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Home> Encyclopedia > Hot Product Listed S   > sulfur dioxide
7446-09-5 structure

sulfur dioxide

CAS No.:7446-09-5
EINECS(EC#): 231-195-2
Molecular Weight:64.0638
Molecular Formula:O2S (isomer)
Names and Identifiers

sulfur dioxide cyl. with 5 L (net ~6 kg) sulfur dioxide pressure tin with 100 ml (net ~128 G) sulphur dioxide

Canonical Smiles
white to yellow solid
1.25 g/mL at 25 °C(lit.)
Melting Point
Boiling Point
1779 mm Hg ( 21 °C)
Refractive Index
1.3047 (20 C)
Flash Point
8.5 g/100 mL (20 C)
Colorless gas or liquid
Colorless gas ... [Note: A liquid below 14 degrees F. Shipped as a liquefied compressed gas].
Stable. Non-corrosive when dry to common materials except zinc; corrosive when wet. Incompatible with strong reducing or oxidizing agents, moisture, zinc and its alloys.
HS Code
Storage temp
Protect against physical damage, store outdoors or in a well ventilated area of noncombustible construction.
Spectral properties
Index of refraction: 1.3396 at 25 deg C
Safety and Handling
Hazard Codes
Risk Statements
Safety Statements
Hazard Note
H280; H314; H331

Hazard Codes of Sulfur dioxide (CAS NO.7446-09-5):?ToxicT
Risk Statements: 23-34?
R23: Toxic by inhalation.?
R34: Causes burns.
Safety Statements: 9-26-36/37/39-45?
S9: Keep container in a well-ventilated place.?
S26: In case of contact with eyes, rinse immediately with plenty of water and seek medical advice.?
S36/37/39: Wear suitable protective clothing, gloves and eye/face protection.?
S45: In case of accident or if you feel unwell, seek medical advice immediately (show the label whenever possible.)
RIDADR: UN 2037 2.3
WGK Germany: 1
RTECS: WS4550000
F: 4.5-31
HazardClass: 2.3
A poison gas. Experimental reproductive effects. Human mutation data reported. Human systemic effects by inhalation: pulmonary vascular resistance, respiratory depression, and other pulmonary changes. Questionable carcinogen with experimental tumorigenic and teratogenic data. It chiefly affects the upper respiratory tract and the bronchi. It may cause edema of the lungs or glottis, and can produce respiratory paralysis. A corrosive irritant to eyes, skin, and mucous membranes. This material is so irritating that it provides its own warning of toxic concentration. Levels of 400–500?ppm are immediately dangerous to life. Its toxicity is comparable to that of hydrogen chloride. However, less than fatal concentration can be borne for fair periods of time with no apparent permanent damage. It is a common air contaminant.
A nonflammable gas. It reacts violently with acrolein, Al, CsHC2, Cs2O, chlorates, ClF3, Cr, FeO, F2, Mn, KHC2, KClO3, Rb2C2, Na, Na2C2, SnO, diaminolithiumacetylene carbide. Will react with water or steam to produce toxic and corrosive fumes. Incompatible with halogens or interhalogens, lithium nitrate, metal acetylides, metal oxides, metals, polymeric tubing, potassium chlorate, sodium hydride.


Organism Test Type Route Reported Dose (Normalized Dose) Effect Source
frog LCLo inhalation 1pph/15M (10000ppm) ? "Abdernalden's Handbuch der Biologischen Arbeitsmethoden." Vol. 4, Pg. 1396, 1935.
guinea pig LCLo inhalation 1039ppm/24H (1039ppm) ? Contributions from Boyce Thompson Institute. Vol. 10, Pg. 281, 1939.
human LCLo inhalation 1000ppm/10M (1000ppm) LUNGS, THORAX, OR RESPIRATION: RESPIRATORY DEPRESSION Clinical Toxicology. Vol. 5, Pg. 198, 1972.
human LCLo inhalation 3000ppm/5M (3000ppm) ? Tabulae Biologicae. Vol. 3, Pg. 231, 1933.
human TCLo inhalation 3ppm/5D (3ppm) LUNGS, THORAX, OR RESPIRATION: OTHER CHANGES Toxicology and Applied Pharmacology. Vol. 22, Pg. 319, 1972.
human TCLo inhalation 12ppm/1H (12ppm) LUNGS, THORAX, OR RESPIRATION: OTHER CHANGES Sangyo Igaku. Japanese Journal of Industrial Health. Vol. 14, Pg. 449, 1972.
mammal (species unspecified) LCLo inhalation 3000ppm/5M (3000ppm) ? Naunyn-Schmiedeberg's Archiv fuer Experimentelle Pathologie und Pharmakologie. Vol. 138, Pg. 65, 1928.

