Liberation Of Nitrogen Research Articles

Effect of VC addition on sinterability and microstructure of ultrafine Ti(C, N)-based cermets in spark plasma sintering

The effect of vanadium carbide (VC) addition on the sinterability and the microstructure of ultrafine Ti(C, N)-based cermets consolidated through spark plasma sintering (SPS) was systematically investigated using optical microscope, scanning electron microscope (SEM) with X-ray energy dispersive spectrometer (EDS), X-ray diffractometer (XRD) and transmission electron microscope (TEM). Our results reveal that the addition of VC increases the porosity of sintering body and depresses the sinterability of Ti(C, N)-based cermets. It is also found that the VC addition has a significant influence on the microstructure of ultrafine Ti(C, N)-based cermets, which inhibits the dissolution of titanium-containing compounds and the formation of inner rim phase and outer rim phase, thus preventing from grain growth. Owing to the depressed dissolution and precipitation, nitrogen liberation is mitigated, therefore resulting in less amount of graphite phase in the samples. In substance, VC changes the solubility of metallic elements in the binder, which makes more elements of Mo and W to be reserved in the binder and thus greatly decreases the content of titanium dissolved into the binder. The re-building solubility rule determines the development of phases and microstructure.

Thermal decomposition of [Mg(NH 3) 6](NO 3) 2, [Ni(NH 3) 6](NO 3) 2 and [Ni(ND 3) 6](NO 3) 2

The thermal decompositions of [Mg(NH 3) 6](NO 3) 2, [Ni(NH 3) 6](NO 3) 2 and [Ni(ND 3) 6](NO 3) 2 were studied by thermal gravimetry analysis (TGA) and simultaneous differential thermal analysis (SDTA) at a constant heating rate. The gaseous products of the decomposition were on-line identified by a quadruple mass spectrometer (QMS).The solid products were identified on the basis of Fourier transform mid infrared spectra (FT-MIR) and X-ray powder diffraction (XRPD) patterns. Deamination of hexaaminemagnesium nitrate(V) to diaminemagnesium nitrate(V) undergoes in two steps and two-third of the all NH 3 molecules are liberated. Deamination of both hexaaminenickel(II) nitrates(V) (non-deuterated and deuterated) to the diamines undergoes in three steps, and at two first steps one half of the NH 3 molecules are liberated. The thermal decomposition of [Ni(NH 3) 2](NO 3) 2 and [Ni(ND 3) 2](NO 3) 2 is also different than that of [Mg(NH 3) 2](NO 3) 2. In both cases the decomposition is connected with the redox processes, but in the case of magnesium compound, contrary to the nickel compounds, in the second stage, besides of liberation of nitrogen, nitrogen oxides and H 2O, undergoes the liberation of NH 3 and the formation of Mg(NO 3) 2, which in turn decomposes next, in the third stage, to the oxygen, nitrogen oxides and MgO. This third stage is not present in the case of both nickel compounds, and the decomposition of diaminenickel(II) nitrates(V) undergoes directly to the final products (NiO 1+ x , nitrogen, nitrogen oxides and H 2O) without the formation of Ni(NO 3) 2, because of the autocatalytic effect of the formed NiO.

Formation of new heterocycles by intramolecular cyclization reactions of alkynethiolates with nitrogen nucleophiles

1,2,3-Thiadiazole-4-carbohydrazides undergo base-catalyzed ring cleavage with liberation of nitrogen and recyclization to 5-thiopyrazolones, 6-thiomethylidene-1,3,4-oxadiazin-5-ones or 5-thio-7 H-pyrazolo[5,1- b][1,3]thiazine-2,7-diones.

Degradation of explosives by nitrate ester reductases.

Explosive-contaminated land poses a hazard both to the environment and to human health. Microbial enzymes, either in their native or heterologous hosts, are a powerful and low-cost tool for eliminating this environmental hazard. As many explosives have only been present in the environment for 10 years, and with similar molecules not known in Nature, the origin of enzymes specialized for the breakdown of explosives is of particular interest. Screening of environmental isolates resulted in the discovery of flavoproteins capable of denitrating the explosives pentaerythritol tetranitrate (PETN) and glycerol trinitrate. These nitrate ester reductases are related in sequence and structure to Old Yellow Enzyme from Saccharomyces carlsbergenisis. All the members of this family have alpha/beta barrel structures and FMN as a prosthetic group, and reduce various electrophilic substrates. The nitrate ester reductases are, however, unusual in that they display activity towards the highly recalcitrant, aromatic explosive 2,4,6-trinitrotoluene, via a reductive pathway resulting in nitrogen liberation. We have embarked on a detailed study of the structure and mechanism of PETN reductase from a strain of Enterobacter cloacae. Work is focused currently on relating structure and function within this growing family of enzymes, with a view to engineering novel enzymes exhibiting useful characteristics.

