Hypochlorite, calcium

Oxidizing bleaches kill microbes by reacting with cell membranes and cell proteins. The most widely used is sodium hypochlorite for household and hospital uses, and calcium hypochlorite for drinking water and swimming pool disinfecting. 

It is made by bubbling chlorine gas through a solution of calcium hydroxide. 

Calcium hypochlorite is the main ingredient in swimming pool chlorine tablets. 

Calcium hypochlorite is one of the best disinfectants known it kills bacteria, yeasts, fungus, spores, and even viruses. It is more commonly used to disinfect water supplies and swimming pools than its close cousin sodium hypochlorite (household bleach) because it can be sold as a solid (it does not attract moisture from the air and clump up as sodium hypochlorite powder does). 

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Prepare a solution containing about 100 g, of potassium hypochlorite from commercial calcium hypochlorite ( H.T.H. ) as detailed under -Dimethylacrylic Acid, Section 111,142, Note 1, and place it in a 1500 ml. three-necked flask provided with a thermometer, a mechanical stirrer and a reflux condenser. Warm the solution to 55° and add through the condenser 85 g, of p-acetonaphthalene (methyl p-naphthyl ketone) (1). Stir the mixture vigorously and, after the exothermic reaction commences, maintain the temperature at 60-70° by frequent cooling in an ice bath until the temperature no longer tends to rise (ca. 30 minutes). Stir the mixture for a further 30 minutes, and destroy the excess of hypochlorite completely by adding a solution of 25 g. of sodium bisulphite in 100 ml. of water make sure that no hypochlorite remains by testing the solution with acidified potassium iodide solution. Cool the solution, transfer the reaction mixture to a 2-litre beaker and cautiously acidify with 100 ml. of concentrated hydrochloric acid. Filter the crude acid at the pump. 

Dichloramine-T and chloramine-T. When p toluenesulphonamide is dissolved in excess of sodium (01 calcium) hypochlorite solution, it is converted into the soluble salt of the N-monochloro derivative ... 

Dichloranrine-T (p-toluenesulphondichloramide). Prepare about 200 ml. of a saturated solution of calcium hjrpochlorite by grinding a fresh sample of bleaching powder with water and filtering with shght suction. Dissolve 5 g. of p-toluenesulphonamide in as small a volume of the calcium hypochlorite solution as possible (about 150 ml.) and filter the solution if necessary. Cool in ice, and add about 50 ml. of a mixture of equal volumes of glacial acetic acid and water slowly and with stirring until precipitation is complete. The dichloramine T separates out first as a fine emulsion, which rapidly forms colourless crystals. Filter the latter... 

Carbon, activated Calcium hypochlorite, all oxidizing agents, unsaturated oils... 

Hoffman Degradation. Polyacrylamide reacts with alkaline sodium hypochlorite [7681-52-9], NaOCl, or calcium hypochlorite [7778-54-3], Ca(OCl)2, to form a polymer with primary amine groups (58). Optimum conditions for the reaction include a slight molar excess of sodium hypochlorite, a large excess of sodium hydroxide, and low temperature (59). Cross-linking sometimes occurs if the polymer concentration is high. High temperatures can result in chain scission. 

Two oxidants commonly used are chlorine and potassium permanganate. The Roe chlorine number, the uptake of gaseous chlorine by a known weight of unbleached pulp (ie. Technical Association of the Pulp and Paper Industry (TAPPl) Standard Method T202 ts-66) has been superseded by the simpler hypo number (ie, TAPPl Official Test Method T253 om-86), eg, chlorine consumption in treatment of the pulp with acidified sodium or calcium hypochlorite. 

Miscellaneous. Both whiting and hydrated lime are used as diluents and carriers of pesticides, such as lime—sulfur sprays, Bordeaux, calcium arsenate, etc. The most widely used bleach and sterilizer, high test calcium hypochlorite, is made by interacting lime and chlorine (see Bleaching AGENTS). Calcium and magnesium salts, such as dicalcium phosphate, magnesium chloride, lithium salts, etc, are made directly from calcific and dolomitic lime and limestone. 

Thiol spills are handled ia the same manner that all chemical spills are handled, with the added requirement that the odor be eliminated as rapidly as possible. In general, the leak should be stopped, the spill should be contained, and then the odor should be reduced. The odor can be reduced by sprayiag the spill area with sodium hypochlorite (3% solution), calcium hypochlorite solution (3%), or hydrogen peroxide (3—10% solution). The use of higher concentrations of oxidant gives strongly exothermic reactions, which iacrease the amount of thiol ia the vapor, as well as pose a safety ha2ard. The apphcation of an adsorbent prior to addition of the oxidant can be quite helpful and add to the ease of cleanup. 

Chemical Treatment. Some organic compounds are attacked by chemical reagents such as potassium permanganate, sodium hydroxide, calcium hypochlorite, and o2one (29,30). 

Sodium hypochlorite and calcium hypochlorite are chlorine derivatives formed by the reaction of chlorine with hydroxides. The appHcation of hypochlorite to water systems produces the hypochlorite ion and hypochlorous acid, just as the appHcation of chlorine gas does. 

