Thermal decomposition, aluminum

Uranium can be prepared by reducing uranium halides with alkali or alkaline earth metals or by reducing uranium oxides by calcium, aluminum, or carbon at high temperatures. The metal can also be produced by electrolysis of KUF5 or UF4, dissolved in a molten mixture of CaCl2 and NaCl. High-purity uranium can be prepared by the thermal decomposition of uranium halides on a hot filament. 

Physical properties of hexachloroethane are Hsted in Table 11. Hexachloroethane is thermally cracked in the gaseous phase at 400—500°C to give tetrachloroethylene, carbon tetrachloride, and chlorine (140). The thermal decomposition may occur by means of radical-chain mechanism involving -C,C1 -C1, or CCl radicals. The decomposition is inhibited by traces of nitric oxide. Powdered 2inc reacts violentiy with hexachloroethane in alcohoHc solutions to give the metal chloride and tetrachloroethylene aluminum gives a less violent reaction (141). Hexachloroethane is unreactive with aqueous alkali and acid at moderate temperatures. However, when heated with soHd caustic above 200°C or with alcohoHc alkaHs at 100°C, decomposition to oxaHc acid takes place. 

Several methods are described for the production of tantalum and niobium metal. Metals can be obtained by reduction of pentachlorides with magnesium, sodium, hydrogen or by thermal decomposition in vacuum [24,28]. Oxides can be reduced using carbon, aluminum, calcium, magnesium [28, 537, 538] or alkali and rare earth metals [539]. 

In addition to these lowtemperature thermal processes, aluminum can be deposited by the decomposition of an alkyl precursor with a UV laser, or with an argon-ion laser in applications such as patterns and... 

Some of the investigations carried out in the first half of the twentieth century were related to CL associated with thermal decomposition of aromatic cyclic peroxides [75, 76] and the extremely low-level ultraviolet emission produced in different reaction systems such as neutralization and redox reactions involving oxidants (permanganate, halogens, and chromic acid in combination with oxalates, glucose, or bisulfite) [77], In this period some papers appeared in which the bright luminescence emitted when alkali metals were exposed to oxygen was reported. The phenomenon was described for derivatives of zinc [78], boron [79], and sodium, potassium, and aluminum [80]. 

Contrary to the statements of Schulman etal. (81) and Taft et al. (77), there is very little similarity between thermal decomposition of aluminum alkoxides and dehydration of alcohols over aluminas. The thermal decomposition mechanism would not explain the skeletal isomerization occurring during the dehydration of 2-methyl-1-propanol (82). 

P.J. Herley, O. Chiistofferson, R.H. Irwin, Decomposition of a-aluminum hydride powder. 1. Thermal decomposition, J. Phys. Chem. 85 (1981) 1874-1881. 

Activation by Thermal Decomposition of Metallic Oxides. The surface of alumina, AI2O3, may be activated by employing laser or ultraviolet irradiation to decompose AI2O3 (68). Decomposition of AI2O3 results in the generation of aluminum particles that are catalytic for electroless deposition of Cu (the first reaction probably is displacement deposition). 

The hydrazide of 2,2-diphenyl-3-hydroxypropanoic acid was reduced with lithium aluminum hydride in 7V-ethylmorpholine at 100° to 3-amino-2,2-di-phenylpropanol in 72.5% yield [1145], Much more useful is reduction of N-arenesulfonylhydrazides of acids to aldehydes McFadyen-Stevens reduction) [284, 285] based on an alkali-catalyzed thermal decomposition according to Scheme 174. 

High-temperature HCl molecules tend to react with metal particles. When particles of Na compounds or Mg particles are incorporated into AP composite propellants, sodium chloride or magnesium chloride are formed. In general, aluminum particles are incorporated into AP composite propellants. However, Cl atoms or CI2 molecules generated by the decomposition of AP react with H2O molecules to produce HCI molecules. Chemicals containing Na or Mg atoms react with HCI after their thermal decomposition. 