Nitrification, denitrification, and N-liberation associated with two types of organic hot-spots in soil

Nitrification, denitrification and nitrogen liberation were studied while liquid cattle manure and duck litter decomposed in aerobic soil contained in a diffusion chamber. The high NH 4 + outflux from the liquid manure initially saturated the indigenous nitrification potential and caused an exponential increase in nitrifying activity with doubling times of the nitrifying bacterial population as low as 1 d. Nitrification rates of 400 nmol N cm −2 h −1 were reached after 7 d of incubation, with most of the nitrifying activity situated <4 mm from the organic matter-soil interface. This location of the nitrification zone caused a tight coupling between nitrification and denitrification, and 40% of the liberated N was converted to N 2 during the 3-week experiment. A decreasing N liberation with time caused a reduction in both nitrification and coupled nitrification–denitrification, and only 20% of the initial activity remained at the end of the experiment. Incubation of duck litter led to NH 4 + outflux rates of 800 nmol N cm −2 h −1 through a 1 cm thick soil phase. The high rate of NH 4 + liberation seemed to inhibit nitrification in the aerobic soil. Ten days without measurable nitrification activity was followed by a slowly increasing nitrifying activity situated >5 mm from the aerobic–anaerobic interface. This suggests that a very high NH 4 + outflux from anaerobic organic material to a surrounding aerobic soil may increase the spatial separation between the nitrification and denitrification zones, thereby significantly reducing the process of coupled nitrification–denitrification.

THE BARLEY PROTEIN DEGRADATION: EFFECT OF NEUTRAL PROTEINASE CONCENTRATION ON PROTEIN DEGRADATION KINETICS

The time course of barley protein degradation was investigated in two cases: (i) in mashing of raw barley with different concentrations of bacterial neutral proteinase in the presence of α-amylase. and (ii) in mashing of spent grains, remaining after barley syrup preparation, with different proteinase concentrations. Protein solubilisation and α-amino nitrogen liberation rates decrease in the course of barley and spent grains hydrolysis. Initial protein degradation rates in spent grains mashing are lower than in native barley. Gel-chromatography of supernatants of the mash in the course of hydrolysis has indicated that the proteinase becomes increasingly occupied with solubilised proteins as the process proceeds. plotting the kinetics data for protein solubilisation in Foster-Niemann coordinates straight lines with high correlation (r=0·999) for both cases of hydrolysis have been obtained. For different enzyme concentrations the straight lines have been closely parallel with positive slope. A high correlation between ordinate intercept in Foster-Niemann coordinates and proteinase concentrations has been obtained. Linear correlations in Foster-Niemann coordinates for α-amino nitrogen liberation process have also been observed. However, for α-amino nitrogen liberation, the correlation between the ordinate intercept and proteinase concentration has not been achieved. The possibilities of application of kinetics parameters (ordinate intercept slope) as quantitative measures of enzyme efficiency in protein degradation under different conditions has been emphasised.

The production of a single steric network by a heterogeneous reaction of elastomers with azodicarbamide

Microscopy and electron microscopy have been used together with determinations of the crosslinking density and of the physico-mechanical properties of vulcanizates before and after the extraction of the azodicarbamide (ADCA), as well as nitrogen liberation, to show that the curing of elastomers with ADCA of differing structures is a heterogeneous reaction. A scheme is suggested for the formation of a single steric network during the curing with the azo-amide. Proof has been obtained that the heterogeneous vulcanization can result in the formation of a heterogeneous (butadiene nitrile rubbers) or homogeneous vulcanization structure (butadiene-styrene rubber, polybutadiene).

