NH NH2 Research Articles

Thermal Decomposition of Energetic Materials 72: Unusual Behavior of Substituted Furazan Compounds upon Flash Pyrolysis

The behavior upon flash pyrolysis is described for two neutral furazan compounds of stoichiometry R 1R 2C 2N 2O (R 1 = −NO 2 or −NH 2 and R 2 = −NHNO 2) and four salts (Na +, NH 4 +, NH 2NH 3 +, and NH 3OH +) in which R 1 = −NO 2 and R 2 = −NNO 2 −. Highly exothermic decomposition occurred in all cases. Rapid-scan IR spectroscopy was used to quantify the IR-active gaseous products in real time, while mass spectrometry was used to identify N 2 and, in two cases, O 2. Good to excellent mass balance was obtained for each compound. Although only a few relationships exist between the stoichiometry and the decomposition characteristics, several compounds exhibit surprising and novel behavior. The most unusual behavior occurs when R 1 = −NO 2 and R 2 = −N(H)NO 2. Linear cyanogen-N-oxide NCCNO is formed by opening of the furazan ring and stripping of the substituents. A complex reaction between the substituents produces HNO 3 and N 2 while leaving residual NO 2, rather than producing N 2O and HNO 3 by a simple reaction.

Unimolecular reactions of protonated hydrazine. Reaction mechanisms and dynamics from observation of metastable ion fragmentations and ab initio calculations

The unimolecular chemistry of the system NH 2NH 3 + has been investigated experimentally and theoretically. In accordance with experiment losses of H 2 and H • are calculated to be the dominating low energy processes on the singlet potential energy surface. A weak signal due to loss of NH with formation of NH 4 + is also observed. This reaction probably takes place by cross-over to the triplet surface. The reaction dynamics of the H 2 loss is investigated in great detail. This process has a substantial reverse barrier, and a large non-statistical translational energy release. An ab initio direct dynamics calculation provides good insight into the process, and is in agreement with the experimentally determined translational energy release. The proton affinity of NH 2NH 2 was calculated, and found to reproduce the experimental figure very well.

Electrocatalytic activity of N,N′,N″,N‴-tetramethyl-tetra-3,4-pyridoporphyrazinocobalt(II) adsorbed on a graphite electrode towards the oxidation of hydrazine and hydroxylamine

The complex N,N′,N″,N‴-tetramethyl-tetra-3,4-pyridoporphyrazinocobalt(II) ([Co(II)Tmtppa] 4+) irreversibly adsorbed on a graphite electrode displays electrocatalytic activity towards the oxidation of both hydrazine and hydroxylamine. The kinetics of the electrocatalytic four-electron oxidation of NH 2NH 2 and two-electron oxidation of NH 2OH are examined using cyclic voltammetric and rotating disk electrode methods, and the corresponding kinetic parameters are obtained. The possible application of the [Co(II)Tmtppa] 4+ modified electrode in sensing NH 2NH 2 and NH 2OH is also discussed in this paper.

Synthesis, characterization and mode of thermal decomposition of oxalate complexes of cadmium(II) and zinc(II) with hydrazine, and cobalt(II), nickel(II) and copper(II) with hydrazinium cation

The reaction of CdSO 4 with hydrazine and hydrazinium oxalate in aqueous solution at several pH values leads to the formation of various complexes. Only three complexes were successfully isolated: Cd 2(C 2O 4) 2·N 2H 4, CdC 2O 4·N 2H 4·O.5H 2O and CdC 2O 4·1.5N 2H 4. The reaction of ZnSO 4 with hydrazine and hydrazinium oxalate produces only the complex ZnC 2O 4·2N 2H 4. On reaction of MSO 4 with hydrazinium oxalate, double oxalates of Co, Ni and Co of general formulate Co(NH 3NH 3)(C 2O 4) 2·2H 2O, Ni 2(NH 3NH 3)(C 2O 4) 3·4H 2O, and Cu(NH 2NH 3) 2(C 2O 4) 2·H 2O were obtained. The complexes obtained were characterized by elemental analysis, X-ray powder patterns, IR spectroscopy, and TG and DTA techniques.

