Hypochlorite formation

Resonance structures of the perchlorate, chlorate, chlorite, hypochlorite, formate, and nitrite ions. 

Sodium hydride, 5 10 dispersions of, 6 13 Sodium hypochlorite, formation of, in preparation of chlorine(I) oxide, 6 159re. solution of, 1 90... 

Foerster, H.J., Thiele, W., Fassler, D. and Guenter, K. (2002) Comparative investigation on hypochlorite formation on platinum and diamond electrodes. New Diam. Front. Carbon Technol. 12, 99-105. 

Chloramines are considered as main products secondary to hypochlorite formation. Taurine is one of the most abundant sources of free amino groups in polymorphonuclear neutrophilic leukocytes, representing approximately 50% of all low-molecular-weight amines released by PMNs (G24, Z5), and taurine chloramine is formed immediately along with MPO-mediated HOC1 synthesis ... 

Buffers which have been widely employed are Tris acetate, pH 7.8 and Tris phosphate, pH 7.7 (Loening 1968). (Tris hydrochloride should be avoided because of hypochlorite formation at the anode.) Buffers may be made up as concentrated stock solutions and mixed in the correct proportions with acrylamide, agarose, initiator and. catalyst. 

FIGURE 14.7 Scheme of the mechanism for the oxidation of half-mustard. Alkyl hypochlorite formation at the oil-water interface enables an oxidation close to the interface or inside the oil subphase. (From Menger, F. M. and Ellington, A. R., J. Am. Chem. Soc., 112, 8201, 1990. With permission)... 

The solubility of the carbonate in water containing carbon dioxide causes the formation of caves with stalagtites and stalagmites and is responsible for hardness in water. Other important compounds are the carbide, chloride, cyanamide, hypochlorite, nitrate, and sulfide. 

If a bromomethyl- or vinyl-substituted cyclopropane carbon atom bears a hydroxy group, the homoallyiic rearrangement leads preferentially to cyclobutanone derivatives (J. Sa-laun, 1974). Addition of amines to cydopropanone (N. J. Turro, 1966) yields S-lactams after successive treatment with tert-butyl hypochlorite and silver(I) salts (H.H. Wasserman, 1975). For intramolecular cyclopropane formation see section 1.16. 

Bis(azol-2-5l)stilbenes (2(i]ll such as (4) have been prepared. 4,4 -Dihydrazinostilbene-2,2 -disulfonic acid, obtained from the diamino compound, on treatment with 2 moles of oximinoacetophenone and subsequent ring closure, leads to the formation of (4) [23743-28 ]. Such compounds are used chiefly as washing powder additives for the brightening of cotton fabrics, and exhibit excellent light- and hypochlorite-stabiUty. 

Peroxide-Ketazine Process. Elf Atochem in France operates a process patented by Produits Chimiques Ugine Kuhhnaim (PCUK). Hydrogen peroxide (qv), rather than chlorine or hypochlorite, is used to oxidize ammonia. The reaction is carried out in the presence of methyl ethyl ketone (MEK) at atmospheric pressure and 50°C. The ratio of H202 MEK NH2 used is 1 2 4. Hydrogen peroxide is activated by acetamide and disodium hydrogen phosphate (117). Eigure 6 is a simplified flow sheet of this process. The overall reaction results in the formation of methyl ethyl ketazine [5921-54-0] (39) and water ... 

Conversion of Aromatic Rings to Nonaromatic Cyclic Structures. On treatment with oxidants such as chlorine, hypochlorite anion, chlorine dioxide, oxygen, hydrogen peroxide, and peroxy acids, the aromatic nuclei in lignin typically ate converted to o- and -quinoid stmctures and oxinane derivatives of quinols. Because of thein relatively high reactivity, these stmctures often appear as transient intermediates rather than as end products. Further reactions of the intermediates lead to the formation of catechol, hydroquinone, and mono- and dicarboxyhc acids. 

Precipitate formation can occur upon contact of iajection water ions and counterions ia formation fluids. Soflds initially preseat ia the iajectioa fluid, bacterial corrosioa products, and corrosion products from metal surfaces ia the iajectioa system can all reduce near-weUbore permeability. Injectivity may also be reduced by bacterial slime that can grow on polymer deposits left ia the wellbore and adjacent rock. Strong oxidising agents such as hydrogen peroxide, sodium perborate, and occasionally sodium hypochlorite can be used to remove these bacterial deposits (16—18). 