Calcium Hypochlorite. This chemical, marketed since 1928, is one of the most widely used swimming-pool water sanitizers. Calcium hypochlorite, a crystalline sofld, is a convenient source of available chlorine and is sold in granular or tablet form for use in home, semiprivate, and commercial pools. When dissolved in water, Ca(OCl)2 forms hypochlorous acid and hypochlorite ion similar to NaOCl. It contains small amounts of stabilizing Ca(OH)2, which has a very small effect on pool pH (7). Calcium hypochlorite has superior storage stabiUty and much higher available CI2 concentration than Hquid bleach, which reduces storage requirements and purchasing frequency. 

Lithium Hypochlorite. Similar in action to other hypochlorites, this chemical is used to a small extent. It is more expensive than sodium and calcium hypochlorite. 

Liquid Eeeders. Liquid feeders employ positive-displacement metering pumps for adding aqueous solutions of sodium or calcium hypochlorite. The feed solutions are typically stored in polyethylene tanks of various capacities up to about 0.19 m (50 gal). 

Superchlorination typically refers to a dding FAC equal to 10 x ppm CAC, whereas shock treatment generally involves addition of 10 ppm FAC. The frequency of superchlorination or shock treatment depends on bather load and temperature. Calcium hypochlorite, because of its convenience, is widely used for superchlorination and shock treatment. Sodium hypochlorite, LiOCl, or chlorine gas are also used. Chloroisocyanurates are not recommended since their use would result in excessive cyanuric acid concentrations. 

Potassium peroxymonosulfate, introduced in the late 1980s, is finding increasing use as an auxiUary oxidant for shock treatment and oxidation of chloramines. Sodium peroxydisulfate is also being sold for shock treatment, however, it is less reactive than peroxymonosulfate. Mixtures of sodium peroxydisulfate and calcium hypochlorite can be used for shock treatment (28). Disadvantages of peroxymonosulfate and peroxydisulfate are they do not provide a disinfectant residual and peroxymonosulfate oxidizes urea and chloramines to nitrate ion, which is a nutrient for algae. 

After World War I, other chlohne-based bleaches were developed. In 1921 the use of chlorine dioxide for bleaching fibers was reported followed by the development of the commercial process for large-scale production of sodium chlorite. In 1928 the first dry calcium hypochlorite containing 70% available chlorine was produced in the United States. This material largely replaced bleaching powder as a commercial bleaching agent. 

The largest use of calcium hypochlorite is for water treatment. It is also used for I I and household disinfectants, cleaners, and mildewcides. Most of the household uses have been limited to in-tank toilet bowl cleaners. In areas where chlorine cannot be shipped or is otherwise unavailable, calcium hypochlorite is used to bleach textiles in commercial laundries and textile mills. It is usually first converted to sodium hypochlorite by mixing it with an aqueous solution of sodium carbonate and removing the precipitated calcium carbonate. Or, it can be dissolved in the presence of sufficient sodium tripolyphosphate to prevent the precipitation of calcium salts. However, calcium hypochlorite is not usually used to bleach laundry and textiles because of problems with insoluble inorganic calcium salts and precipitation of soaps and anionic detergents as their calcium salts. 

Bleach Liquor. Bleach Hquor or lime bleach Hquor is an aqueous solution of calcium hypochlorite and calcium chloride. It typically contains 30—35 g/L of available chlorine, though it may be as high as 85 g/L. It has been used in pulp bleaching, when it can be made more cheaply than sodium hypochlorite. It is prepared on site by chlorinating lime solutions. 

Historically, bleaching powder and tropical bleach were significant sources of available chlorine but very Httle are used today. This is because of the greater availabiUty of sodium hypochlorite solutions and the development of calcium hypochlorite. They are stiU used to sanitize fields, drainage ditches, and reservoirs where its insoluble portion is not important. And, they are important sources of available chlorine within some less developed tropical countries. 

Dibasic Magnesium Hypochlorite. This salt Mg(OCl)2 2Mg(OH)2, [11073-21-5], is safer than calcium hypochlorite because of its higher... 

A study of the North American bleaching agent market was completed in June 1988 and includes consumption quantities for the year 1986 (156). Chlorine consumption for 1986 was 1.86 x 10 t. The North American consumption volume of other chlorine-containing bleaching compounds including sodium and calcium hypochlorite, chlorinated isocyanurates, and hydantoins was 286,000 t. The 1986 North American consumption of sodium chlorate was estimated at 5.5 x 10 t. 

Dichlorine monoxide is an intermediate in the manufacture of calcium hypochlorite. It has been used in sterilization for space appHcations (70) (see Sterilization techniques). Its use in the preparation of chlorinated solvents (71) and chloroisocyanurates has been described. Chlorine monoxide has been shown to be effective in bleaching of pulp (qv) and textiles (72—74). 

Dichlorides and e2thers are the main by-products in this reaction. Treatment with base produces propylene oxide. Specialty epoxides, eg, butylene oxide, are also produced on an industrial scale by means of HOCl generated from calcium hypochlorite and acetic acid followed by dehydrohalogenation with base. 

Reaction of HOCl, formed from calcium hypochlorite and CO2, with highly substituted alkenes in CH2CI2 is a convenient route to aHyUc chlorides (111). Ketones are chlorinated to a-chloroketones by reaction with HOCl Acetone initially gives CH2COCH2CI (112). Methyl ethyl ketone gives 78% CH3CHCICOCH3, 15% CH3CH2COCH2CI, and 7% dichlorides (113). 

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