Ammonia Analogy

These parameters often parallel one another since they are related to similar characteristic of the system (ehange in number of particles involved in the reaction etc.). The catalyzed hydrolysis of CrjO by a number of bases is interpreted in terms of a bimolecular mechanism, and both AS and AK values are negative. In contrast the aquation of Co(NH2CH3)5L (L = neutral ligands) is attended by positive AS and AK values. The steric acceleration noted for these complexes (when compared with the rates for the ammonia analogs) is attributed to an mechanism.There is a remarkably linear AK vs AS plot for racemization and geometric isomerization of octahedral complexes when dissociative or associative mechanisms prevail, but not when twist mechanisms are operative (Fig. 2.15). For other examples of parallel AS and AF values, see Refs. 103 and 181. In general AK is usually the more easily understandable, calculable and accurate parameter and AK is... 

For reactions with ammonia analogous products such as HN=PCl3 and HN =P(NH,)3 were proposed, but characterization was hampered by incomplete reactions, separation-resistant mixtures, and sensitivity to moisture. Furthermore, gradual polymerization occurred with loss of ammonia to yield phosph.im , a poorly characterized solid of approximate formula (PN2H)r us the ullimuie product. If instead of free ammonia its less reactive conjugate acid is used, reaction with PCI, proceeds at a moderate rate and the results are more definitive ... 

The trinuclear cation Cr,(NH,) 0(OH)45 and the tetranuclear cation Crj(OH),Cr(NH have been prepared similarly by the Cr(II) charcoal catalytic method and were separated by cation-exchange chromatography (40). The trinuclear species was isolated as a bromide salt and has structure 5 in Fig. 1. The tetranuclear species Cr[(0H),Cr(NH,)4[/f has been shown to be a chromium ammonia analog of the so-called Werner s brown salt, Co[(OH)2Co(en),J 3f,f (structure 6 in Fig. 1) (41). 

The tetranuclear complex Co (OH)2Co(en)2 36 + was first prepared by Werner (6) and has subsequently been the subject of several studies (53, 54, 57,156,245 247). Its ammonia analog has already been mentioned in Section IV,A. As mentioned in Section II,B, the en tetranuclear species may exist in eight optically isomeric forms. All eight isomers are formed during the oxidation reaction and have been separated by column chromatography (57). The yields of the isomers decrease in the order A(AAA) > A(AAA) > A(AAA) > A(AAA). The X-ray crystal structures of... 

Other investigations of the properties of aqueous solutions have been made by various experimenters.1 Bonnefoi2 has prepared complex compounds of lithium bromide and ammonia analogous to those formed by the chloride (p. 62). 

Valine (Val, V) has also been synthesized by the Strecker process beginning with isobutyraldehyde and by adding cyanide in the presence of ammonia (analogously... 

The commercial preparation of ammonia is accomplished in huge quantities by the Haber process [Equation (16.12)], discussed in Section 16.4 under Nitrogen Fixation. In the laboratory the most common preparation is the treatment of ammonium salts with strong bases, as represented in Equation (16.13).The self-ionization of liquid ammonia (analogous to that of liquid water) is shown in Equation (16.14). NH3(/) is often used as a nonaqueous solvent. As shown in Equation (16.15), NH3 acts as a weak base in water and serves as a prototype for a number of nitrogen-containing bases such as methylamine, pyridine, and aniline, which you may recall from studying acid-base equilibria in earlier courses. 

Ammonia is a two-state system [16], in which the two base states lie at a minimum energy. They are connected by the inversion reaction with a small baiiier. The process proceeds upon the spin re-pairing of four electrons (Fig. 15) and has a very low barrier. The system is analogous to the tetrahedral carbon one... 

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. 

By the action of concentrate aqueous ammonia solution upon esters. This process is spoken of as ammonolysls of the ester, by analogy with hydrolysis applied to a similar reaction with water. If the amide is soluble in water, e.g., acetamide, it may be isolated by distillation, for example ... 

Methylthio- and 2-ethylthio-4-methylthiazoles undergo reductive ring opening when treated by sodium in liquid ammonia (204). The first step of this reaction consists of the formation of the A-4-thiazoline anion (80). The next steps are analogous to those given for 80a to 83. 

