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CHEMINFO Record Number: 305
CCOHS Chemical Name: Potassium isobutyl xanthate

Carbonic acid, dithio-, O-isobutyl ester, potassium salt
Carbonodithioic acid, O-(2-methylpropyl) ester, potassium salt
Dithiocarbonic acid, O-isobutyl ester, potassium salt
O-Isobutyl potassium dithiocarbonate
Isobutylxanthic acid, potassium salt
Potassium butyl xanthate (non-specific name)
Potassium O-isobutyl dithiocarbonate
Potassium O-isobutyl xanthate
Xanthic acid, isobutyl-, potassium salt

CAS Registry Number: 13001-46-2
UN/NA Number(s): 3342
RTECS Number(s): FG1581000
Chemical Family: Dithiocarbonic acid ester salt / dithiocarbonic acid O-ester salt / O-alkyldithiocarbonate salt / xanthic acid salt / xanthate
Molecular Formula: C5-H9-K-O-S2
Structural Formula: (CH3)2-CH-CH2-O-C(=S)-S.K


Appearance and Odour:
Pale yellow crystals or powder, when pure. Also available in solution. Disagreeable odour of carbon disulfide (similar to decaying cabbage); solid is hygroscopic (absorbs moisture from the air).(1)

Odour Threshold:
Not available

Warning Properties:
Information not available for evaluation.

Potassium isobutyl xanthate is available in technical grade only and is generally 90-95% pure. It is generally available as powder or pellets. May contain traces of potassium hydroxide, water of hydration and decomposition products such as carbon disulfide, carbonyl sulfide, isobutanol, isobutanethiol, potassium carbonate, potassium thiocarbonate and potassium sulfide. May also be sold as solutions in water.

Uses and Occurrences:
Potassium isobutyl xanthate is used mainly in the mining industry as a collector in the flotation of metal sulfide ores. Minor uses include curing and vulcanization of rubber; as an antioxidant for rubber; as a herbicide, pesticide and fungicide; as a high-pressure lubricant additive; as a fortifying agent for certain oils; for analytical procedures; and in a froth flotation process for soils contaminated with mercury.(1,11)


Pale yellow crystals or powder when pure. Also available in solution. Disagreeable odour of carbon disulfide (similar to decaying cabbage). The solid is hygroscopic. The solid is a REACTIVE FLAMMABLE MATERIAL. It reacts with moisture to form very toxic and extremely flammable carbon disulfide, especially at increased temperatures. Spontaneous combustion may occur due to the formation of carbon disulfide. Water solutions are relatively stable, unless they are heated, the pH is below 8 or greater than 13, or they have aged. Heating or burning may result in the formation of carbon disulfide, carbonyl sulfide, ethyl mercaptan, diethyl sulfide, ethyl disulfide, hydrogen sulfide, and sulfur oxides. The dry powder is a COMBUSTIBLE DUST and may form explosive dust-air mixtures. The solid and solutions may be harmful if absorbed through the skin and may be irritating to eyes, skin and respiratory tract.


Effects of Short-Term (Acute) Exposure

Potassium isobutyl xanthate solid or water solutions can give off very toxic and extremely flammable carbon disulfide vapour. The rate at which carbon disulfide is generated from the solid material increases with temperature and humidity (moisture). The rate of carbon disulfide generation from solution increases with temperature and/or low pH (acidic conditions), as well as with time.(1,2)
Relatively low concentrations of carbon disulfide can harm the central nervous system (CNS). Early symptoms may include headache, dizziness, fatigue, excitement or depression. High concentrations can cause serious psychological disturbances (excitability, confusion, extreme, irritability, nightmares) and death. For further information, refer to the CHEMINFO review of carbon disulfide.

