Chloramines dichloramine

Dichloramine. The least stable chloramine, dichloramine [3400-09-7] has not been prepared in pure form. However, it has sufficient stabiUty in dilute organic or aqueous solutions for deterrnination of some physical and chemical properties. It has a pungent odor and can impart an odor or off-taste to water at concentrations above 0.8 ppm. Dichloramine can be produced by reaction of HOCl with a slight excess of NH in the pH range 4—7 or by disproportionation of NH2CI at pH 3.5—4.0 ... 

In analogy to chloramines, dichloramine can react as a chlorinating agent and can transfer positive chlorine to ammonia or water. 

Both chloramine-T and dichloramine-T have marked antiseptic properties, chloramine-T being most frequently used because of its solubility in water. Aqueous solutions of chloramine-T can be used either for external application, or for internal application to the mouth, throat, etc, as chloramine-T in moderate quantities is non-toxic its aqueous solution can also be effectively used when the skin has come in contact with many of the vesicant liquid poison-gases, as the latter are frequently organic sulphur or arsenic derivatives which combine with or are oxidised by chloramine-T and are thus rendered harmless. 

Both chloramine-T and dichloramine-T can be readily estimated, because they liberate iodine from potassium iodide quantitatively in the presence of... 

Dichloramine-T and chloramine-T. When p toluenesulphonamide is dissolved in excess of sodium (01 calcium) hypochlorite solution, it is converted into the soluble salt of the N-monochloro derivative ... 

When the dichloramine-T is heated with sodium hydroxide solution, the reverse change occurs and sodium N-chloro-p-toluenesulphoiiamide (chloramine-T) crystallises out on cooling at a suitable concentration ... 

Both chloramine-T and dichloramine-T slowly liberate hypochlorous aeid in eontaet with water and are therefore employed as antiseptics the former is employed in the form of a dilute (e.g., 0-2 per eent.) aqueous solution, and the latter (which is insoluble in water) as a solution in an organic solvent, such as a chlorinated paraffin. 

A number of perhalides aie known, and one of the most stable is ammonium tetiachloioiodide [19702 3-3] NH IQ. Ammonia reacts with chlorine in dilute solution to give chloramines, a reaction important in water purification (see Cm,ORAMINES AND BROMAMINEs). Depending upon the pH of the water, either monochloramine [10599-90-3] NH2CI, or dichloramine [3400-09-7] NHCI2, is formed. In the dilutions encountered in waterworks practice, monochloramine is neady always found, except in the case of very acidic water (see Bleaching AGENTS Water). 

In reahty the chemistry of breakpoint chlorination is much more complex and has been modeled by computer (21). Conversion of NH/ to monochloramine is rapid and causes an essentially linear increase in CAC with chlorine dosage. Further addition of chlorine results in formation of unstable dichloramine which decomposes to N2 thereby causing a reduction in CAC (22). At breakpoint, the process is essentially complete, and further addition of chlorine causes an equivalent linear increase in free available chlorine. Small concentrations of combined chlorine remaining beyond breakpoint are due primarily to organic chloramines. Breakpoint occurs slightly above the theoretical C1 N ratio (1.75 vs 1.5) because of competitive oxidation of NH/ to nitrate ion. Organic matter consumes chlorine and its oxidation also increases the breakpoint chlorine demand. Cyanuric acid does not interfere with breakpoint chlorination (23). 

The lack of dependence on ionic strength in the first reaction indicates that it occurs between neutral species. Mono- or dichloramine react much slower than ammonia because of their lower basicities. The reaction is faster with CI2 because it is a stronger electrophile than with HOCl The degree of chlorination increases with decreasing pH and increasing HOCINH mol ratio. Since chlorination rates exceed hydrolysis rates, initial product distribution is deterrnined by formation kinetics. The chloramines hydrolyze very slowly and only to a slight extent and are an example of CAC. 

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). 

