Ammonium complexes

For deliming, ammonium salts and acids are used. The proportion of ammonium salts to acids and the type of acids employed is a matter of the tanner s choice. The acid neutralizes the lime, Ca(OH)2, thereby adjusting the pH. The ammonium salts have two functions to buffer the solution to a pH required for bating, and to form calcium ammonium complexes. The acidity and the complex formation solubilize the calcium and serve to bring the hide to the desired pH. 

Ammonium complex fluorometalates are generally susceptible to hydrolysis by water formed in the course of the fluorination process (see 25). Such interactions, resulting in the formation of oxyfluoride metalates can be described as follows ... 

Predominant formation of either complex fluoride or complex oxyfluoride depends on the interaction rates ratio of processes (25) and (26). The relatively high interaction rates of (27) and (28) lead to the synthesis of simple fluorides or oxyfluorides, respectively. With the availability of two or more cations in the system, the ammonium complex fluorometalates interact forming stable binary fluorides or oxyfluorides or mixtures thereof. 

Although this reaction may cause slight problems, the primary issue concerning ammonia is ammoniacal corrosion of CR system metals where oxygen is present and the pH is over 8.3. Under these circumstances, copper and its alloys and other nonferrous metals are attacked, and severe damage results due to the formation of a stable cupric ammonium complex ion. 

Halogens are frequently used as oxidation agents and, under two-phase conditions, they can either be employed as ammonium complex halide salts [3], or in the molecular state with or without an added quaternary ammonium catalyst [4]. Stoichiometric amounts of tetra-n-butylammonium tribromide under pH controlled conditions oxidize primary alcohols and low-molecular-weight alkyl ethers to esters, a,cyclic ethers produce lactones [3], and secondary alcohols yield ketones. Benzoins are oxidized to the corresponding benzils (80-90%) by the tribromide salts in acetonitrile in the presence of benzoyl peroxide [5]. 

To the second half of the raffinate, ammonia is added to form a nickel ammonium complex, which is extracted with a hydroxyaryloxime (LIX84). Due to simultaneous formation of metal hydroxides, the solution is carefully... 

The first step in the hydrometallurgical treatment is leaching the feed material with an ammoniacal solution. Metals such as copper, nickel, and zinc form metal ammonium complexes and will therefore dissolve in the leach solution. Other metals like iron and chromium form insoluble hydroxides and will be found in the residue. This residue is dried and treated in the induction converter. Copper and nickel are separated from the filtered leach... 

The iiii stereochemistry of the host is of prime importance for the stability of the ammonium complexes. As an example weak association was measured between c-hexylammonium cation and the iiio isomer of phosphato-cavitand 10b (fCa=1370 [58]. We will see in the next section that the... 

Cadmium carbonate forms a cyanide complex ion, Cd(CN)42+ in cyanide solutions. It dissolves in concentrated aqueous solutions of ammonium salts forming ammonium complexes. 

Na2PtCl6 to ammonium platinum chloride (NH4)2PtCl6. The purified ammonium complex is then ignited to form platinum sponge. 

Hydrazine Nitrate Complexes. Salts of bivalent metals (Ni, Co, Zn, Cd and Mn) of complex hydrazine nitrates may be represented by the following formulas [M(N 2H4 )2 ] (N03 )2, or by [M(N2 H, )3 ] (N03 )2. In these complexes, called nitrohydrazinates, each N Ii, group plays the same role as two NH3 groups in the corresponding ammonium complexes... 

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