Chloramine-T
Chloramine-T, also known as tosylchloramide sodium or N-chloro-p-toluenesulfonamide sodium salt, is an organic compound with the chemical formula C₇H₇ClNNaO₂S and the trihydrate form C₇H₇ClNNaO₂S·3H₂O.[1] It appears as a white to pale yellow crystalline powder that is soluble in water and acts as a source of electrophilic chlorine due to its N-Cl bond.[1] Developed as a stable alternative to hypochlorites, Chloramine-T has been used as a disinfectant since the early 20th century, offering mild oxidizing properties that make it effective against bacteria, fungi, viruses, and algae without the rapid decomposition seen in free chlorine solutions.[2] In medical and veterinary applications, Chloramine-T serves as an antiseptic for wound care, burn treatment, and hydrotherapy, where it is applied in solutions or pastes to sterilize tissues and promote healing while exhibiting low cytotoxicity.[3][4] It is also employed in dental practices, poultry sanitation, and fish disease control at concentrations of 8.5–12 mg/L to combat bacterial gill infections.[5] Beyond disinfection, its role as a versatile reagent in organic synthesis includes facilitating aziridination, pyrazole formation, and chlorination reactions under mild aqueous conditions, owing to its low cost and compatibility with acidic, neutral, or basic media.[5] Additionally, Chloramine-T finds use in analytical chemistry for detecting cyanide and in water treatment as a biocide to prevent microbial fouling.[5] Despite its efficacy, it can act as an allergen, potentially causing skin or respiratory reactions upon exposure.[1]Overview
Chemical identity
Chloramine-T is an organic compound with the chemical formula C₇H₇ClNNaO₂S (anhydrous).[1] Its IUPAC name is sodium N-chloro-4-methylbenzenesulfonamide.[1] The compound is also known by other names, including tosylchloramide sodium, Chloramine T, and N-chlorotosylamide sodium salt.[1] It has the CAS number 127-65-1 and a molecular weight of 227.64 g/mol.[1] The common commercial form is the trihydrate C₇H₇ClNNaO₂S·3H₂O with CAS 7080-50-4 and molecular weight 281.69 g/mol.[6] The structural formula of Chloramine-T features a tosyl group (p-toluenesulfonyl, consisting of a methyl-substituted benzene ring attached to a sulfonyl moiety, CH₃C₆H₄SO₂-) bonded to a nitrogen atom that forms an N-Cl bond, with a sodium cation serving as the counterion to balance the charge.[1] This arrangement represents it as the sodium salt derivative of N-chlorotoluene-4-sulfonamide.[7]History
Chloramine-T, the sodium salt of N-chlorotoluene-4-sulfonamide, was first synthesized in 1905 by British chemist Frederick Daniel Chattaway through the reaction of p-toluenesulfonamide with hypochlorite, establishing it as a stable source of electrophilic chlorine for chlorination reactions.[8] This preparation addressed the instability of earlier chloramines, providing a more reliable reagent for chemical applications. This work followed Friedrich Raschig's development in 1906 of a process for hydrazine synthesis that involved the unstable monochloramine (NH₂Cl) as an intermediate, revealing the volatility of such N-chloro compounds.[9] In 1916, Henry Drysdale Dakin and colleagues introduced it as an antiseptic agent, demonstrating its efficacy in wound treatment during World War I through controlled release of active chlorine.[10] Post-World War I, Chloramine-T saw adoption in medical disinfection for its germicidal properties and in water treatment as a stable biocide, particularly in scenarios requiring sustained chlorine activity without rapid decomposition. By the mid-20th century, its utility expanded into organic synthesis, where it served as a versatile oxidant and chlorinating agent in reactions such as aziridine formation and alpha-amino acid oxidations, as documented in analytical reviews from the 1950s onward.[11] Primary credit for its development belongs to Chattaway, with commercial production refined by chemical manufacturers in the 20th century.Properties
Physical properties
Chloramine-T is typically observed as a white to off-white or pale yellow crystalline powder.[1][12] It exhibits a slight chlorine-like odor, attributable to minor decomposition releasing chlorine gas.[1] The compound decomposes at approximately 167–170 °C without melting, releasing chlorine gas.[12][1] Its density is about 1.4 g/cm³ for the common trihydrate form.[1][13] Chloramine-T demonstrates high solubility in water, approximately 150 g/L at 25 °C, which facilitates its application in aqueous disinfectants.[14][15] It is moderately soluble in alcohols such as ethanol (around 5–46 mg/mL), though decomposition may occur in these solvents.[16][17] In contrast, it is insoluble in non-polar solvents like ether, benzene, and chloroform.[1] Aqueous solutions of Chloramine-T are alkaline, with a pH ranging from 8.0 to 10.0 at 20 °C for concentrations around 50 g/L.[12]Chemical properties
Chloramine-T, chemically known as sodium N-chlorotoluene-4-sulfonamide, is an N-chloro compound that functions as a source of electrophilic chlorine and hypochlorite in aqueous media, enabling its role as a versatile oxidizing and chlorinating agent.[18] In solution, it equilibrates to form species such as TsNCl⁻, TsNHCl, TsNCl₂, HOCl, and OCl⁻ (where Ts denotes the p-toluenesulfonyl group), with hypochlorite being the primary active form in neutral or alkaline conditions.[19] The compound exhibits good stability in its solid form and in neutral or alkaline aqueous solutions, where it maintains its integrity without significant decomposition at ambient temperatures.[20] However, in acidic conditions, chloramine-T decomposes rapidly, undergoing protonation to form TsNHCl followed by hydrolysis, ultimately releasing chlorine gas (Cl₂) and p-toluenesulfonamide (TsNH₂).[13] A simplified equation for this acid-induced decomposition is:\text{Chloramine-T} + \text{H}^+ + \text{H}_2\text{O} \rightarrow \text{TsNH}_2 + \text{HOCl}
In neutral water, the process simplifies to the generation of active chlorine species like HOCl through hydrolysis.[21] Due to its hygroscopic nature, particularly in the common trihydrate form, chloramine-T absorbs atmospheric moisture, leading to gradual hydrolysis and slow liberation of active chlorine over time.[1] As a mild oxidant, chloramine-T operates via the chloramine-T/sulfonamide redox couple, with a standard potential of approximately 1.0 V in aqueous solutions, decreasing with increasing pH (e.g., 1.139 V at pH 0.65 and 0.499 V at pH 9.2).[22] This potential supports its selective oxidation capabilities while containing 11.5–13% available chlorine, equivalent to its oxidizing power.[1]