Excess chlorination

Disinfeetion. Chlorine, as gaseous chlorine or as the h5rpochlorite ion, is widely used as a disinfectant. However, its use in some cases can lead to the formation of toxic organic chlorides, and the discharge of excess chlorine can be harmful. Ozone as an alternative disinfectant leads to products that have a lower toxic potential. Treatment is enhanced by ultraviolet light. Indeed, disinfection can be achieved by ultravifflet light on its own. 

Phosphorus pentachloride is prepared by the action of chlorine on phosphorus trichloride. To push the equilibrium over to the right, the temperature must be kept low and excess chlorine must be present. Hence the liquid phosphorus trichloride is run dropwise into a flask cooled in ice through which a steady stream of dry chlorine is passed the solid pentachloride deposits at the bottom of the flask. 

Chlorine reacts with most elements, both metals and non-metals except carbon, oxygen and nitrogen, forming chlorides. Sometimes the reaction is catalysed by a trace of water (such as in the case of copper and zinc). If the element attacked exhibits several oxidation states, chlorine, like fluorine, forms compounds of high oxidation state, for example iron forms iron(III) chloride and tin forms tin(IV) chloride. Phosphorus, however, forms first the trichloride, PCI3, and (if excess chlorine is present) the pentachloride PCI5. 

Halides. Indium trichloride [10025-83-8] InCl, can be made by heating indium in excess chlorine or by chlorinating lower chlorides. It is a white crystalline soHd, deUquescent, soluble in water, and has a high vapor pressure. InCl forms chloroindates, double salts with chlorides of alkaLi metals, and organic bases. 

The preparation of mercuric chloride is identical to the chamber method for mercurous chloride, except that an excess of chlorine is used to ensure complete reaction to the higher oxidation state. Very pure product results from this method. Excess chlorine is absorbed by sodium hydroxide in a tower. 

At present, thionyl chloride is produced commercially by the continuous reaction of sulfur dioxide (or sulfur trioxide) with sulfur monochloride (or sulfur dichloride) mixed with excess chlorine. The reaction is conducted in the gaseous phase at elevated temperature over activated carbon (178). Unreacted sulfur dioxide is mixed with the stoichiometric amount of chlorine and allowed to react at low temperature over activated carbon to form sulfuryl chloride, which is fed back to the main thionyl chloride reactor. 

In addition to bonding with the metal surface, triazoles bond with copper ions in solution. Thus dissolved copper represents a "demand" for triazole, which must be satisfied before surface filming can occur. Although the surface demand for triazole filming is generally negligible, copper corrosion products can consume a considerable amount of treatment chemical. Excessive chlorination will deactivate the triazoles and significantly increase copper corrosion rates. Due to all of these factors, treatment with triazoles is a complex process. 

In the steaming-out process excess chlorine is used and recycled. The major process conditions that are measured and controlled are temperature, pressure, pH, and oxidation potential. 

The conditions for chlorate formation are high pH, low reactant concentrations, and the presence of excess chlorine or hypochlorous acid. Thus, the addition of free chlorine or hypochlorite to chlorine dioxide treated water, which contains chlorite as a by-product of the chlorine dioxide treatment, predominandy forms chlorate in the pH 5—8 range typically used in water treatment (140). 

Methane, chlorine, and recycled chloromethanes are fed to a tubular reactor at a reactor temperature of 490—530°C to yield all four chlorinated methane derivatives (14). Similarly, chlorination of ethane produces ethyl chloride and higher chlorinated ethanes. The process is employed commercially to produce l,l,l-trichloroethane. l,l,l-Trichloroethane is also produced via chlorination of 1,1-dichloroethane with l,l,2-trichloroethane as a coproduct (15). Hexachlorocyclopentadiene is formed by a complex series of chlorination, cyclization, and dechlorination reactions. First, substitutive chlorination of pentanes is carried out by either photochemical or thermal methods to give a product with 6—7 atoms of chlorine per mole of pentane. The polychloropentane product mixed with excess chlorine is then passed through a porous bed of Fuller s earth or silica at 350—500°C to give hexachlorocyclopentadiene. Cyclopentadiene is another possible feedstock for the production of hexachlorocyclopentadiene. 

Phosphorus pentacfaloride [10026-13-8] M 208.2, m 179-180 (sublimes). Sublimed at 160-170° in an atmosphere of chlorine. The excess chlorine was then displaced by dry N2 gas. All subsequent manipulations were performed in a dry-box [Downs and Johnson J Am Chem Soc 77 2098 1955]. Fumes in moist air. HARMFUL VAPOURS. 