Factors inhibiting nitrification of ammonia in deep wastewater reservoirs

Nitrification of ammonia in wastewater reservoirs is very slow, in spite of the ubiquitous presence of nitrifying bacteria. In an attempt to identify the reasons, the effect of several factors on the rate of nitrification and viability of N. europaea was studied. Light, NH 2OH and NH 2NH 2 were found to be inhibitory to exponentially growing cells of Nitrosomonas europaea, while ammonia provided limited protection. Stationary phase cells were unaffected by light. Water samples from two wastewater reservoirs had a variable effect upon viability and nitrification of laboratory cultures of N. europaea upon illumination, while long-term incubation of N. europaea cells placed in semi-permeable containers at different depths in the reservoirs had generally no effect on their viability.

Chemical reduction of the water splitting enzyme system of photosynthesis and its light-induced reoxidation characterized by optical and mass spectrometric measurements: A basis for the estimation of the states of the redox active manganese and of water in the quaternary oxygen-evolving S-state cycle

The chemical reduction and over-reduction of the water-splitting enzyme and its subsequent light-induced reoxidation was followed by simultaneous measurements of (i) UV and (ii) electrochromic absorption changes, accompanied (iii) by O 2 measurement and (iv) mass spectrometric analysis of the evolved 15N 2 and 15N 2O of the applied reductant, 15NH 2OH. (1) On this reversible pathway, the measured four characteristics attributed to changes of Mn valences, surplus charges, water oxidation and oxidation of the reductant are quantitatively coupled with each other. (2) Treatment with NH 2OH (or NH 2NH 2) leads to a three-digit reverse shift of O 2 evolution and UV and electrochromic absorption changes. This is interpreted as the reduction of the enzyme in the dark from the S 1 state via the S 0 and the overreduced S −1 state to the superreduced state, S −2. (3) S −2 is stable for hours. (4) S −2 is a terminal state, not further reducible without being deactivated. (5) Each step on this reversible pathway from state S 1 to S −2 is accompanied by a 1 2- 15 N 2 evolution from 15NH 2OH interpreted as a three-electron reduction of state S 1 which is in accordance with the three-digit reverse shifts. (6) The results are explained by a reversible reduction of 3 redox-active Mn ions. Based on the obtained data, the possible valence states of these photooxidizable Mn ions in state S −2 to S 3 have been estimated. (7) Irreversible deactivation of S −2 with release of Mn into the solution is coupled with an approx. 1- 15N 2O evolution from 15NH 2OH. (8) The electrochromic changes indicate at pH 7 a surplus charge at S −1, S 2 and S 3. This is explained by an H + release of approx. 2:1:0:1 with the 1:1:1:1 electron extraction in the S −1 → S 0 → S 1 → S 2 → S 3 transition. On this basis, the possible states of the water derivatives up to S 3 have been estimated. (9) The results are compared with information obtained from UV-difference spectra and XAS, EPR and NMR measurements.

Dissociative electron attachment ot NH 3, NH 2OH, NH 2NH 2 and NH 2CH 3

NH 2 − formation by the attachment of electrons to NH 3, NH 2OH, NH 2NH 2 and NH 2CH 3 is studied using a low energy (0–10 eV), narrow electron beam. Formation of NH 2 − shows a narrow resonance with an onset around 4.5 eV and maximum around 6.0 eV from all these compounds. This slow variation of the appearance potential of NH 2 − within the series is rather unexpected from the energy balance equation since the bond energies vary considerably from one compound to the other.

Synthesis and x-ray structural characterization of oxo-persulphido dinuclear tungstate anions: {W 2O 2(μ 2-S)(S 2) 4} 2− and {W 2O 2(μ 2-S 2)(S 2) 4} 2−

The reaction of WOS 3 2− and elemental sulphur with the participation of NH 2NH 2·2HCl in DMF solvent at ambient temperature has led to the dinuclear complex anions [W 2O 2(μ 2-S)(S 2) 4] 2− and [W 2O 2(μ 2-S 2)(S 2) 4] 2− as a solid mixture in the structure of [Et 4N] 2{W 2O 2(μ 2-S)(S 2) 4} 0.77 {W 2O 2(μ 2-S 2)(S 2) 4} 0.23. Both anions are composed of two neutral [WO(S 2) 2] subunits bridged by either a sulphide (in W 2O 2S 9 2−) or an η 1,η 1-di-sulphide (in W 2O 2S 10 2−). Each anion contains tungsten(VI) ions with pentagonal bipyramidal environments, with the axial site occupied by a terminal oxo atom and the other one by the intramolecular approach of a sulphur from a disulphido group bonded to the other tungsten atom. The five equatorial atoms of each pentagonal bipyramid, which are defined by two η 2S 2 2− ligands and a coordinating sulphur atom, are almost planar. The possible pathway for the formation of the title complexes is depicted and the spectroscopic properties of the solid mixture are reported.

