Acetate anions, decomposition

The fusion of uranium oxides with alkali or alkaline earth carbonates, or thermal decomposition of salts of the uranyl acetate anion, gives orange or yellow materials generally referred to as uranates, for example,... 

At temperatures greater than a 100°C, thermal degradation of carboxylic acids produces methane and carbon dioxide (Surdam et ai, 1984). As the carboxylic acid anions are consumed due to increasing temperature, the carbonate system becomes internally buffered, and thus the pH may decrease due to increased in the system, leading to carbonate dissolution and the enhancement of secondary porosity (Surdam et ai, 1984). Factors influencing the thermal destruction rate of organic acids include coupled sulphate reduction and hydrocarbon oxidation, and the mineralogy of host sediments (Bell, 1991) the presence of hematite causes rapid rates of acetic acid decomposition. 

In a search for an aprotic solvent for acidity function studies with (Li, Na, K) acetate eutectic at200°C (Na, K)SCN was suitably miscible however, even small concentrations (1 %) inhibited the known reaction of trimethylol-ethane, which probably requires proton abstraction by the acetate anion to form an alkoxide intermediate. Since haloacetates are weaker bases than acetates, these salts were considered for diluents. Potassium trifluoroacetate (mp 135-I37°C), reported to be the most stable member of the series, was prepared from potassium hydroxide and excess trifluoroacetic acid with vacuum drying and fractional recrystallization from absolute alcohol. DTA of the white crystalline product detected decomposition as low as 125°C. Since the molten salt decomposed with bubbling at I45-150°C, this effort was discontinued. 

If, after the nitrogen molecule has been ejected, the p orbital of the cation and the counter ion are not aligned for orbital overlap, some rotation of the cation will be required for bonding. In some cases, sufficient rotation will occur so that bond formation can occur on what was the back side of the cation thus the intramolecular inversion observed in the nitrosoamide decomposition and the nitrous add deamination can be accounted for at this stage in the reaction. This interpretation also accounts for the fact that in the acetic acid decomposition of the tolyltriazene of 1-phenylethylamine, the reaction of the cation with tolylamine proceeds with more retention of configuration than the reaction of the cation with the add anion that is, the position of the counter ion with respect to the cation determines the overall stereospecificity (section b). 

When diazomethane is slowly added to excess lactam, the anions formed can interact with unreacted lactam by means of hydrogen bonds to form ion pairs similar to those formed by acetic acid-tri-ethylamine mixtures in nonpolar solvents. The methyldiazonium ion is then involved in an ion association wdth the mono-anion of a dimeric lactam which is naturally less reactive than a free lactam anion. The velocity of the Sn2 reaction, Eq. (7), is thus decreased. However, the decomposition velocity of the methyldiazonium ion, Eq. (6a), is constant and, hence, the S l character of the reaction is increased which favors 0-methylation. It is possible that this effect is also involved in kinetic dependence investigations have shown that with higher saccharin concentrations more 0-methylsaccharin is formed. 

Salts of diazonium ions with certain arenesulfonate ions also have a relatively high stability in the solid state. They are also used for inhibiting the decomposition of diazonium ions in solution. The most recent experimental data (Roller and Zollinger, 1970 Kampar et al., 1977) point to the formation of molecular complexes of the diazonium ions with the arenesulfonates rather than to diazosulfonates (ArN2 —0S02Ar ) as previously thought. For a diazonium ion in acetic acid/water (4 1) solutions of naphthalene derivatives, the complex equilibrium constants are found to increase in the order naphthalene < 1-methylnaphthalene < naphthalene-1-sulfonic acid < 1-naphthylmethanesulfonic acid. The sequence reflects the combined effects of the electron donor properties of these compounds and the Coulomb attraction between the diazonium cation and the sulfonate anions (where present). Arenediazonium salt solutions are also stabilized by crown ethers (see Sec. 11.2). 

Many of these salts melt or sublime before or during decomposition and reaction temperatures generally increase with molar mass. Thermal analyses for a selection of ammonium carboxylates have been given by Erdey et al. [915] who conclude that the base strength of the anion increases with temperature until it reaches that of NH3. Decompositions of ammonium acetate (>333 K) and ammonium oxalate (>473 K) proceed through amide formation. Ammonium benzoate and ammonium salicylate sublime (>373 K) without decomposition but ammonium citrate decomposes (>423 K) to yield some residual carbon. 

First, a-nitrosoalkenes can be generated from BENAs in the presence of bases, for example, of triethylamine (499), which can initiate chain decomposition of these nitroso acetals (Eq. 1). Then, the more active trialkylsiloxy anion is involved in this process. (Apparently, this is responsible for the well-known spontaneous decomposition of BENA in the presence of nitrogen bases.)... 

The formation of RDX cluster ions in LC/MS and the origin of the clustering agents have been studied in order to determine whether the clustering anions originate from self-decomposition of RDX in the source or from impurities in the mobile phase [19], IsotopicaUy labeled RDX ( C3-RDX and Ng-RDX) were used in order to estabhsh the composition and formation route of RDX adduct ions produced in ESI and APCI sources. Results showed that in ESI, RDX clusters with formate, acetate, hydroxyacetate and chloride anions, present in the mobile phase as impurities at ppm levels. In APCI, part of the RDX molecules decompose, yielding NO2 species, which in turn cluster with a second RDX molecule, producing abundant [M- -N02] cluster ions. 

Furthermore, the heterolysis reaction is catalyzed by the addition of anions (organic and inorganic oxy anions, e.g., acetate) (44,107, 110,111). Comparing the acetate effect in the presence of different chelating ligands ([15]aneN4 and nta) to those of the aquated system led to the conclusion that the oxy anions have to occupy the trans position to the R group in order to labilize the M-R bond (trans labilization effect) and thus catalyze the heterolytic decomposition (44,107,110,111). 

It is possible that some acetate radicals are formed by the direct discharge of the ions as, it will be seen shortly, is the case in non-aqueous solutions but an additional mechanism must be introduced, such as the one proposed above, to account for the influence of electrode material, catalysts for hydrogen peroxide decomposition, etc. It is significant that the anodes at which there is no Kolbe reaction consist of substances that are either themselves catalysts, or which become oxidized to compounds that are catalysts, for hydrogen peroxide decomposition. By diverting the hydroxyl radicals or the peroxide into an alternative path, viz., oxygen evolution, the efficiency of ethane formation is diminished. Under these conditions, as well as when access of acetate ions to the anode is prevented by the presence of foreign anions, the reactions mentioned above presumably do not occur, but instead peracetic acid is probably formed, thus,... 

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