4-Bromobenzenesulfonyl chloride (p-Bromobenzenesulfonyl chloride) is a key sulfonyl chloride intermediate widely used in pharmaceutical synthesis, particularly for angiotensin II receptor antagonists and endothelin receptor inhibitors. This compound melts at 74-77°C with a boiling point of 153°C (15 mmHg). It shows characteristic reactivity as a sulfonyl chloride, undergoing nucleophilic substitution with amines/alcohols. The material is moisture-sensitive and decomposes in water, requiring storage under inert atmosphere (argon/nitrogen) at 2-8°C. Safety precautions are critical due to its corrosive nature (UN 3261, Packing Group II) and ability to release toxic gases (HCl/SO₂) upon decomposition. Handling requires acid-resistant PPE and adequate ventilation.
