Sulfur dioxide

64.06

64.06

3535237

231-195-2

TSCA listed

colorless

2811290090

66.23000

Colorless gas; pungent suffocating odor; gas density 2.927 g/L at 20°C; heavier than air, vapor density 2.263 (air=1); condenses to a colorless liquid at -10°C; density of liquid SO21.434 g/mL; freezes at -72.7°C; critical temperature 157.65°C; critical pressure 77.78 atm; critical volume 122 cc/g; dielectric constant 17.27 at -16.5°C; dissolves in water forming sulfurous acid, solubility 22.97 g and 11.58 g/100mL water at 0° and 20°C, respectively, under atmospheric pressure; very soluble in acetone, methyl isobutyl ketone, acetic acid, and alcohol; soluble in sulfuric acid; liquid SO2slightly miscible in water.

0.41060

Sulfur dioxide appears as a colorless gas with a choking or suffocating odor. Boiling point -10°C. Heavier than air. Very toxic by inhalation and may irritate the eyes and mucous membranes. Under prolonged exposure to fire or heat the containers may rupture violently and rocket. Used to manufacture chemicals, in paper pulping, in metal and food processing. Rate of onset: Immediate & Delayed Persistence: Minutes to hours Odor threshold: 1 ppm Source/use/other hazard: Disinfectant and preserving in breweries and food/canning; textile industry; batteries.

1.25 g/mL at 25 °C (lit.)

-73 °C (lit.)

-10 °C (lit.)

1.510

%H2O: 17.7 (0°C), 11.9 (15°C), 8.5 (25°C), 6.4 (35°C); % other solvents: 25, alcohol; 32, methanol [MER06]

Sulfur dioxide is noncorrosive and stable when dry. It is usually stored under pressure in cylinders, and should be kept in a cool, dry, well-ventilated area, away from flammable materials.

1779 mm Hg ( 21 °C)

2.26 (21 °C, vs air)

Conversion of sulfur dioxide to bisulfite in the airway may initiate bronchoconstriction, due to the ability of the more reactive bisulfite ion to disrupt disulfide bonds in tissue proteins, resulting in tissue damage and an inflammatory response. Sulfites and bisulfites can further inhibit DNA synthesis and cause human lymphocyte aberrations and can lead to crosslinking in proteins and nucleic acids in general, as well as generate free radicals during their oxidation to sulfates.Bronchoconstriction and other related effects may be mediated by release of leukotrienes, prostaglandins, or other inflammatory factors. Some evidence suggests that free radicals and oxidative stress may play a role, and that metabolites of SO2 (especially sulfites) may be responsible for clastogenicity. Sulfur dioxide–induced bronchoconstriction, occurs when the gas acts on tracheobronchial receptors to induce a cholinergic reflex. Inhaled sulfur dioxide elicited a stronger reaction in sulfite oxidase–deficient rats than endogenously accumulated sulfites and S-sulfocysteine (a reaction product of sulfite with cysteine residues in proteins). Noncholinergic mechanisms for sulfur dioxide–induced bronchoconstriction have been demonstrated in humans as well. In one study, asthmatic subjects were administered indomethacin – a prostaglandin synthetase inhibitor – followed by challenge with sulfur dioxide gas; a reduction in airway responsiveness was observed.

Sulfur dioxide is a noncombustible substance (NFPA rating = 0).

An explosive when compressed.

Pungent odor detectable at 0.3 to 5 ppm

Acid taste

1.3×10-2mol/(m3Pa) at 25℃, Burkholder et al. (2019)

Dissolves in water to form sulfurous acid, a corrosive liquid. Moist Sulfur dioxide is very corrosive due to the slow formation of sulfuric acid [Handling Chemicals Safely 1980 p. 876].

Sulfur dioxide is acidic. Reacts exothermically with bases such as amines, amides, metal oxides, and hydroxides. Frequently used as a reducing agent although Sulfur dioxide is not a powerful one. Acts as a reducing bleach to decolorize many materials. Can act as an oxidizing agent. Supports combustion of powdered aluminum [Mellor 5:209-212 1946-47]. Reacts explosively with fluorine [Mellor 2:1 1946-47]. Supports burning of manganese [Mellor 12:187 1946-47]. Readily liquefied by compression. Contact between the liquid and water may result in vigorous or violent boiling and extremely rapid vaporization. If the water is hot an explosion may occur. Pressures may build to dangerous levels if the liquid contacts water in a closed container [Handling Chemicals Safely 1980]. Supports incandescent combustion of monocesium acetylide, monopotassium acetylide, cesium oxide, iron(II) oxide, tin oxide, and lead oxide [Mellor]. Ethylene oxide and SO2 can react violently in pyridine solution with pressurization if ethylene oxide is in excess (Nolan, 1983, Case History 51).