The reactivity of hydrazine with photosystem II strongly depends on the redox state of the water oxidizing system

The decay kinetics of the redox states S 2 and S 3 of the water-oxidizing enzyme have been analyzed in isolated spinach thylakoids in the absence and presence of the exogenous reductant hydrazine. In control samples without NH 2NH 2 a biphasic decay is observed. The rapid decline of S 2 and S 3 with y D as reductant exhibits practically the same kinetics with t 1/2 = 6-7 s at pH = 7.2 and 7°C. The slow reduction (order of 5-10 min at 7°C) of S 2 and S 3 with endogenous electron donors other than y D is about twice as fast for S 2 as for S 3 under these conditions. In contrast, the hydrazine-induced reductive shifts of the formal redox states S i (i = 0⋯3) are characterized by a totally different kinetic pattern: (a) at 1 mMNH 2NH 2 and incubation on ice the decay of S 2 is estimated to be at least 25 times faster ( t 1/2⩽0.4 min) than the corresponding reaction of S 3 ( t 1/2≈13 min); (b) the NH 2NH 2-induced decay of S 2 is even slower (about twice) than the transformation of S 1 into the formal redox state ‘S −1’ ( t 1/2≈6 min), which gives rise to the two-digit phase shift of the oxygen-yield pattern induced by a flash train in dark adapted thylakoids. (c) the NH 2NH 2-induced transformation S 0→‘S −2’ [Renger, Messinger and Hanssum (1990) in: Curr. Res. Photosynth. (Baltscheffsky, M., ed). Vol. 1, pp. 845-848, Kluwer, Dordrecht] is about three times faster ( t 1/2≈ min) than the reaction ▪. Based on these results, the following dependence on the redox state S i of the reactivity towards NH 2NH 2 is obtained: S 3 < S 1 < S 0 ⪡ S 2. The implications of this surprising order of reactivity are discussed.

Mass spectroscopic analysis of N 2 formation by flash-induced oxidation of hydrazine and hydroxylamine in normal and tris-treated tobacco chloroplasts

The flash-induced dinitrogen evolution was analyzed in normal and Tris-inhibited tobacco chloroplasts ( Nicotiana tabacum var. John William's Broadleaf) which were dark-incubated (at least 20 min) in the presence of NH 2NH 2 and/or NH 2OH. (a) The N 2 yield due to a single turnover flash as a function of NH 2NH 2 concentration is practically the same in both normal and Tris-washed chloroplasts, even in a range where the oxygen evolution remains almost unaffected by NH 2NH 2. Illumination with ten flashes leads to higher integral N 2 evolution in Tris-washed samples at limiting NH 2NH 2 concentrations. (b) Under aerobic conditions oxidation of NH 2NH 2 and NH 2OH is coupled with significant O 2 uptake. Both N 2 formation and O 2 uptake remain unaffected by DCMU in a single turnover flash but become drastically inhibited under multiple flash excitation. (c) The N 2 yield per flash due to PS-II-induced NH 2NH 2 oxidation markedly depends on the O 2 content of the suspension. This effect is also observed in the presence of superoxide dismutase (SOD). (d) If chloroplasts are incubated with an equimolar ratio of 14NH 2 14NH 2 and 15NH 2 15NH 2, hardly any 14N 15N formation is detected, indicating that the nitrogen-nitrogen bond remains intact during the oxidation process. A totally different isotope distribution is obtained in the case of an equimolar mixture of 14NH 2OH and 15NH 2OH which reflects a statistical bimolecular reaction between NHOH radicals. In a mixture of 14NH 2OH and 15NH 2 15NH 2 the ratio of mass 29 to mass 30 increases with increasing 14NH 2OH content. Based on the present results, flash-induced N 2 formation is inferred to occur via univalent oxidation of NH 2OH and NH 2NH 2 either by P-680 + or by the functionally connected tyrosine(s) of polypeptide D-1 (Y ox Z) and/or D-2 (Y ox D). NH 2OH and NH 2NH 2 do not interact with the S 1 state of the catalytic site of water oxidation in a way that leads to flash-induced N 2 production.

