Chloramine compounds

Chemical precipitation Precipitation induced by addition of chemicals the process of softening water by the addition of lime and soda ash as the precipitants. Chloramines Compounds formed by the reaction of hypochlorous acid (or aqueous chlorine) with ammonia. 

A number of organic chlorine, or chloramine, compounds are now available for disinfection and antisepsis. These are the N-chloro (=N-C1) derivatives of, for example, sulphonamides giving compounds such as chloramine-T and dichloramine-T and halazone (Fig. 10.5), which may be used for the disinfection of contaminated drinking water. 

When water, chlorine, and ammonia are combined, three different species of chloramine compounds can be generated ... 

Effectiveness questioned Possible future regulations High oxidation capacity Does not form dangerous chloramine compounds More effective than chlorine due to high reduction potential Higher effectiveness than ozone in reducing viable aerobes on whole lettuce... 

The organo chlorine compounds are more expensive than inorganic chlorine compounds, but offer improved stabiUty against photolytic breakdown ia swimming pools (21). Swimming pool sanitation is generally accompHshed with 1—3 ppm free chlorine residual (see CHLORAMINES AND BROMAMINES Water, treati nt of swifting pools, spas, and hot tubs). ... 

Because of the time and expense involved, biological assays are used primarily for research purposes. The first chemical method for assaying L-ascorbic acid was the titration with 2,6-dichlorophenolindophenol solution (76). This method is not appHcable in the presence of a variety of interfering substances, eg, reduced metal ions, sulfites, tannins, or colored dyes. This 2,6-dichlorophenolindophenol method and other chemical and physiochemical methods are based on the reducing character of L-ascorbic acid (77). Colorimetric reactions with metal ions as weU as other redox systems, eg, potassium hexacyanoferrate(III), methylene blue, chloramine, etc, have been used for the assay, but they are unspecific because of interferences from a large number of reducing substances contained in foods and natural products (78). These methods have been used extensively in fish research (79). A specific photometric method for the assay of vitamin C in biological samples is based on the oxidation of ascorbic acid to dehydroascorbic acid with 2,4-dinitrophenylhydrazine (80). In the microfluorometric method, ascorbic acid is oxidized to dehydroascorbic acid in the presence of charcoal. The oxidized form is reacted with o-phenylenediamine to produce a fluorescent compound that is detected with an excitation maximum of ca 350 nm and an emission maximum of ca 430 nm (81). 

Cyanide compounds are classified as either simple or complex. It is usually necessary to decompose complex cyanides by an acid reflux. The cyanide is then distilled into sodium hydroxide to remove compounds that would interfere in analysis. Extreme care should be taken during the distillation as toxic hydrogen cyanide is generated. The cyanide in the alkaline distillate can then be measured potentiometricaHy with an ion-selective electrode. Alternatively, the cyanide can be determined colorimetricaHy. It is converted to cyanogen chloride by reaction with chloramine-T at pH <8. The CNCl then reacts with a pyridine barbituric acid reagent to form a red-blue dye. 

SuperchlorinationShock Treatment. Superchlorination or shock treatment of pool water is necessary since accumulation of organic matter, nitrogen compounds, and algae consumes free available chlorine and impedes disinfection. Reaction of chlorine with constituents of urine or perspiration (primarily NH" 4, amino acids, creatinine, uric acid, etc) produces chloramines (N—Cl compounds) which are poor disinfectants because they do not hydrolyze significantly to HOCl (19). For example, monochloramine (NH2CI) is only 1/280 as effective as HOCl against E. coli (20). 

Urea (24), amino acids (25), and creatinine (26) are also decomposed during superchlorination or shock treatment, with formation of N2 and other oxidation products. However, the process is slower than with ammonium ion (see Chloramines and BROMAMINEs). Urea is the principal nitrogen-containing compound in swimming pools. Since it is an amide, it reacts slowly with chlorine, yielding N2, NCl, and NO/ (27). 

OtherH-Chloro Compounds. Sodium N-chlorobenzenesulfonamide (chloramine B) [127-52-6] (4), sodium A/-chloro-/)-toluenesulfonamide (chloramine T) [127-65-1] (5), /V-cb1orosuccinimide [128-09-6] (6), and tricbloromelamine [12379-38-3] (7) have also had minor roles as bleaching agents. 

Chloral forms well-crystallized adducts (126) with diaziridines containing at least one NH group (B-67MI50800). Carbonyl addition products to formaldehyde or cyclohexanone were also described. Mixtures of aldehydes and ammonia react with unsubstituted diaziridines with formation of a triazolidine ring (128). Fused diaziridines like (128) are always obtained in ring synthesis of diaziridines (127) from aldehyde, ammonia and chloramine. The existence of three stereoisomers of compounds (128) was demonstrated (76JOC3221). Diaziridines form Mannich bases with morpholine and formaldehyde (64JMC626), e.g. (129). 

Compound (253) is formed from benzaldehyde and methylhydroxylamine-O-sulfonic acid in 35% yield. With ethyl-substituted chloramine or hydroxylamine-O-sulfonic acid yields do not exceed 10%, which is assumed to be due to steric hindrance and is foreseeable for both carbonyl addition and O —N bond formation. 

Two substituents on two N atoms increase the number of diaziridine structures as compared with oxaziridines, while some limitations as to the nature of substituents on N and C decrease it. Favored starting materials are formaldehyde, aliphatic aldehydes and ketones, together with ammonia and simple aliphatic amines. Aromatic amines do not react. Suitable aminating agents are chloramine, N-chloroalkylamines, hydroxylamine-O-sulfonic acid and their simple alkyl derivatives, but also oxaziridines unsubstituted at nitrogen. Combination of a carbonyl compound, an amine and an aminating agent leads to the standard procedures of diaziridine synthesis. 

The parent compound, cyclic diazomethane , was first obtained from formaldehyde, ammonia and chloramine by dichromate oxidation of the initially formed higher molecular diaziridine-formaldehyde condensation product (61TL612). Further syntheses of (44) started from Schiff bases of formaldehyde, which were treated with either difluoramine or dichloramine to give (44) in a one-pot procedure. Dealkylation of nitrogen in the transient diaziridine was involved (65JOC2108). 

The amount of HOCl plus OCl in wastewater is referred to as the free available chlorine. Chlorine is a very active oxidizing agent and is therefore highly reactive with readily oxidized compounds such as ammonia. Chlorine readily reacts with ammonia in water to form chloramines. 

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