2,3-Dimethylbutane

0.6616 at 68 °F (NTP, 1992) - Less dense than water; will float

0.6616 @ 20 °C/4 °C

0.6616

less than 1 mg/mL at 74.3 °F (NTP, 1992)

SOL IN ETHANOL, ETHER; VERY SOL IN ACETONE

Water solubility = 22.5 mg/l at 25 °C

-20 °F (NTP, 1992)

-29 °C

-20 °F (-29 °C) (CLOSED CUP)

-20 °F

136.4 °F at 760 mmHg (NTP, 1992)

57.9 °C @ 760 MM HG

136.4 °F

-199.3 °F (NTP, 1992)

-128.8 °C

Heat of Fusion at Melting Point = 7.9914X10+5 J/kmol

-199.3 °F

3 (NTP, 1992) - Heavier than air; will sink (Relative to Air)

3.0 (AIR= 1)

3

Danger

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

P210, P233, P240, P241, P242, P243, P261, P264, P271, P273, P280, P301+P316, P302+P352, P303+P361+P353, P304+P340, P319, P321, P331, P332+P317, P362+P364, P370+P378, P391, P403+P233, P403+P235, P405, and P501 (click each P-code to see the statement)

Danger

H225 (100%): Highly Flammable liquid and vapor [Danger Flammable liquids]

P210, P233, P240, P241, P242, P243, P261, P264, P271, P273, P280, P301+P316, P302+P352, P303+P361+P353, P304+P340, P319, P321, P331, P332+P317, P362+P364, P370+P378, P391, P403+P233, P403+P235, P405, and P501 (click each P-code to see the statement)

Chemical: Butane, 2,3-dimethyl-

Butane, 2,3-dimethyl- is listed on the EPA's Chemical Data Reporting (CDR) system. Manufacturers and importers of Butane, 2,3-dimethyl- are required to report information about their production and use of this chemical to the EPA under the Toxic Substances Control Act (TSCA). (40 eCFR Part 711)

Status: Active Update: 01-11-2022 https://echa.europa.eu/registration-dossier/-/registered-dossier/28205

2,3-Dimethylbutane: Does not have an individual approval but may be used under an appropriate group standard

The New Jersey Worker and Community Right to Know Act requires public and private employers to provide information about hazardous substances at their workplaces. (N.J.S.A. 34:5A-1 et. seq.)

Excerpt from ERG Guide 128 [Flammable Liquids (Water-Immiscible)]:

· HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames.

Excerpt from ERG Guide 128 [Flammable Liquids (Water-Immiscible)]:

CAUTION: Petroleum crude oil (UN1267) may contain TOXIC hydrogen sulphide gas.

Dutch Expert Committee on Occupational Standards/Department of Social Affairs and Employment, Directorate-General of Labor; Health Based Recommended Occupational Exposure Limits for 2-Methylpentane, 3-Methylpentane, 2,2-Dimethylbutane, 2,3-Dimethylbutane (Hexane Isomers) (1993)

Saturated aliphatic hydrocarbons, such as 2,3-DIMETHYLBUTANE, may be incompatible with strong oxidizing agents like nitric acid. Charring of the hydrocarbon may occur followed by ignition of unreacted hydrocarbon and other nearby combustibles. In other settings, aliphatic saturated hydrocarbons are mostly unreactive. They are not affected by aqueous solutions of acids, alkalis, most oxidizing agents, and most reducing agents. This compound is incompatible with oxidizing materials. It is also incompatible with oxygen. (NTP, 1992).

· CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper not available or no answer, refer to appropriate telephone number listed on the inside back cover.

· ELIMINATE all ignition sources (no smoking, flares, sparks or flames) from immediate area.

EYES: First check the victim for contact lenses and remove if present. Flush victim's eyes with water or normal saline solution for 20 to 30 minutes while simultaneously calling a hospital or poison control center. Do not put any ointments, oils, or medication in the victim's eyes without specific instructions from a physician. IMMEDIATELY transport the victim after flushing eyes to a hospital even if no symptoms (such as redness or irritation) develop.

General First Aid:

· Wear positive pressure self-contained breathing apparatus (SCBA).

