tert-Butyl mercaptan

H225 (35.5%): Highly Flammable liquid and vapor [Danger Flammable liquids]

H304 (64.5%): May be fatal if swallowed and enters airways [Danger Aspiration hazard]

H317 (91.8%): May cause an allergic skin reaction [Warning Sensitization, Skin]

H319 (65%): Causes serious eye irritation [Warning Serious eye damage/eye irritation]

H411 (27.2%): Toxic to aquatic life with long lasting effects [Hazardous to the aquatic environment, long-term hazard]

P210, P233, P240, P241, P242, P243, P261, P264+P265, P272, P273, P280, P301+P316, P302+P352, P303+P361+P353, P305+P351+P338, P321, P331, P333+P317, P337+P317, P362+P364, P370+P378, P391, P403+P235, P405, and P501 (click each P-code to see the statement)

Aggregated GHS information provided per 691 reports by companies from 9 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

Information may vary between notifications depending on impurities, additives, and other factors. The percentage value in parenthesis indicates the notified classification ratio from companies that provide hazard codes. Only hazard codes with percentage values above 10% are shown. For more detailed information, please visit ECHA C&L website.

H225: Highly Flammable liquid and vapor [Danger Flammable liquids]

H317: May cause an allergic skin reaction [Warning Sensitization, Skin]

H320: Causes eye irritation [Warning Serious eye damage/eye irritation]

H335: May cause respiratory irritation [Warning Specific target organ toxicity, single exposure; Respiratory tract irritation]

H336: May cause drowsiness or dizziness [Warning Specific target organ toxicity, single exposure; Narcotic effects]

H373: May causes damage to organs through prolonged or repeated exposure [Warning Specific target organ toxicity, repeated exposure]

P210, P233, P240, P241, P242, P243, P260, P261, P264+P265, P271, P272, P280, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P319, P321, P333+P317, P337+P317, P362+P364, P370+P378, P403+P233, P403+P235, P405, and P501 (click each P-code to see the statement)

Fresh air, rest. Refer for medical attention.

Remove contaminated clothes. Rinse and then wash skin with water and soap.

First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then refer for medical attention.

Rinse mouth.

Excerpt from ERG Guide 130 [Flammable Liquids (Water-Immiscible / Noxious)]:

Refer to the "General First Aid" section. Specific First Aid: Wash skin with soap and water. In case of burns, immediately cool affected skin for as long as possible with cold water. Do not remove clothing if adhering to skin. (ERG, 2024)

Excerpt from ERG Guide 130 [Flammable Liquids (Water-Immiscible / Noxious)]:

CAUTION: The majority of these products have a very low flash point. Use of water spray when fighting fire may be inefficient.

SMALL FIRE: Dry chemical, CO2, water spray or regular foam. If regular foam is ineffective or unavailable, use alcohol-resistant foam.

LARGE FIRE: Water spray, fog or regular foam. If regular foam is ineffective or unavailable, use alcohol-resistant foam. Avoid aiming straight or solid streams directly onto the product. If it can be done safely, move undamaged containers away from the area around the fire.

FIRE INVOLVING TANKS, RAIL TANK CARS OR HIGHWAY TANKS: Fight fire from maximum distance or use unmanned master stream devices or monitor nozzles. Cool containers with flooding quantities of water until well after fire is out. Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank. ALWAYS stay away from tanks in direct contact with flames. For massive fire, use unmanned master stream devices or monitor nozzles; if this is impossible, withdraw from area and let fire burn. (ERG, 2024)

Use foam, carbon dioxide, powder. In case of fire: keep drums, etc., cool by spraying with water.

Alcohol foam, dry chemical, mist, fog.

If material on fire or involved in fire: Do not extinguish fire unless flow can be stopped or safely confined. Use water in flooding quantities as fog. Solid streams of water may spread fire. Cool all affected containers with flooding quantities of water. Apply water from as far a distance as possible. Use "alcohol" foam, dry chemical or carbon dioxide. /Butyl mercaptan/

Excerpt from ERG Guide 130 [Flammable Liquids (Water-Immiscible / Noxious)]:

IMMEDIATE PRECAUTIONARY MEASURE: Isolate spill or leak area for at least 50 meters (150 feet) in all directions.