The mechanism by which the Birch reduction of benzene takes place (Figure 118) IS analogous to the mechanism for the metal-ammonia reduction of alkynes It involves a sequence of four steps m which steps 1 and 3 are single electron transfers from the metal and steps 2 and 4 are proton transfers from the alcohol... 

Analogously, aldehydes react with ammonia [7664-41-7] or primary amines to form Schiff bases. Subsequent reduction produces a new amine. The addition of hydrogen cyanide [74-90-8] sodium bisulfite [7631-90-5] amines, alcohols, or thiols to the carbonyl group usually requires the presence of a catalyst to assist in reaching the desired equilibrium product. 

Iron(III) bromide [10031-26-2], FeBr, is obtained by reaction of iron or inon(II) bromide with bromine at 170—200°C. The material is purified by sublimation ia a bromine atmosphere. The stmcture of inoa(III) bromide is analogous to that of inon(III) chloride. FeBr is less stable thermally than FeCl, as would be expected from the observation that Br is a stronger reductant than CF. Dissociation to inon(II) bromide and bromine is complete at ca 200°C. The hygroscopic, dark red, rhombic crystals of inon(III) bromide are readily soluble ia water, alcohol, ether, and acetic acid and are slightly soluble ia Hquid ammonia. Several hydrated species and a large number of adducts are known. Solutions of inon(III) bromide decompose to inon(II) bromide and bromine on boiling. Iron(III) bromide is used as a catalyst for the bromination of aromatic compounds. 

Hydrogenolysis is analogous to hydrolysis and ammonolysis, which involve the cleavage of a bond induced by the action of water and ammonia, respectively. Chemical bonds that are broken by hydrogenolysis reactions include carbon—carbon, carbon—oxygen, carbon—sulfur, and carbon—nitrogen bonds. An example of hydrogenolysis is the hydrodealkylation of toluene to form benzene and methane ... 

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. 

This is an example of an ammonolytic reaction ia which a chemical bond is broken by the addition of ammonia. It is analogous to the hydrolysis reactions of water. An impressive number of inorganic and organic compounds undergo ammonolysis. 

At room temperature, the bisulfite pH inflection poiat occurs at pH 4.5 and the monosulfite at pH 9. Analogous equations can be written for magnesium, calcium, and ammonia. The starting raw materials, ia addition to sulfur, are sodium hydroxide, magnesium oxide, calcium carbonate, or ammonia, depending on the base used. The four commercial bases used ia the sulfite process are compared ia Table 4. 

The analogous reaction with ammonia leads ultimately to sihcon nitride. In the past, hydrocarbon soluble fractions of the ammonolysis were iacorrecdy referred to as sihcon diimide. This improper designation occasionally persists as of the mid-1990s. 

Amines. Although the chlorination of aqueous aLkylamines is analogous to that of ammonia, mono- and diaLkylarnines generally chlorinate faster because of their higher basicities (13). Bromination rates are significantly faster than chlorination rates, and in some cases, eg, (CH2)2NH... 

Benzisothiazoles are formed by the action of ammonia or amines on benzenesulfenyl halides bearing an o-carbonyl function (72AHC 14)43, 80MI41700). Analogous diphenyl disulfides behave similarly (77SST(4)339). Sulfinyl chlorides or phenylsulfoxides produce... 

Oxaziridines substituted in the 2-position with primary or secondary alkyl groups undergo decomposition at room temperature. In the course of some weeks, slow decomposition of undiluted compounds occurs, the pattern of which is analogous to that of acidic or alkaline N—O cleavage (Sections 5.08.3.1.3 and 4), Radical attack on a C—H bond in (109) effects N—O cleavage, probably synchronously (57JA5739). In the example presented here, methyl isobutyl ketone and ammonia were isolated after two hour s heating at 150 °C. 

The amines are a group of compounds with the general formula R-NHj, and all the common amines are hazardous. As a class the amines pose more than one hazard, being flammable, toxic, and, in some cases, corrosive. The amines are an analogous series of compounds and follow the naming pattern of the alkyl halides and the alcohols that is, the simplest amine is methyl amine, with the molecular formula of CH NHj. Methyl amine is a colorless gas with an ammonia-like odor and an ignition temperature of 806°F. It is a tissue irritant and toxic, and it is used as an intermediate in the manufacture of many chemicals. Ethyl amine is next in the series, followed by propyl amine, isopropyl amine, butyl amine and its isomers, and so on. 

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