500.0 [ppm]

...MATERIALS WHICH ARE TOXIC AS STORED OR...DECOMP INTO TOXIC COMPONENTS...SHOULD BE STORED IN COOL, WELL-VENTILATED PLACE, OUT OF DIRECT RAYS OF SUN, AWAY FROM AREAS OF HIGH FIRE HAZARD...PERIODICALLY INSPECTED & MONITORED. INCOMPATIBLE MATERIALS SHOULD BE ISOLATED...

SRP: At the time of review, criteria for land treatment or burial (sanitary landfill) disposal practices are subject to significant revision. Prior to implementing land disposal of waste residue (including waste sludge), consult with environmental regulatory agencies for guidance on acceptable disposal practices.

Excerpt from ERG Guide 128 [Flammable Liquids (Water-Immiscible)]:

Immediate precautionary measure

200.0 [ppm]

500 ppm [1979]

1000 ppm [1979]

100 ppm (350 mg/m³)

510 ppm (1800 mg/m³) [15 minutes]

Hexane mainly affects the nervous system. It causes degeneration of the peripheral nervous system (and eventually the central nervous system), starting with damage to the nerve axons. Exposure to hexane may also damage the lungs and reproductive system. (L977, L978)

TERRESTRIAL FATE: Based on a recommended classification scheme(1), an estimated Koc value of 1700(SRC), determined from an experimental log Kow(2) and a recommended regression-derived equation(3), indicates that 2,3-dimethylbutane will have low mobility in soil(SRC). Volatilization of 2,3-dimethylbutane may be important from moist soil surfaces(SRC) given an estimated Henry's Law constant of 1.2 atm-cu m/mole(SRC), calculated from experimental values for vapor pressure(4) and water solubility(5), and from dry soil surfaces(SRC) based on an experimental vapor pressure of 235 mm Hg(4). Insufficient data are available to determine the rate or importance of biodegradation of 2,3-dimethylbutane(SRC).

AQUATIC FATE: Based on a recommended classification scheme(1), an estimated Koc value of 1700(SRC), determined from an experimental log Kow(2) and a recommended regression-derived equation(3), indicates that 2,3-dimethylbutane would adsorb to suspended solids and sediment(SRC) in the water. 2,3-Dimethylbutane would volatilize from water surfaces based on an estimated Henry's Law constant of 1.2 atm-cu m/mole(SRC), calculated from experimental values for vapor pressure(4) and water solubility(5). Estimated half-lives for a model river and model lake are 2.7 hours and 3.7 days, respectively(3,SRC). An estimated BCF value of 230(3,SRC), from an experimental log Kow(2), suggests that 2,3-dimethylbutane will bioconcentrate in aquatic organisms(SRC) according to a recommended classification scheme(6). Insufficient data are available to determine the rate or importance of biodegradation of 2,3-dimethylbutane(SRC).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), 2,3-dimethylbutane, which has an experimental vapor pressure of 235 mm Hg at 25 °C(2) will exist as a vapor in the ambient atmosphere. Vapor-phase 2,3-dimethylbutane 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 about 5.4 days(3,SRC). Vapor-phase 2,3-dimethylbutane is also degraded in the atmosphere by reaction with nitrate radicals(4); the half-life for this reaction in air is estimated to be about 334 days(4,SRC).

Hexane's toxicity is caused by it neurotoxic metabolite, 2,5-hexanedione. It damages the central and peripheral nervous system by causing axonal swelling and degeneration. 2,5-Hexanedione also reacts with lysine side-chain amino groups in axonal cytoskeletal proteins to form pyrroles. This results in neurofilament cross-linking and loss of function. (L175)

Breathing large amounts of hexane causes numbness in the feet and hands, followed by muscle weakness in the feet and lower legs. Continued exposure may lead to paralysis of the arms and legs. However, if removed from the exposure, recovery occurs in 6 months to a year. Inhalation of high concentrations produces first a state of mild euphoria, followed by somnolence with headaches and nausea. (L175, A121)

