Chloramine B，127-52-6, chemically known as N-chlorobenzenesulfonamide sodium salt, is a versatile oxidative and chlorinating reagent widely used in organic synthesis, disinfection, analytical chemistry, and pharmaceutical processes. With the molecular formula C₆H₅SO₂NClNa·H₂O, Chloramine B，127-52-6 is the sodium salt of N-chlorobenzenesulfonamide and is structurally related to Chloramine-T (p-toluenesulfonamide sodium salt). It is recognized by the CAS number 127-52-6 and is a white to slightly yellow crystalline powder with high stability under normal storage conditions.

Chemical Identity and Structure

Physical and Chemical Properties

• Appearance: White crystalline solid or powder

• Odor: Mild chlorine-like odor

• Solubility: Freely soluble in water; slightly soluble in ethanol; insoluble in ether and benzene

• pH (1% solution): 8–9

• Melting Point: Decomposes before melting (~190–195 °C)

• Stability: Stable under dry, cool, and dark conditions; slowly decomposes in presence of moisture and light releasing hypochlorous acid

• Oxidation Potential: Comparable to hypochlorite and Chloramine-T

Chemical Reactivity and Mechanism of Action

Chloramine B acts as a source of electrophilic chlorine (Cl⁺) and serves as an oxidizing and chlorinating agent. The reactive chlorine atom attached to the nitrogen is labile and can transfer to nucleophilic substrates. Its reactions typically proceed via nitrenium ion (N⁺–Cl) or chloronium transfer mechanisms, depending on solvent and pH.

Representative reactions:

• Oxidation: Converts primary and secondary alcohols to aldehydes and ketones.

• Chlorination: Substitutes chlorine onto aromatic or aliphatic substrates under mild conditions.

• Amination: Converts alkenes into chloramines and aziridines.

• Oxygen Transfer: Oxidizes sulfides to sulfoxides or sulfones.

Reaction Example:

RCH2OH+PhSO2NClNa→RCHO+PhSO2NHNa+HCl

Synthesis and Industrial Production

Chloramine B is typically synthesized by chlorination of sodium benzenesulfonamide using sodium hypochlorite or chlorine gas in an alkaline medium:

C6H5SO2NHNa+NaOCl→C6H5SO2NClNa+NaOH

Reaction Conditions:

• Temperature: 0–10 °C (to control decomposition)

• pH: Basic (pH 8–9)

• Medium: Aqueous or mixed solvent (water/ethanol)

Purification is achieved via crystallization or vacuum drying. The resulting product has high purity (>98%) and is often stabilized with small amounts of sodium carbonate.

Analytical Methods

Several analytical techniques are employed to characterize and quantify Chloramine B:

Spectroscopic methods:

• UV–Vis: Absorption at ~260 nm (due to aromatic sulfonamide chromophore).

• IR spectroscopy: Strong bands near 1170–1350 cm⁻¹ (S=O stretch) and 3300–3400 cm⁻¹ (N–H stretch).

• ¹H NMR: Aromatic protons at δ 7.3–7.9 ppm.

• Mass spectrometry: Molecular ion peak at m/z = 231 (M⁺).

• Titrimetric methods: Iodometric titration using KI under acidic conditions for available chlorine estimation.

• Chromatographic methods: HPLC or ion chromatography for quantitative analysis in formulations.

Applications

Organic Synthesis

Chloramine B is an excellent mild oxidant and chlorinating agent used in:

• Oxidation of sulfides to sulfoxides and sulfones.

• Oxidation of secondary alcohols to ketones.

• Regioselective halogenation of aromatic compounds.

• Oxidative cyclization reactions and aziridination.

• Green chemistry processes where aqueous reactions are preferred.

Disinfectant and Sanitizer

• Acts as a slow-releasing chlorine disinfectant, effective against bacteria, fungi, and viruses.

• Used in water purification, surface sanitation, and hospital disinfection.

• Often considered a safer, more stable alternative to sodium hypochlorite.

Analytical Chemistry

• Standard reagent in iodometric titration for available chlorine.

• Used in amperometric titrations and oxidative assays for phenols and anilines.

• Employed in kinetic studies as a model oxidant due to predictable reaction rates.

Pharmaceutical and Biochemical Uses

• Used in oxidative degradation studies of drug compounds.

• Functions as a mild oxidant in peptide synthesis and biochemical oxidation experiments.

Safety, Handling, and Storage

Hazard Identification

• Hazard Class: Oxidizing solid (GHS03), Irritant (GHS07)

• Risk Phrases: R8 (may cause fire in contact with combustible material); R36/37/38 (irritating to eyes, respiratory system, and skin)

Precautions

• Avoid contact with organic materials, acids, and reducing agents.

• Store in a cool, dry, and well-ventilated area, away from direct sunlight and moisture.

• Use gloves, goggles, and lab coat when handling.

• Avoid inhalation of dust; handle under fume hood if in bulk quantities.

Decomposition Products

On decomposition, releases chlorine gas (Cl₂), nitrogen oxides, and sulfur oxides. Heating above 200 °C or exposure to strong acids causes rapid decomposition.

First Aid Measures

• Skin contact: Wash immediately with plenty of water.

• Eye contact: Rinse thoroughly with water for at least 15 minutes and seek medical attention.

• Inhalation: Move to fresh air; provide oxygen if breathing is difficult.

• Ingestion: Rinse mouth; do not induce vomiting; seek medical attention immediately.

Environmental Impact

• Chloramine B degrades into benzenesulfonamide and hypochlorous acid, which can contribute to chlorine residuals in water.

• Classified as moderately hazardous to aquatic life; therefore, disposal must follow local regulations.

• Decomposition products are neutralized by sodium thiosulfate or sodium bisulfite before discharge.

Comparison with Related Reagents

Recent Research and Developments

Recent studies focus on:

• Kinetic modeling of oxidation reactions using Chloramine B.

• Green synthesis utilizing aqueous-phase Chloramine B for selective transformations.

• Nanocatalyst-assisted oxidation reactions to enhance selectivity.

• Exploration of photochemical and electrochemical activation of Chloramine B for advanced oxidative processes.

Chloramine B (CAS 127-52-6) is a multifunctional reagent combining oxidative and chlorinating capabilities with manageable safety and stability. Its balanced reactivity makes it a valuable tool in synthetic chemistry, analytical applications, and disinfection processes. Despite its long-standing use, ongoing research continues to refine its mechanistic understanding and expand its role in sustainable and green chemical methodologies.