LARGE SPILL: Consider initial downwind evacuation for at least 300 meters (1000 feet).

FIRE: If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions. (ERG, 2024)

Evacuate danger area! Personal protection: filter respirator for organic gases and vapours adapted to the airborne concentration of the substance. Remove all ignition sources. Collect leaking and spilled liquid in sealable containers as far as possible. Absorb remaining liquid in sand or inert absorbent. Then store and dispose of according to local regulations. Do NOT wash away into sewer.

Evacuate danger area! Remove all ignition sources. Collect leaking and spilled liquid in sealable containers as far as possible. Absorb remaining liquid in sand or inert absorbent and remove to safe place. Do NOT wash away into sewer. Carefully collect remainder, then remove to safe place.

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational exposure 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, aquatic, and plant life; and conformance with environmental and public health regulations.

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.

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.

Ventilation control: generally process from which mercaptan vapor is liable to be evolved should as far as practicable be enclosed, and exhaust ventilation should be provided to prevent vapors from diffusing into atmosphere of workroom. /mercaptans/

If material not on fire and not involved in fire: Keep sparks, flames, and other sources of ignition away. Keep material out of water sources and sewers. Build dikes to contain flow as necessary. Attempt to stop leak if without undue personnel hazard. Use water spray to disperse vapors and dilute standing pools of liquid. /Butyl mercaptan/

For more Preventive Measures (Complete) data for T-BUTYL MERCAPTAN (8 total), please visit the HSDB record page.

Excerpt from ERG Guide 130 [Flammable Liquids (Water-Immiscible / Noxious)]:

ELIMINATE all ignition sources (no smoking, flares, sparks or flames) from immediate area. All equipment used when handling the product must be grounded. Do not touch or walk through spilled material. Stop leak if you can do it without risk. Prevent entry into waterways, sewers, basements or confined areas. A vapor-suppressing foam may be used to reduce vapors. Absorb or cover with dry earth, sand or other non-combustible material and transfer to containers. Use clean, non-sparking tools to collect absorbed material.

LARGE SPILL: Dike far ahead of liquid spill for later disposal. Water spray may reduce vapor, but may not prevent ignition in closed spaces. (ERG, 2024)

Fireproof. Separated from strong oxidants, strong bases, strong acids, metals and strong reducing agents.

Fireproof. Separated from strong oxidants, strong bases, strong acids, metals, strong reducing agents.

...Materials which are toxic as stored or which can decompose into toxic components...should be stored in a cool, well ventilated place, out of the direct rays of the sun, away from areas of high fire hazard, and should be periodically inspected. Incompatible materials should be isolated...

1.0 [ppm]

3.74 mg/m

A harmful contamination of the air can be reached rather quickly on evaporation of this substance at 20 °C.

The substance is irritating to the eyes and respiratory tract. Exposure at high levels could cause lowering of consciousness.

Excerpt from ERG Guide 130 [Flammable Liquids (Water-Immiscible / Noxious)]:

Wear positive pressure self-contained breathing apparatus (SCBA). Structural firefighters' protective clothing provides thermal protection but only limited chemical protection. (ERG, 2024)

According to degree of possible exposure, persons working with mercaptans should wear personal protective equipment; contact with skin and mucous membranes of mercaptans in high or unknown concn should be avoided. /mercaptans/

Personnel protection: ... Wear appropriate chemical protective gloves, boots and goggles. ... Wear positive pressure self-contained breathing apparatus when fighting fires involving this material. /Butyl mercaptan/

NO open flames, NO sparks and NO smoking. Closed system, ventilation, explosion-proof electrical equipment and lighting. Do NOT use compressed air for filling, discharging, or handling.

Use ventilation, local exhaust or breathing protection.

Protective gloves.

Wear safety goggles or eye protection in combination with breathing protection.

Do not eat, drink, or smoke during work.

Tert-butyl mercaptan is a foul-smelling organosulfur compound which is a colorless, clear liquid at ambient temperatures. It is primarily used as an odorant for natural gas, and it has an odor threshold of less than 0.33 ppb. Non-toxic at the very low concentrations used in natural gas, but the smell can cause nausea at concentrations as low as 2-3 ppm. The pure chemical is highly flammable and may cause skin and eye irritation upon direct exposure.