Journal of Combustion Toxicology. Vol. 4, Pg. 236, 1977.
rat LC50 inhalation 2520ppm/1H (2520ppm) ? National Technical Information Service. Vol. AD-A148-952,

Skin, Eye, and Respiratory Irritations
Vapors cause severe irritation of eyes and throat ...
Irritating to ... resp system & skin.
HAZARD WARNING: Because of the high solubility of sulfur dioxide, it is extremely irritating to the eyes and upper respiratory tract.
Cleanup Methods
1. Ventilate area of spill or leak to disperse gas. 2. If in gaseous form, stop flow of gas. If source of leak is cylinder and leak cannot be stopped in place, remove leaking cylinder to safe place in open air, and repair the leak or allow ... to empty. 3. If in liq form, allow to vaporize.
Approach release from upwind. Stop or control the leak, if this can be done without undue risk. Use water spray to cool and disperse vapors and protect personnel. Control runoff and isolate discharged material for proper disposal. Releases may require isolation or evacuation.
UN 1079
Fire Fighting Procedures
If material involved in fire: Extinguish fire using agent suitable for type of surrounding fire. (Material itself does not burn or burns with difficulty.) Cool all affected containers with flooding quantities of water. Apply water from as far a distance as possible. Use water spray to knock-down vapors.
In case of fire: cool cylinder by spraying with water but avoid contact of the substance with water.
Use water spray to keep fire-exposed containers cool. Extinguish fire using agent suitable for surrounding fire.
Fire Potential
Not combustible.
... Not flammable with air.
The sulfur dioxide products are formulated as a compressed liquid that converts to a gas upon release.
Grades: commercial; USP; technical; refrigeration; anhydrous 99.98% min.
The main grade of liquid sulfur dioxide is known as the technical, industrial, or commercial grade. This grade contains a minimun of 99.98 wt% sulfur dioxide & is a water white liquid free of sulfur trioxide and sulfuric acid. ... Its most important specification is the moisture content, which is generally set at 100 ppm max. The only other grade sold is the refrigeration grade of liquid sulfur dioxide, which is a premium grade having the same purity and specifications as the industrial grade, except for moisture content, which is specified as 50 ppm max. At least one manufacturer sells a single grade for which specifications have been established as follows: color, APHA 25 max; nonvolatile residue, 25 ppm max; moisture, 50 ppm max.
Compressed gas: technical, food grades; liquefied gas
The Fruit Doctor/Compressed Sulfur Dioxide; Active ingredient: 100% sulfur dioxide
Sea Fresh 150; Active ingredient: 100% Sulfur dioxide
DOT Emergency Guidelines
If ... THERE IS NO FIRE, go directly to the Table of Initial Isolation and Protective Action Distances /(see table below)/ ... to obtain initial isolation and protective action distances. IF THERE IS A FIRE, or IF A FIRE IS INVOLVED, go directly to the appropriate guide /(see guide(s) below)/ and use the evacuation information shown under PUBLIC SAFETY. /Sulfur dioxide/ Table of Initial Isolation and Protection Action Distances for Sulfur dioxide Small Spills (from a small package or small leak from a large package) -------------------- First ISOLATE in all Directions 60 meters (200 feet) Then PROTECT persons Downwind during DAY: 0.3 kilometers (0.2 miles) Then PROTECT persons Downwind during NIGHT: 1.2 kilometers (0.7 miles) ==================== Large Spills (from a large package or from many small packages) -------------------- First ISOLATE in all Directions 400 meters (1250 feet) Then PROTECT persons Downwind during DAY: 2.1 kilometers (1.3 miles) Then PROTECT persons Downwind during NIGHT: 5.7 kilometers (3.6 miles)
/GUIDE 125: GASES - CORROSIVE/ Health: TOXIC; may be fatal if inhaled, ingested or absorbed through skin. Vapors are extremely irritating and corrosive. Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite. Fire will produce irritating, corrosive and/or toxic gases. Runoff from fire control may cause pollution.
/GUIDE 125: GASES - CORROSIVE/ Fire or Explosion: Some may burn, but none ignite readily. Vapors from liquefied gas are initially heavier than air and spread along ground. Some of these materials may react violently with water. Cylinders exposed to fire may vent and release toxic and/or corrosive gas through pressure relief devices. Containers may explode when heated. Ruptured cylinders may rocket.
/GUIDE 125: GASES - CORROSIVE/ Public Safety: CALL Emergency Response Telephone Number ... As an immediate precautionary measure, isolate spill or leak area for at least 100 meters (330 feet) in all directions. Keep unauthorized personnel away. Stay upwind. Many gases are heavier than air and will spread along ground and collect in low or confined areas (sewers, basements, tanks). Keep out of low areas. Ventilate closed spaces before entering.
/GUIDE 125: GASES - CORROSIVE/ Protective Clothing: Wear positive pressure self-contained breathing apparatus (SCBA). Wear chemical protective clothing that is specifically recommended by the manufacturer. It may provide little or no thermal protection. Structural firefighters' protective clothing provides limited protection in fire situations ONLY; it is not effective in spill situations where direct contact with the substance is possible.
/GUIDE 125: GASES - CORROSIVE/ Evacuation: ... Fire: If tank, rail car or tank truck is involved in a fire, ISOLATE for 1600 meters (1 mile) in all directions; also, consider initial evacuation for 1600 meters (1 mile) in all directions.
