N-OCTANE

Description

Octane is a hydrocarbon that has a chain of eight carbon atoms, but it should not be confused with the octane rating of gasoline. Octane rating compares a fuel''s antiknock properties on a scale in which 100 is pure 2,2,4-trimethylpentane (isooctane, an isomer of octane) and 0 is pure?n-heptane.

Description

Octane is a colorless liquid with a gasolinelike odor. The odor threshold is 4 ppm and 48 ppm (NewJersey Fact Sheet). Molecular weight = 114.26; Specificgravity (H2O:1)= 0.70; Boiling point = 125.6℃; Freezing/Melting point = 256.7℃; Vapor pressure =10 mmHg at20℃; Flash point =13℃(cc); Autoignition temperature =206℃. Explosive limits: LEL 5 1.0%; UEL = 6.5%.Hazard Identification (based on NFPA-704 M RatingSystem): Health 0, Flammability 3, Reactivity 0. Practicallyinsoluble in water; solubility = 7 × 10-5.

Chemical properties

colourless liquid

Chemical properties

Octane is a colorless liquid with a gasoline-like odor. The odor threshold is 4 ppm and 48 ppm (New Jersey Fact Sheet).

Physical properties

Clear, colorless, flammable liquid with a gasoline-like odor. An odor threshold concentration of 1.7 ppm_v was reported by Nagata and Takeuchi (1990).

The Uses of N-OCTANE

n-Octane occurs in petroleum crackingproducts, gasoline, petroleum ether, andpetroleum naphtha. It is used as a solventand in organic synthesis.

The Uses of N-OCTANE

As a constituent in motor and aviation fuels; as an industrial solvent; in organic synthesis

The Uses of N-OCTANE

n-Octane is used as a solvent and raw material for organic synthesis reactions and is a very important chemical in the petroleum industry. It is also widely used in the rubber and paper processing industries. Isooctane, along with other nalkanes and isoparaffins, is used in the blending of fuels to achieve desired antiknock properties.

Definition

ChEBI: A straight chain alkane composed of 8 carbon atoms.

Definition

A liquid alkane obtained from the light fraction of crude oil. Octane and its isomers are the principal constituents of gasoline, which is obtained as the refined light fraction from crude oil.

Production Methods

Octane is produced from the fractional distillation and refining of petroleum.

Synthesis Reference(s)

The Journal of Organic Chemistry, 55, p. 6194, 1990 DOI: 10.1021/jo00312a029
Tetrahedron, 48, p. 8881, 1992 DOI: 10.1016/S0040-4020(01)81987-6
Tetrahedron Letters, 31, p. 5093, 1990 DOI: 10.1016/S0040-4039(00)97814-6

General Description

Colorless liquid with an odor of gasoline. Less dense than water and insoluble in water. Hence floats on water. Produces irritating vapor.

Air & Water Reactions

Highly flammable. Insoluble in water.

Reactivity Profile

May be incompatible with strong oxidizing agents like nitric acid. Charring may occur followed by ignition of unreacted material and other nearby combustibles. In other settings, mostly unreactive. Not affected by aqueous solutions of acids, alkalis, most oxidizing agents, and most reducing agents. When heated sufficiently or when ignited in the presence of air, oxygen or strong oxidizing agents, burns exothermically to produce mostly carbon dioxide and water.

Health Hazard

Inhalation of concentrated vapor may cause irritation of respiratory tract, depression, and pulmonary edema. Liquid can cause irritation of eyes and (on prolonged contact) irritation and cracking of skin. Ingestion causes irritation of mouth and stomach. Aspiration causes severe lung irritation, rapidly developing pulmonary edema, and central nervous system excitement, followed by depression.

Health Hazard

The toxic properties of n-octane are similarto those of other paraffinic hydrocarbons. Itis an irritant to mucous membranes, and athigh concentrations it shows narcotic actions.The narcotic concentrations in mice werereported to be 8000–10,000 ppm (Patty andYant 1929) and the fatal concentration was13,500 ppm (Flury and Zernick 1931). Deathoccurred from respiratory arrest. The acutetoxicity of n-octane is somewhat greater thanthat of n-heptane.

Fire Hazard

Behavior in Fire: Vapor is heavier than air and may travel a considerable distance to a source of ignition and flash back.

Chemical Reactivity

Reactivity with Water No reaction; Reactivity with Common Materials: No reaction; Stability During Transport: Stable; Neutralizing Agents for Acids and Caustics: Not pertinent; Polymerization: Not pertinent; Inhibitor of Polymerization: Not pertinent.

Safety Profile

Poison by intravenous route. May act as a simple asphyxiant. See also ARGON for a description of simple asphyxiants. A narcotic in high concentration. Human dermal exposure to undiluted octane for five hours resulted in blister formation but no anesthesia; exposure for one hour caused diffuse burning sensation. A very dangerous fire hazard and severe explosion hazard when exposed to heat, flame, or oxidizers. When heated to decomposition it emits acrid smoke and irritating fumes. See also ALKANES.

Potential Exposure

Octane is used as a solvent; as a fuel; as an intermediate in organic synthesis; and in azeotropicdistillations.

First aid

If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts theskin, remove contaminated clothing and wash immediatelywith soap and water. Seek medical attention immediately. Ifthis chemical has been inhaled, remove from exposure,begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR ifheart action has stopped. Transfer promptly to a medicalfacility. When this chemical has been swallowed, get medical attention. Do NOT induce vomiting. Give victim nothing to drink.Note to physician: Inhalation: bronchodilators, decongestants, and oxygen may be used if necessary.Corticosteroids are useful for treating pneumonitis.