Liquid with a strong skunky odor; [Merck Index] Clear colorless liquid with an unpleasant odor; [MSDSonline]

COLOURLESS LIQUID WITH CHARACTERISTIC ODOUR.

Mobile liquid

COLORLESS LIQUID

Heavy skunk odor

Strong offensive odor

149-153 °F at 760 mmHg (NFPA, 2010)

63.7-64.2 °C

-32 °F (ICSC, 2024)

Heat of fusion at melting point = 2.0782X10+7 J/kmol

less than -20 °F (NFPA, 2010)

<-20 °F (<-29 °C) (closed cup)

-26 °C c.c.

Insoluble (NFPA, 2010)

Slightly sol in water; very sol in alcohol, ether, liquid hydrogen sulfide

Very soluble in acetone; soluble in carbon tetrachloride

0.8 (NFPA, 2010) - Less dense than water; will float

0.79426 at 25 °C/4 °C

Relative density (water = 1): 0.80

3.1 (NFPA, 2010) - Heavier than air; will sink (Relative to Air)

3.1 (Air= 1)

Relative vapor density (air = 1): 3.1

142.5 mmHg at 68 °F (ICSC, 2024)

181.0 [mmHg]

181 mm Hg at 25 °C /Extrapolated/

Vapor pressure, kPa at 20 °C: 19.0

Remarkably stable to oxidizing agents.

The substance decomposes on burning producing toxic gases including sulfur oxides.

When heated to decomposition or on contact with acid or acid fumes it emits highly toxic fumes of /sulfur oxides/.

Odor Threshold Low: 0.00081 [ppm]

The Guide in the Emergency Response Guidebook is for "Butyl mercaptan." Odor threshold (100% recognition) from CHEMINFO

Index of refraction: 1.41984 at 25 °C/D

pKa = 11.22 at 25 °C

WT/GALLON: 6.71 LB; DISTILLATION RANGE: 62-67 °C

Freezing point = 34 °F

Hydroxyl radical reaction rate constant = 3.31X10-11 cu cm/molec-sec at 25 °C

Schoenflies notation

Boiling point

Chemical bond

Does not react with air or water under normal conditions.

Sulfides, Organic

Highly Flammable

Thiols, like TERT-BUTYL MERCAPTAN, can react with strong reducing agents, like alkali metals, nitrides, and hydrides, to form flammable hydrogen gas and strongly basic metal thiolates. Many of these compounds may liberate hydrogen sulfide upon decomposition or reaction with an acid. They are oxidized readily in the presence of oxidants. They may also react with isocyanates, similarly to alcohols.

Reacts with strong acids, strong bases, metals, strong oxidants, strong reducing agents to produce sulfur oxides.

It can react vigorously with oxidizing materials.

The substance can be absorbed into the body by inhalation.

Cough. Dizziness. Headache. Nausea. Drowsiness.

Redness.

Nausea. Vomiting.

Other Poison - Chemical Asphyxiant

LC50 (rat) = 22,200 ppm/4h

LD50 Rat oral 4729 mg/kg

LD50 Rat inhalation 22,000 ppm/4 hr

LD50 Rat ip 590 mg/kg

LD50 Mouse inhalation 16,500 ppm/4 hr

For more Non-Human Toxicity Values (Complete) data for T-BUTYL MERCAPTAN (6 total), please visit the HSDB record page.

/SRP:/ Basic treatment: Establish a patent airway. Suction if necessary. Watch for signs of respiratory insufficiency and assist ventilations if necessary. Administer oxygen by nonrebreather mask at 10 to 15 L/min. Monitor for pulmonary edema and treat if necessary ... . Anticipate seizures and treat if necessary ... . For eye contamination, flush eyes immediately with water. Irrigate each eye continuously with normal saline during transport ... . Do not use emetics. For ingestion, rinse mouth and administer 5 m1/kg up to 200 ml of water for dilution if the patient can swallow, has a strong gag reflex, and does not drool ... . Administer activated charcoal ... . Cover skin burns with dry sterile dressings after decontamination ... . /Sulfur and related compounds/

