| Chemical Properties | n-Heptane is a flammable liquid, present in crude oil and widely used in the auto-
mobile industry. For example, as a solvent, as a gasoline knock testing standard, as
automotive starter fl uid, and paraffi nic naphtha. n-Heptane causes adverse health
effects in occupational workers, such as CNS depression, skin irritation, and pain.
Other compounds such as n-octane (CH 3 (CH 2 ) 6 CH 3 ), n-nonane (CH 3 (CH 2 ) 7 CH 3 ), and
n-decane (CH 3 (CH 2 ) 8 CH 3 ) have different industrial applications. Occupational workers
exposed to these compounds also show adverse health effects. In principle, manage-
ment of these aliphatic compounds requires proper handling and disposal to avoid
health problems and to maintain chemical safety standards for safety to workers and
the living environment. |
| Chemical Properties | n-Heptane is a clear liquid which is highly
flammable and volatile with a mild, gasoline-like odor.
The odor threshold is 40 547 ppm; also reported @
230 ppm. |
| Physical properties | Clear, colorless, very flammable liquid with a faint, pleasant odor resembling hexane or octane.
Based on a triangle bag odor method, an odor threshold concentration of 670 ppbv was reported by
Nagata and Takeuchi (1990). |
| Uses | Suitable for HPLC, spectrophotometry, environmental testing |
| Uses | As standard in testing knock of gasoline engines. |
| Uses | heptane is a solvent and viscosity-decreasing agent. |
| Definition | A colorless
liquid alkane obtained from petroleum refining.
It is used as a solvent. |
| Definition | heptane: A liquid straight-chainalkane obtained from petroleum,C7H16; r.d. 0.684; m.p. -90.6°C; b.p.98.4°C. In standardizing octanenumbers, heptane is given a valuezero. |
| Production Methods | Heptane is produced in refining processes. Highly purified
heptane is produced by adsorption of commercial heptane on
molecular sieves. |
| Synthesis Reference(s) | Tetrahedron Letters, 3, p. 43, 1962 DOI: 10.1007/BF01499754 |
| General Description | Clear colorless liquids with a petroleum-like odor. Flash point 25°F. Less dense than water and insoluble in water. Vapors heavier than air. |
| Air & Water Reactions | Highly flammable. Insoluble in water. |
| Reactivity Profile | HEPTANE is incompatible with the following: Strong oxidizers . |
| Hazard | Toxic by inhalation. Flammable, dangerous
fire risk. |
| Health Hazard | VAPOR: Not irritating to eyes, nose or throat. If inhaled, will cause coughing or difficult breathing. LIQUID: Irritating to skin and eyes. If swallowed, will cause nausea or vomiting. |
| Fire Hazard | FLAMMABLE. Flashback along vapor trail may occur. Vapor may explode if ignited in an enclosed area. |
| Chemical Reactivity | Reactivity with Water No reaction; Reactivity with Common Materials: No reactions; Stability During Transport: Stable; Neutralizing Agents for Acids and Caustics: Not pertinent; Polymerization: Not pertinent; Inhibitor of Polymerization: Not pertinent. |
| Potential Exposure | n-Heptane is used in graphics, textiles,
adhesives, and coatings; as an industrial solvent and in the
petroleum refining process; as a standard in testing knock
of gasoline engines. |
| Source | Schauer et al. (1999) reported heptane in a diesel-powered medium-duty truck exhaust at
an emission rate of 470 g/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 heptane was 28.9 mg/kg of pine burned. Emission rates of heptane were not measured
during the combustion of oak and eucalyptus.
California Phase II reformulated gasoline contained heptane at a concentration of 9,700 mg/kg.
Gas-phase tailpipe emission rates from gasoline-powered automobiles with and without catalytic
converters were 1.82 and 268 mg/km, respectively (Schauer et al., 2002). |
| Environmental fate | Biological. Heptane may biodegrade in two ways. The first is the formation of heptyl
hydroperoxide, which decomposes to 1-heptanol followed by oxidation to heptanoic acid. The
other pathway involves dehydrogenation to 1-heptene, which may react with water forming 1-
heptanol (Dugan, 1972). 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-heptanol). The alcohol may undergo
a series of dehydrogenation steps forming heptanal followed by oxidation forming heptanoic acid.
The acid may then be metabolized by β-oxidation to form the mineralization products, carbon
dioxide and water (Singer and Finnerty, 1984). Hou (1982) reported hexanoic acid as a
degradation product by the microorganism Pseudomonas aeruginosa.
Photolytic. The following rate constants were reported for the reaction of hexane and OH
radicals in the atmosphere: 7.15 x 10-12 cm3/molecule?sec (Atkinson, 1990). Photooxidation
reaction rate constants of 7.19 x 10-12 and 1.36 x 10-16 cm3/molecule?sec were reported for the
reaction of heptane with OH and NO3, respectively (Sablji? and Güsten, 1990). Based on a
photooxidation rate constant 7.15 x 10-12 cm3/molecule?sec for heptane and OH radicals, the
estimated atmospheric lifetime is 19 h in summer sunlight (Altshuller, 1991).
Chemical/Physical. Complete combustion in air yields carbon dioxide and water vapor. Heptane
will not hydrolyze because it has no hydrolyzable functional group. |
| Shipping | UN1206 Heptanes, Hazard Class: 3; Labels:
3-Flammable liquid. |
| Toxicity evaluation | The acute mechanism of toxicity is suspected be similar to other
solvents that rapidly induce anesthesia-like effects, i.e.,
a ‘nonspecific narcosis’ because of disruption (solvation) of the
integrity of the cellular membranes of the central nervous
system (CNS). This disruptive narcosis may also contribute to
the pathology seen with chronic toxicity, although the gamma
diketone metabolite of n-heptane would be responsible for any
delayed peripheral neurotoxicity seen in humans following
chronic exposure, similar to the mechanism seen for hexane.
Although the mechanism of toxicity of n-heptane, with respect
to polyneuropathy, is believed to be similar to hexane, human
exposures in the workplace are often a mixture of other solvents
and the animal data are not compelling.
Heptane is generally considered to be less toxic than hexane
but slightly more toxic than octane. This is probably because it
is less volatile than the former but more volatile than the latter
(consistent with the nonspecific narcotic mechanism of toxicity
of volatile organic compounds). If it is aspirated into the lungs,
however, n-heptane will cause adverse effects similar to those
seen with petroleum distillates. |
| Incompatibilities | May form explosive mixture with air.
Strong oxidizers may cause fire and explosions. Attacks
some plastics, rubber and coatings. May accumulate static
electric charges that can ignite its vapors. |
| Waste Disposal | Dissolve or mix the material
with a combustible solvent and burn in a chemical incinera tor equipped with an afterburner and scrubber. All federal,
state, and local environmental regulations must be observed. |
