Ammonium chloride disposal

The chemistry of indium metal is the subject of current investigation, especially since the reactions induced by it can be performed in aqueous solution.15 The selective reductions of ethyl 4-nitrobenzoate (entry 1), 2-nitrobenzyl alcohol (entry 2), l-bromo-4-nitrobenzene (entry 3), 4-nitrocinnamyl alcohol (entry 4), 4-nitrobenzonitrile (entry 5), 4-nitrobenzamide (entry 6), 4-nitroanisole (entry 7), and 2-nitrofluorenone (entry 8) with indium metal in the presence of ammonium chloride using aqueous ethanol were performed and the corresponding amines were produced in good yield. These results indicate a useful selectivity in the reduction procedure. For example, ester, nitrile, bromo, amide, benzylic ketone, benzylic alcohol, aromatic ether, and unsaturated bonds remained unaffected during this transformation. Many of the previous methods produce a mixture of compounds. Other metals like zinc, tin, and iron usually require acid-catalysts for the activation process, with resultant problems of waste disposal. 

The electrolyte was a solution of ammonium chloride that bathed the electrodes. Like Plante s electrochemistry of the lead-acid battery, Leclanche s electrochemistry survives until now in the form of zinc-carbon dry cells and the use of gelled electrolyte.12 In their original wet form, the Leclanche electrochemistry was neither portable nor practicable to the extent that several modifications were needed to make it practicable. This was achieved by an innovation made by J. A. Thiebaut in 1881, who through encapsulating both zinc cathode and electrolyte in a sealed cup avoided the leakage of the liquid electrolyte. Modern plastics, however, have made Leclanche s chemistry not only usable but also invaluable in some applications. For example, Polaroid s Polar Pulse disposable batteries used in instant film packs use Leclanche chemistry, albeit in a plastic sandwich instead of soup bowls.1... 

The ammonium chloride solution goes to an ammonia still where the ammonia is recovered and recycled. The remaining calcium chloride solution is an important by-product of this process, although in large amounts it is difficult to sell and causes a disposal problem. 

The Leclanche cell, the inexpensive disposable flashlight-type cell, has been on the market for over 100 years, yet its chemistry is not completely understood. The cell consists of an outer zinc shell that acts as the anode (seen by the external circuit as the source of electrons and hence the negative terminal) and oxidizes away during operation of the cell, a carbon rod or disk that serves as the cathodic current collector (positive terminal), and a moist paste of manganese dioxide, ammonium chloride, and zinc chloride that fills the cell and acts as both the electrolyte and the source of the cathodic reaction (reduction of MnIV). Usually, graphite in the form of carbon black is added to the paste to increase the electrical conductivity. The basic reactions are... 

Small Quantities. Wear eye protection, nitrile rubber gloves, and a laboratory coat. Work in the fume hood. Cover the potassium amide with toluene or kerosene and add 95% ethanol slowly while stirring.7 When reaction is complete, the solution should be placed in a separate labeled container for disposal by burning. Alternatively, small portions of potassium amide can be stirred into excess solid ammonium chloride in the fume hood. The resulting mixture is slowly added to a pail of cold water and the solution washed into the drain.8 9... 

Hydrogen chloride is corrosive and toxic TLV 5ppm. Prepare by adding concentrated sulphuric acid to anhydrous ammonium chloride and dry by passage over molecular sieves. Dispose by dissolving in water. 

Dispose of cobalt solutions according to state, federal, and local regulations, being aware that some contain ammonium chloride and sodium chloride. 

It may be noted that no hydrogen is formed in the reaction above. Ethyl acetate is added gradually with stirring. This is followed by the addition of a saturated aqueous solution of ammonium chloride. The upper organic layer is separated and sent for incineration or landfill disposal. The aqueous phase containing the inert inorganic products is flushed down the drain with a large volume of water. 

To the hydride solution in a flask equipped with a stirrer, ethyl acetate is added slowly. The mixture sometimes becomes so viscous after the addition that stirring is difficult and additional solvent may be required. When the reaction with ethyl acetate has ceased, a saturated aqueous solution of ammonium chloride is added with stirring. The mixture separates into an organic layer and an aqueous layer containing inert inorganic solids. The upper, organic layer should be separated and disposed of as a flammable liquid. The lower, aqueous layer can often be disposed of in the sanitary sewer. 

In accordance with the purity of the feed materials (plus any reworked product) and provided the plant has been properly designed and maintained in good condition, the direct-neutralization method will produce ammonium chloride of high purity. For example, in one Indian plant a product of a quality well in excess of British Pharmacopea specifications can be achieved. Production of ammonium chloride could be a convenient way to use byproduct HCl which often has a low value and poses a difficult disposal problem. 

Other by-products are triethylenetetramine, tetraethylenepentamine, pentaethylenehex-amine, and polyethylene polyamines. A low reaction temperature and low pressure are more selective for EDA, but conversion is low. High temperature and high pressure, on the other hand, increase conversions, but with less selectivity for EDA. The reaction system is noncatalytic. In a typical EDA process, ethylene dichloride reacts with excess aqueous ammonia at about 100 to 200°C and at 10 to 20 atmospheres. The crude product is an aqueous solution of ammonia, ammonium chloride, ethylenediamine hydrochloride, and higher amine hydrochlorides. Caustic is added to neutralize the crude product and free the ethylenediamine, the higher amines, and the ammonia from the amine hydrochloride and ammonium chloride. The chloride salts must be disposed of. The crude product is refined by fractionation, in which the unreacted ammonia is recycled and the amines are purified. The EDA yield is estimated to be between 45 and 70 percent. ... 

Copper etchants do not directly influence the electroless plating process, but are used merely to remove unwanted copper, and should not affect the deposit properties. The costs of waste treatment and disposal have led to disuse of throw-away systems such as chromic—sulfuric acid, ferric chloride, and ammonium persulfate. Newer types of regenerable etchants include cupric chloride, stabilized peroxide, and proprietary ammoniacal etchant baths. 

The initial process to achieve success was developed by Miyata of Kyowa in the mid 1970s [101].This process is based on the hydrothermal conversion in an autoclave of the fine agglomerated particles formed by addition of ammonia or lime to a magnesium salt solution. This hydrothermal conversion results in the formation of particles of about 1 micron in size and with a fairly low aspect ratio. This original process appears to be expensive to operate because of the low value of the ammonium or calcium chloride co-product which has to be disposed of and because the reported reaction conditions give a low yield and a relatively slow reaction. 

In SMOBC processing, the metal-plated resist is removed to present a flat, clean copper surface for solder mask definition. Tin/lead alloys can be stripped in oxidizing fluoride solutions such as fluoboric acid and hydrogen peroxide or ammonium bifluoride with hydrogen peroxide or nitric acid. (Caution machine construction must be made compatible with fluorides by elimination of titanium and glass components.) Commercial formulations are available to be used inline after the etch machine rinses. Accumulations of spent solution or filtered lead-fluoride deposits must be treated as hazardous waste and have been accepted by solution vendors for treatment and disposal costs. Modern applications usually use lead-free tin plating resists, which can be fluoride containing as previously discussed, or compounds of ferric chloride... 

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