In the 1960s materials became available which are said to have been obtained by chlorination at lower temperatures. In one process the reaction is carried out photochemically in aqueous dispersion in the presence of a swelling agent such as chloroform. At low temperatures and in the presence of excess chlorine the halogen adds to the carbon atom that does not already have an attached chlorine. The product is therefore effectively identical with a hypothetical copolymer of vinyl chloride and symmetrical dichloroethylene. An increase in the amount of post-chlorination increases the melt viscosity and the transition temperature. Typical commercial materials have a chlorine content of about 66-67% (c.f. 56.8% for PVC) with a Tg of about 110% (c.f. approx. 80°C for PVC). 

Hliiull. In v.tive B 5th ijifcni-.O pr< SM re ViilvL-. fail [jpai C)peration Excessive chlorine How to Tower Water Basin - high chlorine level to cooling water -potential for excessive corrosion in cooling water system Rotameter Relief valve an pressure check valve outlet in Nnilk-... 

Tlie bifunctional sulfenyl chloride 213 was obtained by chlorination of 144 in good yield, although excessive chlorination led to the saturated compound 214 (94CB533). A series of compounds 215-220 were obtained from 213 by reactions with secondary amines ferf-butyl methyl ketone hexane-2,4-dione 2,6-dimethylcyclohexanone diethyl malonate and acetylacetone, respectively. 

Excess chlorine in acetonitrile converted 1,4-diazaphenothiazine (221 X = S) into 2-carboxamidobenzothiazole. The corresponding phenosele-nazine (221 X = Se) was ring-opened under the same conditions (80T2681). 

The mixture is then flushed with nitrogen to expel excess chlorine. During this process the product crystallizes from the solution and precipitation is completed by cooling the reaction mixture to 20°. The mixture is filtered and the product is washed with 1 1. of water, and air dried to yield 112 g. (77%) of 2,3-dichloro-2,5-di-[Pg.33]

Cl2(g) — 4 PCl3(g). A sample of PC13 of mass 300.5 g was collected from the reaction of 77.25 g of P4 with excess chlorine. What is the percentage yield of the reaction ... 

Gaseous chlorine, under room temperature, was bubbled into liquid bromine maintained at -5°C. Excess chlorine left the reactor through a vent into an absorption column. The chlorine addition rate was adjusted to the reactor s cooling capacity, to prevent the temperature from rising above 0°C. 

Primary and secondary amines and amides are first chlorinated at nitrogen by the chlorine released by the gradually decomposing calcium hypochlorite. Excess chlorine gas is then selectively reduced in the TLC layer by gaseous formaldehyde. The reactive chloramines produced in the chromatogram zones then oxidize iodide to iodine, which reacts with the starch to yield an intense blue iodine-starch inclusion complex. 

The chromatograms are freed from mobile phase in a stream of warm air and treated with chlorine gas for 1-5 min, for example, by placing in the vacant trough of a twin-trough chamber filled with 10 ml each of solution I and solution II [10]. After the excess chlorine has been removed (ca. 5-10 min stream of cold air) the chromatograms are immersed in the dipping solution for 1 s [12] or homogeneously sprayed with the spray solution [10],... 

The chromatograms are freed from mobile phase (15 min 100 °C), placed in the empty chamber of a twin-trough chamber containing 20 ml solution I (chlorine chamber) for 1 min or homogeneously sprayed with solution I until the layer begins to be transparent. They are then freed from excess chlorine in a stream of warm air for 30 min and immersed in the dipping solution for 3 s or sprayed homogeneously with it. 

Detection and result The chromatogram was freed from mobile phase and placed in an atmosphere of chlorine gas (twin-trough chamber, containing 20 ml solution I in the second chamber) for 1 min. Then the excess chlorine was removed (30 min stream of warm air), the treated chromatogram immersed in the dipping solution for 3 s and dried on a hotplate (60-70 °C). 

Detection and resuit The chromatogram was freed from mobile phase in a stream of warm air and placed for 5 min in a twin-trough chamber in which a chlorine gas atmosphere had been produced (by pouring ca. 6 ml hydrochloric acid (20%) over 0.4 g potassium permanganate in the vacant trough). After removal of the excess chlorine... 

Detection and result The chromatogram was first dried in a stream of cold air for 10 min, it was then placed for 2 min in a chamber filled with chlorine gas (cyUnder), then freed from excess chlorine in a stream of cold air for exactly 5 min (fume cupboard ) and immersed in the dipping solution for 2 s. 

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