Ammonia cation

Although Phase I of a TIE characterizes the types of toxicants suspected of being active in a sample, Phase II is designed to identify the specific toxicant(s) active. Methods for accomplishing this objective are described for freshwater samples in Durhan et al. (1993). Specific Phase II marine TIE methods are not available but Phase II of a marine TIE can be performed based on Durhan et al. (1993) methods. The procedures used to identify active toxicants characterized in Phase I are specifically designed to demonstrate the role of non-polar organic toxicants, ammonia, cationic metals, oxidants and filterable toxicants. 

In aminations requiring copper, it appears that copper ammonia cations complex with the chloro compound and that this complex addition compound acts as a cyclic catalyst by reacting with ammonia, —OH ion, and the amine. ... 

Elution order of alkali and alkaline earth metals and ammonia cations depends on many factors (e.g., column selectivity, eluent type) but is usually as follows Li+, Na, NH4+, K+, Mg +, Ca +, and Ba +. 

Quaternary ammonia (cationic products) with a surfactant effect. 

Finally it is worth mentioning that the clusters of ammonia cation, with... 

H2 molecules—(NH4 )-(H2)n (n up to 8) were calculated [69,78]. It was also found that the whole molecular surface of ammonia cation (0.001 au electron density surface was considered) is characterized by the positive EP however the EP maxima are attributed to H-atoms [50]. Hence the increase of the number of molecular hydrogen molecules surrounding ammonia cation results in the N-H...o hydrogen bonds formation and when all N-H bonds are saturated by those interactions (for n = 4) thus next H2 molecules (for clusters with n > 5) are linked with the nitrogen center of the cation, however aU H2 molecules for those clusters act as Lewis bases through their o-electrons. The situation is very similar to that one occurring for the (NH4 )-(HCN) clusters [61] mentioned earlier here (see also Fig. 15.16). 

Figure C2.12.2. Fonnation of Br0nsted acid sites in zeolites. Aqueous exchange of cation M witli an ammonium salt yields tlie ammonium fonn of tlie zeolite. Upon tliennal decomposition ammonia is released and tire proton remains as charge-balancing species. Direct ion-exchange of M witli acidic solutions is feasible for high-silica zeolites.

By analogy, ammonium salts should behave as acids in liquid ammonia, since they produce the cation NH4 (the solvo-cation ), and soluble inorganic amides (for example KNHj, ionic) should act as bases. This idea is borne out by experiment ammonium salts in liquid ammonia react with certain metals and hydrogen is given off. The neutralisation of an ionic amide solution by a solution of an ammonium salt in liquid ammonia can be carried out and followed by an indicator or by the change in the potential of an electrode, just like the reaction of sodium hydroxide with hydrochloric acid in water. The only notable difference is that the salt formed in liquid ammonia is usually insoluble and therefore precipitates. 

Aqueous ammonia can also behave as a weak base giving hydroxide ions in solution. However, addition of aqueous ammonia to a solution of a cation which normally forms an insoluble hydroxide may not always precipitate the latter, because (a) the ammonia may form a complex ammine with the cation and (b) because the concentration of hydroxide ions available in aqueous ammonia may be insufficient to exceed the solubility product of the cation hydroxide. Effects (a) and (b) may operate simultaneously. The hydroxyl ion concentration of aqueous ammonia can be further reduced by the addition of ammonium chloride hence this mixture can be used to precipitate the hydroxides of, for example, aluminium and chrom-ium(III) but not nickel(II) or cobalt(II). 

The solid readily dissolves chemically in concentrated hydrochloric acid, forming a complex, and in ammonia as the colourless, linear, complex cation [H3N -> Cu <- NHj] (cf AgCl) if air is absent (in the presence of air, this is oxidis to a blue ammino-copper(II) complex). This solution of ammoniacal copper(I) chloride is a good solvent or carbon monoxide, forming an addition compound CuCl. CO. H2O, and as such is used in gas analysis. On passing ethyne through the ammoniacal solution, a red-brown precipitate of hydrated copper(I) dicarbide (explosive when dry) is obtained ... 

The aquo-complex [ZnlHjOlg] and the tetrahedral [ZnCU] have already been mentioned. Numerous hydroxo-complexes, foi example [ZnfOH) ], [Zn(OH)4] have been described. Additior. of excess ammonia to an aqueous Zn(II) solution produces the tetraamminozinc cation [Zn(N 113)4]-. Hence zinc tends to form 4-coordinate, tetrahedral or (less commonly) 6-coordinate octahedral complexes. 

Silver chloride is readily soluble in ammonia, the bromide less readily and the iodide only slightly, forming the complex cation [Ag(NH3)2]. These halides also dissolve in potassium cyanide, forming the linear complex anion [AglCN) ] and in sodium thiosulphate forming another complex anion, [Ag(S203)2] ... 

Neutral and Cationic Ligands. Neutral and cationic ligands are used without change in name and are set off with enclosing marks. Water and ammonia, as neutral ligands, are called aqua and ammine, respectively. The groups NO and CO, when linked directly to a metal atom, are called nitrosyl and carbonyl, respectively. 

Lactams can also be polymerized under anhydrous conditions by a cationic mechanism initiated by strong protic acids, their salts, and Lewis acids, as weU as amines and ammonia (51—53). The complete reaction mechanism is complex and this approach has not as yet been used successfully in a commercial process. 

In 1945, cationic urea resins were introduced and quickly supplanted the anionic resins, since they could be used with any type of pulp (62). Although they have now become commodities, their use in the industry has been steadily declining as the shift towards neutral and alkaline papermaking continues. They are commonly made by the reaction of urea and formaldehyde with one or more polyethylene—polyamines. The stmcture of these resins is very compHcated and has not been deterrnined. Ammonia is evolved during the reaction, probably according to the following ... 

Dispersions to be added to latex must have good storage stabiHty and be compatible with the latex the pH of each should be similar to that of the latex, eg, pH 8.5—11 for ammonia-preserved latex and pH 3.5 for cationic-preserved concentrates. Addition of low pH materials to high pH latex or vice versa generally results in mutual precipitation and coagulation of the suspended mbber particles. 

The y-radiation-induced polymerization requires an extremely high purity reaction system. Trace amounts of water can terminate a cationic reaction and inhibit polymerization. Organic bases such as ammonia and trimethylamine also inhibit polymerization. The y-radiation-induced polymerization of a rigorously dried D obeys the Hayashi-WilHams equation for completely pure systems (150). 

---