Hydrazine decomposition temperature

This is the dominant overall reaction for the decomposition on platinum or tungsten at 200 and 380 °C, respectively40. Most workers on hydrazine decomposition flames41-44, in which the reactions are homogeneous, report a stoichiometric equation similar to (b) for final flame temperatures up to 1900 °K. Measurements of MacLean and Wagner45 on decomposition flames and of Husain and Norrish37 on the flash photolysis of hydrazine indicate the contribution of the overall reaction... 

Determine the adiabatic decomposition temperature and the product composition a, b, and c. Take the standard heat of formation of liquid hydrazine as 50.07 kJ/mol. The hydrazine enters the system at 298 K. 

Because of the relatively low temperatures of decomposition of monopropellants, the attainment of non-equilibrium products is observed in some cases. The specific impulse and equilibrium combustion temperature of several monopropellants, are summarized in table IV. C. 1 and IV. C. 2. The non-equilibrium character of hydrazine decomposition was discussed previously in section m. A. The methyl substituted hydrazines are observed to behave in the same manner (32). These characteristics are summarized in table IV.C. 3. The non-equilibrium decomposition of the hydrazine is particularly interesting because it results in combustion temperatures and performances which are higher than those which are predicted from equilibrium considerations. 

NIMPHE = nuclear isotope mono propellant hydrazine engine (temperature maintenance device for decomposition catalysts in moner-gol driven rockets)... 

Hydrazine has been studied extensively for use in monopropellant thrusters for space flights of long duration. Thrusters are used or altitude control of communication satellites. Here the decomposition of hydrazine over a packed bed of alumina-supported iridium catalyst is of interest. " In a proposed study, a 2% hydrazine in 98% helium mixture is to be passed over a packed bed of cylindrical particles 0.25 cm in diameter and 0.5 cm in length at a gas-phase velocity of 15m/s and a temperature of 750 K. The kinematic viscosity of helium at this temperature is 4.5 X 10 nF/s. The hydrazine decomposition reaction is believed to be externally mass transfer-limited under these conditions. If the packed bed is 0.05 m in length, what conversion can be expected Assume isothermal operation. 

Very reactive substances are treated with NBS alone, but in other cases a radical-former is added. The favored radical activator for bromination of olefins by NBS is 2,2/-azoisobutyronitrile, 1 part per 100-1000 parts of NBS. This nitrile is obtained by reaction of bromine water with 2,2 -hydrazoiso-butyrodinitrile, which is prepared from acetone, KCN, and hydrazine sulfate in warm water365 (see also Dox366). The decomposition temperature of dibenzoyl peroxide is higher than that of 2,2 -azoisobutyrodinitrile, and about 30° above the boiling point of CC14. 

The thermal properties of explosives and propellanl compositions are widely studied by DTA and DSC. Fauth (47) recorded the DTA curves of some hydrazine, guanidine and guanidinium picrates, slyphnates, and sulfates. The decomposition temperatures found were generally considerably lower than those reported in the literature. Other picrates, those with thallium, ammonium, tetramethylammonium, and letraethylammonium, were studied by Stammler (27). David (28) and Bohon (29) examined the thermal behavior of explosives and propellants under various external pressures up... 

The major types of chemical blowing agents include the azo compounds, hydrazine derivatives, semicarbazides, tetrazoles, and benzoxazines. Table 1.10 shows some of the common blowing agents, their decomposition temperatures, and primary uses. 

These complexes are crystalline solids with characteristic colors. As the reactions are carried out under reducing conditions, iron is present as Fe in these complexes. The presence of Fe " " makes them rather susceptible to atmospheric oxidation and they are unstable and decompose on storage, losing hydrazine. They need to be prepared and stored in an atmosphere of nitrogen. Table 3.15 gives the thermal decomposition temperatures of the complexes. 

The first step shows an endothermic peak due to dehydration occurring at a fairly high temperature (—250 °C), indicating the presence of coordinated water. The second and third steps of decomposition, involving dissociation of hydrazine, are both exothermic. Owing to the close similarity in the structure of rare-earth-metal complexes, the observed decomposition temperatures are identical. 

The classical procedure for the Wolff-Kishner reduction—i.e. the decomposition of the hydrazone in an autoclave at 200 °C—has been replaced almost completely by the modified procedure after Huang-Minlon The isolation of the intermediate is not necessary with this variant instead the aldehyde or ketone is heated with excess hydrazine hydrate in diethyleneglycol as solvent and in the presence of alkali hydroxide for several hours under reflux. A further improvement of the reaction conditions is the use of potassium tcrt-butoxide as base and dimethyl sulfoxide (DMSO) as solvent the reaction can then proceed already at room temperature. ... 

Compound 24a was also obtained in 17% yield by heating of 4-hydroxy-3-nitrocoumarin 27 [12] with hydrazine hydrate in ethanol. A similar reaction of 27 with methylhydraine in boiling ethanol did not afford 24b because of the decomposition of the starting coumarin. However, when 27 was treated with methylhydrazine at room temperature for 24 h without solvent, the ring-opened methylhydrazine adduct 28 (36% yield) and 1,2-dihydro-5-(2-hydroxyphenyl)-l-methyl-4-nitro-3H-pyrazol-3-one 26 (ll%yield) were... 

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