Formation of Chloramines

When water containing ammonia or ammonium ions is treated with chlorine gas, chloramines are rapidly formed  

HOCl -f- NH3 NH2CI -E HOCl ir NHCI2 + HOCl =5 NCI3 (5.18) 

This reaction can be considered as a nucleophilic displacement on chlorine by the free electron pair of nitrogen. 

Monochloramine predominates at pH 7.5, whereas dichloramine prevails down to pH 5, except at high ammonium ion concentrations, where it is destroyed by the following reaction (Fair et al., 1948)  

Trichloramine occurs in appreciable concentrations only at pH 3.5. At very high relative HOCl concentrations, combined chlorine species disappear by a complex process referred to as the breakpoint reaction, characterized by decreasing concen- 

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The formation of chloramine as an intermediate, followed by reaction with nitric acid to produce the corresponding nitramine and HOC1, may explain the catalytic action of HC1 in the nitration of amines... 

The formation of chloramines is an initial step of another mechanism of oxidative modification of LDL. It has been shown that the MPO-hydrogen peroxide-chloride system reacts with L-tyrosine to form p-hydroxyphenylacetaldehyde [163], As activated neutrophils release both MPO and hydrogen peroxide, it was suggested that neutrophils can stimulate the formation of p-hydroxyphenylacetaldehyde by producing chloramines as intermediates during the oxidation of LDL [164],... 

Treatment of municipal water with chlorine and ammonia results in the formation of chloramines, a long-lasting disinfectant. Too much ammonia, however, enhances nitrification by bacteria in the water, which, in turn, increases the nitrate and nitrite levels. High nitrate and nitrite levels in drinking water is a health hazard, particularly for infants. 

The intermediate formation of chloramine explains the catalytic action of hydrochloric acid in the nitration of amines, as mentioned above. The following reaction mechanism was drawn up by Wright [41]... 

NOTE Chlorine is widely used in the protection of drinking water, the manufacture of pharmaceuticals, crop pesticides, paper, rubbers, resins and plastics, and thousands of other products. Nevertheless, since the early 1990s, there has been a groundswell of opinion to either ban or severely limit the use of chlorine in all manners of processes. This is based on observations associated with the probable adverse effect to the environment from certain chlorinated organic chemicals, such as polychlorinated biphenyl (PCB) and the insecticide DDT. There is also concern in a number of other areas, for example, that free chlorine may contribute to effluent toxicity due to the formation of chloramines and trihalomethanes (THMs). In the United States in 1993 to 1994, this opinion was fueled by the possibility that the Environmental Protection Agency (EPA) would... 

Hawkins CL, Davies MJ (2001) Hypochlorite-Induced Damage to Nucleosides Formation of Chloramines and Nitrogen-Centered Radicals. Chem Res Toxicol 14 1071... 

Trypsin attacks the peptide bonds following the basic amino acids arginine and lysine. Formation of chloramines decrease trypsin binding sites, which causes a decrease in protein susceptibility to trypsin digestion. On the other hand, chloramine formation from free amino residues may induce changes in tertiary albumin structure, revealing some normally inaccessible amino residues. Therefore, removal... 

It is well-known that organoboranes can be utilized to yield primary amines by treating them with chloramine or hydroxylamine-O-sulfonic acid Recently Kabalka et al. reported a convenient synthesis of primary alkyl amines via the reaction of organoboranes with ammonium hydroxide in the presence of sodium hypochlorite (Eq. 13) The reaction presumably proceeds through the in situ formation of chloramine. 

Effluents from sewage treatment plants can contain significant amounts of ammonia that when disinfected, instead of finding free chlorine, subsfilufion producfs of ammonia called chloramines are found. In addition, in water treatment plants, ammonia are often purposely added to chlorine. This, again, also forms the chloramines. Chloramines are disinfectants like chlorine, but they are slow reacting, and it is this slow-reacting property that is the reason why ammonia is used. The purpose is to provide residual disinfectant in the distribution system. In other words, the formation of chloramines assures that when the water arrives at the tap of the consumer, a certain amount of disinfectant still exists. 

The formation of chloramines is a stepwise reaction sequence. When ammonia and chlorine are injected into the water that is to be disinfected, the following reactions occur, one after the other in a stepwise manner. 

Chloramines Water chlorination in the presence of NH leads to the formation of chloramines (for reviews, see Isaac and Morris, 1983, and Brezonik, 1994). Reaction rates and product distribution depend on pH, relative concentration of NH.i and HOCl, time, and temperature. The pH dependence of NH2CI formation is consistent with a rate law involving the neutral species HOCl and NH3 as reactants ... 

The u.v. and i.r. spectra of NH3 and Cl2 codeposited in a N2 matrix at 20 K are consistent with the formation of a charge-transfer complex between these molecules.21 The formation of chloramine in high yield from Cl2 and NH3 in the presence of a ketone has been reported.22 Gas-phase as well as gas-liquid-phase reactions were investigated to assess the suitability of this reaction for the production of hydrazine. However, from a study of the acid-base properties of Br2 in liquid NH3 it has been deduced that BrNH2 does not exist in dilute solutions at low temperatures, owing to the stability of the solvated Br+ species.23... 

After development on TLC plates, amino-substituted 1,3,5-triazines can be revealed by use of the chloro-toluidine reaction <83JC97>. This is a sensitive method developed for the detection of amino and imino compounds on paper chromatograms. The method depends on the formation of chloramines which are then detected by liberation of iodine from a starch-potassium iodide reagent. 

Because of the effect of pH on the formation of chloramine, pH has a profound effect on the species of combined chlorine that make up the "hump" of the breakpoint curve. At pH 7 and above, essentially only NHgCl is present, while below 7, significant amounts of NHClj are found, particularly at mole ratios between 1 1 and the breakpoint. NHCI2 at mole ratios less than 1 1 is favored only below a pH of approximately 5. NCI3 will not appear in significant quantities under the "hump" unless the pH is of the order of 4 or lower. 

The interaction between toluene-p-sulphonamide with freshly prepared sodium hypochlorite solution (2 M) in the presence of 10% NaOH solution results into the formation of chloramine-T, and a mole of H2O gets eliminated. 

Hawkins CL, Davies MJ. Hypochlorite-induced damage to DNA, RNA, and polynucleotides formation of chloramines and nitrogen-centered radicals. Chem Res Toxicol. 2002 15 83-92. 

An FAC residual is regarded by the US Environmental Protection Agency as a sign of adequate disinfection. The problem encountered in ensuring that water leaving the treatment plant has been treated with enough chlorine to leave an FAC residual is illustrated by breakpoint chlorination. In breakpoint chlorination, dissolved chlorine is added to the water in a stepwise manner to determine the chlorine demand and to allow for the formation of chloramines. 

Chlorine reacts with amine or ammonia constituents in water or in air, often replacing the hydrogens. Formation of chloramines, trihalomethanes, and other chlorinated organic compounds during natural water chlorination and wastewater treatment are the result of substitution reactions, as illustrated by the following equations ... 

Nitrogen trichloride can be formed during the chlorination of water containing traces of ammonia. In the chlorination by hypochlorous acid there is a slow formation of chloramine, followed by more rapid reactions that give successively dichloramine and nitrogen trichloride. The kinetic rate law (10) has been obtained, the two terms presumably indicating chlorination by HOCl and CI2 ... 

This reaction proceeds via the formation of chloramine, NH2CI, a highly toxic and volatile gas. For this reason, household bleach or scouring powders, which may contain the hypochlorite ion, and ammonia cleansers should never be mixed ... 

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