Preparation reaction with ammonia

Reactions with Nitrogen Compounds. The reaction with ammonia is the classical method for preparing primary carbamates. Excess ammonia is used as an acid acceptor to remove the HCI formed (see Carbamic acid). 

Formation of Amines. Mono-, di-, and triaEyl amines are prepared by reaction with ammonia. The ratio of reagents determines product distribution with sufficient time and excess of aEyl chloride, tetraaEylammonium chloride [13107-10-3] and triallylamine [102-70-5] predominate. Mixed amines are prepared in similar fashion by using a substituted amine in place of ammonia they may also be prepared with allylamine [107-11-9] and a suitable organic chloride. 

The solvent-free material, isolated at — 70°C, disproportionates violently (sometimes explosively) at — 50°C to ammonium chloride and nitrogen trichloride [1]. Ethereal solutions of chloramine are readily handled [2], In the preparation of chloramine by reaction of sodium hypochlorite with ammonia, care is necessary to avoid excess chlorine in the preparation of the hypochlorite from sodium hydroxide, because nitrogen trichloride may be formed in the subsequent reaction with ammonia [3]. 

Iodopyrimidine 7 was prepared by iodination of 2,4-diaminopyrimidine 6, which was derived from commercially available 2-amino-4-chloro-6-methylpyrimidine (5) via an SNAr reaction with ammonia [8]. Similarly, iodination of 6-chloro-2,4-dimethoxypyrimidine (8) with N-iodosuccinimide in trifluoroacetic acid led to dihalopyrimidine 9 [9],... 

Experiment 6. Reaction with Ammonia.—Of the formaldehyde prepared 10 c.c. are mixed with a small excess of ammonia and the mixture is evaporated in a small glass dish on the water bath. The colourless crystals which remain consist of hexamethylenetetramine (CH2)6N4 (urotropine.) This reaction proceeds quantitatively. It should be so carried out and the result compared with that obtained by titration. 

Nitrile 241 was reduced to the amine 242 with Red-Al in morpholine at —40 °C. However aluminium hydrides are mostly unsuitable if there is an A-acetyl group that is required to be conserved and this is discussed further in Section 8.06.8. Also, 240 could be prepared from the ester 243 by reaction with ammonia <1982AP538>. 

The direct replacement of the hydroxyl group in simple phenols by an amino or substituted amino group requires drastic conditions and the method is not suitable for laboratory preparations. With the polyhydric phenols, and more particularly with the naphthols, such replacements occur more readily. Thus 2-naphthol is converted into 2-naphthylamine by heating with ammoniacal ammonium sulphite solution at 150°C in an autoclave. The reaction (the Bucherer reaction) depends upon the addition of the hydrogen sulphite ion to the keto form of the naphthol and the subsequent reaction with ammonia. 

This method cannot be applied to polynitro amines, since these are so weakly basic that they can be diazotised only under special conditions in strongly acidic media (Section 6.7.1, p. 922). In such cases use may be made of the susceptibility to nucleophilic displacement of halogen when activated by ortho and para nitro groups. Thus the valuable reagent 2,4-dinitrophenylhydrazine (Expt 6.93) is readily prepared by reacting l-chloro-2,4-dinitrobenzene with hydrazine. Reaction with ammonia similarly gives 2,4-dinitroaniline (cognate preparation in Expt 6.93). 

A very wide range of nucleophiles other than water and alcohols has been shown to react with co-ordinated nitriles (Fig. 4-15). The reaction with ammonia or amines is a particularly convenient method for the preparation of amidine complexes. Specific examples of these reactions are presented in Fig. 4-16, illustrating the formation of amide, imino-ether or amidine complexes. 

Direct ring syntheses are also available for the preparation of hydroxypyrazines. Thus, haloacylation of an a-aminoketone, followed by reaction with ammonia and oxidation represents a general synthesis of 5,6-disubstituted and 3,5,6-trisubstituted 2-hydroxypyrazines.339 This is illustrated by the preparation of 5,6-dimethyl-2-hydroxy-pyrazine (Scheme 39). Hydroxypyrazines are very conveniently... 

The resistance of the furoxan ring to chemical attack allows derivatives to be prepared via the reactions of the substituents (Section 4.22.3.4). Carboxylic acids are available by permanganate oxidation of methyl derivatives or by hydrolysis of the corresponding esters reaction with ammonia affords carboxamides. Acylfuroxans provide a source of hydroxyalkyl compounds by reduction, and oximes, for example, via nucleophilic addition. Acylation and oxidation of aminofuroxans allows the amide and nitro derivatives to be prepared. Nucleophilic displacements of nitro substituents can take place, but can be somewhat hazardous on account of the explosive nature of these compounds. Alkoxy derivatives are formed with sodium alkoxide, while reaction with thiolate anions yields sulfides, from which sulfones can be synthesized by peracid oxidation. Nitrofuroxans have also been reduced to... 

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