Titrimetric study of the reaction of chloramine-T with ammonia

A titrimetric study of the reaction between chloramine-T (CAT) and ammonia is described. The effects of the presence of bromide, the ratio of CAT to ammonia concentrations, the time for reaction and the pH of the reaction media are all significant in the quantitativeness of the reaction that occurs.     

N-Bromosuccinimide-mediated reaction of cyclic styrenes with chloramine-T

A facile route toward substituted allylic sulfonamides 3 is developed from the N-bromosuccinimide (NBS)-mediated allylic amination of cyclic styrenes 2 with chloramine-T (1a). Skeleton 2 is prepared by Grignard addition of cyclic ketones with different arylmagnesium bromides in THF followed by dehydration of the resulting tertiary alcohols with BF₃·OEt₂ in CH₂Cl₂. The synthetic route obtained moderate yields from the one-step operation and the key structures of skeleton 3 were confirmed by X-ray crystallographic analysis.     

Chlorination as a side reaction in radioiodination with chloramine-T

Chloramine-T is often used as an oxidizing agent for radioiodide in the electrophilic labeling of proteins and phenolic compounds. We have found that chloramine-T is also capable of introducing chlorine under the right conditions. Thus, treatment of fluorescein with no-carrier added¹²⁵I-sodium iodide and chloramine-T resulted in a uv-absorbing, fluorescent product in addition to the (no-carrier-added)¹²⁵I labeled material. The by product was tentatively identified as a chlorinated fluorescein by comparison with a known sample. The potential of macrochlorination should be kept in mind when using chloramine-T for radioiodination.     

Steric effects in the reaction of alkyl-phenyl and dialkyl-sulphides with chloramine-T

The rate of the reaction of dialkyl- and alkyl-phenyl-sulphides with TsNHCl increases with the increasing +I effect of the S-substituents, while the steric effect is only of minor importance. Rate constants of the reaction of dialkyl sulphides can be correlated with the Taft equation (?^* = ?1.96, δ = 0.285). The effect of ring size of cyclic sulphides on the reaction is discussed. The change of the rate constants with varying S-alkyl substituents is in agreement with a sterically unhindered electrophilic addition of Cl⁺ on bivalent sulphur, leading to chlorosulphonium ion. Sulphimides and sulphoxides are formed from the chlorosulphonium intermediates in the subsequent S_N-type reactions with different steric control.     

Unusual reaction of iodofurazans with nucleophilic reagents

Nucleophilic reagents cause detachment of the iodine atom from 3-iodo-4-R-furazans and opening of the furazan ring to give salts of the corresponding -hydroxyiminoacetonitriles.     

Unusual methylation reaction of gem-bromofluorospiropentanes with methyllithium

A series of novel gem-bromofluorospiropentanes were synthesized and investigated in the reaction with methyllithium. Either substitution of the fluorine atom for a methyl group or rearrangement into methylated cyclobutene derivatives occurred under these conditions.     

Determination of iodide with chloramine-T

A method is described for the estimation of iodide, based on its oxidation to iodate by the addition of excess of chloramine-T, destruction of the excess of chloraniine-T with dimethyl sulphoxide and determination of the iodate iodometrically. In addition, the dimethyl sulphoxide eliminates any interference from bromide or bromate.     

Estimation of xylenes with chloramine-T

The reaction between xylenes and chloramine-T has been found to proceed quantitatively over a wide range of experimental conditions. A back-titration procedure in which xylenes are reacted with excess of chloramine-T in 1M perchloric acid-0.03M sodium chloride medium has been developed. Inorganic ions other than chloride do not interfere. The method can be used for estimating xylenes in the presence of some other petrochemicals.     

Estimation of thiosemicarbazide with chloramine-T

A rapid and accurate method for the estimation of thiosemicarbazide in aqueous solution has been developed based on its oxidation with chloramine-T at room temperature and pH 4. The effect of such variables as pH, mode of addition of reagents and concentration of chloride ion on the extent of oxidation has been studied.     

Estimation of dimethylsulphoxide with chloramine-T

A rapid and accurate method for the estimation of dimethyl-sulphoxide has been developed based on its oxidation to dimethyl-sulphone at room temperature by chloramine-T at pH 4-4.5. The effect of variables such as the pH, the mode of addition of reagents and the concentration of chloride ion on the extent and nature of oxidation has been studied and optimal conditons for analytical determination of dimethylsulphoxide derived.     

Oxidation of polythionates with chloramine-T

Summary Chloramine-T has been found to bring about the rupture of S-S link in polythionates in acid medium and oxidise all the sulphur present in the chain into sulphuric acid. Quantitative estimation of a polythionate may be made on the basis of this oxidation reaction.Our thanks are due to Prof. M. R. A. Rao for his interest in the work.     

Assay of p-aminobenzenesulphonamides with chloramine-T

New spectrophotometric and titrimetric methods for the assay of p-aminobenzenesulphonamides with chloramine-T have been developed. They are simple, reproducible and accurate within the limits described (+/-3%) and are useful at high concentration levels. These methods are also applicable to the assay of p-aminobenzenesulphonamides in rat urine.     

Titrimetric determination of mercaptans with chloramine-T

Propyl mercaptan, allyl mercaptan, 2-mercaptoethanol, cysteamine hydrochloride, thio-p-cresol, 2-aminobenzenethiol, 2-mercaptopropionic acid and thioglycollic acid react with chloramine-T in 2:1 molar ratio in the presence of iodide, forming the corresponding disulphides. Mercaptans having a free beta-carbonyl group do not react quantitatively. The oxidation of the mercaptans is a function of time, and the corresponding sulphonic acids are formed on allowing them to stand with excess of chloramine-T. The oxidation to sulphonic acid is, however, instantaneous in the presence of iodine cyanide which acts as a catalyst and preoxidizer. This method is simple, accurate and rapid, and as little as 0.5 mg of the mercaptan can be determined with +/- 0.25% error.