Sodium hypochlorite/hypochlorous

Sodium hypochlorite Hypochlorous acid, sodium salt (7681-52-9), 76, 47 for scavenging sulfur compounds, 76, 124... 

Exposure to a chemical can cause damage at the point or site of exposure if the substance is reactive, irritant, corrosive, or caustic. Thus substances such as kettle descaler (formic acid), battery acid (sulphuric acid), caustic soda (sodium hydroxide), and bleach (sodium hypochlorite/hypochlorous acid) can cause serious, and maybe permanent, damage to the skin, the eyes or the oesophagus, and stomach if they come into contact with these parts of the body. Unfortunately, people sometimes attempt suicide by swallowing such substances for example, drinking kettle descaler or bleach causes serious damage to the lining of the gut (see case notes, p- 193). 

Chlorine and Bromine Oxidizing Compounds. The organo chlorine compounds shown in Table 6 share chemistry with inorganic compounds, such as chlorine/77< 2-3 (9-j5y and sodium hypochlorite/7 )< /-j5 2-5 7. The fundamental action of chlorine compounds involves hydrolysis to hypochlorous acid (see Cm ORiNE oxygen acids and salts). 

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. 

The dissociation of hypochlorous acid depends on the pH. The unionized acid is present in greater quantities in acid solution, although in strongly acid solution the reaction with water is reversed and chlorine is Hberated. In alkaline solutions the hypochlorite ion OCL is increasingly Hberated as the pH is increased. The pH is important because unionized hypochlorous acid is largely responsible for the antimicrobial action of chlorine in water. Chlorine compounds are therefore more active in the acid or neutral range. The hypochlorites most commonly employed are sodium hypochlorite [7681-52-9] or calcium hypochlorite [7778-54-3]. 

A 3-1., three-necked flask fitted with a mechanical stirrer, a dropping funnel, and a thermometer is then charged with an aqueous solution of 2.2 moles of calcium hypochlorite [Hypochlorous acid, calcium salt] (Note 3), and the piperidine acetate prepared above is placed in the dropping funnel. The hypochlorite solution is stirred and cooled to 0° to — 5° with a methanol-ice bath, and the piperidine acetate is added dropwise over a period of 1.25 hours while the temperature is maintained below 0°. After a further 15 minutes of stirring, equal portions of the mixture are placed in two 2-1. separatory funnels and extracted three times with a total of about 1300 ml. of ether. The ether extract is placed in a 2-1. flask and dried over anhydrous sodium sulfate in a cold room at 4° overnight. After filtration to remove inorganic material, the bulk of the ether is removed by boiling on a water bath maintained below 60° (Note 4). 

PPG [Pittsburgh Plate Glass Company] A process for making calcium hypochlorite. Hypochlorous acid and chlorine monoxide, generated by reacting chlorine and carbon dioxide with sodium carbonate monohydrate, are passed into lime slury. Invented in 1938 by I. E. Muskatt and G. H. Cady at the Pittsburgh Plate Glass Company. 

The chlorination of water is usually carried out by adding chlorine gas, sodium hypochlorite, or calcium hypochlorite to the water in low concentrations. The active antibacterial agent in each case is hypochlorous acid, HClO(aq). For example, when chlorine gas is added to water, hypochlorous acid is formed by the following reaction. 

Hypochlorous acid is obtained by dissolving chlorine in water, or by adding bleaching powder or sodium hypochlorite to water. A better method of production is passing chlorine gas into a well-agitated suspension of mercuric oxide ... 

The hypochlorous acid oxidizes the cell walls and kills bacteria. Solid calcium hypochlorite, Ca(OCl)2, and liquid solutions of sodium hypochlorite, NaOCl, can be used to generate hypochlorous acid in place of chlorine gas, for example, in chlorinating swimming pools. The hypochlorite ion generated from Ca(OCl)2 and NaOCl forms an equilibrium with water represented by the equation ... 

Sodium hypochlorites (and calcium hypochlorite s) disinfection property is due to its ability to form hypochlorous acid, HOC1. The hypochlorous acid oxidizes the cell walls and kills bacteria. Sodium hypochlorite generates hypochlorous acid according to the reaction NaOCl( H2offi —> HOCl + NaOH(Ml. The hypochlorite ion generated from NaOCl exists... 

The catalytic procedure described here allows a fast, cheap and highly selective conversion of primary alcohols into aldehydes, using sodium hypochlorite as the oxidant in a two-phase (dichloromethane-water) system. Aqueous sodium hypochlorite is buffered at pH 8.6-9.5 to ensure the presence of hypochlorous acid in the organic layer.13... 

The paper pulp should be basic. Sodium hypochlorite (NaCIO) is a salt prepared from a strong base (NaOH) and a weak acid (HCIO). Salts of strong bases and weak acids are basic. The solution is basic because the hypochlorous ion (CIO1) bonds with hydrogen ions (H+) from water leaving an excess of hydroxide ions (OH1-). The following equations describe the salt formation and the hydroxide ion formation ... 

The resulting aqueous solution containing sodium chloride and sodium hypochlorite is known as Javelle water and is used as an antiseptic (Dakin s solution). Treatment of Javelle water with a strong acid results in liberation (in solution) of the weak and unstable hypochlorous acid... 

Both hypochlorous acid and the hypochlorites are relatively unstable and decompose readily with liberation of oxygen and the formation of chlorides. In fact, the acid is known only in solution. These compounds are excellent oxidizing agents they are used as bleaching agents, as antiseptics, as disinfectants, and in the production of ethylene glycol. The commercial production of sodium hypochlorite by electrolysis has been described previously. 

The salt solution at the equivalence point of a titration involving a weak acid or base will not be at neutral pH. For example, an equimolar solution of NaOH and hypochlorous acid HCIO at the equivalence point of a titration will be a base because it is indistinguishable from a solution of sodium hypochlorite. A pure solution of NaCIO(ag) will be a base because the CIO" ion is the conjugate base of HCIO, and it consumes H+(aqr) in the reaction CIO + H+ HCIO. 

Fig. 17.17. Sodium chlorite oxidation of aliphatic or aromatic aldehydes to form a carboxylic acid. The extra additive destroys the reduction product of the oxidant, i.e., sodium hypochlorite or hypochloric acid.

Chlorine is commonly used to kill microbes in pretreatment prior to RO and to break up organics that may foul RO membranes. It is used rather than other halogens because of its higher ORP. Chlorine is available in many forms, such as chlorine gas, sodium hypochlorite (bleach), chloramines, and chlorine dioxide. Chlorine gas and sodium hypochlorite each react with water to form hypochlorous acid, as shown in Equations 8.5 and 8.6, respectively. 

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