/SRP:/ Advanced treatment: Consider orotracheal or nasotracheal intubation for airway control in the patient who is unconscious. Early intubation at the first sign of upper airway obstruction may be necessary. Monitor cardiac rhythm and treat arrhythmias if necessary ... . Start an IV with D5W /SRP: "To keep open", minimal flow rate/. Use lactated Ringer's if signs of hypovolemia are present. Watch for signs of fluid overload. Consider drug therapy for pulmonary edema ... . Treat seizures with diazepam ... . For hypotension with signs of hypovolemia, administer fluid cautiously. Consider vasopressors for hypotension with a normal fluid volume. Watch for signs of fluid overload ... . Use proparacaine hydrochloride to assist eye irrigation ... . /Sulfur and related compounds/

/SIGNS AND SYMPTOMS/ /t-Butyl mercaptan/ is irritating to the eyes and the respiratory tract. Exposure at high levels may result in lowering of consciousness.

/SIGNS AND SYMPTOMS/ Strong, offensive smell of mercaptans can cause headache and nausea. High concentrations of their vapors in atmosphere can produce unconsciousness with cyanosis, a sense of coldness at the extremities and quickning of pulse ... Pulmonary edema /is also observed. /Mercaptans/

/SIGNS AND SYMPTOMS/ /T-butyl mercaptan may cause/ cough, dizziness, headache, nausea, drowsiness /by inhalation/.

/LABORATORY ANIMALS: Acute Exposure/ A variety of mercaptans, especially the beta-mercaptocarboxylic acids, inhibited the selenium dependent glutathione peroxidase activity of chick liver postmitochondrial supernatant or cytosol and of purified bovine erythrocyte selenium dependent glutathione peroxidase. The effects of mercaptans and a glutathione analogue on selenium utilization were determined by subcutaneous injection of test compounds into vitamin E deficient chicks fed diets containing 0.1 ppm selenium (as Na2SeO3) at times when greater than 50% of vitamin E and selenium deficient chicks showed the vitamin E , selenium deficiency disease exudative diathesis. D-(-)-Penicillamine hydrochloride (the positive control model compound), sodium beta-mercaptopyruvate, t-butyl mercaptan and S-methylglutathione (nonmercaptan glutathione analogue) decreased selenium dependent glutathione peroxidase activity in chick liver postmitochondrial supernatants within 24 hr of injection and increased the incidence of exudative diathesis within 4 days. Other mercaptans tested did not increase exudative diathesis incidence or affect liver, kidney or plasma selenium dependent glutathione peroxidase activities. Although mercaptosuccinic acid, N-(2-mercaptopropionyl)glycine and sodium thioglycolate each strongly inhibited selenium dependent glutathione peroxidase activity in vitro, each also significantly increased chick mortality in the dosage range tested; therefore, their effects on selenium dependent glutathione peroxidase activity in vivo could not be evaluated. It appears that the beta-mercaptocarboxylic acids, mercaptans with a high degree of steric hindrance in close proximity to the thiol group and a close structural analogue of glutathione, are capable of altering selenium status in chicks.

/LABORATORY ANIMALS: Acute Exposure/ Slight irritation, no injury on rabbit eyes.

/LABORATORY ANIMALS: Acute Exposure/ /In LD50 studies using rabbits,/ skin reactions consisted of mild erythema and discoloration of the skin at the application site. Moderate to severe inactivity and weakness were noted during the first 3 days after skin contact ceased.

/LABORATORY ANIMALS: Acute Exposure/ The median lethal level by the inhalation route was 22,200 ppm/4 hr for rats and 16,500/4 hr for mice. The higher toxicity in mice was probably due to the larger respiratory minute volume per unit body weight compared to the rat. Clinical signs in both species included initial stimulant effects on respiration and activity followed by CNS depression, weakness, muscular paralysis, lack of coordination, and cyanosis.

For more Non-Human Toxicity Excerpts (Complete) data for T-BUTYL MERCAPTAN (7 total), please visit the HSDB record page.

