Hypochlorite generation

Transfer of an active chemical agent in an inherently safer form (e.g. sulphur dioxide as sodium metabisulphite, chlorine as sodium hypochlorite). Generation of an active agent in this manner clearly reduces the inventory in use. 

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... 

Dimethylborane has been used to hydroborate alkenes regiospecifically. The resulting dimethylalkylborane reacted with ammonium hydroxide and sodium hypochlorite (generation of NH2C1 in situ) to yield isomerically pure alkylamines [21] (Table 2.1). 

Chlorine is applied in a number of forms from chlorine gas to hypochlorite solution. It is important that the source of chlorine is not contaminated. For example, chlorine gas has been found to be contaminated with carbon tetrachloride, hypochlorite that is stored for a long time gradually breaks down to give chlorate, and hypochlorite generated electrolytically from seawater or brine with a high bromide content can have high concentrations of bromate. 

Halogens, alkyl nitrites and alkyl hypochlorites also undergo photolysis easily (Scheme 2.30). Alkyl nitrites and alkyl hypochlorites generate alkoxy radicals. 

Some aldehyde-derived diaziridines are unstable and hamper the Schmitz synthesis of the corresponding diazirines <1975J(P2)686>. A one-pot derivative of the standard Schmitz reaction has been developed to circumvent such problems, in which an intermediate diaziridine is stabilized by a trimethylsilyl group <2000TL795>. Treatment of the aldehydes 68a-c with LiHMDS, then HOSA, gave the silicon-stabilized diazirines 69a-c. In situ oxidation with f-butyl hypochlorite generated the diazirines 70a-c in moderate yields (Scheme 24). 

The success of indirect electrochemical oxidation and disinfection lies in the production of safe drinking water especially in rural areas where the necessity for skilled maintenance personnel should be avoided. The simplicity, stability, and low power consumption of devices such as the sodium hypochlorite generator described by Bashtan et al. [71] and the TiN reactor described by Matsunaga et al. [34] make these devices most cost effective for small-scale applications in remote locations. 

Fig. 6. On-site ultra pure hypochlorite generation system schematic (Electrol5hic Technologies Corporation, North Miami Beach, FL 33179).

L. W. Casson and J. W. Bess, Conversion to On-site Sodium Hypochlorite Generation, Lewis Publishers CRC Press, New York, 2003. 

Pepcon Systems Inc., Sodium Hypochlorite Generation, Pepcon Systems, Inc., Cedar City, UT, www.pepconsystems.com, 2005. 

On-Site Sodium Hypochlorite Generation System Comparison of High Strength 12% to Low Strength 0.8%... 

Potable Water Chlorination and Chloramination chapter introduces the detailed engineering procedures for calculation of CT values for disinfection, and both conventional and innovative process equipment, including the on-site chlorine gas and hypochlorite generation facilities (2). 

Disinfectant Usually hypochlorite-generating compound (e.g., trichlorocyanuric acid) 0-2... 

A stereocontrolled total synthesis of (+)-vinblastine (329), a prominent alkaloid used in cancer chemotherapy, was reported by the Fukuyama/ Tokuyama team and features an INOC reaction for the preparation of a key reaction intermediate utilized in their synthesis (2010CR101). Thus, the oxidation of oxime 323 with sodium hypochlorite generated the expected nitrile oxide 324 which imderwent a subsequent 1,3-dipolar cycloaddition to produce isoxazoline 325 as a single isomer (Scheme 59). The INOC proceeded via a six-membered chairlike transition state (i.e., 324) to furnish 325 with the desired stereochemistry. After reductive cleavage of the N—O bond in isoxazoftne 325 with zinc dust in acetic acid, a... 

Hypochlorites are direct substitutes for chlorine in such applications as bleaching and disinfecting. Their use removes the need to handle or store liquid chlorine at the processing facility, except as it is needed for hypochlorite generation. On-site production from salt or brine removes even that need. 

The efficiency of hypochlorite generation depends on the rate of its reduction at the cathode, which is a diffusion-controlled process. The reaction is... 

Girault and co-workers reported the application of plane interdigitated microband electrodes to an inorganic electrosynthesis of industrial interest die hypochlorite generation from sea water electrolysis. The system was studied in a laboratory cell [17] and also in a pilot plant [19]. A major problem in this synthesis is related to the deposition of scale (calcium and magnesium hydroxide) on the cathode due to the local production of OH anions. The coupling of the electrode processes permits the pH excursions on the cathode to be restricted, leading to a decrease in scale deposition. 

A system for the disinfection of swimming pools based on hypobromite is available. This is a modification of a hypochlorite generator system marketed by Olin, called the Lectranator [44]. 

Figure 11.13 A small scale hypochlorite generator (with permission from Electrocell AB [85]).

Most hypochlorite generators electrolyze brine in undivided cells. The chlorine and hydroxide react to form hypochlorite directly in the cell. A typical unit uses 30 g L sodium chloride to make 8 g L sodium hypochlorite. Higher concentrations can be made only with nontypical coated electrodes that prevent the oxidation of hypochlorite to chlorate. A maximum of 3 g sodium hypochlorite is made from seawater. Excess salt increases cell efficiency and suppresses hypochlorite oxidation. The sodium hypochlorite is usually stored in a tank from which it is metered, and hydrogen is allowed to escape to air. In some cases, especially with swimming pools, 3-6 g... 

Bennett JE (1974) Non-diaphragm electrolytic hypochlorite generators. In Chemical engineering progress... 

On-site hypochlorite generation systems (Figures 7-9 and 7-10) generally include water softener, a brine (salt water source) tank, electrolytic cells, and a hypochlorite storage tank. Sodium chloride (salt) is converted to hypochlorite by electrolysis. Some systems use seawater as the salt source, but it is common to make a brine solution... 

Most hypochlorite generation systems produce low-concentration solutions (around 1 percent hypochlorite). Some systems produce higher concentrations and some membrane systems even generate chlorine gas and sodium hydroxide (chlor-alkah cells). Several proprietary systems produce either chlorine or a liquid solution of mixed oxidants (e.g., ozone, chlorine dioxide, and chlorine). Most of these systems employ salt hrine and an electrolytic cell to produce the chemical product(s). 

Aerobic bacteria, which require oxygen and are present in large quantities when seawater or surface water is used for water-flood injection. Chlorine, usually from a hypochlorite generator, is used for control. 

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