Skin Contact:
The dust can absorb moisture from the skin and may produce irritation. Solutions may also cause irritation, depending on the pH and presence of certain contaminants like potassium hydroxide and potassium carbonate.
Potassium isobutyl xanthate may be absorbed through the skin and may cause harmful effects by this route of exposure based on limited animal information for a related chemical (sodium ethyl xanthate) and a human case report involving exposure to an unspecified xanthate compound.
A 32-year old male reagent mixer became covered in xanthate powder and water solution (specific xanthate not specified) staining his skin green from the chest down. He was wearing disposable paper overalls over cotton overalls, polyvinyl chloride gloves and an acid-gas/particulate full-face negative pressure respirator. Twenty hours later, he experienced abdominal pain, loss of appetite, nausea, vomiting, headache and fatigue, and had mild itchiness at the wrists only. His symptoms resolved within 4 days. Based on spot measurements taken following the incident, concentrations of carbon disulfide in the air at the site were less than 10-60 ppm. A metabolite of carbon disulfide was detected in his urine at a low level. Many of the reported symptoms are consistent with carbon disulfide toxicity. However, the delayed onset of symptoms made the diagnosis of carbon disulfide toxicity slightly less certain. Skin contamination was probably the major exposure route in this situation, but inhalation exposure may also have occurred.(13)

Eye Contact:
The solid material may cause some tearing, blinking and mild, temporary pain as it is rinsed from the eye by tears. Solutions may also be irritating, depending on the pH and presence of certain contaminants like potassium hydroxide and potassium carbonate. There is no human or animal information available.

Potassium isobutyl xanthate is probably moderately toxic following ingestion, based on unconfirmed animal toxicity information and comparison to other xanthates. There is no human information available. Potassium isobutyl xanthate may form carbon disulfide in the body, if ingested. Therefore, harmful effects may be similar to those observed following ingestion of carbon disulfide. These effects have included tremors, exhaustion, shortness of breath, reduced body temperature, dilation of the pupils, convulsions, coma and possibly even death. Ingestion is not a typical route of occupational exposure.

Effects of Long-Term (Chronic) Exposure

There is no human or animal information available for potassium isobutyl xanthate.

Consult the CHEMINFO review for a discussion of the potential long-term effects of occupational exposure to carbon disulfide.

Potassium isobutyl xanthate may cause dry, red, itchy skin (dermatitis), based on unconfirmed reports.(1)


There is no human or animal information available for potassium isobutyl xanthate.

The International Agency for Research on Cancer (IARC) has not evaluated the carcinogenicity of this chemical.

The American Conference of Governmental Industrial Hygienists (ACGIH) has no listing for this chemical.

The US National Toxicology Program (NTP) has not listed this chemical in its report on carcinogens.

Teratogenicity and Embryotoxicity:
There is no human or animal information available for potassium isobutyl xanthate.

Reproductive Toxicity:
There is no human or animal information available for potassium isobutyl xanthate.

There is no information available for potassium isobutyl xanthate.

Toxicologically Synergistic Materials:
Ingestion of alcoholic beverages may increase the toxicity of xanthates.(1, unconfirmed) In a study with guinea pigs, it was found that the amount of carbon disulfide exhaled, increased as the amount of ethanol in which a xanthate (diethylxanthate disulfide) was dissolved, increased.(3)

Potential for Accumulation:
There is no specific information available. Potassium isobutyl xanthate probably does not accumulate in the body. Carbon disulfide was detected in the exhaled air after oral administration of single doses of 150 and 250 mg of sodium ethyl xanthate (a closely related chemical) to humans.(3)


If irritation is experienced, remove source of contamination or move victim to fresh air and obtain medical advice. If symptoms of carbon disulfide exposure develop (e.g. headache, dizziness, fatigue or excitement), take proper precautions to ensure your own safety before attempting rescue (e.g. wear appropriate protective equipment, use the "buddy" system). Remove source of contamination or move victim to fresh air. If breathing has stopped, trained personnel should begin artificial respiration or, if the heart has stopped, cardiopulmonary resuscitation (CPR) immediately. Avoid mouth-to-mouth contact by using mouth guards or shields. Immediately transfer victim to an emergency care facility.

Skin Contact:
Avoid direct contact with this chemical. Wear chemical protective gloves, if necessary. Remove contaminated clothing, shoes and leather goods (e.g. watchbands, belts). As quickly as possible, flush contaminated area with lukewarm, gently flowing water for at least 20 minutes, or until the chemical is removed. Obtain medical attention immediately. Completely decontaminate clothing before re-use or discard. Do not re-use contaminated shoes or leather goods.

