Ammoniation reactions

Ammoniation reactions. When solids crystallize from aqueous solutions, many are obtained as hydrates. In an analogous way, ammonia forms ammoniates ... 

Antiseptics. Ammoniated mercury [10124-48-8] Hg(NH2)Cl, is a white odorless powder that is iasoluble ia water and has a specific gravity of 5.38. It is formed by the reaction of aqueous ammonia (qv) and mercuric chloride. 

Ammonia forms a great variety of addition or coordination compounds (qv), also called ammoniates, ia analogy with hydrates. Thus CaCl2 bNH and CuSO TNH are comparable to CaCl2 6H20 and CuSO 4H20, respectively, and, when regarded as coordination compounds, are called ammines and written as complexes, eg, [Cu(NH2)4]S04. The solubiHty ia water of such compounds is often quite different from the solubiHty of the parent salts. For example, silver chloride, AgQ., is almost iasoluble ia water, whereas [Ag(NH2)2]Cl is readily soluble. Thus silver chloride dissolves ia aqueous ammonia. Similar reactions take place with other water iasoluble silver and copper salts. Many ammines can be obtained ia a crystalline form, particularly those of cobalt, chromium, and platinum. 

Other advantages claimed for the disc graniilator include low equipment cost, sensitivity to operating controls, and easy observation of the granulation/classification action, all of which lend versatility in agglomerating many different materials. Dusty materials and Chernies reactions such as the ammoniation of fertilizer are handled less readily in the disc granulator than in the drum. 

If dicy is heated just above its melting point of 209°C there is a vigorous exothermic reaction results in the evolution of ammonia and the formation of some melamine together with a number of complex water-insoluble de-ammoniation products. In order to achieve a high yield of melamine in commercial manufacture the reaction is carried out in the presence of ammonia at about 300°C under pressure Figure 24.6). 

As first demonstrated by Stork,the metal enolate formed by metal-ammoni reduction of a conjugated enone or a ketol acetate can be alkylated in liquic ammonia. The reductive alkylation reaction is synthetically useful since ii permits alkylation of a ketone at the a-position other than the one at whicf thermodynamically controlled enolate salt formation occurs. Direct methyl-ation of 5a-androstan-17-ol-3-one occurs at C-2 whereas reductive methyl-... 

Lewis Bases. A variety of other ligands have been studied, but with only a few of the transition metals. There is still a lot of room for scoping work in this direction. Other reactant systems reported are ammoni a(2e), methanol (3h), and hydrogen sulfide(3b) with iron, and benzene with tungsten (Tf) and plati num(3a). In a qualitative sense all of these reactions appear to occur at, or near gas kinetic rates without distinct size selectivity. The ammonia chemisorbs on each collision with no size selective behavior. These complexes have lower ionization potential indicative of the donor type ligands. Saturation studies have indicated a variety of absorption sites on a single size cluster(51). 

Ammonia compounds are a primary chemical component of many reconstituted tobaccos. The importance of ammoniation in the development of the characteristic flavor popularized by Marlboro has been widely pubhcized (Bates et al. 1999 Freedman 1995 Hurt and Robertson 1998). The chemical impact of ammoniation is complex and appears to influence the form and delivery of nicotine in a variety of interconnected ways (see BW Fig. 4) (Johnson 1989). Ammoniated reconstituted tobacco has a characteristic mild sensory profile, and features a number of important compounds created through the reaction between ammonia and sugars (J.R. Reynolds 1980 Wells and Kendrick 1995). Addition of ammonia as a strong base leads to increased smoke pH, which corresponds with increased levels of free nicotine in smoke (Hurt and Robertson 1998). Thus, a 1982 position paper from RJR observed that ... ammonia in smoke is one of the major pH controlling components and that ... studies of the effect of ammonia on smoke composition showed... an increase in physiological satisfaction with increasing ammonia content (Bemasek and Nystrom 1982). 

