Reactions with chloramine

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. 

In addition there is a further rapid but undesirable reaction with chloramine which destroys the N2H.1 produced ... 

Interesting examples of the addition of N-nucleophiles to nitrile oxides are syntheses of chelated Z-amidoxime, N-[2-(dimethylaminomethyl)phenyl]mesitylene-carboamidoxime (118), and pyranosyl amidoximes (119) from the respective nitrile oxides and amines. Aromatic aldoximes undergo unusual reactions with chloramine-T (4 equiv, in refluxing MeOH). N-(p-toly 1 )-N-(p-tosy 1 )benzamides are formed via addition of 2 equiv of chloramine-T to the intermediate nitrile oxide followed by elimination of sulfur dioxide (120). 

Caution Because obnoxious fumes are liberated during the reaction with chloramine, the apparatus should be set up in a well-ventilated hood. 

A spectroelectrochemical sensor has been developed for the bromide monitoring in industrial brine samples [154]. The bromide is oxidized to bromine and a sensitive colorimetric reaction with chloramine-T is employed for detection with a fiber-optic device. 

Telturoxide elimination.2 Tellurides are converted to alkenes by reaction with chloramine-T, presumably via the adduct a (equation I). This elimination proceeds In low yield with r-butyl hydroperoxide. 

Chlorolactonization. Unsaturated carboxylic acids are converted into chloro lactones in moderate yield by reaction with chloramine-T and methanesulfonic acid. Example ... 

As stated in the introduction, chloramine-T (where T denotes three crystalline water molecules) is a commonly used nitrene precursor, which is commercially available and costs less than do most other nitrene sources. The benefit of a silver salt in nitrene transfer reactions with chloramine-T is surprisingly simple. Because silver chloride is insoluble in most solvents, substoichiometric amounts of silver salts (like silver nitrate) can be used to remove the chloride from chloramine to facilitate the release of a free nitrene radical, which can aziridinate olefins. Since the amount of silver is near stoichiometric, it should not be called silver-based catalysis, although turnover numbers (TONs) higher than 1 have been observed in some cases. 

Activated carbon can also be used for chloramine removal, but the reaction time is much longer, about 5-10 minutes in a new bed and up to 30 minutes in a bed near equilibrium. The reaction with chloramine is a two-step process ... 

Boiling a solution of (2,2-dimethylhydrazino)diphenyl-phosphine in benzene overnight in contact with dry air causes precipitation of the oxide, (C8H5)2P(0)NHN(CH3)2 (m.p. 167 to 168°). Addition of a stoichiometric amount of sulfur to a boiling benzene solution of (2,2-dimethylhydrazino) diphenylphosphine yields, on cooling, the sulfide, (C H5)2P(S)NHN(CH3)2 (m.p. 95.5 to 97.0°). Alkylation to [(C6H5)2(CH3)PNHN(CH3)2]I (m.p. 156 to 158°) occurs upon reaction with methyl iodide in ether. Reaction with chloramine in ether yields the aminophosphonivun salt, [(C,H,)2P(NH2)NHN(CH,)2]C1 (m.p. 195°). All of the above-described derivatives are colorless solids. 

Fig. 4 Copper salts catalyze amination reactions with chloramine-T as the nitrogen source...

In the colorimetric measurement the cyanide is converted to cyanogen chloride, by reaction with chloramine-T at a pH less than 8 without hydrolyzing to the cyanate. After the reaction is complete, color is formed on the addition of pyridine - pyrazolone reagent and the absorbance is read at 620 nm. 

A-Tosylaziridines can be obtained directly from alkenes by reaction with Chloramine T, as shown below. ... 

A simple, sensitive, and selective method for the determination of amodiaquine hydrochloride in tablets has been developed. It is based on a color reaction with chloramine-T in the pH range 7.4- 8.0. The chromogen is extracted with chloroform and the absorbance is measured at 442 nm. Beer s law is obeyed in the concentration range 1-200 n%/. The coefficient of variation has been found to be 0.64% and the recovery ranges between 100.3 and 102.5%. Chloroquine phosphate or primaquine phosphate do not interfere with the method (29). 

This reaction was initially reported by Forster in 1915. It is the synthesis of diazoketones, especially for the cyclic diazoketones from a-keto oximes by the reaction with chloramines. Therefore, it is known as the Forster reaction. Although two mechanisms have been proposed for this reaction,experimental evidence favors the one involving the attack of NH2CI by the lone-pair electrons of the oxime nitrogen. " This reaction has been modified via the generation of chloramine in situ, which is used in the preparation of 2-diazo-1 -indanones. ... 

Secondary amines do not form isoindoles. Attempts have been made to overcome this difficulty by reaction with chloramine T [279], N-chlorosuccinimide [339] or sodium hypochlorite [276,315]. 

Formation of diazoketones from a-oximinoketones by reaction with chloramine ... 

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