Eye Contact:
DUSTS: Do not allow victim to rub eye(s). Let the eye(s) water naturally for a few minutes. Have victim look right and left, and then up and down. If particle/dust does not dislodge, flush with lukewarm, gently flowing water for 5 minutes or until the particle/dust is removed, while holding the eyelid(s) open. If irritation persists, obtain medical attention. DO NOT attempt to manually remove anything stuck to the eye(s). SOLUTIONS: Immediately flush the contaminated eye(s) with lukewarm, gently flowing water for 20 minutes or until the chemical is removed, while holding the eyelid(s) open. Obtain medical attention immediately.

NEVER give anything by mouth if victim is rapidly losing consciousness, or is unconscious or convulsing. Have victim rinse mouth thoroughly with water. DO NOT INDUCE VOMITING. Have victim drink 240 to 300 mL (8 to 10 oz) of water. If vomiting occurs naturally, repeat administration of water. If breathing has stopped, trained personnel should begin artificial respiration or, if the heart has stopped, cardiopulmonary resuscitation (CPR) immediately. Avoid mouth-to-mouth contact by using mouth guards or shields. Quickly transport victim to an emergency care facility.

First Aid Comments:
Provide general supportive measures (comfort, warmth, rest).
Consult a doctor and/or the nearest Poison Control Centre for all exposures except minor instances of inhalation or skin contact.
All first aid procedures should be periodically reviewed by a doctor familiar with the material and its conditions of use in the workplace.


Flash Point:
Solid xanthates release extremely flammable carbon disulfide (closed cup flash point: -30 deg C (-22 deg F)) on contact with moisture.(2,14) Freshly prepared solutions do not normally exhibit a flash point by standard methods until heated to a point well above room temperature when decomposition occurs.(2)

Lower Flammable (Explosive) Limit (LFL/LEL):
1% (carbon disulfide) (2,5); 1.3% (carbon disulfide) (4,5)

Upper Flammable (Explosive) Limit (UFL/UEL):
50% (carbon disulfide) (2,4,5)

Autoignition (Ignition) Temperature:
Approximately 250 deg C (482 deg F) (dry solid xanthates) (2); 90 deg C (190 deg F) (carbon disulfide) (4)

Sensitivity to Mechanical Impact:
No information is available

Combustion and Thermal Decomposition Products:
Carbon disulfide, carbonyl sulfide, isobutanol, isobutanethiol, aldehydes, di-isobutyl sulfide, hydrogen sulfide and potassium sulfide form when potassium isobutyl xanthate is heated to decomposition.(1,7) In a fire, these chemicals can decompose further to carbon monoxide, carbon dioxide and sulfur oxides.(8)

Flammable Properties:

Specific Hazards Arising from the Chemical:
Exposure to the heat of a fire can cause decomposition of potassium isobutyl xanthate solid and solutions to extremely flammable and very toxic carbon disulfide. A combination of moisture and heat may result in spontaneous combustion, due to the formation of carbon disulfide. The heat generated by hydration and/or decomposition reactions may be sufficient to raise the temperature to the autoignition temperature of carbon disulfide (90 deg C). Closed containers may explode if exposed to excess heat for a sufficient period of time releasing large quantities of carbon disulfide.

Extinguishing Media:
Carbon dioxide, dry chemical powder or appropriate foam. Foam manufacturers should be consulted for recommendations regarding types of foams and application rates.

Extinguishing Media to be Avoided:
DO NOT use water or water-based extinguishers on solid xanthates since extremely flammable and very toxic carbon disulfide will be released. Water may be used to keep non-leaking, fire-exposed containers cool.

Fire Fighting Instructions:
If a fire occurs in the vicinity of containers of potassium isobutyl xanthate, evacuate area and fight fire from a safe distance or a protected location. Approach fire from upwind to avoid extremely flammable and very toxic carbon disulfide and other toxic and flammable compounds. Wear full protective suit if exposure is possible. See Protection of Firefighters.
Closed containers may rupture violently when exposed to the heat of the fire. If possible, isolate materials not yet involved in the fire. Move containers from the fire area if this can be done without risk. Protect personnel. Otherwise, use water in flooding quantities as a spray to keep fire-exposed containers, drums, or tanks cool and absorb heat to help prevent rupture. Cooling should begin as soon as possible (within the first several minutes) and should concentrate on any unwetted portions of the container. Apply water from the side and from a safe distance. Take care not to get water inside the containers, since a very hazardous situation may result. Cooling should continue until well after the fire is out.
Stay away from the ends of tanks, but be aware that flying material (shrapnel) from ruptured tanks may travel in any direction. Withdraw immediately in case of rising sound from venting safety device or any discolouration of tank.
For an advanced or a massive fire, it may be prudent to use unmanned hose holders or monitor nozzles and evacuate the area.
Containers should not be approached directly after they have been involved in a fire, until they have been completely cooled down. After the fire has been extinguished, explosive and toxic atmospheres may be present. Before entering such an area, especially confined areas, check the atmosphere with an appropriate monitoring device while wearing full protective suit.