Acidification of chloramine T with sulfuric acid produces the formation of dichloramine T (DCT) and hypochlorous acid (HCIO), species which react with C=C bonds of the butadiene units. The effectiveness of the treatment is ascribed to the introduction of chlorine and oxygen moieties on the mbber surface. A decrease in the pH of the chloramine T aqueous solutions produced more extended surface modifications and improved adhesion properties in the joints produced with waterborne polyurethane adhesive (Figure 27.9). The adhesive strength obtained is slightly lower than that obtained for the rubber treated with 3 wt% TCI/MEK, and its increases as the pH of the chloramine T solution decreases (Figure 27.9). A cohesive failure in the rubber is generally obtained. 

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. 

Trichloramine is the most irritant of the chloramines together with dichloramine it is largely responsible for the chlrorine odours and eye irritation. 

The success of this reaction was ascribed to the solubility of the chlorozinc intermediate, whereas other chloramine-T derivatives (e.g. the sodium salt) are insoluble. An alternative non-nitrene pathway was not eliminated from consideration. On the other hand, no aromatic substitution or addition, characteristic of a free sulphonyl nitrene (see below), took place on treatment of jV,lV-dichloromethanesulphonamides with zinc powder in benzene in the cold or on heating. The only product isolated was that of hydrogen-abstraction, methanesulphonamide 42>, which appears to be more characteristic of the behaviour of a sulphonyl nitrene-metal complex 36,37). Photolysis of iV.iV-dichloromethanesulphonamide, or dichloramine-B, or dichloramine-T in benzene solution led to the formation of some unsubstituted sulphonamide and some chlorobenzene but no product of addition of a nitrene to benzene 19>. 

Ammonia (NH3) and hypochlorite ion (OC1-) combine to produce three different chloramine species—that is, compounds that are derivatives of ammonia in which one or more of the hydrogen atoms has been replaced by a chlorine atom. In order of increasing degree of chlorine substitution, these chloramines are named monochloramine (NH2CI), dichloramine (NHCh), and nitrogen trichloride (NCI3) ... 

Reacts with chlorine forming chloramines monochloramine, dichloramine and nitrogen trichloride ... 

Chlorine forms carbonyl chloride, COCl with carbon monoxide suhuryl chloride SO2CI with sulfur dioxide and chloramines (monochloramine, NH2CI, and dichloramine, NHCI2) with ammonia. Chloramines are often found at trace concentrations in sewage wastewater following chlorine treatment. 

Wright et al. [40] elaborated a new method of preparing nitramines by acting on chloramines with nitric acid in the presence of acetic anhydride. A typical example is the preparation of sec-butylnitramine (III) (Smart and Wright Suggitt, Myers and Wright [40]) from dichloramine (I) ... 

When toluene-p-sulphonamide is dissolved in excess calcium hypochlorite solution and then acidified with acetic acid, the /V,/V-dichloro derivative [(6) dichloramine-T] separates rapidly. When this is heated with sodium hydroxide solution the sodium salt of the N-monochloro derivative [(7) chloramine-T)] is formed and crystallises out on cooling at a suitable concentration (Expt 6.43). 

Experiment 6.43 TOLUENE-p-SlJLPHON AMIDE, DICHLORAMINE-T AND CHLORAMINE-T... 

Chloramine-T (sodium N-chlorotoluene-p-sulphonamide). For this preparation use dichloramine-T which has been prepared as above and thoroughly drained but not necessarily dried. Heat 45 ml of 10 per cent aqueous sodium hydroxide solution in a beaker to a temperature of about 80 °C, add 3.5 g (0.015 mol) of dichloramine-T in small quantities, stirring the mixture gently after each addition until a clear solution is obtained. When the addition is complete, filter the hot solution if turbid, and then allow it to cool spontaneously. Filter the crystals with suction, wash with a little saturated sodium chloride solution and dry upon filter paper or in a desiccator over anhydrous calcium chloride. The resulting chloramine-T weighs 3g (75%) and is almost pure. It may be recrystallised, if desired, from twice its weight of hot water. 

Chloramine B , see Sodium A-chlorobenzenesulfonamide, 2222 Chloratomercurio(formyl)methylenemercury(II), 0650 Chloric acid, 3990 Chlorimide, see Dichloramine, 4057... 

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