Decomposition in air

Sulfathiazole is advised as an hair lotion additive defatting the hair and reducing formation of dandruff (1024). The polymeric 2-aminothiazoles derivatives (427) exhibit good thermal stability with decomposition in air starting at 350°C (1025). 

The kinetics of the contributory rate processes could be described [995] by the contracting volume equation [eqn. (7), n = 3], sometimes preceded by an approximately linear region and values of E for isothermal reactions in air were 175, 133 and 143 kJ mole-1. It was concluded [995] that the rate-limiting step for decomposition in inert atmospheres is NH3 evolution while in oxidizing atmospheres it is the release of H20. A detailed discussion of the reaction mechanisms has been given [995]. Thermal analyses for the decomposition in air [991,996] revealed only the hexavanadate intermediate and values of E for the two steps detected were 180 and 163 kJ mole-1. 

The most important synthetic routes to iron oxide pigments involve either thermal decomposition or aqueous precipitation processes. A method of major importance for the manufacture of a-Fe203, for example, involves the thermal decomposition in air of FeS04-7H20 (copperas) at temperatures between 500 °C and 750 °C. The principal method of manufacture of the yellow a-FeO(OH) involves the oxidative hydrolysis of Fe(n) solutions, for example in the process represented by reaction (1). 

Whereas several reports of doubly bonded tin compounds being sensitive to decomposition in air are to be found in the literature, there is only one instance of a controlled oxidation. Tetrakis[bis(trimethylsilyl)methyl]-distannene was treated with Me3NO to give the corresponding cyclo-1,3-distannoxane."2... 

Oda, T., Kato, T., Takahashi, T. et al. (1998) Nitric oxide decomposition in air by using nonthermal plasma processing with additives and catalyst, IEEE Trans. Ind. Appl. 34, 268-72. 

While the rate of decomposition in air was more rapid than in nitrogen, the kinetics of oxidative decomposition cannot be estimated reliably by isothermal weight loss because ofthe possibility of competing oxidative weight gain process. For this reason the kinetics were not estimated from the available data... 

S- and Se-donor ligands. The e.s.r. and electronic spectra of [Co(sacsac)2] and [Co(sacsac)2L] (sacsac = dithioacetylacetonate, L = py or piperidine) have been studied, and a polarographic study of [Co(sacsac)J (n = 2 or 3) in acetone has shown the complexes to have a well-defined capacity to accept one or two electrons in a reversible stepwise manner. The magnitude of the potentials and their reversible nature suggest that isolation of cobalt-sacsac complexes of low formal oxidation states should be possible." Co complexes of l,5-bis-(2-methylmercaptoethylthio)pentane are both hydrated and polymeric, and thermal decomposition in air or nitrogen leads to oxida tion to Co . Ethylenethiourea (etu) and tetramethylthiourea (tmtu) form the complexes [Co(etu) ](N03)2 and [Co(tmtu) ](C10 )2, which are tetrahedral, and [Co(etu)2(N03)2] and [Co(tmtu)2(N03)2] which have distorted octahedral co-ordination. 3-Diphenylphosphinothioyl-l-phenylthiourea, -1,1-diethyl-thiourea, and -1,1-dimethylthiourea form complexes with Co in which the ligands are bidentate. ... 

Definitive toxicity data for cobalt hydrocarbonyl do not exist because of the rapid decomposition in air of the chemical to a solid particulate. In most cases, exposures are primarily to inorganic cobalt compounds. 

Morris et al. (1991) obtained hematite of very small particle size ( 10 nm), termed nanophase by slow thermal decomposition in air of tri-Ee -acetato-hy-droxy-nitrate. XRD shows only two broad lines as in a 2-line ferrihydrite, but the magnetic hyperfine field at 4.2 K of 50.4 T appears to be more in agreement with poorly crystalline hematite. Well-crystalline hematite and Al-hematite were produced by decomposing Ee-Al-oxinates at 700 °C (da Costa et al. 2001). 

The liquid has a characteristic pungent smell and undergoes slow decomposition in air at elevated (> 50°C) temperatures. It is stable for months under dry dinitrogen or argon when stored in a refrigerator. 1H NMR (chloroform-d) 8 2.5-2.6(mult), 2.8-2.9(mult), 2.06(s), 1.40(s). 

