Acetone ions, decomposition

Tetramethyl-l,2-oxathietane (138) was prepared by diazotization of 139, which was prepared from the aziridine (140) (86JA3811).Tlie reaction presumably involves the decomposition of the sulfonium ion intermediate (141).Tire dichloromethane solution of 138 at -20°C is sufficiently stable to permit exploration of the chemical reactions. Tire oxathietane 138 undergoes a formal [[Pg.248]

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. 

Owing to the rapid decomposition of the cyanate ion in water, the use of aprotic solvents was necessary for the preparation of the Ag(NCO)J ion. Since alkali cyanates are poorly soluble in aprotic solvents, the cyanate salts used were the tetraethylammonium, tetramethylammonium and tetraphenylarsonium cyanates. Either dry acetone or acetonitrile could be used as solvent as silver isocyanate was reasonably soluble in both. Once prepared the silver salts were found to be light- and moisture-sensitive.136-137... 

The complex /rara-PtH(02CH)[PEt3]2 catalyzes the decomposition of formic acid in the presence of sodium formate. A mechanism based on the equilibria described in Scheme 2 has been proposed by Paonessa and Trogler (60). The role of formate ion is to promote catalysis by reaction with the platinum dimer (10) or the solvated complex [frans-PtH(S)L2]+, where S = acetone, to reform the catalytically active monomeric species 11 and 12. 

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