National Toxicology Program

A. Production

1. Manufacturing Process

Several methods have been used to prepare halazone. A common method involves the chlorination of p-sulfonamidobenzoic acid in an alkaline medium [Budavari, 1989; Saljoughian and Sadeghi, 1986]. In this process, p-sulfonamidobenzoic acid is chlorinated using either chlorine gas in dilute sodium hydroxide or sodium hypochlorite in sodium hydroxide resulting in a 93% and 78% halazone yield, respectively. It has also been reported that when p-sulfonamidobenzoic acid is treated with an excess of sodium hypochlorite, the addition of hydrochloric acid or acetic acid also results in the precipitation of halazone as the main reaction product [Saljoughian and Sadeghi, 1986]. Other sources report that halazone can be synthesized by oxidizing the methyl group of p-toluenesulfonamide to a carboxyl and treating the resultant compound [Kirk-Othmer, 1979], p-sulfonamidobenzoic acid [Hranilovic et al., 1977] with hypochlorite [Kirk-Othmer, 1979] to form halazone at a 60-80% yield [Hranilovic et al., 1977]. Halazone may also be prepared when p-toluenesulfonyl chloride (obtained by the reaction of toluene and chlorosulfonic acid) is converted to the amide, which is treated with hypochlorite to form p-toluenesulfondichloramide. The methyl group is then oxidized with dichromate or permanganate to form halazone [Gennaro, 1985].

An additional method, which is reportedly both fast and efficient, involves the oxidation of dichloramine-T with potassium permanganate in a mildly alkaline medium containing sodium carbonate. In this procedure, the sodium salt of halazone is initially formed which, following hydrolysis with dilute acetic acid, results in a halazone yield of 95% [Saljoughian and Sadeghi, 1986]. As described in the abstract of a Japanese patent, halazone has been prepared by diaphragmic electrolysis using aqueous chlorides ( e.g., 25% sodium chloride solutions) as catholytes, and mixtures of p-sulfonamidobenzoic acid as anolytes. This process, which was carried out at 20°C for 1-6 hours using 0.5 amperes, resulted in a 93.2% halazone yield. The authors reported that 2.5% sodium chloride can be substituted with 40% calcium chloride, 33% magnesium chloride, or 23% potassium chloride [Miyazaki, 1975]. According to another paper by the same authors, halazone has also been prepared by electrolytic N-chlorination of p-sulfonamidobenzoic acid in aqueous solutions of sodium chloride at a platinized titanium anode under constant current conditions. The halazone yield varied from 81%-94%, decreasing at temperatures greater than 40°C, and increasing as the amount of electricity passed through the system increased [Mikazaki, 1976].

2. Producers and Importers

U.S. Producers:

Importers:

No information was found on importers of halazone from the public file of the EPA Toxic Substances Control Act (TSCA) Inventory [USEPA, 1991].

3. Volume

One company is listed as a processor of halazone in the public file of the EPA Toxic Substances Control Act (TSCA) Inventory, but no information was provided on volume [USEPA, 1991]. Halazone is not listed in the United States International Trade Commission's publication, Synthetic Organic Chemicals for the years 1985-1989 [USITC, 1986-1990]. This compound is not listed in SRI's Chemical Economics Handbook [SRI, 1991].

4. Technical Product Composition

The commercially available product is a mixture of mono- and di-chloroamides; the dichloro compound predominates [Budavari, 1989]. Halazone contains not less than 91.5% and not more than 100.5% pure halazone {calculated on a dried basis}[USPC, 1990].

B. Use

Halazone is used for the extemporaneous disinfection of drinking water [Reynolds, 1989; Gennaro, 1985; Olin, 1989; Budavari, 1989, Grant, 1974], primarily on a small-scale and under adverse conditions when populations or individuals must depend on sources of water that are potentially contaminated. This compound has been used for this purpose since World War II [O'Connor and Kapoor, 1970]. Halazone tablets are used to disinfect water when boiling is not feasible. The use of halazone for this purpose has been recommended for individuals traveling abroad, especially to developing nations [Newsday, 1991], and for backpackers and hunters who cannot conveniently boil water [Newsday, 1991].

Following reports in September, 1988 that hurricane Gilbert was approaching, Halazone was recommended by the International Bottled Water Association (IBWA) for consumer use to prepare for potential damage to public water supply systems. For consumers who were unable to buy bottled water because of its limited supply, the IBWA recommended that consumers add halazone tablets to boiled tap water before storing to further reduce the risk of contamination [PR Newswire, 1991]. In addition, in its publication, Will Your Drinking Water Be Safe When?, concerning what the public can do to prepare for emergencies (including earthquakes, droughts, and hurricanes) that may affect the availability of the drinking water supply, the IBWA recommends the use of halazone tablets for tap water disinfection [IBWA, 1991].

Halazone is used at a concentration of 2 to 10 ppm for water disinfection [Gennaro, 1985]. Halazone tablets employed for this purpose have the following composition: 5.3 mg halazone, 5.18 mg soda ash, 11.92 mg boric acid and 114.0 mg sodium chloride [O'Connor and Kapoor, 1970]. One halazone tablet per quart of water is generally used to treat contaminated water (one tablet dissolved in one quart of water liberates 2.3 ppm chlorine and 1.1 ppm hypochlorous acid {as chlorine gas}). Halazone is available to consumers in drug stores and camping supply stores [Magazine ASAP, 1991].

Halazone has also been patented for the following uses:

Disinfection of biological solid wastes (hospitals and biological laboratories) before incineration [Gasparotti, 1988].

Ingredient of a disinfectant for contact lenses [Hopkinson and Cannell, 1986].

Determination of iodine numbers of fats and oils [Budavari, 1989].