T-butyl mercaptan (CAS # 75-66-1) was evaluated for subchronic inhalation toxicity. The test substance was administered to rats (15/sex/group, strain not reported) at concentrations of 0 ppm, 9 ppm, 97 ppm, or 196 ppm for 6 hours/day, 5 days/week for 13 weeks. At 9 ppm, histopathology indicated inflammatory lesions in the lungs. At 97 ppm, minimal to mild interstitial fibrosis was indicated. At 196 ppm, interstitial fibrosis in the lungs of males and females, and nephrosis in male rats only was indicated.

t-Butyl mercaptan's production and use as an odorant in natural gas, as an intermediate, and as a bacterial nutrient may result in its release to the environment through various waste streams. If released to air, an extrapolated vapor pressure of 181 mm Hg at 25 °C indicates t-butyl mercaptan will exist solely as a vapor in the ambient atmosphere. Vapor-phase t-butyl mercaptan will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is estimated to be 12 hours. t-Butyl mercaptan does not absorb light at wavelengths >290 nm and therefore is not expected to be susceptible to direct photolysis by sunlight. If released to soil, t-butyl mercaptan is expected to have very high mobility based upon an estimated Koc of 49. Volatilization from moist soil surfaces is expected to be an important fate process based upon an estimated Henry's Law constant of 6.1X10-3 atm-cu m/mole. t-Butyl mercaptan may volatilize from dry soil surfaces based upon its vapor pressure. If released into water, t-butyl mercaptan is not expected to adsorb to suspended solids and sediment based upon the estimated Koc. Biodegradation data were not available. Volatilization from water surfaces is expected to be an important fate process based upon this compound's estimated Henry's Law constant. Estimated volatilization half-lives for a model river and model lake are 3 hours and 4 days, respectively. An estimated BCF of 9 suggests the potential for bioconcentration in aquatic organisms is low. Hydrolysis is not expected to be an important environmental fate process since this compound lacks functional groups that hydrolyze under environmental conditions. Occupational exposure to t-butyl mercaptan may occur through inhalation and dermal contact with this compound at workplaces where t-butyl mercaptan is produced or used. Use data suggest that general population exposure may occur via inhalation of ambient air near natural gas refineries and operations due to use as a natural gas odorant. (SRC)

t-Butyl mercaptan's production and use as an odorant in natural gas, as an intermediate, and as a bacterial nutrient(1) may result in its release to the environment through various waste streams(SRC).

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 49(SRC), determined from a structure estimation method(2), indicates that t-butyl mercaptan is expected to have very high mobility in soil(SRC). Volatilization of t-butyl mercaptan from moist soil surfaces is expected to be an important fate process(SRC) given an estimated Henry's Law constant of 6.1X10-3 atm-cu m/mole(SRC), using a fragment constant estimation method(3). t-Butyl mercaptan is expected to volatilize from dry soil surfaces(SRC) based upon an extrapolated vapor pressure of 181 mm Hg(4). Biodegradation data were not available(SRC, 2005).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 49(SRC), determined from a structure estimation method(2), indicates that t-butyl mercaptan is not expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is expected(3) based upon an estimated Henry's Law constant of 6.1X10-3 atm-cu m/mole(SRC), developed using a fragment constant estimation method(4). Using this Henry's Law constant and an estimation method(3), volatilization half-lives for a model river and model lake are 3 hours and 4 days, respectively(SRC). According to a classification scheme(5), an estimated BCF of 9(SRC), from an estimated log Kow of 2.1(6) and a regression-derived equation(7), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Biodegradation data were not available(SRC, 2005).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), t-butyl mercaptan, which has an extrapolated vapor pressure of 181 mm Hg at 25 °C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase t-butyl mercaptan is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 12 hours(SRC), calculated from its rate constant of 3.31X10-11 cu cm/molecule-sec at 25 °C(3). t-Butyl mercaptan does not absorb light at wavelengths >290 nm and therefore is not expected to be susceptible to direct photolysis by sunlight.

AEROBIC: While data specific to t-butyl mercaptan were not available(SRC, 2005), this compound would probably be difficult to biodegrade because of the branching in its structure(1).

The rate constant for the vapor-phase reaction of t-butyl mercaptan with photochemically-produced hydroxyl radicals is 3.31X10-11 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 12 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). Other experimental rates constant for the vapor-phase reaction of t-butyl mercaptan with photochemically produced hydroxyl radicals were measured as 2.9X10-11(2) and 3.51X10-11(3) cu cm/molecule-sec at 25 °C, corresponding to half-lives of 13.3 and 11.0 hours, respectively, based on a hydroxyl radical concentration of 5X10+5(1). t-Butyl mercaptan is not expected to undergo hydrolysis in the environment due to the lack of hydrolyzable functional groups(4). t-Butyl mercaptan is difficult to convert to the disulfide or oxidize to the sulfonic acid under normal environmental conditions(5). t-Butyl mercaptan does not absorb light at wavelengths >290 nm and therefore is not expected to be susceptible to direct photolysis by sunlight.