Carcinogenicity

The promoting activity of octane in skin carcinogenesis, including its physical effect on micellar models of biological membranes, was tested. Octane proved to have significant promoting activity when tested as a 75% solution in cyclohexane.

Source

Schauer et al. (1999) reported octane in a diesel-powered medium-duty truck exhaust at an emission rate of 260 μg/km.
Identified as one of 140 volatile constituents in used soybean oils collected from a processing plant that fried various beef, chicken, and veal products (Takeoka et al., 1996).
Schauer et al. (2001) measured organic compound emission rates for volatile organic compounds, gas-phase semi-volatile organic compounds, and particle-phase organic compounds from the residential (fireplace) combustion of pine, oak, and eucalyptus. The gas-phase emission rate of octane was 1.7 mg/kg of pine burned. Emission rates of octane were not measured during the combustion of oak and eucalyptus.
California Phase II reformulated gasoline contained octane at a concentration of 6.38 g/kg. Gasphase tailpipe emission rates from gasoline-powered automobiles with and without catalytic converters were 1.07 and 131 mg/km, respectively (Schauer et al., 2002).

Environmental Fate

Biological. n-Octane may biodegrade in two ways. This first is the formation of octyl hydroperoxide, which decomposes to 1-octanol followed by oxidation to octanoic acid. The other pathway involves dehydrogenation to 1-octene, which may react with water giving 1-octanol (Dugan, 1972). 1-Octanol was reported as the biodegradation product of octane by a Pseudomonas sp. (Riser-Roberts, 1992). Microorganisms can oxidize alkanes under aerobic conditions (Singer and Finnerty, 1984). The most common degradative pathway involves the oxidation of the terminal methyl group forming the corresponding alcohol (1-octanol). The alcohol may undergo a series of dehydrogenation steps forming an aldehyde (octanal) then a fatty acid (octanoic acid). The fatty acid may then be metabolized by β-oxidation to form the mineralization products, carbon dioxide and water (Singer and Finnerty, 1984).
Photolytic. The following rate constants were reported for the reaction of octane and OH radicals in the atmosphere: 5.1 x 10^-12 cm³/molecule?sec at 300 K (Hendry and Kenley, 1979); 1.34 x 10^-12 cm³/molecule?sec (Greiner, 1970); 8.40 x 10^-12 cm³/molecule?sec (Atkinson et al., 1979), 8.42 x 10^-12 cm³/molecule?sec at 295 K (Darnall et al., 1978). Photooxidation reaction rate constants of 8.71 x 10^-12 and 1.81 x 10^-18 cm³/molecule?sec were reported for the reaction of octane with OH and NO3, respectively (Sablji? and Güsten, 1990).
Surface Water. Mackay and Wolkoff (1973) estimated an evaporation half-life of 3.8 sec from a surface water body that is 25 °C and 1 m deep.
Chemical/Physical. Complete combustion in air produces carbon dioxide and water vapor. Octane will not hydrolyze because it does not contain a hydrolyzable functional group.

storage

Color Code—Red: Flammability Hazard: Store ina flammable liquid storage area or approved cabinet awayfrom ignition sources and corrosive and reactive materials.Prior to working with this chemical you should be trainedon its proper handling and storage. Before entering confinedspace where this chemical may be present, check to makesure that an explosive concentration does not exist. Octanemust be stored to avoid contact with strong oxidizers (suchas chlorine and bromine) because violent reactions occur.Store in tightly closed containers in a cool, well-ventilatedarea away from heat. Sources of ignition, such as smokingand open flames, are prohibited where octane is used, handled, or stored. Metal containers used in the transfer of 5gallons or more of octane should be grounded and bonded.Drums must be equipped with self-closing valves, pressurevacuum bungs, and flame arresters. Use only nonsparkingtools and equipment, especially when opening and closingcontainers of octane.

Shipping

UN1262 Octanes, Hazard Class: 3; Labels: 3-Flammable liquid.

Purification Methods

Extract the octane repeatedly with conc H2SO4 or chlorosulfonic acid, then wash it with water, dry and distil it. Alternatively, purify it by azeotropic distillation with EtOH, followed by washing with water to remove the EtOH, drying and distilling it. For further details, see n-heptane. It is also purified by zone melting. [Beilstein 1 H 159, 1 I 60, 1 II 122, 1 III 457, 1 IV 412.]

Toxicity evaluation

The mechanism of toxicity is suspected to be similar to other solvents that rapidly induce anesthesia-like effects, i.e., a ‘nonspecific narcosis’ due to disruption (solvation) of the integrity of the cellular membranes of the central nervous system (CNS).
Octane is generally considered to be relatively nontoxic relative to the effect seen following exposure to other aliphatic hydrocarbons. This is probably due to the fact that it is less volatile than the shorter chain aliphatic hydrocarbons (e.g., pentane or heptane) and may not be as readily transferred across either the pulmonary alveoli or the blood–brain barrier. If it is aspirated into the lungs, however, n-octane will cause adverse effects similar to effects seen following aspiration of other petroleum distillates or compounds.

Incompatibilities

Reacts with strong oxidizers, causing fire and explosion hazard. Attacks some forms of plastics, rubber and coatings.

Waste Disposal

Dissolve or mix the material with a combustible solvent and burn in a chemical incinerator equipped with an after burner and scrubber. All federal, state, and local environmental regulations must be observed.