2.3

UN 2037 2.3

1

T

9-26-36/37/39-45

WS4550000

T

Sulfur dioxide is noncorrosive and stable when dry. It is usually stored under pressure in cylinders, and should be kept in a cool, dry, well-ventilated area, away from flammable materials.

Steel cylinders can explode when exposed to heat and sunlight; highly toxic gases are released

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.

P260, P261, P264, P271, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P311, P321, P363, P403+P233, P405, P501

Toxic by inhalation, strong irritant to eyes and mucous membranes, especially under pressure. Dangerous air contaminant and constituent of smog. Not permitted in meats and other sources of vitamin B1. U.S. atmospheric standard 0.140 ppm. Pulmonary function inhibitor and lower respiratory tract irritant. Questionable carcinogen.

Sulfur dioxide reacts vigorously with strong alkalis and oxidizing agents. The moist gas corrodes most metals. Sulfur dioxide is incompatible with chlorates, fluorine, interhalogens, powdered metals, metal oxides, metal acetylides, sodium hydroxide, and diethyl zinc. It is also incompatible with thiamine and gelatin.

UN 1079

Containers may explode in heat of fire or they may rupture and release irritating toxic Sulfur dioxide. Sulfur dioxide has explosive properties when Sulfur dioxide comes in contact with sodium hydride; potassium chlorate at elevated temperatures; ethanol; ether; zinc ethylsulfurinate at very cool temperatures (-15C); fluorine; chlorine trifluoride and chlorates. Sulfur dioxide will react with water or steam to produce toxic and corrosive fumes. When the liquid is heated Sulfur dioxide may release irritating, toxic Sulfur dioxide gas. Avoid ammonia, monocesium or monopotassium acetylide; dicesium monoxide; iron (II) oxide; tin oxide; lead (IV) oxide; chromium; manganese; molten sodium, powder aluminum and rubidium. Sulfur dioxide has explosive properties when Sulfur dioxide comes in contact with sodium hydride; potassium chlorate at elevated temperatures; ethanol; ether; zinc ethylsulfurinate at very cool temperatures (-15C); fluorine; chlorine trifluoride and chlorates. Sulfur dioxide will react with water or steam to produce toxic and corrosive fumes. Hazardous polymerization may not occur.

moderately toxic

Concentrations of sulfur dioxide as low as 1–2 ppm have been reported to cause severe stress to green plants, and dissolved sulfur dioxide can be toxic to aquatic life. Sulfur, however, is the sixth most abundant element in living creatures, and is important in the structure and synthesis of proteins and kinetics of cellular components. For the most part, sulfur dioxide and other sulfites are rapidly metabolized by living organisms, which avoids cytotoxic effects. Sulfite metabolism pathways abound in plants and animals due to the ubiquity of sulfur and its compounds. For example, in certain plants, it has been shown that more than 80% of injected sulfite was metabolized to sulfate within 3 h.Sulfur dioxide and other sulfites are generally highly soluble compounds that interact with the environment through a variety of processes. The primary functions of sulfites are those of reducing agents, which can remove dissolved oxygen from waterways; in the air, this ismanifested in the oxidation of sulfur dioxide to produce someinsoluble particulate sulfate salts as well as sulfuric acid. In waterways, the reduction of dissolved oxygen in turn generates a favorable environment for anaerobic bacteria, disrupting the local microbiota. Decreases in dissolved oxygen caused by the presence of sulfites – typically below 5 ppm dissolved oxygen – can negatively affect fish and other organisms present in polluted waterways. Another effect of sulfite contamination of waterways is the production of hydrogen sulfide gas, which is a by-product of sulfite-induced redox processes.

TLV-TWA 2 ppm (～5 mg/m3) (ACGIH), 5 ppm (OSHA and MSHA); IDLH 100 ppm (NIOSH).

Exposures to sulfur dioxide cause adverse health effects to users and occupational workers. The gaseous sulfur dioxide is particularly irritating to the mucous membranes of the upper respiratory tract. Chronic exposure to sulfur dioxide produces dryness of the throat, cough, rhinitis, conjunctivitis, corneal burns, and corneal opacity. Acute exposure to high concentrations of sulfur dioxide may also result in death due to asphyxia. By contrast, chronic exposures to sulfur dioxide lead to nasopharyngitis, fatigue, and disturbances of the pulmonary function. Animals exposed to chronic doses of sulfur dioxide have shown thickening of the mucous layer in the trachea and also hypertrophy of goblet cells and mucous glands resembling the pathology of chronic bronchitis. It has been found that penetration of sulfur dioxide into the lungs is greater during mouth breathing than during nose breathing. In fact, an increase in the fl ow rate of the gas would markedly increase the penetration. Human subjects exposed for very brief periods to sulfur dioxide also showed alterations in pulmonary mechanics. More information on the adverse effects of sulfur dioxide and the manner of its potentiation in association with other chemicals may be found in literature.