Pyrrolidone is a lactone used for the production of nylon-4. This reactant may be produced by the reduction ammoniation of maleic anhydride. s-Caprolactam, used in the production of nylon-6, may be produced by the Beckman rearrangement of cyclohexanone oxime (structure 17.11). The oxime may be produced by the catalytic hydrogenation of nitrobenzene, the photolytic nitrosylation of cyclohexane (structure 17.9), or the reaction of cyclohexanone and hydroxylamine (structure 17.10). Nearly one-half of the production of caprolactam is derived from phenol. 

An important improvement in the oxy-Cope reaction was made when it was found that the reactions are markedly catalyzed by base.145 When the C-3 hydroxyl group is converted to its alkoxide, the reaction is accelerated by factors of 10lo-1017. These base-catalyzed reactions are called anionic oxy-Cope rearrangements. The rates of anionic oxy-Cope rearrangements depend on the degree of cation coordination at the oxy anion. The reactivity trend is K+ > Na+ > Li+. Catalytic amounts of tctra-w-butylammonium salts lead to accelerated rates in some cases. This presumably results from the dissociation of less reactive ion-pair species promoted by the tetra-w-buty I ammoni um ion.146 Entries 5, 6, and 7 in Scheme 6.11 illustrate the mild conditions under which rearrangement occurs. 

Phenyl-l,2,4-triazoline-3,5-dione has been prepared by oxidizing 4-phenylurazole with lead dioxide,7 and with ammoni-acal silver nitrate followed by an ethereal solution of iodine.8 The yields are low for both methods. 4-Substituted triazoline-diones can also be made by oxidation of the corresponding urazole with fuming nitric acid9 or dinitrogen tetroxide.10 Oxidation by <-butyl hypochlorite in acetone solution has also been described 1112 it, however, yields an unstable product, even after sublimation. Either dioxane12 or ethyl acetate are preferred as solvents for the reaction, since the product is obtained in a stable form. The latter solvent is superior since... 

The hexahydrate is prepared either by the action of hot dilute hydrochloric acid on nickel powder or by dissolving nickel oxide in dilute hydrochloric acid followed by crystallization. For the preparation of ammoniate, see Reactions below. 

Direct reaction of ammonia and diborane results in the "ammoniate of diborane, which has been shown to be ionic.137... 

We may conclude that the divalent cobalt ions move out into the large cavities upon adsorption of NH3 to form a hexacoordinate cobalt(II)-ammonia complex. Following adsorption of 02 in the ammoniated Co(II)Y zeolites, oxygen enters the coordination sphere of the Co2+ ions. This is accompanied by a charge-transfer process to form a [Co(III) (NH3)502 ]2+ complex. The general intermolecular redox process can be approximated by the reactions... 

In the century since its discovery, much has been learned about the physical and chemical properties of the ammoniated electron and of solvated electrons in general. Although research on the structure of reaction products is well advanced, much of the work on chemical reactivity and kinetics is only qualitative in nature. Quite the opposite is true of research on the hydrated electron. Relatively little is known about the structure of products, but by utilizing the spectrum of the hydrated electron, the reaction rate constants of several hundred reactions are now known. This conference has been organized and arranged in order to combine the superior knowledge of the physical properties and chemical reactions of solvated electrons with the extensive research on chemical kinetics of the hydrated electron. 

Physical chemical studies of dilute alkali metal-ammonia solutions indicate the principal solution species as the ammoniated metal cation M+, the ammoniated electron e , the "monomer M, the "dimer" M2 and the "metal anion" M. Most data suggest that M, M2, and M are simple electrostatic assemblies of ammoniated cations and ammoniated electrons The reaction, e + NH3 - lf 2 H2 + NH2 is reversible, and the directly measured equilibrium constant agrees fairly well with that estimated from other thermodynamic data. Kinetic data for the reaction of ethanol with sodium and for various metal-ammonia-alcohol reductions of aromatic compounds suggest that steady-state concentrations of ammonium ion are established. Ethanol-sodium reaction data allow estimation of an upper limit for the rate constant of e + NH4+ 7, H2 + NH3. 

The reaction of gaseous ammonia with silica has been investigated by several researchers. Most studies1 2,3 4,5 6 7 8 conclude that the adsorption is reversible at low temperatures (< 500 K). Ammoniation of silica at very high temperatures leads to a nitridation of the surface.9101112... 

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