Ammonium chloride decomposition reaction

Alkaline solutions of mononitroparaffins undergo many different reactions when stored for long periods, acidified, or heated. Acidification of solutions of mononitro salts is best effected slowly at 0°C or lower with weak acids or buffered acidic mixtures, such as acetic acid—urea, carbon dioxide, or hydroxyl ammonium chloride. If mineral acids are used under mild conditions, eg, dilute HCl at 0°C, decomposition yields a carbonyl compound and nitrous oxide (Nef reaction). 

Manufacture. The history of ammonium chloride manufacture is linked to the birth of the soda and synthetic ammonia iadustries. Consequendy this haUde has always been a by-product ia great supply. Production by direct reaction of ammonia and hydrochloric acid is simple but usually economically unattractive a process based on metathesis or double decomposition is generally preferred. 

Several commercial grades are available fine crystals of 99 to 100% purity, large crystals, pressed lumps, rods, and granular material. Double-Decomposition Methods. Double-decomposition processes all iavolve the reaction of sodium chloride, the cheapest chlorine source, with an ammonium salt. The latter may be suppHed directiy, or generated in situ by the reaction of ammonia and a supplementary iagredient. Ammonium chloride and a sodium salt are formed. The sodium salt is typically less soluble and is separated at higher temperatures ammonium chloride is recovered from the filtrate by cooling. 

A.mmonium Sulfate—Sodium Chloride Process. Ammonium sulfate, a readily available by-product, has been much used to make ammonium chloride by a double decomposition reaction with sodium chloride. 

The formation of ammonium bisulfate is strongly temperature dependent. Formation is favored at the lower temperatures. The temperature at which ammonium bisulfate is not formed depends strongly on the SO concentration in the exhaust gas. The temperature needed to minimize bisulfate formation has been reported to increase by about I5°C (around about 350°C) when the SO concentration increases from 5 to 15 ppm (23). The formation of the bisulfate is reversible, ie, if the temperature is raised to 20°C above the minimum temperature, the reaction is shifted to result in the decomposition of the bisulfate formed. When chlorides are present, ammonium chlorides can be formed ... 

When potassium fluoride is combined with a variety of quaternary ammonium salts its reaction rate is accelerated and the overall yields of a vanety of halogen displacements are improved [57, p 112ff. Variables like catalyst type and moisture content of the alkali metal fluoride need to be optimized. In addition, the maximum yield is a function of two parallel reactions direct fluorination and catalyst decomposition due to its low thermal stability in the presence of fluoride ion [5,8, 59, 60] One example is trimethylsilyl fluoride, which can be prepared from the chloride by using either 18-crown-6 (Procedure 3, p 192) or Aliquot 336 in wet chlorobenzene, as illustrated in equation 35 [61],... 

In the other method, particularly popular in Germany, the ammonium nitrate is replaced by an equimolar mixture of ammonium chloride and potassium or sodium nitrate. The reaction between the salts, which gives potassium or sodium chloride and ammonium nitrate or its decomposition products, is relatively slow and does not occur to a marked extent when the explosive is fired in an unconfined condition. This method of working is particularly effective in reducing the power of an explosive in the unconfined condition. Used alone it has not proved popular in Britain, because of the low power which tends to be developed under practical firing conditions. Moreover, the finely divided sodium chloride smoke which is produced by the explosive tends to be unpleasant for the miners. 

To the Grignard solution, 75 g. (71.5 cc., 0.5 mole) of ethyl benzoate (Org. Syn. 10, 51) in 200 cc. of dry benzene (Note 2) is added at such a rate that the mixture refluxes gently. The flask is cooled in a pan of cold water during the addition, which requires about an hour. After the addition is complete, the mixture is refluxed for an hour on a steam bath. The reaction mixture is cooled in an ice-salt bath and then poured slowly, with constant stirring, into a mixture of 1.5 kg. of cracked ice and 50 cc. of concentrated sulfuric acid. The mixture is stirred at intervals until all the solid which separates at the benzene-water interface has dissolved. If necessary, 50 g. of ammonium chloride is added to facilitate the decomposition of the magnesium salt, and additional benzene may be added if the amount present... 

The reaction must be quenched into 6% aq ammonium chloride, or substantial decomposition will occur. The amount of ammonium chloride is optimized. 

The preferred preparation method is to introduce chlorine into the solution while dissolving lead dioxide in cold concentrated HCl. This prevents decomposition of PbCL to PbCb and enhances the formation of chloroplumbic acid, H2PbCl6 in solution. Addition of ammonium chloride precipitates out yellow ammonium chloroplumbate, (NH4)2PbCl6, which is filtered out. The yellow precipitate, on treatment with cold concentrated sulfuric acid, forms lead tetrachloride, which separates out as a yellow oily liquid. The reactions are ... 

The product decomposes on sublimation forming mercury(ll) chloride, ammonia, and nitrogen. However, in the presence of ammonium chloride, the same reaction with ammonia with HgCb in aqueous solution yields fusible white precipitate, (NH3)2HgCl2. Similar product also is obtained by reaction of gaseous ammonia with solid mercury(II) chloride. However, the solid mer-cury(II) chloride is more stable than the above infusible product and can be melted without decomposition. 

A mixture of sodium nitrite with ammonium chloride may decompose with time to form unstable ammonium nitrite. The presence of moisture and of acids favours the decomposition of a mixture of sodium nitrite with ammonium chloride. On the other hand, alkaline reaction and absence of moisture stabilize the system. Experiments have shown that for all practical purposes the mixture is best stabilized by the addition of 2% sodium carbonate. Ammonium carbonate or magnesium oxide may also be used. 

Concentrated hydrochloric acid also dissolves the trichloride, about 100 g. of the latter dissolving in 1 litre of acid at 100° C.7 Dissolution in hydriodic acid is accompanied by evolution of heat and the triiodide is formed.8 Ethyl iodide reacts similarly.9 Double decomposition reactions occur w hen arsenic trichloride is heated with phosphorus triiodide, stannic iodide or germanium iodide, the reactions being complete.10 Similarly, potassium iodide heated with arsenic trichloride in a sealed tube at 210° C., and potassium bromide at 180° to 200° C., form respectively arsenic triiodide and tribromide.11 Stannous chloride, added to the solution in hydrochloric acid, causes reduction to arsenic (see p. 29). Arsenic trichloride may be completely separated from germanium chloride by extraction with concentrated hydrochloric acid.12 Ammonium, sodium and cobaltic chlorides react with arsenic trichloride to form additive compounds with magnesium, zinc and chromic chlorides there is no reaction.13... 

As tiie decomposition in this reaction is catalyzed by the presence of ammonium chloride, the starting material must be specially treated beforehand by any one of the following methods ... 

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