An estimated BCF of 9 was calculated for t-butyl mercaptan(SRC), using an estimated log Kow of 2.1(1) and a regression-derived equation(2). According to a classification scheme(3), this BCF suggests the potential for bioconcentration in aquatic organisms is low(SRC).

Using a structure estimation method based on molecular connectivity indices(1), the Koc of t-butyl mercaptan can be estimated to be 49(SRC). According to a classification scheme(2), this estimated Koc value suggests that t-butyl mercaptan is expected to have very high mobility in soil. Natural gas containing 0.5 lb of t-butyl mercaptan per million cubic feet was passed through a bed of pulverized, dry, raw montmorillonite clay and then measured for loss of odorant. Within 100 standard cubic feet, over 85% of the average influent concentration of t-butyl mercaptan was present in the effluent(3).

The Henry's Law constant for t-butyl mercaptan is estimated as 6.1X10-3 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This Henry's Law constant indicates that t-butyl mercaptan is expected to volatilize from water surfaces(2). Based on this Henry's Law constant, the volatilization half-life from a model river (1 m deep, flowing 1 m/sec, wind velocity of 3 m/sec)(2) is estimated as 3 hours(SRC). The volatilization half-life from a model lake (1 m deep, flowing 0.05 m/sec, wind velocity of 0.5 m/sec)(2) is estimated as 4 days(SRC). t-Butyl mercaptan's Henry's Law constant indicates that volatilization from moist soil surfaces may occur(SRC). t-Butyl mercaptan is expected to volatilize from dry soil surfaces(SRC) based upon an extrapolated vapor pressure of 181 mm Hg(3).

SURFACE WATER: t-Butyl mercaptan was detected not quantified in samples from the Winfield Dam at Winfield, West Virginia, and from the Kanawha-Ohio River confluence at Huntington, West Virginia, sampled from August 30 to November 11, 1962(1).

t-Butyl mercaptan was identified as a volatile component of cooked beef flavor(1).

NIOSH (NOES Survey 1981-1983) has statistically estimated that 4,717 workers are potentially exposed to t-butyl mercaptan in the US(1). Occupational exposure to t-butyl mercaptan may occur through inhalation and dermal contact with this compound at workplaces where t-butyl mercaptan is produced or used(SRC). Use data suggest that general population exposure may occur via inhalation of ambient air near natural gas refineries and operations due to use as a natural gas odorant(SRC).

t-Butyl mercaptan's production and use as an odorant in natural gas, as an intermediate, and as a bacterial nutrient may result in its release to the environment through various waste streams. If released to air, an extrapolated vapor pressure of 181 mm Hg at 25 °C indicates t-butyl mercaptan will exist solely as a vapor in the ambient atmosphere. Vapor-phase t-butyl mercaptan will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is estimated to be 12 hours. t-Butyl mercaptan does not absorb light at wavelengths >290 nm and therefore is not expected to be susceptible to direct photolysis by sunlight. If released to soil, t-butyl mercaptan is expected to have very high mobility based upon an estimated Koc of 49. Volatilization from moist soil surfaces is expected to be an important fate process based upon an estimated Henry's Law constant of 6.1X10-3 atm-cu m/mole. t-Butyl mercaptan may volatilize from dry soil surfaces based upon its vapor pressure. If released into water, t-butyl mercaptan is not expected to adsorb to suspended solids and sediment based upon the estimated Koc. Biodegradation data were not available. Volatilization from water surfaces is expected to be an important fate process based upon this compound's estimated Henry's Law constant. Estimated volatilization half-lives for a model river and model lake are 3 hours and 4 days, respectively. An estimated BCF of 9 suggests the potential for bioconcentration in aquatic organisms is low. Hydrolysis is not expected to be an important environmental fate process since this compound lacks functional groups that hydrolyze under environmental conditions. Occupational exposure to t-butyl mercaptan may occur through inhalation and dermal contact with this compound at workplaces where t-butyl mercaptan is produced or used. Use data suggest that general population exposure may occur via inhalation of ambient air near natural gas refineries and operations due to use as a natural gas odorant. (SRC)

t-Butyl mercaptan's production and use as an odorant in natural gas, as an intermediate, and as a bacterial nutrient(1) may result in its release to the environment through various waste streams(SRC).

