© 2026 Sinochem Nanjing Corporation,
All Right Reserved
Name: Chlorosulfonic Acid
Chemical Formula: ClSO3H
Common Uses: A go-to for making detergents, dyes, pharmaceuticals, and as a sulfonating and chlorinating agent.
Appearance: Clear to pale yellow fuming liquid
Odor: Sour, pungent, similar to strong acids
Hazard Statements: Strongly corrosive to skin, eyes, and respiratory tract. Reacts violently with water. Exposure can mean severe burns and tissue destruction. The risks start with splashes, but inhaling the fumes also does damage. Direct contact might mean needing immediate medical care.
Signal Word: Danger
GHS Classification: Skin Corrosion, Serious Eye Damage, Acute Toxicity through inhalation
Pictograms: Corrosive, Health Hazard
Potential Risk: Releasing sulfuric acid and hydrogen chloride vapors in air; both leave a punch to the senses and the lungs.
Chemical Name: Chlorosulfonic Acid
CAS Number: 7790-94-5
Purity: Approaches 99%, with possible traces of sulfur trioxide or hydrochloric acid as process-related contaminants.
Eye Contact: Immediate flushing with copious amounts of water for at least 15 minutes—not just a quick rinse. Medical help isn’t optional.
Skin Contact: Remove soaked clothing, wash skin thoroughly with running water. Chemical burns often progress after contact, so hospital visits aren’t just protocol—they’re a necessity.
Inhalation: Get into fresh air at once, and seek medical assistance if symptoms start up. Chlorosulfonic acid fumes sting lungs and can trigger dangerous respiratory reactions.
Ingestion: Never try to neutralize with household chemicals or induce vomiting. Quick rinsing of the mouth and urgent hospital treatment are the right steps.
Suitable Extinguishing Media: Dry chemical powder or carbon dioxide are the choices. Water only makes things worse, given that violent reactions spawn heat and hazardous gases.
Hazardous Combustion Products: Hydrochloric acid and sulfur oxides fill the air in a blaze, making breathing protection a must.
Protective Equipment: Full chemical-resistant suit with self-contained breathing apparatus is non-negotiable. Most regular fire gear doesn’t stand up to the challenge.
Firefighting Tips: Evacuate non-essential personnel, stay upwind, and contain runoff due to damage risk to local waterways.
Personal Precautions: Limit entry to trained responders in splash-proof gear with full respiratory protection.
Containment: Use sand, dry earth, or commercial absorbents. Never reach for water; it fuels more hazardous vapor release.
Cleanup: Scoop up residue in appropriate chemical waste containers. Ventilate the area thoroughly.
Environmental Precautions: Prevent any run-off from getting near storm drains or surface waters. Chlorosulfonic acid transforms quickly, harming aquatic life through acidification and toxic discharges.
Safe Handling: Only work in well-ventilated spaces with eyewash stations and emergency showers ready. Double-check the integrity of all glassware or containers.
Storage Conditions: Keep tightly sealed in corrosion-resistant containers away from moisture, bases, organic materials, and out of sunlight. Segregate from incompatible substances and install secondary containment—one drip can ruin a whole storeroom.
Engineering Controls: Local exhaust ventilation and sealed process lines restrict vapor stings.
Personal Protection: Chemical goggles, face shield, acid-resistant gloves (nitrile or neoprene), and full aprons are the bare minimum.
Respiratory Protection: If fumes build up, a certified respirator with acid gas cartridges keeps lungs from getting burned.
Hygiene Measures: Never eat, drink, or smoke near where chlorosulfonic acid is handled. Handwashing on exit is a must.
State: Fuming liquid
Color: Colorless to pale yellow
Odor: Pungent, biting acid
Boiling Point: Roughly 152°C
Melting Point: -80°C
Solubility: Reacts fiercely with water, releasing heat and corrosive gases
Density: About 1.75 g/cm³
Vapor Pressure: Noticeable at room temperature
Chemical Stability: Can fume on contact with air due to moisture. Long-term storage leads to slow decomposition, especially if moisture sneaks in.
Reactivity: Water, alcohols, bases, and organics set off explosive or high-heat reactions. Incompatible with most metals and reducing agents.
Hazardous Decomposition: Hydrochloric acid gas, sulfur dioxide, and other acidic vapors fill the air once instability creeps in.
Acute Toxicity: Even brief skin or eye exposure brings severe burns. Inhalation stings respiratory tissues, irritates eyes, nose, and throat, and can cause lung damage at high exposures.
Chronic Effects: Ongoing low-level exposure might lead to lasting respiratory and eye sensitivity. Scarring and functional loss are genuine risks if first aid isn’t immediate.
Ingestion Risks: Severe burns to mouth, throat, and stomach result from just a swallow—survival often comes down to rapid treatment.
Aquatic Toxicity: Lethal to aquatic life at even low concentrations. The acidification potential also wrecks water pH balance, harming organisms that thrive in narrow pH ranges.
Persistence and Degradability: Fast hydrolysis in water leads to sulfuric and hydrochloric acids—neither does ecosystems any favors.
Bioaccumulation: Not known to build up in animals, but immediate water and soil damage follows a spill.
Waste Disposal: Neutralize cautiously under expert supervision, then dispose of diluted waste through licensed hazardous waste handlers.
Container Cleaning: Remaining residues need special neutralization—never rinse with water in an uncontrolled setting. Everything—piping, storage vessels, used gloves—must be checked as hazardous waste.
Proper Shipping Name: Chlorosulfonic Acid
Hazard Class: Corrosive liquid, dangerous for air, road, and sea
Packaging: Approved corrosion-resistant drums or tanks with clear hazard markings; secure secondary containment eliminates leaks during bumps or drops.
Transport Precautions: Drivers, handlers, and recipients need to know spill handling and emergency protocols like the back of their hands.
Workplace Limits: National and regional bodies often set workplace air limits for both hydrogen chloride and sulfur oxides, the main by-products.
Transportation Restrictions: Listed as a hazardous substance for all major shipping routes. Extra notification and permits cover mass quantities.
Community Right-to-Know: Facilities using or storing over threshold amounts report inventories to local authorities.
Environmental Regulations: Strict discharge and emission limitations follow its use—catching a spill early beats the fines and ecosystem setbacks.