Synthesis of polyazine blocks with functional end groups

Polymers with a system of conjugated multiple bonds have semiconductor and in many cases other valuable properties such as high magnetic suspectibility, catalytic activity, etc. However, owing to chain rigidity and low molecular weight of polyconjugated systems prepared by polymerization or polycondensation, these systems do not have the physical and mechanical properties required for practical use. As a possible method of overcoming the difficulties described, a method was proposed for obtaining block-copolymers from blocks with a system of conjugation and with functional end groups. The first data published was obtained using Schiff's poly-bases [1]. Several papers are known concerning the synthesis of polyazines prepared from hydrazine and some discarbonyl compounds [2–4]. However, by polycondensation of equimolecular amounts of reagents, insoluble and infusible polymers were obtained. In spite of the fact that the polyazines obtained at increased temperatures tend to decompose with liberation of nitrogen, these polymers are also interesting as heat-resistant polymers since, according to a former paper [4], polymeric products of decomposition have a fairly definite structure and high heat stability.

Chemistry of α‐diazosulfones, XII: α‐Alkoxy‐α‐chloro‐sulfones from tert‐butyl hypochlorite and α‐diazosulfones

AbstractThe reaction of α‐diazosulfones with tert‐butyl hypochlorite in tert‐butyl alcohol/dichloromethane gives α‐tert‐butoxy‐α‐chloro‐sulfones (II) in good yields. In dichloromethane as solvent the same compounds were obtained, while in ethanol/dichloromethane the corresponding α‐chloro‐α‐ethoxy‐sulfones were formed (Scheme 1, Table I). α‐Diazo‐carbonyl compounds and tert‐butyl hypochlorite give acetals in alcoholic solvents and α‐tert‐butoxy‐α‐chloro‐carbonyl compounds in dichloromethane (Scheme II, Table I). An ionic pathway for the reaction of these diazo compounds with t‐BuOCI is proposed. The initially formed ion pair RSO2CH(Cl)N2⊖. t‐BuO⊖ solvolyses or collapses with liberation of nitrogen.

3-Hydroxyphenyl derivatives of pyrazolines and tetrahydropyridazines in a catalytic decomposition reaction

The isomeric 3-(hydroxyphenyl)-1,4,5,6-tetrahydropyridazines differ from their five-membered-ring analogs, the 3-(hydroxyphenyl)-Δ2-pyrazolines, in their behavior in catalytic-decomposition reactions. The catalytic conversion of 3- (hydroxyphenyl)-1,4,5,6-tetrahydropyridazines takes place at 120–200° C, dehydrogenation being the main reaction. The hydroxyphenylpyrazolines, under the same conditions, undergo decomposition with liberation of nitrogen and formation of the corresponding cyclopropanes.