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 49(SRC), determined from a structure estimation method(2), indicates that t-butyl mercaptan is expected to have very high mobility in soil(SRC). Volatilization of t-butyl mercaptan from moist soil surfaces is expected to be an important fate process(SRC) given an estimated Henry's Law constant of 6.1X10-3 atm-cu m/mole(SRC), using a fragment constant estimation method(3). t-Butyl mercaptan is expected to volatilize from dry soil surfaces(SRC) based upon an extrapolated vapor pressure of 181 mm Hg(4). Biodegradation data were not available(SRC, 2005).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 49(SRC), determined from a structure estimation method(2), indicates that t-butyl mercaptan is not expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is expected(3) based upon an estimated Henry's Law constant of 6.1X10-3 atm-cu m/mole(SRC), developed using a fragment constant estimation method(4). Using this Henry's Law constant and an estimation method(3), volatilization half-lives for a model river and model lake are 3 hours and 4 days, respectively(SRC). According to a classification scheme(5), an estimated BCF of 9(SRC), from an estimated log Kow of 2.1(6) and a regression-derived equation(7), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Biodegradation data were not available(SRC, 2005).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), t-butyl mercaptan, which has an extrapolated vapor pressure of 181 mm Hg at 25 °C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase t-butyl mercaptan is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 12 hours(SRC), calculated from its rate constant of 3.31X10-11 cu cm/molecule-sec at 25 °C(3). t-Butyl mercaptan does not absorb light at wavelengths >290 nm and therefore is not expected to be susceptible to direct photolysis by sunlight.

AEROBIC: While data specific to t-butyl mercaptan were not available(SRC, 2005), this compound would probably be difficult to biodegrade because of the branching in its structure(1).

The rate constant for the vapor-phase reaction of t-butyl mercaptan with photochemically-produced hydroxyl radicals is 3.31X10-11 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 12 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). Other experimental rates constant for the vapor-phase reaction of t-butyl mercaptan with photochemically produced hydroxyl radicals were measured as 2.9X10-11(2) and 3.51X10-11(3) cu cm/molecule-sec at 25 °C, corresponding to half-lives of 13.3 and 11.0 hours, respectively, based on a hydroxyl radical concentration of 5X10+5(1). t-Butyl mercaptan is not expected to undergo hydrolysis in the environment due to the lack of hydrolyzable functional groups(4). t-Butyl mercaptan is difficult to convert to the disulfide or oxidize to the sulfonic acid under normal environmental conditions(5). t-Butyl mercaptan does not absorb light at wavelengths >290 nm and therefore is not expected to be susceptible to direct photolysis by sunlight.

An estimated BCF of 9 was calculated for t-butyl mercaptan(SRC), using an estimated log Kow of 2.1(1) and a regression-derived equation(2). According to a classification scheme(3), this BCF suggests the potential for bioconcentration in aquatic organisms is low(SRC).

Using a structure estimation method based on molecular connectivity indices(1), the Koc of t-butyl mercaptan can be estimated to be 49(SRC). According to a classification scheme(2), this estimated Koc value suggests that t-butyl mercaptan is expected to have very high mobility in soil. Natural gas containing 0.5 lb of t-butyl mercaptan per million cubic feet was passed through a bed of pulverized, dry, raw montmorillonite clay and then measured for loss of odorant. Within 100 standard cubic feet, over 85% of the average influent concentration of t-butyl mercaptan was present in the effluent(3).

The Henry's Law constant for t-butyl mercaptan is estimated as 6.1X10-3 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This Henry's Law constant indicates that t-butyl mercaptan is expected to volatilize from water surfaces(2). Based on this Henry's Law constant, the volatilization half-life from a model river (1 m deep, flowing 1 m/sec, wind velocity of 3 m/sec)(2) is estimated as 3 hours(SRC). The volatilization half-life from a model lake (1 m deep, flowing 0.05 m/sec, wind velocity of 0.5 m/sec)(2) is estimated as 4 days(SRC). t-Butyl mercaptan's Henry's Law constant indicates that volatilization from moist soil surfaces may occur(SRC). t-Butyl mercaptan is expected to volatilize from dry soil surfaces(SRC) based upon an extrapolated vapor pressure of 181 mm Hg(3).