A study conducted in Atlanta found the average source profiles of 2,3-dimethylbutane in roadway, whole gas (average of six octanes), whole gas (87 octane), whole gas (89 octane), whole gas (92/93 octane), headspace gas (at 24 °C and average of six octanes), headspace gas (at 32 °C and average of six octanes), airport, and aircraft emissions were: 0.863, 0.88, 0.96, 0.83, 0.70, 1.49, 1.55, 0.55, and 0.332 ppbC%, respectively(1). A study conducted in Chicago found the average concentration of 2,3-dimethylbutane/2-methylpentane in regular fuel (87 octane), mid-grade (89 octane), premium (93 octane), hot soak, cold start, roadway, and petroleum refinery emissions to be 3.2, 2.34, 1.33, 4.62, 4.4, 3.21, and 2.62 wt%, respectively(2). Refueling emission profiles for 2,3-dimethylbutane/2-methylpentane were 2.58 and 2.26 wt% in the summer and winter, respectively and 4.17 and 3.2 wt% in Atlanta and Chicago respectively(2). The emission rate of 2,3-dimethylbutane is estimated to be 5 metric tons/day in a southern California mountain forest location impacted with urban photochemical smog(3). The profile for 2,3-dimethylbutane in gasoline engine exhaust (noncatalyst and catalyst equipped), unburned gasoline (whole and headspace vapors) was 0.6, 1.0, 1.1, and 1.1 wt%, respectively(4). 2,3-Dimethylbutane was identified in influent and effluent food refuse gas samples(5). The average 2,3-dimethylbutane contribution to emissions from 67 different vehicles was 0.6 wt% in Sydney, Australia(6). 2,3-Dimethylbutane content in moped exhaust with alkylate-based and reformate-based fuels was 1.2 and 1.5 wt% (alkylate: exhaust and fuel) and 0.48 and 0.6 (reformate: exhaust and fuel)(7).

In Southern California, the 2,3-dimethylbutane profile for various emissions for vehicle exhaust was 0.81, 0.89, 1.24, 0.00, 1.68, and 1.91 wt% for a 46 car study, 13 samples from the Caldecott Tunnel, cold start, stabilized, hot start, and from an older fleet, respectively(1). Gasoline emission profiles for 2,3-dimethylbutane are as follows: 4.99, 5.36, 3.34, 2.59, 2.32, 2.33, and 2.03 wt% for diurnal evaporative emissions (older fleet), hot soak evaporative emissions (older fleet), running loss (older fleet), summer liquid gas, winter liquid gas, summer gas headspace, and winter gas headspace, respectively(1). In oil field emissions (Tulsa, OK), 2,3-dimethylbutane was detected at average concentration of 24.5 ppbC and approximately 12 ppbC for two different samples(2). The concentration of 2,3-dimethylbutane in gasoline vapors from refueling cars at service stations ranged between 0.005 and 9.2 ppm(3).

The Koc of 2,3-dimethylbutane is estimated as approximately 1700(SRC), using an experimental log Kow of 3.42(1) and a regression-derived equation(2,SRC). According to a recommended classification scheme(3), this estimated Koc value suggests that 2,3-dimethylbutane has low mobility in soil(SRC).

Subchronic toxicity was evaluated in two groups of 10 male Fischer 344 rats receiving 0.5 or 2.0 g/kg 2,3-dimethylbutane once daily by oral gavage, 5 days/week for four weeks. Mortality was observed in the low dose group (2 rats), and in the high dose group (3 rats) during the test; surviving animals were sacrificed 24 hours after administration of the final dose. Terminal body weights were statistically significantly (students t-test, p < 0.05) lower in high dose, but not in low dose groups. Mean kidney weights were significantly (p < 0.05) higher in both high and low dose groups. Gross necropsy observations in individual animals included lightly speckled cortical surfaces in kidneys, clear fluid in abdomens, reddened thymal lobes, congested lungs, scattered pale and dark foci on lungs, grey discoloration on livers, prominent lobular patterns on livers, diffuse reddening of cecums, reddened mediastinal lymph nodes, dark foci on nonglandular stomachs, moderately enlarged adrenals, hemorrhages in hearts, and mottled lungs, thymus glands and left kidneys. Histopathological findings in kidneys included hyaline droplet change (in 10 low, and 10 high dose rats), regenerative epithelium (in 10 low, and 10 high dose rats), and tubular dilatation with granular material (in 6 low, and 4 high dose rats). These kidney findings were used to calculate an index of hydrocarbon nephrotoxicity, defined as a sum of scores ranging from 1 to 4 in severity for each endpoint for the degree of hyaline droplet change, number of foci of regenerative epithelium, and the number of foci of tubular dilatation with granular material; values were 7.6 for the low dose group, 6.1 for the high dose group, and 3.0 for the saline treated control group. Additional histopathological findings in kidneys included mononuclear cell infiltrate (in 7 low, and 9 high dose rats), hyaline casts (in 5 low, and 2 high dose rats), and tubular mineralization (in 2 low dose rats).