Struktur und reaktivität aliphatischer diazoverbindungen—VI

Die Geschwindigkeitskonstanten pseudo-erster Ordnung der Hydrolyse p-substituierter Phenyl-benzoyl-diazomethane Ia-n und Phenyl-acetyl-diazomethane XVIIa-c in Dioxan—Wasser/ HClO4, die D2O-Lösungsiiiittel-Isotopieeffekte sowie die allgemeine Säurekatalyse von Ia, Ig und XVIIb wurden mittels manometrischer Messtechnik bestimmt. Aus dem Substituenteneinfluss auf den Solvens-Isotopieeffekt und auf die katalytische Wirksamkeit der undissoziierten Säure in Puffergemischen sowie aus dem Ergebnis der Produktanalyse der Hydrolyse von Ia und Ic kann geschlossen werden, dass die Gesamtreaktion der Zersetzung dieser sekundären α-Diazoketone eine Überlagerung der Hydrolyse-mechanismen A-1 und A-SE2 darstellt. Für diese ambidenten Diazoverbindungen ist die rasche reversible O-Protonierung am Carbonyl-Sauerstoff gegenüber einer geschwindigkeitsbestimmenden irreversiblen Protonierung des Diazo-Kohlenstoffatoms stets bevorzugt. Der Anteil der konkurrierenden Mechanismen wird durch die von den Substituenten ausgehenden Stabilisierungseffekte auf die entsprechenden Diazonium-Ionen VIII bzw. II und auf die daraus durch Stickstoff-Freisetzung entstehenden Arylvinyl-Kationen XII und α-Ketocarbonium-Ionen III bestimmt. Die kH2O/kD2O-Werte liegen zwischen 1·83 für vorwiegend geschwindigkeitsbestimmende C-Protonierung und einem inversen Isotopieeffekt von 0·58 für ein der geschwindigkeitsbestimmenden Stickstoff-Abspaltung aus VIII vorgelagertes O-Protonierungs-gleichgewicht. Die Güligkeit von ϱσ-Beziehungen nach Hammett und Yukawa-Tsuno sowie die Korrelation der Lösungsmittel-Isotopieeffekte mit den Substituentenkonstanten σ+p bzw. mit der Reaktivität 1g k1 zeigen, dass innerhalb der betrachteten Reaktionsserien eine kontinuierliche Änderung im Anteil des A-1- und A-SE2-Mechanismus der Hydrolyse auftritt. The rates of the acid-catalysed hydrolysis and the solvent deuterium isotope effects of p-substituted phenylbenzoyldiazomethanes (Ia–n) and phenylacetyldiazomethanes (XVIIa–c) have been studied in dioxan water/HClO4. The general acid catalysis of Ia, Ig and XVIIb has been stated in buffer solutions. The pseudo first-order rate constants were measured by a manometric technique. From the variation of the solvent isotope effect and of the catalytic effect of the weak acid in buffer solutions as a function of electronic properties of substituents and from the results of product analysis of hydrolysis of Ia and Ic a superposition of two different pathways (A-1 and A-SE2 mechanisms) is proposed. Two nucleophilic centres are present in the ambidente α-diazoketones Ia–n and XVIIa–c: the O atom of the CO group and the diazo C atom. There are several arguments that favour the fast and reversible O protonation over the rate-controlling and irreversible C protonation. Two different factors determine the relative importance of the two competitive mechanisms : the first is the stability of the diazonium ions VIII and II, respectively, and the second is the stability of the corresponding aryl vinyl cations (XII) and the α-keto-carbonium ions (III) formed by the loss of nitrogen. These relative stabilities of the intermediate species and consequently the predominant mechanism depend on the nature of the ring substituent. The values of the solvent isotope effect kH2O/kD2O which have been observed fall in the range from 1·83 in the case of predominant rate-controlling C protonation to 0·58 for preequilibrium O protonation, followed by rate-determining liberation of nitrogen from VIII. The validity of ϱσ relationships of Hammett and Yukawa-Tsuno type equations and the correlation of the solvent isotope effect with σ+p constants and with the reactivity 1g k1, respectively, reveal that no abrupt change in the mechanism of hydrolysis has occurred in the reaction series.

The reaction of Bis(cyclopentadienyl)titanium(III) chloride with organic azides

Bis(cyclopentadienyl)titanium(III) chloride reacts with organic azides with the liberation of nitrogen and the formation of nitrogen-bridged Ti1V compounds of varying thermal stability. Whhen the reaction is carried out in xylene, the initial products from phenyl and p-chlorophenyl azide can be isolated in an impure state, although they disproportionate on attempted purification. In tetrahydrofuran solution all the azides studied yield products which cannot be isolated, since they are transformed rapidly into mixtures of bis(cyclopentadienyl)titanium dichloride and other products.

The oxidation of hydrazine by silver(I) oxide

At room temperatures, the oxidation of hydrazine solutions by silver(1) oxide proceeds primarily in the solution phase, the rate of reaction being directly related to the concentration of free hydrazine and silver ions present. The reduction of the silver ions is catalysed by a conducting surface, such as a silver film, and it is suggested that the liberation of nitrogen involves the successive formation of several short-lived hydro-nitrogen species. The rate of reaction is influenced also by factors such as pH, particle size, and composition of the solution phase, since these alter either the solubility of the solid or the activity of the silver ions.

Synthesis and rearrangements of 2-azidovinyl ketones

1. A method was developed for the synthesis of the previously unknown 2-azidovinyl ketones from 2-chlorovinyl ketones. 2. Under the action of hydrochloric acid 2-azidovinyl phenyl ketone undergoes rearrangement with the liberation of nitrogen; as a result benzoylacetonitrile and 5-phenylisoxazole were prepared and identified.

Effects of tolbutamide, mesoxalate and phenformin in vitro on the liberation of nitrogen by rat liver slices.

Effects of tolbutamide, mesoxalate and phenformin in vitro on the liberation of nitrogen by rat liver slices.

