Isocyanuric acids, chlorinated

The preferred method for analyzing chlorinated isocyanuric acids and their salts is the iodometric titration (J) The main limitation of the iodometric titration method is sample size generally one would need a minimum of 100 milligrams for titrating either compound. For industrial hygiene samples, this is a problem because sample weights are usually smaller by a factor of 20,... 

The solution to the problem was discovered when a titrated sample (clear solution) was left on the bench and, after a period, it started changing back to a faint yellow color. We hypothesized that air oxidation may have caused that effect and, consequently, air may have interfered with analysis. Standard samples prepared and purposely delayed during the analysis showed that end-point volumes were larger, indicating that some of the iodide ions turned into free-iodine by air oxidation which, in turn, required more thiosulfate for titration and, therefore, larger end-point volume. The following chemical equations obtained from the literature 8) show what happens before, during, and after titration. The reaction of a chlorinated isocyanuric acid compound with potassium iodide in acidic pH is ... 

Conclusions. A sampling and analytical method for two chlorinated isocyanuric acids, NaDCC and TCCA, in air has been described. Briefly, these acids can be collected from air with DM-5000 (PVC copolymer) filters. The filter samples are extracted with water and titrated against sodium thiosulfate using constant-current potentiometry. The titration method will neither separate or distinguish NaDCC in the presence of TCCA or the reverse. The identity of either compound must be known in the workplace environment along with the identities of any other interfering... 

The starting point for the production of chlorinated isocyanurates is isocyanuric acid [8,85], The most important member of this group is potassium dichloro-cyanurate, made by chlorinating isocyanuric acid and neutralizing with potassium hydroxide. Isocyanuric acid may be made from phosgene and ammonia or from urea [85]. 

Definition Potassium salt of chlorinated isocyanuric acid Empirical C3HCI2KN3O3... 

At 25°C, pH 7.5, 1.5 ppm FAC, and 25 ppm cyanuric acid, the calculated HOCl concentration is only 0.01 ppm. Although the monochloroisocyanurate ion hydrolyzes to only a small extent, it serves as a reservoir of HOCl because of rapid hydrolysis. Indeed, this reaction is so fast that HClCy behaves like FAC in all wet methods of analysis. Furthermore, since HClCy absorbs uv only below 250 nm, which is filtered out of solar radiation by the earth s atmosphere, it is more resistant to decomposition than the photoactive C10 , which absorbs sunlight at 250—350 nm and represents the principal mode of chlorine loss in unstabilized pools (30). As Httie as 5 ppm of bromide ion prevents stabilization of FAC by cyanuric acid (23) (see also Cyanuric and ISOCYANURIC acids). 

When chlorine is employed for outdoor swimming pool sanitation, it is relatively rapidly decomposed by sunlight. Isocyanuric acid stabilizes chlorine by formation of photostable chloroisocyanurates (12). By contrast, bromine is not stabilized by isocyanuric acid. 

Stable A/-chloro compounds are formed by reaction of hypochlorous acid and appropriate N—H compounds. For example, HOCl, formed in situ via chlorine hydrolysis, converts di- or trisodium cyanurates to dichloro- and trichloroiso-cyanuric acids, respectively (114). Chloroisocyanurates can also be prepared from isocyanuric acid or monosodium cyanurate and preformed HOCl (115—117). Hydrolysis of chloroisocyanurates provide HOCl for use in swimming pool disinfection and in bleaching appHcations. 

Hypochlorous acid, preformed or generated in situ from chlorine and water, is employed in the manufacture of chlorohydrins (qv) from olefins, en route to epoxides, and in the production of chloramines (qv), especially chloroisocyanurates from cyanuric acid (see Cyanuric and isocyanuric acids). 

Appllca.tlons. The principal uses are in scouring cleansers and acid metal cleaners for dairy equipment. Use in dishwasher detergents has been supplanted by chlorinated isocyanurates, which are more cost-effective, more stable in hot water, and possess water softening properties. 

Inorganic Chemical Manufacture Anliydrous aluminum clUoride Antimony pentaeldoride Antimony trichloride Arsenic cliloride Bismutli trichloride Chlorinated isocyanurates Clilorine tri fluoride Ferric chloride Hydrochloric acid... 

The epoxy resin component is made by a 2-stage process involving reaction of l-chloro-2,3-epoxypropane (epichlorhydrin) with isocyanuric acid to give the l,3,5-tris(2-hydroxy-3-chloropropyl) derivative, which is then treated with sodium hydroxide to eliminate hydrogen chloride to form the title compound. One batch contained more than the normal amount of hydroly sable chlorine, and when excess epichlorhydrin was distilled off, the residual material decomposed with explosive violence. It was later established that the abnormal chlorine content was associated with reduced thermal stability, and criteria for hydrolysable chlorine, epoxy content and pH have been set to prevent distillation of off-spec, material. 

Canelli E. Chemical, bacteriological and toxicological properties of cyanuric acid and chlorinated isocyanurates as applied to swimming pool disinfection. Am J Public Health 1974 62 155-162. 

Note Miscellaneous uses include cyanuric acid for chlorinated isocyanurates, crystalline adducts, deicing agents, pharmaceutical intermediates and sulfamic acid and its ammonium salt. 

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