Acetone decomposition effects

During water-gas shift in pyridine solution, they isolated [PtH(py)L2]BF4, while from water-gas shift run in acetone solution, they isolated raft -[PtF[(CO)L2]BF4. The results indicated a solvent effect. That is, it was difficult to substitute coordinated pyridine with CO, but it was easier to substitute acetone with CO, via [PtH(Solvent)L2]OH + CO <-> [PtH(CO)L2]OH + Solvent. Following this important solvent-facilitated CO addition, they proposed a nucleophilic attack of OH-on the coordinated CO, via [PtH(CO)L2]OH <-> [PtH(COOH)L2]. The next step is thermal decomposition of the species, liberating C02, via the decomposition [PtH(COOH)L2] <-> [PtH2L2] + C02. CO addition was proposed to assist in decomposing the hydride to liberate H2. A more detailed description of the catalytic cycle is provided in Scheme 19. 

There are certain reactions, e.g. inversions of sucrose and methane etc. in which the rate of reactions were found to be proportional to the concentration of H+ ions. Similarly, there are reactions which are catalyzed by OH ions, e.g. conversion of acetone into diacetone alcohol or decomposition of nitroso-triacetoneamine. These are known as specific hydrogen ion catalyzed or specific hydroxyl-ion catalyzed reactions. Also there are some reactions in which both H+ and OFF ions act as catalysts probably along with water. The undissociated acid or base have negligible effect on the rate of reaction. The hydrolysis of ester is an example in which both H+ and OH ions act as catalyst... 

In formamide, acetone, and nitromethane the bromide ion is the most mobile of the halides. The difference is slight in nitromethane, but pronounced in the other two solvents. Because mobilities reflect a variety of factors it is possible that opposing effects could result in an ion of intermediate size being more mobile than others in the series. Another possible factor could be the presence of impurities in formamide and acetone, formamide because of decomposition on standing even a short time, and acetone because of the difficulty in removing last traces of water. The presence of impurities could have a significant but unpredictable effect on mobilities. 

Acetylene is widely sold as the fuel for welding torches, and it is stored in large cylinders at high pressures in many welding shops. In fact, this acetylene is mixed with acetone, which has been found to be an effective scavenger of acetylene decomposition, so that these tanks are relatively safe. 

The kinetic and activation parameters for the decomposition of dimethylphenylsilyl hydrotrioxide involve large negative activation entropies, a significant substituent effect on the decomposition in ethyl acetate, dependence of the decomposition rate on the solvent polarity (acetone-rfe > methyl acetate > dimethyl ether) and no measurable effect of the radical inhibitor on the rate of decomposition. These features indicate the importance of polar decomposition pathways. Some of the mechanistic possibilities involving solvated dimeric 71 and/or polymeric hydrogen-bonded forms of the hydrotrioxide are shown in Scheme 18. 

Trinitrotriazidobenzene is insoluble in water, easily soluble in acetone and moderately soluble in chloroform and alcohol. It is not hygroscopic and is moisture-resistant. In the presence of moisture it has no effect on iron, steel, copper or brass. At its melting point, 131°C, it undergoes decomposition to evolve nitrogen and to form benzotrifuroxane ( hexanitrosobenzene ) also an explosive substance (Vol. I, p. 603). 

The slow combustion reactions of acetone, methyl ethyl ketone, and diethyl ketone possess most of the features of hydrocarbon oxidation, but their mechanisms are simpler since the confusing effects of olefin formation are unimportant. Specifically, the low temperature combustion of acetone is simpler than that of propane, and the intermediate responsible for degenerate chain branching is methyl hydroperoxide. The Arrhenius parameters for its unimolecular decomposition can be derived by the theory previously developed by Knox. Analytical studies of the slow combustion of methyl ethyl ketone and diethyl ketone show many similarities to that of acetone. The reactions of methyl radicals with oxygen are considered in relation to their thermochemistry. Competition between them provides a simple explanation of the negative temperature coefficient and of cool flames. 

Solvent Effect. The effect of solvent when using an organic soluble molybdenum catalyst is shown in Table IV. Nonpolar solvents such as benzene and methylcyclohexane give higher conversions and yields than polar solvents such as ethyl alcohol and tert-butyl alcohol. Acetone is an especially poor solvent. The low conversion is caused by competition between the solvent and hydroperoxide for molybdenum catalyst. The poor yield of epoxide is primarily caused by hydroperoxide decomposition... 

Formamide is an excellent solvent for many polar organic compounds and for a selection of inorganic salts. It is very hygroscopic and readily hydrolysed by acids or bases. The commercial product frequently contains formic acid, water and ammonium formate. Purification may be effected by passing ammonia gas into the solvent until a slight alkaline reaction is obtained addition of dry acetone then precipitates the ammonium formate. The filtered solution is dried over magnesium sulphate and fractionally distilled under reduced pressure distillation at atmospheric pressure causes decomposition. Pure formamide has b.p. 105 °C/11 mmHg. 

Capello et al.16 applied LCA to 26 organic solvents (acetic acid, acetone, acetonitrile, butanol, butyl acetate, cyclohexane, cyclohexanone, diethyl ether, dioxane, dimethylformamide, ethanol, ethyl acetate, ethyl benzene, formaldehyde, formic acid, heptane, hexane, methyl ethyl ketone, methanol, methyl acetate, pentane, n- and isopropanol, tetrahydrofuran, toluene, and xylene). They applied the EHS Excel Tool36 to identify potential hazards resulting from the application of these substances. It was used to assess these compounds with respect to nine effect categories release potential, fire/explosion, reaction/decomposition, acute toxicity, irritation, chronic toxicity, persistency, air hazard, and water hazard. For each effect category, an index between zero and one was calculated, resulting in an overall score between zero and nine for each chemical. Figure 18.12 shows the life cycle model used by Capello et al.16... 

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