Spatial Profiles of CN c2 NH NH2 H2O CO+ and CO+2 in Comet p/ Halley

Spatial Profiles of CN c2 NH NH2 H2O CO+ and CO+2 in Comet p/ Halley

Thermal decomposition of energetic materials 31—Fast thermolysis of ammonium nitrate, ethylenediammonium dinitrate and hydrazinium nitrate and the relationship to the burning rate

High-heating-rate (≤100°C/s) thermolysis studies at various pressures (1–1000 psi) are described for NH 4NO 3(AN), [NH 3CH 2CH 2NH 3](NO 3) 2(EDDN), [NH 2NH 3](NO 3)(HN), 50 50 AN/EDDN, and 67 33 HAN/HN (HAN = hydroxylammonium nitrate) by using the rapid-scan FTIR/thermal profiling technique. For all of the solid materials, melting is detected in advance of decomposition. HNO 3 is the first gas decomposition product detected, and undoubtedly is formed by endothermic proton transfer. Pressures above atmospheric are required to produce exothermic events, probably because the gas decomposition products are able to build around the condensed phase to the critical concentration needed for ignition. HN 3 is a significant decomposition product of HN and mixtures containign HN, which may contribute to the high impact sensitivity of the material. For all of the nitrate salts and mixtures investigated, AN is found to be a recombination product during thermal decomposition. This fact may contribute to the similarity of the burning rates of aluminized propellants made from these materials.

Notizen: Cyclotriphosphazen-2-spiro-3′ -cyclodi[phosphadiazan] — Eine Spiroverbindung aus Hexachlortriphosphazen und Dihydrazidothiophosphorsäure-O-phenylester / Cyclotriphosphazene-2-spiro-3′-cyclodi[phosphadiazane] — A Spiro Compound from Hexachlorocyclotriphosphazene and Dihydrazidothiophosphoric Acid 0-Phenylester

Hexachlorocyclotriphosphazene (Cl2P=N)3 reacts with dihydrazidothiophosphoric acid 0-phenylester C6H5O—P(=S)(NH—NH2)2 in THF in the presence of triethylamine at room temperature to give the spirocyclic title compound, whose constitution has been confirmed by MS, IR, 31P NMR and elemental analysis.

Thermal analysis of some methylhydrazine and methylhydrazinium complexes of copper(II), copper(I) and mixed valence species

Novel methylhydrazine and methylhydrazinium chloride complexes of copper in various oxidation states (1, 4 3 , 2) have been prepared and characterised by elemental analyses and magnetic data. The thermal decomposition of these complexes was studied by simultaneous DTA, TG and DTG. The complex Cu(II)Cl 2(NH 2NH 2CH 3Cl) decomposes on heating with reduction to Cu(I)Cl. Significantly the complex Cu 3(2I, II)Cl 6(NH 2NH 2CH 3) 2 on heating disproportionates as follows 3Cu( 4 3 ) → 2 Cu(I) + Cu(II).

Heats of formation of some small molecules and radicals

In this work, we determine the heat of formation of some small neutral molecules and radicals (NH 2F, NHF, HOOH, HOO, NH 2NH 2, NH 2OH, NH 2O, NHOH, CH 3NH 2, CH 3NH, CH 2NH 2, HNO 2 and CH 3BH 2). Atomization energies of these compounds are computed at the Møller—Plesset level to full fourth order using a series of extended basis sets of 6-31G type. The results that we obtain confirm some experimental values (NH 3, NH 2, H 2O 2,…); nevertheless, some other computed heats of formation call into question the experimental values of CH 3NH 2 and HOO. We also predict Δ H f298 0 for CH 3BH 2 (24.25 kcal mol −1), HNO 2 (−16.72), NHOH (25.25), NH 2O (−16.73) and NH 2F (−9.64).