In an atmosphere of nitric oxide, thermal decomposition produces barium nitrite, Ba(N02)2. Reactions with soluble metal sulfates or sulfuric acid yield barium sulfate. Many insoluble barium salts, such as the carbonate, oxalate and phosphate of the metal, are precipitated by similar double decomposition reactions. Ba(N03)2 is an oxidizer and reacts vigorously with common reducing agents. The solid powder, when mixed with many other metals such as aluminum or zinc in their finely divided form, or combined with alloys such as... 

Aluminum nitride UFPs have been synthesized by thermal decomposition from many kinds of precursor such as polyminoalanef l/ ) AIH(NR)] (50), aluminum polynuclear complexes of basic aluminum chloride (BAC) or basic aluminum lactate (BAL) (51), and (hydroxo)(succinato) aluminum(lll) complex, A1(0H)(C4H404) jfLO (52). These precursors were calcined under N2 or NH, gas flow. The calcination temperatures, which depend on the individual precursor, can be lower by 600-200°C than the 1700°C in ihe conventional carbothermal reduction method. The XRD measurements at intermediate stages of the calcination process showed the phase change from an amorphous state to a trace of y-alumina with very fine grains and finally to wurtzite-type AIN (51,52). Lowering the calcination... 

Reduction of 1-ethoxycarbonyl-l/f-azepine with lithium aluminum hydride in ether at -15 °C yields the thermally unstable 1-(hydroxymethyl) derivative in boiling ether further reduction occurs to N-methyl- lH-azepine, which subsequently dimerizes to the [6+6]ir adduct (see Section 5.16.3.2.3) (B-69MI51600). Surprisingly, the action of phenyllithium on 1 -ethoxycarbonyl-l//-azepine produced the carbinol (2 R CPlhOH, R2 = H), thermal decomposition of which led to the first characterization of 3//-azepine (73CB1033). 

Thiepane (35) has been purified by distillation at normal pressure (b.p. 170-174 °C) and may therefore be considered a thermally stable compound. At higher temperatures (400 °C) and in the presence of an aluminum silicate catalyst, however, thermal decomposition does occur to give hydrogen sulfide as one product (72HC(26)573). 

Evaporation of solutions of alumina in sulfuric acid yields crystals of A12(S04)3T6H20. If a group I sulfate is also present, the products are alums MA1(S04)2T2H20, in which aluminum exists as [Al(OH2)fi]3+. Analogous selenates but not tellurates have been prepared. Basic salts, e.g. Al2(OH)2(SO4)210H2O, and solids obtained from aluminum sulfate solutions above 100 °C also contain complex ions in which the coordination sphere of Al3+ is occupied by OH groups and/or water molecules rather than sulfate ions. Thermal decomposition of the hydrate A12(S04)3-16H20 yields practically anhydrous A12(S04)3 at 450 °C further decomposition to... 

In two patents40 41 the thermal disproportionation of chlorofluorobenzenes is claimed. The data given show that the additives used have an influence on the conversion of the disproportionation of l,3,5-trichloro-2,4,6-trifiuorobcnzcnc and 1,3-dichloro-2,4,5,6-tetrafiuoroben-zene. The additives are aluminum trifluoride (prepared by thermal decomposition of NH4-A1F4), cesium fluoride, and aluminum trifluoride on magnesium fluoride. 

Herley et al, Recent Radiation Effect Studies on Ammonium Perchlorate. Part II The Effect of Fast Neutron, Gamma Ray and Combined Radiation on the Thermal Decompositions of- Ammonium Perchlorate Powder—Aluminum Particle Mixtures , Ibid, paper 2.2b, pp 301—15 (1975) 242) W.D. Hutchinson, Neutron Effects on Solid Propellants , Ibid, paper 2.6, pp 281-99 (1975) 243) R.A. Benham F.H. Mathews,... 

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