Nonoxidizing anions

Ammonium salts decompose when heated if the salt contains a nonoxidizing anion, NH3 is produced. The reaction is (NH4)2S04(s) — 2NH3(g) + H2S04(1). 

There is good evidence that the general solution of many metals in their molten salts may be classified as oxidation-reduction equilibria, although in order to include properly the entire range of metals involved the definition probably must be extended to include general delocalization as well as discrete transfer of valence electrons. The evidence for this classification is fairly direct in that metals evidently dissolve only in their own molten salts (nonoxidizing anions) since attempts to form mixed solutions result either in no appreciable reaction (Pb in CaCh) or in a normal, two-phase oxidation-reduction (Cd in PbCR) superimposed on the reaction of interest. 

Again, in aqueous solution, the reaction proceeds on oxidized noble metal surfaces and, at the potentials at which it takes place, the reactant anion, RCOO , is strongly adsorbed. The R must be aliphatic at the a carbon as the Kolbe reaction does not proceed if, for example, benzoic acid is the reactant however, fi-, or y-aryl alkyl carboxylic acids, for example, phenylacetic acid, will undergo the Kolbe coupling reaction but with rather poor efficiency. The reaction will also proceed on nonoxidized noble metal surfaces, for example, Pt in anhydrous CH3COOH or CF3COOH, gettered with acetic anhydride... 

Silver(I) sulfamate is remarkable for its considerable solubility in water over a wide range of temperatures and the fact that the anion is normally nonoxidizing. The substance is also a very important starting material for numerous syntheses of other sulfamates, imidodisulfates, and their derivatives. 

Several other acyl anions or potential acyl anion equivalents bearing at least one nonoxidized sulfur atom have since been proposed, and some of them have been alkylated successfully. This is effectively the case for the following metallated compounds (i) yV-methylthioformaldine (Scheme 73, entry c) (ii) 1,3-oxathianes, and a-trimethylsilylmethyl analogs (iii) a-methoxythioanisole (Scheme 74, entry a Scheme 75, entry the parent compound also allows the synthesis of acetals (on acid-... 

The metal dissolves in dilute mineral acids. It passivates only in nitric acid. At low nonoxidizing potentials, Ni is stable and immime to corrosion attack. The corrosion areas represent regions where the metal is susceptible to corrosion, and is transformed into stable cationic (Nr ) or anionic species (HNiO ) In the passive region, the Ni is coated with oxides Ni02 or Ni203. Ni02 is insoluble in water, but dissolves in acids at... 

There are two types of passivating inhibitors oxidizing anions such as chromate, nitrite, and nitrate, which can passivate steel in the absence of oxygen, and the nonoxidizing ions such as phosphate, tungstate, and molybdate, which require the presence of oxygen to passivate steel. Examples of passivators (anodic inhibitors) include chromate, nitrite, and orthophosphate (Dihua et al. 1999). 

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