URBAN/SUBURBAN: 2,3-Dimethylbutane was identified in downtown Los Angeles morning air at concns of 2-8 ppbv(1). A study of Washington, DC air identified 2,3-dimethylbutane in 62.5% of the samples at an average concn of 0.21 ppbv(2). 2,3-Dimethylbutane was identified in the air of the following industrial cities of the USSR: Leningrad, Tashkent, Baku, Tbilisi, Kemerovo, and Murmansk(3). 2,3-Dimethylbutane was also identified in the air of three large South African cities: Pretoria, Johannesburg, and Durban(4). 2,3-Dimethylbutane was identified in the air of Sydney, Australia at an average concn of 0.9 ppbv(5). 2,3-Dimethylbutane was identified in the air of Huntington Park, Los Angeles at 0.6 ppb (ground level, afternoon), 7.8 (groundlevel, morning), 2.1 (at 1500 ft, morning), and 0.1 ppb (at 2200 ft, morning)(6). A study conducted in the Riverside, CA area identified 2,3-dimethylbutane at concns of approximately 0.5, 0.2, 0.5, 0.7, and 0.6 ppb at five different sites(7). 2,3-Dimethylbutane was identified in the air of suburban, urban, and source dominated sites at the following average concns: 0.572 (219 samples), 0.6 (521 samples), and 0.666 ppbv (20 samples), respectively(8).

RURAL/REMOTE: 2,3-Dimethylbutane was identified in the air of six remote sites in North Carolina at the following median concns (ppb carbon): Roan Mountain, 0.1; Grandfather Mountain, 0.2; Linville Gorge, 0.1; Rich Mountain, 0.1; Boone Center, 3.1; and Boone Outskirts, 0.3(1).

2,3-Dimethylbutane's production and use as a high octane fuel and in organic synthesis(1) may result in its release to the environment through various waste streams(SRC). 2,3-Dimethylbutane is released into the atmosphere from auto, biomass combustion, and gasoline vapor emissions(2).

Using the Clark oxygen electrode, a resting cell suspension of Corynebacterium (which used n-octane as sole carbon and energy source) oxidized 2,3-dimethylbutane with an activity of 43% that of n-octane (specific activity 78.5 ul oxygen/hour/mg cells)(1). 2,3-Dimethylbutane was not able to support the growth of any of the 32 microorganisms isolated from groundwater(2). Pure culture studies provide little insight into the biodegradation of 2,3-dimethylbutane in environmental samples(3,SRC).

Hexane is mainly absorbed via inhalation, as it is readily absorbed by the lungs. It is distributed throughout the body in the blood, and metabolized by mixed function oxidases in the liver to a number of metabolites. The initial reaction is oxidation by cytochrome P-450 isozymes to hexanols, predominantly 2-hexanol. Further reactions convert 2-hexanol to 2-hexanone, 2,5-hexanediol, 5-hydroxy-2-hexanone, 4,5-dihydroxy-2-hexanone and the neurotoxicant 2,5-hexanedione. Hexane metabolites are excreted in the urine, while unchanged hexane is excreted in expired air. (L175)

Used in high-octane fuel and to make other organic chemicals; [Hawley] Used as solvent (vegetable oils, glues, coatings, and paints); Occur in gasoline, rubber solvent, and petroleum ether; [ACGIH]

Painting (Solvents) [Category: Paint]

HIGH OCTANE FUELS

ORGANIC SYNTHESIS

Pure hexane is used in laboratories. Most of the hexane used in industry is mixed with similar chemicals called solvents. The major use for solvents containing hexane is to extract vegetable oils from crops such as soybeans. These solvents are also used as cleaning agents in the printing, textile, furniture, and shoemaking industries. Certain kinds of special glues used in the roofing and shoe and leather industries also contain hexane. Several consumer products contain hexane, such as gasoline, quick-drying glues used in various hobbies, and rubber cement. (L175)

HYDROISOMERIZATION OF 2-METHYLPENTANE (ISOHEXANE) IN THE PRESENCE OF A CATALYST

ALKYLATION OF ETHYLENE WITH ISOBUTANE USING ALUMINUM CHLORIDE CATALYST.

Petroleum Refineries

Butane, 2,3-dimethyl-: ACTIVE