler water using the proposed modified electrode are in agreement with the data obtained by a standard spectrophotometric method, at the 95% confidence level.
TL;DR: In this paper, the tetrazole ring cleavage under the action of hydrazine was shown to yield the unique 2,3diaminothieno[2,3-d ]pyrimidin-4(3 H )-one system.
TL;DR: The reaction of hydroxylamine with 2,4-dinitrophenyl diethyl phosphate gives the O-phosphorylated product, which is rapidly converted to hydrazine and nitrogen gas in the presence of the excess of hydroXYlamine.
TL;DR: In this article, a new and efficient strategy for the systematic synthesis of hydrazine derivatives is reported, which allows the synthesis of up to tetrasubstituted hydrazines derivatives with minimal number of steps using only one protecting group or without any of them at all.
TL;DR: Alkynyl heterocycles are also shown to be effective dipolarophiles for pyridine N-imine, and analogous compounds can be accessed directly in modest yields through the reaction of 6-(alkyn-1-yl)pyridazin-3-one derivatives.
Abstract: Cycloaddition of pyridine N-imine with 6-alkyl-4-oxohex-5-ynoates followed by condensation with hydrazine provides concise access to pharmacologically active 6-(pyrazolo[1,5-a]pyridin-3-yl)pyridazinones. For the first time alkynyl heterocycles are also shown to be effective dipolarophiles for pyridine N-imine, and analogous compounds can be accessed directly in modest yields through the reaction of 6-(alkyn-1-yl)pyridazin-3-one derivatives.
TL;DR: In this article, a single-step, low-temperature spray pyrolysis of iron precursors with hydrazine in a furnace aerosol reactor (FuAR) is described.
Abstract: Oxides of iron in different crystalline forms such as hematite, maghemite, and magnetite have been used in number of industrial and biomedical applications in recent years. These materials are often synthesized in multiple-step processes in which simultaneous control of particle size, shape, morphology, and crystallinity is difficult. A single-step, low-temperature spray pyrolysis of iron precursors with hydrazine in a furnace aerosol reactor (FuAR) is described. To help select viable precursors and guide selection of operating conditions for the aerosol process, hydrazine derivatives of iron precursors are prepared in batch and analyzed with TGA, FTIR, and XRD. These results were also used to identify the chemical formula of hydrazinated precursors and elucidate the reaction pathway for the precursors such as ferrous acetate, ferric nitrate, and ferrous oxalate that are suitable for single-step aerosol reactor synthesis. These iron precursors are aerosolized and reacted in situ with hydrazine vapor to de...