Halides of ammonia

NH Cl and NH F are the most acceptable ammonia halides for the use in SHS-Az processes. The reason is that they are safe to handle and there is presently sufficient base of initial products for it. The chemical reaction equations with the use of halides of ammonia have the form ... 

The experiments have shown that complexing halides of ammonia and elements to be nitrided are most effective in SHS azide systems today. Additional introduction of ammonia group can considerably increase the final product quality due to significant gas generation and the fact that the reaction mostly occurs in gas phase. 

It was found that most advantages typical for the above-listed different kinds of halides can be realized using only halides of ammonia and elements to be nitrided. Incidentally, the use of this kind of halides solves a problem of obtaining final powders in a form of anisotropic fibers due to reactions in gas phase. 

The optimal conditions for synthesis of different kinds of final products have been found. The chemical stages and forming mechanism for a number of nitrides have been found as well. The technological process of refractory powders synthesis in SHS-Az regime has been developed with the use of complexing halides of ammonia and elements to be nitrided. 

The quality of final powder compositions is analogous to the quality of individual refractory compounds obtained from similar systems. Besides that, the fibrous structure is preserved when using complexing halides of ammonia and elements to be nitrided. 

CH rCHCH NHCSNH. Colourless crystalline solid with a faint garlic-like odour m.p. 74 C. Manufactured by treating propenyl isothiocyanate with a solution of ammonia in alcohol. It has been given by injection in the treatment of conditions associated with the formation of excessive fibrous tissue. Toxic side reactions may occur. Propenyl thiourea is a chemical sensitizer for photographic silver halide emulsions. 

The preparation of pure primary amines by the interaction of alkyl halides and ammonia is very difficult, because the primary amine which is formed reacts with unchanged alkyl halide to give the secondary amine the latter... 

Alkylamines are in principle capable of being prepared by nucleophilic substitution reactions of aUtyl halides with ammonia... 

Because alkylation of ammonia can lead to a complex mixture of products it is used to prepare primary amines only when the starting alkyl halide is not particularly expensive and the desired amine can be easily separated from the other components of the reaction mixture... 

A method that achieves the same end result as that desired by alkylation of ammonia but which avoids the formation of secondary and tertiary amines as byproducts is the Gabriel synthesis Alkyl halides are converted to primary alkylamines without contam mation by secondary or tertiary amines The key reagent is the potassium salt of phthal imide prepared by the reaction... 

The reaction of amines with alkyl halides was seen earlier (Section 22 7) as a complicat ing factor in the preparation of amines by alkylation of ammonia... 

Ammonia can act as a nucleophile toward primary and some secondary alkyl halides to give primary alkylamines Yields tend to be modest because the primary amine IS itself a nucleophile and undergoes alkylation Alkylation of ammonia can lead to a mixture containing a primary amine a secondary amine a tertiary amine and a quaternary ammonium salt... 

A number of 2eohtic materials have been claimed to cataly2e this reaction and reaction temperatures are on the order of 200—350°C with pressures as high as 18000 kPa (2600 psi) reported. This is a low conversion process and recycle of the unconverted starting materials is necessary to provide an economical process. Amination of ethylene to produce ethylamines cataly2ed by ammonium iodide is reported, but not beheved to be practiced commercially (15,16). Alkyl Halide Amination (Method 7). The oldest technology for pioducing amines is the reaction of ammonia with an alkyl hahde. This... 

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... 

Nitric oxide is made commercially by oxidation of ammonia above 500°C in the presence of platinum, or by reduction of nitrous acid with ferrous sulphate or feiTous halides. The physical ... 

Gas-phase deposition In this process, a halide of the solute metal is passed in vapour form over the surface of the metal to be coated, which is heated to a temperature at which diffusion can take place. Temperatures of 500-1 300°C or more can be used, depending on the particular system considered. Generally, filler atmospheres are provided to carry the halide vapour these atmospheres are usually reducing gases such as hydrogen, cracked ammonia, etc. or inert gases (helium, argon). 

Ammonia and other amines are good nucleophiles in SN2 reactions. As a result, the simplest method of alkylamine synthesis is by Sn2 alkylation of ammonia or an alkylamine with an alky) halide. If ammonia is used, a primary amine results if a primary amine is used, a secondary amine results and so on. Even tertiary amines react rapidly with alkyl halides to yield quaternary ammonium salts, R4N+ X-... 

Reactions of metal halides with ammonia and aliphatic amines. G. W. A. Fowles, Prog. Inorg. Chem., 1964, 6,1-36(88). 

Coatings and monolithic components of h-BN are usually produced by CVD by the reaction of a boron halide with ammonia. MOCVD and plasma-CVD are also used. The reaction of boron trichloride and ammonia is as follows ... 

Amorphous Si3N4 powder from silicon halides and ammonia at high temperature.P lP l The powder can also be produced by using the same reaction at 1000°C in an RF plasma with a mean particle size of 0.05-0.1... 

The reaction between alkyl halides and ammonia or primary amines is not usually a feasible method for the preparation of primary or secondary amines, since they are stronger bases than ammonia and preferentially attack the substrate. However, the... 

The treatment of acyl halides with ammonia or amines is a very general reaction for the preparation of amides.The reaction is highly exothermic and must be carefully controlled, usually by cooling or dilution. Ammonia gives unsubstituted amides, primary amines give A-substituted amides, and secondary amines give N,N-disubstituted amides. Arylamines can be similarly acylated. In some cases aqueous... 

When arylhydrazones of aldehydes or ketones are treated with a catalyst, elimination of ammonia takes place and an indole is formed, in the Fischer indole synthesis,Zinc chloride is the catalyst most frequently employed, but dozens of others, including other metal halides, proton and Lewis acids, and certain transition metals have also been used. Microwave irradiation has been used to facilitate this reaction. Aniline derivatives react with a-diazoketones, in the presence of a... 

Organic derivatives of ammonia are called amines. Because nitrogen is trivalent, amines can be primary (attached to one carbon), secondary (attached to two carbons), or tertiary. All amines are basic, and their strength as bases increases with the number of alkyl groups attached to the nitrogen that is, methyl amine is a stronger base than ammonia and trimethylamine is stronger than dimethylamine. Amines can be prepared from ammonia and an alkyl halide ... 

A simple and atom-economical synthesis of hydrogen halide salts of primary amines directly from the corresponding halides, which avoids the production of significant amounts of secondary amine side products, has been described by researchers from Bristol-Myers Squibb [227]. Microwave irradiation of a variety of alkyl halides or tosylates in a commercially available 7 m solution of ammonia in methanol at 100-130 °C for 15 min to 2.5 h followed by evaporation of the solvent provided the corre-... 

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