Cyanide destmction by alkaline chlorination is a widely used process. With alkaline chlorination, cyanide is first converted to cyanate with hypochlorite [7681-52-9] at a pH greater than 10. A high pH is required to prevent the formation of cyanogen chloride [506-77-4] which is toxic and may evolve in gaseous form at a lower pH. With additional hypochlorite, cyanate is then oxidized to bicarbonate, nitrogen gas, and chloride. The pH for this second stage is 7—9.5 (6). 

Sodium bicarbonate is generally added to increase alkalinity and muriatic acid (HCl) or sodium bisulfate (NaHSO ) to reduce it. In general, with acidic sanitizers such as chlorine gas or trichloroisocyanuric acid, ideal total alkalinity should be in the 100—120 ppm range, whereas, with alkaline products such as calcium, lithium, or sodium hypochlorite, a lower ideal total alkalinity of 80—100 ppm is recommended (14). Alkalinity is deterrnined by titration with standard sulfuric acid using a mixed bromcresol green—methyl red indicator after dechlorination of the sample with thiosulfate. Dechlorination with thiosulfate causes higher readings due to formation of hydroxyl ion (32) ... 

Anhydrous zinc chloride can be made from the reaction of the metal with chlorine or hydrogen chloride. It is usually made commercially by the reaction of aqueous hydrochloric acid with scrap zinc materials or roasted ore, ie, cmde zinc oxide. The solution is purified in various ways depending upon the impurities present. For example, iron and manganese precipitate after partial neutralization with zinc oxide or other alkah and oxidation with chlorine or sodium hypochlorite. Heavy metals are removed with zinc powder. The solution is concentrated by boiling, and hydrochloric acid is added to prevent the formation of basic chlorides. Zinc chloride is usually sold as a 47.4 wt % (sp gr 1.53) solution, but is also produced in soHd form by further evaporation until, upon cooling, an almost anhydrous salt crystallizes. The soHd is sometimes sold in fused form. 

Hypochlorous acid reacts very rapidly and quantitatively with a slight excess of free ammonia forming monochloramine, NH2CI, which reacts at a slower rate with additional HOCl forming dichloramine, NHCI2. Trichloramine is formed when three moles of HOCl are added per mole of ammonia between pH 3—4 (100). Hypochlorous acid in the form of chlorine or hypochlorite is used in water treatments to oxidize ammonia by the process of break-point chlorination, which is based on formation of unstable dichloramine. The instabiHty of NHCI2 is caused by presence of HOCl and NCl (101,102). The reaction is most rapid at a pH of about 7.5 (103). Other nitrogen compounds such as urea, creatinine, and amino acids are also oxidized by hypochlorous acid, but at slower rates. Unstable iV-chloro compounds are intermediates in deammination of amino acids (104,105). 

The solubilities of Li, Na, and Ca hypochlorites in H2O at 25°C ate 40, 45, and 21%, respectively. Solubility isotherms in water at 10°C have been determined for the following systems Ca(OCl)2—CaCl2, NaOCl—NaCl, and Ca(OCl)2—NaOCl (141). The densities of approximately equimolar solutions of NaOCl and NaCl ate given in several product bulletins (142). The uv absorption spectmm of C10 shows a maximum at 292 nm with a molar absorptivity of 350 cm ( 5)- Heats of formation of alkali and alkaline earth hypochlorites ate given (143). Thermodynamic properties of the hypochlorite ion ate ... 

The rate-conttolling step to chlorate is the bimoleculat formation of chlorite, which reacts rapidly with hypochlorite. The temperature dependence of the rate constants is expressed by the equations = 2.1 x 10 g-io3.8/i T 3 2 x 10 g-87.o/i T L/(mol-s) (144). The uncataly2ed decomposition to... 

Anhydrous hypochlorites ate oxidi2ed to chlorates by CI2O (176). The rate of chlorate formation decreases in the order Na > Ba > Si > Li > Ca. In the presence of gaseous chlorine, dry hypochlorites decompose in two ways ... 

Strontium, Li, and Ca hypochlorites react primarily by the first path and NaOCl mainly by the second. In the presence of moisture, chlorate formation is the predominate reaction in all cases. 

Calcium hypochlorite can also be prepared by reaction of soHd lime (212), quicklime (213), or CaCl2 (214) with CI2O chlorate formation is a competing side reaction. 

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