Protection of Fire Fighters:
The decomposition and combustion products of potassium isobutyl xanthate are extremely hazardous. Firefighter's normal protective equipment (Bunker Gear) will not provide adequate protection. A full-body encapsulating chemical protective suit with positive pressure self-contained breathing apparatus (NIOSH approved or equivalent) may be necessary.


NFPA - Comments:
NFPA has no listing for this chemical in Codes 49 or 325.


Molecular Weight: 188.35

Conversion Factor:
Not applicable

Physical State: Solid
Melting Point: 260-270 deg C (500-518 deg F) (9,11)
Boiling Point: Not applicable. Decomposes at 250-265 deg C (482-509 deg F) (7)
Relative Density (Specific Gravity): Not available
Solubility in Water: Very soluble (10.7 g/100 g at 0 deg C; approximately 48 g/100 g at 35 deg C) (1,11)
Solubility in Other Liquids: Soluble in alcohols (e.g. ethanol and isobutanol), lower ketones (e.g. acetone), pyridine, and acetonitrile. Not soluble in nonpolar solvents, such as diethyl ether, ligroin and petroleum ether.(1,11)
Coefficient of Oil/Water Distribution (Partition Coefficient): Log P (oct) = -1.33 (estimated) (12)
pH Value: Water solutions are alkaline.
Vapour Density: Not applicable
Vapour Pressure: Probably almost zero.
Saturation Vapour Concentration: Not applicable
Evaporation Rate: Not available; probably extremely low.


Solid xanthates are relatively stable if kept dry and cool. Solutions are also relatively stable if they are kept cool and the pH is maintained within an acceptable range. Under certain conditions, potassium isobutyl xanthate decomposes to very toxic and extremely flammable carbon disulfide. The rate of carbon disulfide generation from the solid increases with temperature and humidity (moisture); and from solutions increases with temperature, pH below 8 (becoming rapid below pH 7; acidic conditions) or pH greater than 13, as well as with time (aging of the solution).(1,11,14,16) Maximum stability of solutions is attained at a pH of approximately 10.(11,16)

Hazardous Polymerization:
Does not occur.

Flammable Gases Released Upon Contact with Water:
Solid xanthates release extremely flammable carbon disulfide gas upon contact with moisture in air at normal temperatures. The rate of carbon disulfide generation increases with increasing temperature. There have been several case reports of fires resulting from contact of solid xanthates with moisture.(11,14,16) Xanthate water solutions are more stable than the solid. The rate of carbon disulfide generation from solutions increases with pH below 8 (accelerating below pH 7) or pH greater than 13, an increase in temperature and/or aging of the solution.(11,14,16)

Incompatibility - Materials to Avoid:

NOTE: Chemical reactions that could result in a hazardous situation (e.g. generation of flammable or toxic chemicals, fire or detonation) are listed here. Many of these reactions can be done safely if specific control measures (e.g. cooling of the reaction) are in place. Although not intended to be complete, an overview of important reactions involving common chemicals is provided to assist in the development of safe work practices.

ACIDS or ACIDIC SOLUTIONS - the hydrolysis of xanthate solutions, which produces carbon disulfide, is accelerated by acidic pH (less than 7).(14,16)
ALKALINE SOLUTIONS (pH greater than 13) - reacts to produce carbon disulfide, hydrogen sulfide, isobutanol, trithiocarbonate and potassium carbonate.(11,14)
STRONG OXIDIZING AGENTS (e.g. peroxides, nitrates and perchlorates) - risk of fire and explosion.
METAL SALTS (e.g. copper, iron, lead or zinc salts) - accelerate the decomposition to carbon disulfide.(14)

Hazardous Decomposition Products:
Decomposition products in water include carbon disulfide, ethanol, trithiocarbonate and potassium carbonate.(2)

Conditions to Avoid:
Heat, age, moisture for solids. Heat, age, pH lower than 8 and higher than 13 for solutions.