/GUIDE 125: GASES - CORROSIVE/ Fire: Small fires: Dry chemical or CO2. Large fires: Water spray, fog or regular foam. Move containers from fire area if you can do it without risk. Do not get water inside containers. Damaged cylinders should be handled only by specialists. Fire involving tanks: Fight fire from maximum distance or use unmanned hose holders or monitor nozzles. Cool containers with flooding quantities of water until well after fire is out. Do not direct water at source of leak or safety devices; icing may occur. Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank. ALWAYS stay away from tanks engulfed in fire.
/GUIDE 125: GASES - CORROSIVE/ Spill or Leak: Fully encapsulating, vapor protective clothing should be worn for spills and leaks with no fire. Do not touch or walk through spilled material. Stop leak if you can do it without risk. If possible, turn leaking containers so that gas escapes rather than liquid. Prevent entry into waterways, sewers, basements or confined areas. Do not direct water at spill or source of leak. Use water spray to reduce vapors or divert vapor cloud drift. Avoid allowing water runoff to contact spilled material. Isolate area until gas has dispersed.
/GUIDE 125: GASES - CORROSIVE/ First Aid: Move victim to fresh air. Call 911 or emergency medical service. Give artificial respiration if victim is not breathing. Do not use mouth-to-mouth method if victim ingested or inhaled the substance; give artificial respiration with the aid of a pocket mask equipped with a one-way valve or other proper respiratory medical device. Administer oxygen if breathing is difficult. Remove and isolate contaminated clothing and shoes. In case of contact with liquefied gas, thaw frosted parts with lukewarm water. In case of contact with substance, immediately flush skin or eyes with running water for at least 20 minutes. ... Keep victim warm and quiet. Keep victim under observation. Effects of contact or inhalation may be delayed. Ensure that medical personnel are aware of the material(s) involved and take precautions to protect themselves.
Exposure Standards and Regulations
Sulfur dioxide is generally recognized as safe when used in accordance with good manufacturing or feeding practice, except that it is not used in meats or in food recognized as source of vitamin B1.
Reactivities and Incompatibilities
Will react with water or steam to produce toxic and corrosive fumes.
Monocesium or monopotassium acetylides, and the ammoniate of monolithium acetylide, all ignite and incandesce in unheated sulfur dioxide. The dimetal derivatives incl sodium acetylide appear to be less reactive, needing heat before ignition occurs.
Cesium monoxide, iron(ii) oxide, tin oxide, and lead(iv) oxide all ignite and incandesce on heating in /sulfur dioxide/ gas. Finely divided (pyrophoric) chromium incandesces in sulfur dioxide, while pyrophoric manganese burns ... on heating in gas. Molten sodium reacts violently with dry gas or liq, while moist gas reacts as vigorously as water with cold sodium.
Heated oxide /barium peroxide/ attains incandescence in a rapid stream of ... Sulfur dioxide.
Acrolein polymerizes with release of heat on contact with minor amt of acids (incl sulfur dioxide) ...
Powdered aluminum burns in the vapor of ... sulfur dioxide ...
Rubidium carbide ignites on warming in sulfur dioxide ... vapor.
When stannous oxide is heated in atmosphere of sulfur dioxide, reaction is attended by incandescence.
Sodium carbide reacts with incandescence when placed in ... sulfur dioxide.
When ferrous oxide, prepared at 300 deg C, is heated in sulfur dioxide, the mass becomes incandescent.
Sulfur dioxide reacts explosively in contact with sodium hydride unless diluted with hydrogen.
Contact /with potassium chlorate/ at temp above 60 deg C causes flashing of the evolved chlorine dioxide. Soln of sulfur dioxide in ethanol or ether cause an explosion on contact at ambient temp.
During prepn of zinc ethylsulfinate, addition of diethylzinc to liq sulfur dioxide at -15 deg C leads to an explosively violent reaction. Condensation of the dioxide into cold diethylzinc leads to a controllable reaction on warming.
Mixt /of propene and sulfur dioxide/ under confinement in a glass pressure bottle at 20 deg C polymerize explosively, the polymerization probably being initiated by access of light through the clear glass container. Such alkene-sulfur dioxide copolymerizations will not occur above a ceiling temp, different for each alkene.
Each bubble of sulfur dioxide gas led into a container of fluorine produces an explosion.
Chlorine trifluoride causes an explosive reaction with ... sulfur dioxide ...
Dry sulfur dioxide reacts on chlorates with evolution of chlorine peroxide which will flash at 60 deg C and can explode.
Reacts with cesium acetylene carbide, becoming incandescent. /From table/
Reacts with chromium, becoming incandescent. /From table/
Reaction of lithium acetylene carbide diamino or lithium acetylide ammonia with sulfur dioxide produces fire. /From table/
Manganese burns when heated in sulfur dioxide vapor.
Fire occurs when reacted with potassium.
A violent reaction occurs with sodium and sulfur dioxide.
Powdered alkali metal (such as sodium & potassium), water, ammonia, zinc, aluminum, brass, copper [Note: Reacts with water to form sulfurous acid (H2SO3)].
Other Preventative Measures
SRP: Local exhaust ventilation should be applied wherever there is an incidence of point source emissions or dispersion of regulated contaminants in the work area. Ventilation control of the contaminant as close to its point of generation is both the most economical and safest method to minimize personnel exposure to airborne contaminants.
