Salts, inert metal complexes effects

Hence, the first clearcut evidence for the involvement of enol radical cations in ketone oxidation reactions was provided by Henry [109] and Littler [110,112]. From kinetic results and product studies it was concluded that in the oxidation of cyclohexanone using the outer-sphere one-electron oxidants, tris-substituted 2,2 -bipyridyl or 1,10-phenanthroline complexes of iron(III) and ruthenium(III) or sodium hexachloroiridate(IV) (IrCI), the cyclohexenol radical cation (65" ) is formed, which rapidly deprotonates to the a-carbonyl radical 66. An upper limit for the deuterium isotope effect in the oxidation step (k /kjy < 2) suggests that electron transfer from the enol to the metal complex occurs prior to the loss of the proton [109]. In the reaction with the ruthenium(III) salt, four main products were formed 2-hydroxycyclohexanone (67), cyclohexenone, cyclopen tanecarboxylic acid and 1,2-cyclohexanedione, whereas oxidation with IrCl afforded 2-chlorocyclohexanone in almost quantitative yield. Similarly, enol radical cations can be invoked in the oxidation reactions of aliphatic ketones with the substitution inert dodecatungstocobaltate(III), CoW,20 o complex [169]. Unfortunately, these results have never been linked to the general concept of inversion of stability order of enol/ketone systems (Sect. 2) and thus have never received wide attention. 

Inorganic and organic alternate valence metal salts and their complexes inhibit O2 absorption and mass loss in PAl at heating in the presence of O2 at high temperature (for example, Figure 9). Under these conditions, non-transition metal compounds are inert. The effect of 0.05 - 1.0 wt.% additions of transition metal compounds on PAl thermal oxidation is... 

The effect of neutral salts (e.g., NaCl) on the composition of borates precipitated from, or in equilibrium with, aqueous solutions doubtless arises from a reduction in water activity, metal borate complexation, and a shift in polyborate equilibria (Sections IV,A, B). The "indifferent or inert component method has frequently been used for the synthesis of borates. Potassium and sodium chlorides can be used to enhance the precipitation of specific nickel (48), aluminum (51), iron (49), and magnesium (151) borates. In the K20-B203-H20 system at 25°C (248), the presence of potassium chloride results in a reduced boric acid crystallization curve, lower borate solubilities, lower pH, and an extended B203 K20 range over which the pentaborate crystallizes. 

In systems where only water molecules are coordinated to the metal ion (but not the organic component), the cause of the higher complex stability is the lower stability of the aquo complex, which is due to the reduced water activity resulting from dilution by the organic solvent [Be 70]. A similar effect may be achieved if the water activity of an aqueous solution is diminished by the dissolution of an inert salt, as shown by the complex stability measurements of Burger et al, [Bu 68] in concentrated alkali metal perchlorate solutions. 

The catalytic effects of salts of Cu(II), Co(II), Al(III) and Ti(IV) on the esterification of acetic acid by BuOH have been studied. Weak acid salts of these metals were inert as catalysts, but sulfates of metals of higher valence state, e.g. Ti(S04)2, were found to be good catalysts.The kinetics of oxidation of ring-substituted cinnamic acids (195) by iodate in aqueous acetic acid containing Ru(III) have been reported. The reaction products were formaldehyde and the corresponding benzaldehyde (196). A mechanism involving the formation of a complex between the acid and Ru(III), which reacts with the oxidant in a slow step, was proposed. ... 

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