Electronic structure of emeraldine and related molecules

The CNDO/S3 molecular orbital model is applied to describe the electronic structure of aniline, (C6H5)NH2, emeraldine, (C6H5)N(C6H4)N(C6H4)NH(C6H4)NH2, its hydrogenated and dehydrogenated forms, and its singly and doubly protonated forms. The cation eigenvalue spectrum, i.e., density of valence states (DOVS), is found to be sensitive to molecular conformation which, in turn, can be inferred from comparison of the calculated DOVS with suitable measured photoemission spectra. For fixed molecular conformation, the major effect of hydrogenation of emeraldine is the occupation of its lowest empty molecular orbital with accompanying electronic and atomic relaxation. Dehydrogenation leads to the emptying of its highest filled molecular orbital. Protonation leads to rearrangements of the valence electron charge among the filled orbitals but not to deviations from a closed shell system. Protonation-induced atomic relaxation can create major changes in the character of the highest filled or lowest empty orbitals. Changes in molecular conformation (e.g., upon hydrogenation or protonation) can yield large alterations in both the DOVS and the character of the radical cation eigenstates. Comparison of calculated DOVS with photoemission spectra from thin films of polyemeraldine does not suffice to determine the molecular conformation, however, because of the low resolution of the measured spectra.

Effects of Photosystem II extrinsic proteins on microstructure of the oxygen-evolving complex and its reactivity to water analogs

We used Triton-prepared PS II membranes in studies of the inactivation of O 2 evolution and solubilization of Mn and specific PS II polypeptides by NH 2OH, N- and O-substituted NH 2OH derivatives, NH 2NH 2 and NH 4Cl. The inactivation of O 2-evolution, solubilization of Mn and the solubilization of the extrinsic PS II polypeptides (17, 23 and 33 kDa) proved closely correlated, half-maximal effects occurring with only 100 μM NH 2OH. NH 2OH (2 mM) and NaCl (1 M) extractions solubilized about one-half the amount of protein solubilized by 0.8 M Tris-HCl (pH 8.0). The inactivation of the Mn-S-state complex proceeded by apparent first-order kinetics, the rate constant dependent on NH 2OH (CH 3NHON) concentration and pH. In the range of micromolar concentrations of NH 2OH, this inactivation did not occur via a cooperative type mechanism. Depletion of the 17 and 23 kDa proteins modified the pH dependency of inactivation (from pH 7.8 to 6.5) and also resulted in an approx. 2-fold maximum increase in the inactivation rate constant. Significantly, reconstitution of such NaCl-TMF-2 membranes with the 17 and 23 kDa proteins reverted both the pH dependency and the inactivation rate constant to that of TMF-2. A hierarchy of effectivity for solubilization of Mn and protein, which was highly correlated with inactivation of the Mn-S-state enzyme, was observed among NH 2OH and its derivatives. This same hierarchy was observed irrespective of prior depletion of the 17 and 23 or the 17, 23 and 33 kDa proteins from TMF-2. The hierarchy of effectivity among derivatives was: NH 2OH > CH 3NHOH > NH 2NH 2, NH 2OSO 3 > NH 2OCH 3 ⪢ CH 3NHOCH 3, NH 4Cl. The function(s) of the extrinsic PS II proteins as determinants of the reactivity of the Mn-S-state complex with polar amine vs other type compounds is discussed.

Multiple molecular forms of diarylpropane oxygenase, an H 2O 2-requiring, lignin-degrading enzyme from Phanerochaete chrysosporium