SURFACE WATER: t-Butyl mercaptan was detected not quantified in samples from the Winfield Dam at Winfield, West Virginia, and from the Kanawha-Ohio River confluence at Huntington, West Virginia, sampled from August 30 to November 11, 1962(1).

t-Butyl mercaptan was identified as a volatile component of cooked beef flavor(1).

NIOSH (NOES Survey 1981-1983) has statistically estimated that 4,717 workers are potentially exposed to t-butyl mercaptan in the US(1). Occupational exposure to t-butyl mercaptan may occur through inhalation and dermal contact with this compound at workplaces where t-butyl mercaptan is produced or used(SRC). Use data suggest that general population exposure may occur via inhalation of ambient air near natural gas refineries and operations due to use as a natural gas odorant(SRC).

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational exposure 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, aquatic, and plant life; and conformance with environmental and public health regulations.

/GUIDE 130: FLAMMABLE LIQUIDS (NON-POLAR/WATER-IMMISCIBLE/NOXIOUS)/ Fire or Explosion: HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames. Vapors may form explosive mixtures with air. Vapors may travel to source of ignition and flash back. Most vapors are heavier than air. They will spread along ground and collect in low or confined areas (sewers, basements, tanks). Vapor explosion hazard indoors, outdoors or in sewers. Those substances designated with a "P" may polymerize explosively when heated or involved in a fire. Runoff to sewer may create fire or explosion hazard. Containers may explode when heated. Many liquids are lighter than water. /Butyl mercaptan/

/GUIDE 130: FLAMMABLE LIQUIDS (NON-POLAR/WATER-IMMISCIBLE/NOXIOUS)/ Health: May cause toxic effects if inhaled or absorbed through skin. Inhalation or contact with material may irritate or burn skin and eyes. Fire will produce irritating, corrosive and/or toxic gases. Vapors may cause dizziness or suffocation. Runoff from fire control or dilution water may cause pollution. /Butyl mercaptan/

/GUIDE 130: FLAMMABLE LIQUIDS (NON-POLAR/WATER-IMMISCIBLE/NOXIOUS)/ Public Safety: CALL Emergency Response Telephone Number ... . As an immediate precautionary measure, isolate spill or leak area for at least 50 meters (150 feet) in all directions. Keep unauthorized personnel away. Stay upwind. Keep out of low areas. Ventilate closed spaces before entering. /Butyl mercaptan/

/GUIDE 130: FLAMMABLE LIQUIDS (NON-POLAR/WATER-IMMISCIBLE/NOXIOUS)/ Protective Clothing: Wear positive pressure self-contained breathing apparatus (SCBA). Structural firefighters' protective clothing will only provide limited protection. /Butyl mercaptan/

For more DOT Emergency Guidelines (Complete) data for T-BUTYL MERCAPTAN (8 total), please visit the HSDB record page.

UN 2347; Butyl mercaptan

IMO 3.2; Butyl mercaptan

No person may /transport,/ offer or accept a hazardous material for transportation in commerce unless that person is registered in conformance ... and the hazardous material is properly classed, described, packaged, marked, labeled, and in condition for shipment as required or authorized by ... /the hazardous materials regulations (49 CFR 171-177)./

The International Air Transport Association (IATA) Dangerous Goods Regulations are published by the IATA Dangerous Goods Board pursuant to IATA Resolutions 618 and 619 and constitute a manual of industry carrier regulations to be followed by all IATA Member airlines when transporting hazardous materials.

The International Maritime Dangerous Goods Code lays down basic principles for transporting hazardous chemicals. Detailed recommendations for individual substances and a number of recommendations for good practice are included in the classes dealing with such substances. A general index of technical names has also been compiled. This index should always be consulted when attempting to locate the appropriate procedures to be used when shipping any substance or article.

Flammable Liquid

UN Hazard Class: 3; UN Pack Group: II