Corrosivity to Metals:
Dry potassium isobutyl xanthate is not expected to be corrosive to metals. (Carbon steel is generally suitable for use with xanthates.(1,2)) The moist material or solutions decompose to form carbon disulfide, which attacks copper and copper alloys at normal temperatures and becomes very corrosive to iron and steel at temperatures above 250 deg C.(10)

Corrosivity to Non-Metals:
Dry potassium isobutyl xanthate is not expected to attack plastics and elastomers. The moist material or solutions decompose to form carbon disulfide, which can attack some plastics, elastomers, rubbers and coatings.(10) However, polyvinyl chloride or polyethylene may be used with xanthate solutions.(11)


LD50 (oral, mouse): 480 mg/kg (1,14-unconfirmed)
LD50 (oral, rat): 1290 mg/kg (1,14-unconfirmed)

There is no other animal information available.


Selected Bibliography:
(1) Harris, G.H. Xanthates. In: Kirk-Othmer encyclopedia of chemical technology. Vol. 25. 4th ed. John Wiley and Sons, 1998. p. 713-734
(2) Aero xanthate handbook. American Cyanamid Company, 1972
(3) Merlevede, E., et al. Metabolism of xanthates in man and the guinea pig. Archives Belges Medecine Sociale Hygiene, Medecine Travail et Medecine Legal. Vol. 23, no. 8 (1965). p. 513-551. (English translation: NIOSHTIC Control Number: 00103282)
(4) Fire protection guide to hazardous materials. 13th ed. Edited by A.B. Spencer, et al. National Fire Protection Association, 2002. NFPA 325 (carbon disulfide)
(5) Emergency action guide for carbon disulfide. Association of American Railroads, Jan.1988
(6) Bretherick's reactive chemical hazards database. Butterworth-Heinemann Ltd., 1996
(7) Tyden, I. Gas chromatographic study of the pyrolysis of potassium salts of xanthic acids. Talanta. Vol. 13 (1966). p. 1353-1360
(8) Larue, M., et al. Hazards related to the use of xanthates in the metal flotation process. CCOHS translation series; no. 348. Commission dé la santé et de la sécurité du travail du Québec, 1984
(9) Shupe, I.S. Use of xanthates in identification of alcohols. Journal of the Association of Official Agricultural Chemists. Vol. 25, no. 2 (1942). p. 495-498
(10) Schweitzer, P.A. Corrosion resistance tables: metals, nonmetals, coatings, mortars, plastics, elastomers and linings, and fabrics. 4th ed. Part A, A-D. Marcel Dekker, Inc., 1995. p. 673-676, 685-688
(11) Roy, K-M. Xanthates. In: Ullmann's encyclopedia of industrial chemistry. 5th completely revised ed. Vol. A 28. VCH Verlagsgesellschaft, 1996. p. 423-432
(12) Syracuse Research Corporation. Interactive LogKow (KowWin) Database Demo. Date unknown. Available at: <>
(13) Donoghue, A.M. Carbon disulfide absorption during xanthate reagent mixing in a gold mine concentrator. Occupational Medicine. Vol. 48, no. 7 (1998). p. 469-470
(14) Sodium ethyl xanthate. Priority existing chemical no. 5. National Industrial Chemicals Notification and Assessment Scheme (NICNAS). Australian Government Publishing Service, May 1995
(15) Sodium ethyl xanthate. Priority existing chemical secondary notification assessment report No. 5S. National Industrial Chemicals Notification and Assessment Scheme (NICNAS). Commonwealth of Australia, Feb. 2000
(16) Harris, P.J. Influence of the substituent group on the decomposition of xanthates in aqueous solutions. South African Journal of Chemistry. Vol. 37, no. 3 (1984). p. 91-95
(17) IUCLID data set for potassium o-isobutyl dithiocarbonate. European Commission. Feb. 2000

Information on chemicals reviewed in the CHEMINFO database is drawn from a number of publicly available sources. A list of general references used to compile CHEMINFO records is available in the database Help.

Review/Preparation Date: 2004-08-05

Revision Indicators:
Bibliography 2005-12-19

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