Chlorine generators

Early demand for chlorine centered on textile bleaching, and chlorine generated through the electrolytic decomposition of salt (NaCl) sufficed. Sodium hydroxide was produced by the lime—soda reaction, using sodium carbonate readily available from the Solvay process. Increased demand for chlorine for PVC manufacture led to the production of chlorine and sodium hydroxide as coproducts. Solution mining of salt and the avadabiHty of asbestos resulted in the dominance of the diaphragm process in North America, whereas soHd salt and mercury avadabiHty led to the dominance of the mercury process in Europe. Japan imported its salt in soHd form and, until the development of the membrane process, also favored the mercury ceU for production. 

In acid solution, Mn02 is an oxidi2ing agent, and is used as such in industry. The classic example is the oxidation of chloride in HCl, which has been a convenient means of chlorine generation, both in the laboratory and in the old Weldon process for the manufacture of chlorine. 

The reaction is carried out over a supported metallic silver catalyst at 250—300°C and 1—2 MPa (10—20 bar). A few parts per million (ppm) of 1,2-dichloroethane are added to the ethylene to inhibit further oxidation to carbon dioxide and water. This results ia chlorine generation, which deactivates the surface of the catalyst. Chem Systems of the United States has developed a process that produces ethylene glycol monoacetate as an iatermediate, which on thermal decomposition yields ethylene oxide [75-21-8]. 

When chlor-alkali electrolysis is conducted in an undivided cell with mild-steel cathode, the chlorine generated anodically will react with the alkali produced cathodically, and a solution of sodium hypochlorite NaClO is formed. Hypochlorite ions are readily oxidized at the anode to chlorate ions this is the basis for electrolytic chlorate production. Perchlorates can also be obtained electrochemically. 

For chlorination we graduated from hypochlorite tanks to in situ chlorine generation by electrochemical means, a major improvement indeed, which we highly recommend. However, we have had more than our share of problems with the chlorine generator we used. 

In another procedure, oxidation is carried out in the presence of chloride ions and ruthenium dioxide [31]. Chlorine is generated at the anode and this oxidises ruthenium to the tetroxide level. The reaction medium is aqueous sodium chloride with an inert solvent for the alkanol. Ruthenium tetroxide dissolves in the organic layer and effects oxidation of the alkanol. An undivided cell is used so that the chlorine generated at the anode reacts with hydroxide generated at the cathode to form hypochlorite. Thus this electrochemical process is equivalent to the oxidation of alkanols by ruthenium dioxide and a stoichiometric amount of sodium hypochlorite. Secondary alcohols are oxidised to ketones in excellent yields. 1,4- and 1,5-Diols with at least one primary alcohol function, are oxidised to lactones while... 

The reactions involving bromine or chlorine generate hydrogen halide and are autocata-lytic. Reactions with /V-bromosuccinimide or tetrabromocyclohexadienone form no hydrogen bromide, and these reagents may therefore be preferable in the case of acid-sensitive compounds. 

A rapid potentiometric flow inject technique for the simultaneous determination of oxychlorine species (e g., CIO2 ) was developed by Ohura et al. (1999). The analytical method is based on the detection of a large transient potential change of the redox electrode due to chlorine generated via the reaction of the oxychlorine species (e.g., CIO2 ). The detection limit for C102 is 3.4 ppb. 

Hazen SL, Hsu FF, Duffin K, Heinecke JW (1996) Molecular Chlorine Generated by the Myeloperoxidase-Hydrogen Peroxide-Chloride System of Phagocytes Converts Low Density Lipoprotein Cholesterol into a Family of Chlorinated Steroids. J Biol Chem 271 23080... 

In basic solutions, the chlorine generated anodically in the electrolyte can be hydrolyzed by the cathodically produced hydroxide ion to form hypochlorite ion ... 

Apparatus 350-cc. tubulated retort or distilling flask, five 8-ounce wide-mouth bottles, chlorine generator (2,000-cc. flask) or cylinder of liquid chlorine. 

Materials waste liquor from chlorine generator, 250 cc. 

Procedure Setup the chlorine generating apparatus as illustrated below. Note your chlorine generator does not have to be as fancy as the apparatus illustrated below, but your system should be similar in design. You can use latex tubing, PVC pipes and other plastic devices as well, steel pipes can be used, but other metals should be avoided due to corrosion. Also, observe the chlorine generator utilizing an electrochemical method. The electrochemical method is sufficient to produce laboratory quantities of gas (see the following illustration). 

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