The decomposition of SrC03 resembles that of BaC03. Wanmaker and Radielovic66 studied the decomposition in air gravimetrically and reported that it commenced at 1120 K and ended at 1450 K. Up to 1220 K the decomposition rate was constant at higher temperatures a change from zero-order to first-order kinetics occurred as the reaction proceeded beyond a = 0.5. A kinetic study of... 

A major difference in reactivity of the tungsten cluster as compared to the molybdenum clusters is evidenced by the extreme sensitivity of the former to decomposition in air. Further work on the synthesis and reactions of the tungsten clusters is in progress. 

SAFETY PROFILE Confirmed carcinogen with experimental carcinogenic, neoplastigenic, and tumorigenic data. A deadly poison by intravenous route. Human systemic effects by inhalation lung fibrosis, dyspnea, and weight loss. Human mutation data reported. See also BERYLLIUM COMPOUNDS. A moderate fire hazard in the form of dust or powder, or when exposed to flame or by spontaneous chemical reaction. Slight explosion hazard in the form of powder or dust. Incompatible with halocarbons. Reacts incandescently with fluorine or chlorine. Mixtures of the powder with CCU or trichloroethylene will flash or spark on impact. When heated to decomposition in air it emits very toxic fumes of BeO. Reacts with Li and P. 

SAFETY PROFILE Confirmed carcinogen with experimental mmorigenic data. When heated to decomposition in air it emits very toxic fumes of BeO. See also BERYLLIUM COMPOUNDS and NIOBIUM. 

The membrane should be a continuous layer, free of defects. Fortunately, due to the synthesis procedure, this can be easily checked for the silicalite-1 membrane. After synthesis the template molecule, tetrapropyl ammonium hydroxyde, is still present and blocks all the pores. This is removed by thermal decomposition in air ( calcination ) at 673 K. During calcination the membrane is placed in the cell and a mixture of Kr in air is used for calcination. A good membrane does not permeate Kr at room temperature and should develop permeability for Kr during the calcination procedure. Ths is illustrated by Figure 13 which shows the permeation development of Kr as a function of time, at a heating rate of 1 K/min. Already around 500 K some permeation is observed, but the large breakthrough is observed above 600 K, until a steady-state permeation level is reached. 

Radwan et al. [110] studied the solid products of decomposition in air as potential catalysts. 

Though salt dehydration was not accompanied [27] by particle disintegration, the anhydrous pseudomorph was shown by X-ray diffiaction measurements to be very poorly crystallized (a characteristic feature of many nickel carboxylates). Decomposition in air (554 to 631 K) proceeded at a constant rate (0.1 < nr < 0.8 and = 96 kJ mol" ), ascribed to the operation of an autocatalytic mechanism. The reaction in vacuum (562 to 610 K) gave a sigmoid ar-time curve which was fitted by the Prout-Tompkins equation. Because the activation energy was the same as that for reaction in air, it was concluded that the same mechanism operated. The reaction in air yielded residual nickel oxide, while reaction in vacuum gave the carbide with excess carbon and some oxide. In addition to carbon dioxide, the volatile products of decomposition included water and acetic acid. 

Properties Deep brown to yellow liquid usually has faint odor. Refr index 1.5367 (25C), d 1.26 (25/4C), bp 375C, fp 6C, vap press 0.003 mm Hg (24C). Very slightly soluble in water (20 ppm) completely soluble in esters, alcohols, ketones, ethers, aromatic hydrocarbons, animal and vegetable oils insoluble in petroleum ether, kerosene, spray oils stable in distilled water and in acid solution hydrolyzed in the presence of alkaline materials slow decomposition in air. 

Radiation-induced changes in a-lead azide caused by X-rays were noted by Todd and Party [88, 89]. The hardness was changed by exposure to soft X-rays. With an X-ray dose rate of 1.4 X 10 R/min in air, the decomposing crystal expanded prefentially along the b axis of its crystal structure. More than 97% de-stmction of the azide was achieved with a total dose of 3.4 X 10 R. It was also shown that the stable endproduct of X-ray decomposition in air was basic lead carbonate of the formula 2PbCO3 Pb(OH)3. After a dose of 6.7 X lO R, there was evidence of residual lead azide together with an unidentified phase. Higher doses produced a further unidentified phase before stable basic lead carbonate was finally formed. 

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