Three different molecular forms of the H 2O 2-requiring heme enzyme, diarylpropane oxygenase, were isolated from the extracellular medium of Na-acetate buffered, agitated cultures of Phanerochaete chrysosporium. Forms I, II, and III were separated by DEAE-Sepharose and further purified on Sephadex G-100. Absorption maxima of the native, reduced, and a variety of ligand complexes of the three enzyme forms are essentially identical, indicating similar heme environments. All forms also have similar, but not identical, reactivity. The homogeneous proteins oxidized a diarylpropane, an olefin, a β-aryl ether dimer, a phenylpropane, phenylpropane diols, and veratryl alcohol. Identical products were produced from each form. However, the specific activities of the three homogeneous enzymes for veratryl alcohol oxidation were 18.75, 11.80, and 8.48 μmol min −1 mg −1. In the presence of one equivalent of H 2O 2 the Soret maximum of diarylpropane oxygenase II shifted from 408 to 418 nm, and two additional maxima appeared at 526 and 553 nm, indicating the presence of an Fe(IV)-oxo species equivalent to horseradish peroxidase II. This oxidized species could be reduced back to the native form by veratryl alcohol and several reducing agents (e.g., Na 2S 2O 4, NH 2NH 2, thiourea, or NADH). The molecular weights of diarylpropane oxygenases I, II, and III were ~39,000, 41,000, and 43,000, respectively. The major form ( II) (85% of the activity) contained ~6% neutral carbohydrate. The affinity of the forms for concanavalin A-agarose suggests that they all are glycoenzymes.

Structural organization of the oxidizing side of photosystem II. Exogenous reductants reduce and destroy the Mn-complex in photosystems II membranes depleted of the 17 and 23 kDa polypeptides

Removal of 23 and 17 kDa water-soluble polypeptides from PS II membranes causes a marked decrease in oxygen-evolution activity, exposes the oxidizing side of PS II to exogenous reductants (Ghanotakis, D.F., Babcock, G.T. and Yocum, C.F. (1984) Biochim. Biophys. Acta 765, 388–398) and alters a high-affinity binding site for Ca 2+ in the oxygen-evolving complex (Ghanotakis, D.F., Topper, J.N., Babcock, G.T. and Yocum, C.F. (1984) FEBS Lett. 170, 169–173). We have examined further the state of the functional Mn complex in PS II membranes from which the 17 and 23 kDa species have been removed by high-salt treatment. These membranes contain a structurally altered Mn complex which is sensitive to destruction by low concentrations of NH 2OH which cannot, in native PS II membranes, cause extraction of functional Mn. In addition to NH 2OH, a wide range of other small (H 2O 2, NH 2NH 2, Fe 2+) and bulky (benzidine, hydroquinone) electron donors extract Mn (up to 80%) from the polypeptide-depleted PS II preparations. This extraction is due to reduction of the functional Mn complex since light, which would generate higher oxidation states within the Mn complex, prevents Mn release by reductants. Release of Mn by reductants does not extract the 33 kDa water-soluble protein implicated in Mn binding to the oxidizing side of PS II, although the protein can be partially or totally extracted from Mn-depleted preparations by exposure to high ionic strength or to high (0.8 M) concentrations of Tris. We view our results as evidence for a shield around the Mn complex of the oxygen-evolving complex comprised of the 33 kDa polypeptide along with the 23 and 17 kDa proteins and tightly bound Ca 2+.

Amino wagging and inversion in hydrazine: K′ = 1 levels in the first excited state of the antisymmetric wagging vibration

The infrared absorption spectrum of NH 2NH 2 vapor has been observed in the region 899–1077 cm −1, where the antisymmetric wagging band ( v a = 1 ← 0) appears, by the use of a Fourier transform spectrometer with a practical resolution of 0.003 cm −1. In the region 925.0–925.6 cm −1, the spectrum was also observed with a tunable diode laser, and a component, β, of the p Q 2 cluster has been further resolved. Most of the absorption lines assignable to β- p P 2( J″), γ- p P 2( J″), β- p Q 2( J″), γ- r Q 0( J″), β- r R 0( J″), and γ- r R 0( J″), where J″ = 2 ∼ 15, have been identified. From these observed transition frequencies, in combination with the ground state energy levels given by microwave spectroscopy, the energy level structure of the K′ = 1 rotational states was determined. From this, the following molecular parameters for the v a = 1 state were determined: molecular asymmetry, B′- C″ = 0.00017 cm −1; a parameter q 5 describing an umbrella motion Coriolis interaction ( q 5 K) about the a axis, q 5 = −0.0030 cm −1; its J( J + 1) variation, q 5 j = 0.00014 cm −1; and a parameter describing an umbrella-motion K-type doubling g 5 J( J + 1), g 5 = 0.000021 cm −1.