Turn leaking cylinder with the leak up to prevent escape of gas in liquid state.
Provide emergency eyewash.
If liquid ... penetrates through the clothing, remove clothing immediately and flush the skin with water.
SRP: The scientific literature for the use of contact lenses in industry is conflicting. The benefit or detrimental effects of wearing contact lenses depend not only upon the substance, but also on factors including the form of the substance, characteristics and duration of the exposure, the uses of other eye protection equipment, and the hygiene of the lenses. However, there may be individual substances whose irritating or corrosive properties are such that the wearing of contact lenses would be harmful to the eye. In those specific cases, contact lenses should not be worn. In any event, the usual eye protection equipment should be worn even when contact lenses are in place.
If material not involved in fire: Keep material out of water sources and sewers. Attempt to stop leak if without undue personnel hazard. Use water spray to knock-down vapors. Do not use water on material itself.
Personnel protection: Avoid breathing vapors. Keep upwind ... Avoid bodily contact with the material ... Do not handle broken packages unless wearing appropriate personal protective equipment. Wash away any material which may have contacted the body with copious amounts of water or soap and water.
If material leaking (not on fire) consider evacuation from downwind area based on amount of material spilled, location and weather conditions.
SRP: Contaminated protective clothing should be segregated in such a manner so that there is no direct personal contact by personnel who handle, dispose, or clean the clothing. Quality assurance to ascertain the completeness of the cleaning procedures should be implemented before the decontaminated protective clothing is returned for reuse by the workers. Contaminated clothing should not be taken home at end of shift, but should remain at employee's place of work for cleaning.
Work clothing that becomes wet or significantly contaminated should be removed and replaced. /Liquid/
Concentration of Interest for sulfur dioxide /in nonindustrial environments/ from unvented space heaters (kerosene) and outdoor air: 80 ug/cu m based on protecting against respiratory morbidity in the general population and avoiding exacerbation of asthma...
Protective Equipment and Clothing
Respirator Recommendations: Up to 20 ppm Assigned Protection Factor (APF) Respirator Recommendation APF = 10 Any chemical cartridge respirator with cartridge(s) providing protection against the compound of concern. Substance reported to cause eye irritation or damage; may require eye protection. APF = 10 Any supplied-air respirator. Substance reported to cause eye irritation or damage; may require eye protection.
Respirator Recommendations: Up to 50 ppm Assigned Protection Factor (APF) Respirator Recommendation APF = 25 Any supplied-air respirator operated in a continuous-flow mode. Substance reported to cause eye irritation or damage; may require eye protection. APF = 25 Any powered, air-purifying respirator with cartridge(s) providing protection against the compound of concern. Substance reported to cause eye irritation or damage; may require eye protection.
Respirator Recommendations: Up to 100 ppm Assigned Protection Factor (APF) Respirator Recommendation APF = 50 Any chemical cartridge respirator with a full facepiece and cartridge(s) providing protection against the compound of concern. APF = 50 Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted canister providing protection against the compound of concern. APF = 50 Any powered, air-purifying respirator with a tight-fitting facepiece and cartridge(s) providing protection against the compound of concern. Substance reported to cause eye irritation or damage; may require eye protection. APF = 50 Any supplied-air respirator that has a tight-fitting facepiece and is operated in a continuous-flow mode. Substance reported to cause eye irritation or damage; may require eye protection. APF = 50 Any self-contained breathing apparatus with a full facepiece. APF = 50 Any supplied-air respirator with a full facepiece.
Respirator Recommendations: Emergency or planned entry into unknown concentrations or IDLH conditions: Assigned Protection Factor (APF) Respirator Recommendation APF = 10,000 Any self-contained breathing apparatus that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode. APF = 10,000 Any supplied-air respirator that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode in combination with an auxiliary self-contained positive-pressure breathing apparatus.
Respirator Recommendations: Escape conditions: Assigned Protection Factor (APF) Respirator Recommendation APF = 50 Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted canister providing protection against the compound of concern/Any appropriate escape-type, self-contained breathing apparatus.
Compressed gases may create low temperatures when they expand rapidly. Leaks and uses that allow rapid expansion may cause a frostbite hazard. Wear appropriate personal protective clothing to prevent the skin from becoming frozen. Wear appropriate personal protective clothing to prevent the skin from becoming frozen.
Wear appropriate eye protection to prevent eye contact with the liquid that could result in burns or tissue damage from frostbite.
Quick drench facilities and/or eyewash fountains should be provided within the immediate work area for emergency use where there is any possibility of exposure to liquids that are extremely cold or rapidly evaporating.