Decomposition of forest litters

Studies have been made on the production of ammonia and nitrate nitrogen, rate of decomposition along with comparative changes in microbial population during decomposition of deciduous and coniferous litters. At the same time the effect of addition of antibiotics on the microbial population and rate of decomposition of coniferous litter was investigated. Liberation of nitrogen in the form of ammonia occurred somewhat more rapidly in decomposing deciduous litter than in that of the coniferous litter. Towards the end of the experiment the nitrification process commenced in the deciduous litter but was absent in the coniferous litter. The deciduous litter decomposed more rapidly than the coniferous litter. The bacteria and actinomycetes were consistently more numerous in the deciduous litter than in the coniferous litter; in the case of fungi the reverse occured. An antifungal antibiotic (cycloheximide) had little or no effect on numbers of fungi in the decomposing coniferous litter while antibacterial antibiotics (streptomycin and chloramphenicol) reduced slightly the numbers of bacteria and actinomycetes. Numbers of bacteria and actinomycetes were increased greatly in cultures receiving the antifungal antibiotic and fungal growth was apparently stimulated where antibacterial antibiotics were added. In spite of the observed shift in the microbial population brought about by the addition of antibiotics the rate of decomposition of the coniferous litter appeared to be unaffected. This would suggest that the type of microbia l population is not as important as the type of litter or some other factor in regard to decomposition rate.

Liberation of nitrogen from alder leaf litter

Liberation of nitrogen from alder leaf litter

ベンゼン置換体とクロラールの反応について (第3報)

R-CO-COOH (II), obtained by the oxidation of R-CH (OH)-COOH (I), (R=5-acetamino-2-methylphenyl) gives R-CN (IV) on application of hydroxylamine on heating, and an oxime (III) at room temperature. The semicarbazone is stable and can be recrystallized from water. The hydrolysis product (V) of (II) possesses securely bound water of hydration and its dehydration results in the formation of a condensate, (C8H7N)xH2O (VI), which is soluble in organic solvents, insoluble in alkalis, and soluble in acids. When its hydrochloric acid solution is basified, a substance soluble in ether is obtained but attempted recrystallization causes reversion to (VI). Application of acetic anhydride to the ether solution gives R-CHO (VII) which is also obtained on warming (I) and conc. sulfuric acid at 40°. The crude acid (II) containing chlorine forms R-CH (NH2)-COOH (IX) on the application of ammonia but the product returns to (I) by the action of nitrous acid. (IX) gives a hydrolysis product (X) of m. p. 210° (decomp.), and an oxidation product of m. p. 242° (decomp.). It is certain, therefore, that R-CHCl-COOH (VIII) is present in the crude acid. It is assumed that (VIII) alone was present during the reaction and formed (I) by hydrolysis during the procedure. Another acid obtained must be R2CH-COOH (XI), which was confirmed by synthesis from (I) and RH. Liberation of nitrogen from (XI) gave di (o-tolyl) acetic acid (XII) which was also obtained from o-tolyl iodide and methyl formate.

Studies on adrenochrome derivatives. I. Determination of the structure of adrenochrome monosemicarbazone.

Adrenochrome possesses >C=O group in the -5 and 6-positions but no synthetic evidence has been offered on which of these >C=O groups had reacted with semicarbazide to form adrenochrome monosemicarbazone. Catalytic reduction of the monosemicarbazone with palladium-carbon catalyst results in absorption of 1 mole of hydrogen to form 1-methyl-5-semicarbazido-6-hydroxyindole (II), whose methylation with dimethyl sulfate and sodium hydroxide affords 1-methyl-5-semicarbazido-6-methoxyindole (III). Pyrolysis of (III) by heating with sodium carbonate in glycerol at 185∼195° ended in liberation of nitrogen and 1-methyl-6-methoxyindole (IV) was formed. On the other hand, methylation of 6-methoxyindole (V) with methyl iodide in liquid ammonia with metallic sodium yielded (IV). This has proved that adrenochrome monosemicarbazone is 1-methyl-3-hydroxy-5-semicarbazono-6-oxo-2, 3, 5, 6-tetrahydroindole.

スルフォンアマイドの研究 第5報

N-nitroso-p-toluenesulfomethylamide and N-nitroso-p-toluenesulfobenzylamide were synthesized and the behavior of their N-nitroso radical was studied. The reaction with hydrocarbons give, not nitroso compounds, but esters of p-toluenesulfonic acid by liberation of nitrogen in thermal decomposition, and, in the case of benzyl compound, formation of benzaldehyde as well.This reaction is similar to decomposition of N-nitrosoacetanilide and can well be explained by the reaction mechanism proposed for it. N-nitrososulfonamide also undergoes nitrosation reaction at temperatures below its decomposition point, e. g. forming N-nitrosodiphenylamine from diphenylamine.