Chemical properties Decomposition

Chemical Properties.—Decomposition.—Phosphine is an unstable gas which can be decomposed by heat alone, and is easily oxidised by oxygen and by oxidising agents such as the halogens. 

BrCHi CHjBr. A colourless liquid with a sweet odour, m.p. 10°C, b.p. 132°C. Manufactured by passing ethene through bromine or bromine and water at about 20 C. Chemical properties similar to those of 1,2-dichloroethane when heated with alkali hydroxides, vinyl bromide is formed. Used extensively in petrols to combine with the lead formed by the decomposition of lead tetraethyl, as a fumigant for stored products and as a nematocide. 

The physical and chemical properties are less well known for transition metals than for the alkaU metal fluoroborates (Table 4). Most transition-metal fluoroborates are strongly hydrated coordination compounds and are difficult to dry without decomposition. Decomposition frequently occurs during the concentration of solutions for crysta11i2ation. The stabiUty of the metal fluorides accentuates this problem. Loss of HF because of hydrolysis makes the reaction proceed even more rapidly. Even with low temperature vacuum drying to partially solve the decomposition, the dry salt readily absorbs water. The crystalline soflds are generally soluble in water, alcohols, and ketones but only poorly soluble in hydrocarbons and halocarbons. 

Chemical Properties. The kinetics of decomposition of OF2 by pyrolysis in a shock tube are different, as a result of surface effects, from those obtained by conventional decomposition studies. Dry OF2 is stable up to 250°C (22). 

Zirconium i dride. Zirconium hydride [7704-99-6] ZrH2, is a britde, metaUic-gray soHd that is stable in air and water, and has a density of 5.6 g/cm. The chemical properties of ZrH2 closely resemble those of titanium hydride. Thermal decomposition in vacuum (1 mPa (7.5 x 10 //mHg)) begins at 300°C and is nearly complete at 500—700°C. It is prepared in the same manner as T1H2. 

Chemical Properties. Diacyl peroxides (20) decompose when heated or photoly2ed (<300 mm). Although photolytic decompositions generally produce free radicals (198), thermal decompositions can produce nonradical and radical iatermediates, depending on diacyl peroxide stmcture. Symmetrical aUphatic diacyl peroxides of certain stmctures, ie, diacyl peroxides (20, = alkyl) without a-branches or with a mono-cx-methyl... 

Chemical Properties. Reactions of quaternaries can be categorized iato three types (169) Hoffman eliminations, displacements, and rearrangements. Thermal decomposition of a quaternary ammonium hydroxide to an alkene, tertiary amine, and water is known as the Hoffman elimination (eq. la) (170). This reaction has not been used extensively to prepare olefins. Some cycHc olefins, however, are best prepared this way (171). Exhaustive methylation, followed by elimination, is known as the Hoffman degradation and is important ia the stmctural determination of unknown amines, especially for alkaloids (qv) (172). 

BM Structure, composition, and properties should be similar and (4) the FM-containing elements should be able to bring about chemical reduction/decomposition or physical removal of BM oxide film. 

Chemical Properties. Although hydrogen sulfide is thermodynamically stable, it can dissociate at very high temperatures. The decomposition thermodynamics and kinetics have been reviewed and the equihbrium constant for the reaction has been deterrnined (101,102) ... 

Chemical Properties. The chemistry of the sulfur chlorides has been reviewed (141,142). Sulfur monochloride is stable at ambient temperature but undergoes exchange with dissolved sulfur at 100°C, indicating reversible dissociation. When distilled at its atmospheric boiling point, it undergoes some decomposition to the dichloride, but decomposition is avoided with distillation at ca 6.7 kPa (50 mm Hg). At above 300°C, substantial dissociation to S2 and CI2 occurs. Sulfur monochloride is noncombustible at ambient temperature, but at elevated temperatures it decomposes to chlorine and sulfur (137). The sulfur then is capable of burning to sulfur dioxide and a small proportion of sulfur trioxide. 

Chemical Properties. Anhydrous sodium sulfite is stable in dry air at ambient temperatures or at 100°C, but in moist air it undergoes rapid oxidation to sodium sulfate [7757-82-6]. On heating to 600°C, sodium sulfite disproportionates to sodium sulfate and sodium sulfide [1313-82-2]. Above 900°C, the decomposition products are sodium oxide and sulfur dioxide. At 600°C, it forms sodium sulfide upon reduction with carbon (332). 

Chemical Properties. Anhydrous sodium dithionite is combustible and can decompose exothermically if subjected to moisture. Sulfur dioxide is given off violentiy if the dry salt is heated above 190°C. At room temperature, in the absence of oxygen, alkaline (pH 9—12) aqueous solutions of dithionite decompose slowly over a matter of days. Increased temperature dramatically increases the decomposition rate. A representation of the decomposition chemistry is as follows ... 

Chemical Properties. On thermal decomposition, both sodium and potassium chlorate salts produce the corresponding perchlorate, salt, and oxygen (32). Mixtures of potassium chlorate and metal oxide catalysts, especially manganese dioxide [1313-13-9] Mn02, are employed as a laboratory... 

Chemical Properties. When heated in a dry CO2 atmosphere, sodium cyanide fuses without much decomposition. A brown-black color... 

Physical and Chemical Properties. Because of decomposition, the melting point of calcium cyanide can only be estimated by extrapolation to be 640°C (70). 

Physical and Chemical Properties — Physical State at 15 T7 and 1 atm. Liquid Molecular Weight Mixture Boiling Point at I atm. Decomposes Freezing Point 17, -8,265 Critical Temperature Not pertinent Critical Pressure Not pertinent Specific Gravity 1.2 at 20 °C (liquid) Vapor (Gas) Density Not pertinent Ratio cf Specific Heats cf Vapor (Gas) Not pertinent Latent Heal of Vaporization Not pertinent Heat of Combustion -15,700, -8750 -366 Heat of Decomposition -50, -28, -1.2. 

Observable Characteristics - Physical State (as normally shipped) Liquid Color Colorless to slight yellow Odor Extremely sharp - lachrymator piercing and disagreeable extremely Physical and Chemical Properties - Physical State at 15 °C and 1 atm. Liquid Molecular Weight 56.1 Boiling Point at 1 atm. 127, 53, 326 Freezing Point -125, -87, 186 Critical Temperature 489, 254, 527 Critical Pressure 737, 50.0, 5.08 Specific Gravity 0.843 at 20 °C (liquid) Vcq>or (Gas) Density 1.94 Ratio of Specific Heats of Vapor (Gas) 1.1487 Latent Heat of Vaporization 216, 120, 5.02 Heat of Combustion -12500, -6950, -290 Heat of Decomposition Not pertinent. 

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