For?Sulfur dioxide's consensus:?EPA Extremely Hazardous Substances List. Reported in EPA TSCA Inventory. EPA Genetic Toxicology Program.

Disposal Methods
SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational harm/injury/toxicity or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal and plant life; and conformance with environmental and public health regulations.

2.Hazard identification

2.1 Classification of the substance or mixture

Gases under pressure: Compressed gas

Skin corrosion, Category 1B

Acute toxicity - Inhalation, Category 3

2.2 GHS label elements, including precautionary statements

Signal word


Hazard statement(s)

H314 Causes severe skin burns and eye damage

H331 Toxic if inhaled

Precautionary statement(s)

P260 Do not breathe dust/fume/gas/mist/vapours/spray.

P264 Wash ... thoroughly after handling.

P280 Wear protective gloves/protective clothing/eye protection/face protection.

P261 Avoid breathing dust/fume/gas/mist/vapours/spray.

P271 Use only outdoors or in a well-ventilated area.


P301+P330+P331 IF SWALLOWED: Rinse mouth. Do NOT induce vomiting.

P303+P361+P353 IF ON SKIN (or hair): Take off immediately all contaminated clothing. Rinse skin with water [or shower].

P363 Wash contaminated clothing before reuse.

P304+P340 IF INHALED: Remove person to fresh air and keep comfortable for breathing.

P310 Immediately call a POISON CENTER/doctor/\u2026

P321 Specific treatment (see ... on this label).

P305+P351+P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.

P311 Call a POISON CENTER/doctor/\u2026


P410+P403 Protect from sunlight. Store in a well-ventilated place.

P405 Store locked up.

P403+P233 Store in a well-ventilated place. Keep container tightly closed.


P501 Dispose of contents/container to ...

2.3 Other hazards which do not result in classification


Precursor and Product
Computational chemical data
  • Molecular Weight:64.0638g/mol
  • Molecular Formula:O2S
  • Exact Mass:63.9619
  • Monoisotopic Mass:63.9619
  • Complexity:18.3
  • Rotatable Bond Count:0
  • Hydrogen Bond Donor Count:0
  • Hydrogen Bond Acceptor Count:3
  • Topological Polar Surface Area:35.1
  • Heavy Atom Count:3
  • Defined Atom Stereocenter Count:0
  • Undefined Atom Stereocenter Count:0
  • Defined Bond Stereocenter Count:0
  • Undefined Bond Stereocenter Count:0
  • Isotope Atom Count:0
  • Covalently-Bonded Unit Count:1
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