Liquid ammonia ammonolysis reactions

Certain substances such as Zn(NH2)2 show amphoteric behaviour in liquid ammonia. Ammonolysis reactions take place in liquid ammonia forming amides and ammonium ions. 

Inorganic amides contain the ion NH2". They are formed by the action of ammonia on metals or by the ammonolysis of nitrides. The heavy metal amides are prepared by meta-thetical reactions in liquid ammonia, e.g. 

Ammonolysis of 2-chlorobenzothiazole in liquid ammonia was studied by Lemons et al. and found to be approximately first-order with respect to this substrate at the fairly high concentrations used. The actual nucleophilic reagent was, as expected, the neutral species NH3, and reaction via the amide ion NH2 arising from the autoprotolysis equilibrium [Eq. (5)] was excluded on the grounds that addition of ammonium chloride did not depress the reaction rate. In accordance with this interpretation and in connection with the existence of aromatic substitutions other than normal it is of interest that 2-chlorobenzothiazole was found to react difiFerently with sodamide, although the products were unidentified in this case. 

Ammonolysis is the direct reaction of ammonia with an organic compd. This reaction is used for the prepn of various amines, ni-tramines, etc and some of these products are or may be converted into expls Refs l)W.C.Fernelius G.B.Bowman,Chem-Revs 26, 3—48(1940)(286 refs)(Ammonoly-sis in liquid ammonia) 2)Kirk Othmer 1 (1947), 826—44(89 refs) 3)A C.Stevenson, IEC Sept 1948 to 1952, under Unit Process Review 4)G.H.Coleman,IEC Sept 1953, under Unit Process Review (No ammonolysis reviews appeared in the years 1954—1957) 5 )Grog gins (195 8),388-485... 

In preparation for the eventual removal of the undesired oxygen function at C-10 of 313 via a Birch reduction, the phenol 313 was phosphorylated with diethyl phosphorochloridate in the presence of triethylamine to give 314, which underwent stereoselective reduction with sodium borohydride with concomitant N-deacylation to deliver the amino alcohol 315. N-Methylation of 315 by the Eschweiler-Clarke protocol using formaldehyde and formic acid followed by ammonolysis of the ester group and acetylation of the C-2 hydroxyl function afforded 316. Dehydration of the amide moiety in 316 with phosphorus oxychloride and subsequent reaction of the resulting amino nitrile 317 with LiAlH4 furnished 318, which underwent reduction with sodium in liquid ammonia to provide unnatural (+)-galanthamine. 

Aminopyrazines are conveniently prepared from carboxamido-pyrazines by application of the Hofmann reaction (see Section V,B). Thus, Camerino and Palamidessi prepared aminopyrazine in 80% yield from carboxamidopyrazine.312 Aminopyrazine may also be prepared from the reaction of pyrazine with sodamide in liquid ammonia,313 and 3-amino-2,5-dimethylpyrazine is the product of amination of 2,5-dimethylpyrazine with sodamide in dimethyl-aniline.311 The ammonolysis of halopyrazines also represents a useful preparative procedure for aminopyrazines (see Section V,C). This reaction proceeds most easily in the case of fluoro compounds for example, fluoropyrazine is converted into aminopyrazine in 70% yield by treatment with concentrated aqueous ammonia at room temperature for 3 days,299 whereas the corresponding reaction with chloropyrazine has been carried out in a sealed tube at 150°.147 Alkaline hydrolysis of 2,4-dihydroxypteridines followed by decarboxylation yields aminopyrazines 315 thus, high-temperature alkaline hydrolysis of 7-methyl-2,4-dihydroxypteridine (7-methyIlumazine) gives, after decarboxylation of the intermediate pyrazinecarboxylic... 

After the reaction, the solid sodium salt is filtered off and methanol is distilled off under reduced pressure. Hydroxylamine can also be prepared by the ammonolysis of hydroxylammonium salts in liquid ammonia. The ammonium salt precipitates and is filtered off Hydroxylamine is obtained after evaporating the excess ammonia. 

Correspondingly, metal amides in liquid ammonia have a basic character. The reaction of ammonium salt with metal amide in liquid ammonia is analogous to the neutralization of acid and base in water. The heats of neutralization in ammonia are even larger than in water. The process of hydrolysis corresponds to ammonolysis in ammonia. This results in ammonobasic compounds, for example, in the infusible precipitate HgNH2Cl from HgCl2. 

Esters of (X-amino acids undergo ammonolysis by methanolic ammonia to give good yields of amino acid amides. This procedure represents an improvement over the bomb reaction using liquid ammonia. 

Hexamethylcyclotrisilazane and octamethylcyclotetra-silazane have been prepared by Brewer and Haber from the reaction of dry, gaseous ammonia with dimethyl-dichlorosilane in benzene. When the ammonolysis was carried out in liquid ammonia, the combined yield of silazanes was only slightly less, but the trimer was formed in greater proportion than the tetramer. Although the yield of cyclic silazanes was always high, it was difficult to reproduce the proportions of the individual compounds. The procedure given here is an adaptation of that of Brewer and Haber. 

The ammonolysis of other alkyldichlorosilanes has also been realized. Thus, the reaction of diethyldichlorosilane with liquid ammonia produces hexaethylcyclotrisilazane and octaethylcyclotetrasilazane. The reaction of methyl-dichlorosilane with liquid ammonia also proceeds rapidly to yield high-molecular-weight silazanes from which no simple compounds have been obtained.8... 

Triphenylbismuth undergoes complete ammonolysis with KNH2 in liquid ammonia to yield the binary bismuth nitride BiN, which is explosive. Bi(NH2)3 is believed to be an intermediate, though it was not detected in this reaction. 

Effect of Agitation. In liquid-phase ammonolysis, the rate of amination depends upon the homogeneity of the reaction mass. Without agitatiouj some insoluble compounds would, on account of their greater density, settle to the bottom of the autoclave while the ammonia liquor remained as a distinct layer above it. Reaction would then take place only at the interface, and a complete conversion of the compound to the amino derivative would not be feasible. 

Studies of the kinetics of the reaction have been concerned principally with the liquid-phase ammonolysis of esters and aromatic chloro compounds, presumably because the reactions are more cleancut and there is less tendency to form by-products. For example, in the ammonolysis of esters, the amide is essentially the only product, whereas with the reaction of aliphatic alcohols and ammonia an equilibrium mixture of mono-, di-, and trialkylainines is obtained. 

Preparation of Catalyst. For each mol of sodium to be converted, 0.2 to 0.3 g. of coarsely powdered iron(III) nitrate 9-hydrate is added to the liquid ammonia after momentarily removing the stopper. The reaction mixture is stirred vigorously for 5 to 10 minutes to disperse the ammonolysis products of the iron(III) nitrate as finely as possible. A quantity of clean sodium, two or three times the weight of the iron(III) salt, is added, and stirring is continued at a slower rate. The reaction that takes place is probably the following ... 

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