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Heptane or ''n''-heptane is the straight-chain
alkane In organic chemistry, an alkane, or paraffin (a historical trivial name that also has other meanings), is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in which ...
with the
chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...
H3C(CH2)5CH3 or C7H16. When used as a test fuel component in
anti-knock An antiknock agent is a gasoline additive used to reduce engine knocking and increase the fuel's octane rating by raising the temperature and pressure at which auto-ignition occurs. The mixture known as gasoline or petrol, when used in high comp ...
test engines, a 100% heptane fuel is the zero point of the
octane rating An octane rating, or octane number, is a standard measure of a fuel's ability to withstand compression in an internal combustion engine without detonating. The higher the octane number, the more compression the fuel can withstand before detonating ...
scale (the 100 point is 100% iso-octane). Octane number equates to the anti-knock qualities of a comparison mixture of heptane and isooctane which is expressed as the percentage of isooctane in heptane and is listed on pumps for
gasoline Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic co ...
(petrol) dispensed globally.


Uses

Heptane (and its many isomers) is widely used in
laboratories A laboratory (; ; colloquially lab) is a facility that provides controlled conditions in which scientific or technological research, experiments, and measurement may be performed. Laboratory services are provided in a variety of settings: physici ...
as a non-polar
solvent A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for ...
. As a
liquid A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of the four fundamental states of matter (the others being solid, gas, a ...
, it is ideal for transport and storage. In the grease spot test, heptane is used to dissolve an oil spot to show the previous presence of organic compounds on a stained paper. This is done by shaking the stained paper in a heptane solution for about half a minute. Aqueous
bromine Bromine is a chemical element with the symbol Br and atomic number 35. It is the third-lightest element in group 17 of the periodic table (halogens) and is a volatile red-brown liquid at room temperature that evaporates readily to form a simila ...
may be distinguished from aqueous
iodine Iodine is a chemical element with the symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a semi-lustrous, non-metallic solid at standard conditions that melts to form a deep violet liquid at , and boils to a vi ...
by its appearance after extraction into heptane. In water, both bromine and iodine appear
brown Brown is a color. It can be considered a composite color, but it is mainly a darker shade of orange. In the CMYK color model used in printing or painting, brown is usually made by combining the colors orange and black. In the RGB color model used ...
. However, iodine turns
purple Purple is any of a variety of colors with hue between red and blue. In the RGB color model used in computer and television screens, purples are produced by mixing red and blue light. In the RYB color model historically used by painters, pu ...
when dissolved in heptane, whereas the bromine solution remains brown. Heptane is commercially available as mixed isomers for use in paints and coatings, as the
rubber cement Rubber cement (cow gum in British English) is an adhesive made from elastic polymers (typically latex) mixed in a solvent such as acetone, hexane, heptane or toluene to keep it fluid enough to be used. This makes it part of the class of drying ...
solvent "Bestine", the outdoor stove fuel "Powerfuel" by Primus, as pure ''n''-heptane for research and development and pharmaceutical manufacturing and as a minor component of
gasoline Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic co ...
(petrol). On average, gasoline is about 1% heptane. Heptane is also used as an
adhesive remover Adhesive remover is a substance intended to break down and remove glue and its remnants from surfaces. Description Adhesive removers are intended to break down glue so that it can be removed from surfaces easily. Formulations may be designed t ...
by stamp collectors. Since 1974, the
United States Postal Service The United States Postal Service (USPS), also known as the Post Office, U.S. Mail, or Postal Service, is an independent agency of the executive branch of the United States federal government responsible for providing postal service in the U ...
has issued
self-adhesive stamp A self-adhesive stamp is a postage stamp with a pressure-sensitive adhesive that does not require moistening in order to adhere to paper. They are usually issued on a removable backing paper. Stamp collectors criticized the format, because the ...
s that some collectors find difficult to separate from envelopes via the traditional method of soaking in water. Heptane-based products like Bestine, as well as
limonene Limonene is a colorless liquid aliphatic hydrocarbon classified as a cyclic monoterpene, and is the major component in the oil of citrus fruit peels. The -isomer, occurring more commonly in nature as the fragrance of oranges, is a flavoring ag ...
-based products, have become popular solvents for removing stamps more easily.


Octane rating scale

''n''-Heptane is defined as the zero point of the
octane rating An octane rating, or octane number, is a standard measure of a fuel's ability to withstand compression in an internal combustion engine without detonating. The higher the octane number, the more compression the fuel can withstand before detonating ...
scale. It is a lighter component in
gasoline Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic co ...
, burns more
explosive An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An expl ...
ly, causing
engine An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy. Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power gen ...
pre-ignition ( knocking) in its pure form, as opposed to
octane Octane is a hydrocarbon and an alkane with the chemical formula , and the condensed structural formula . Octane has many structural isomers that differ by the amount and location of branching in the carbon chain. One of these isomers, 2,2,4-Tri ...
isomers, which burn more slowly and give less knocking. It was originally chosen as the zero point of the scale because of the availability of very high purity ''n''-heptane, unmixed with other isomers of heptane or other alkanes, distilled from the
resin In polymer chemistry and materials science, resin is a solid or highly viscous substance of plant or synthetic origin that is typically convertible into polymers. Resins are usually mixtures of organic compounds. This article focuses on natu ...
of
Jeffrey pine ''Pinus jeffreyi'', also known as Jeffrey pine, Jeffrey's pine, yellow pine and black pine, is a North American pine tree. It is mainly found in California, but also in the westernmost part of Nevada, southwestern Oregon, and northern Baja Califo ...
and from the fruit of ''
Pittosporum resiniferum ''Pittosporum resiniferum'', the resin cheesewood or petroleum nut, is a tree that grows in the Philippines and Malaysia, particularly in the wilderness surrounding the Mayon Volcano and in the Cordillera of the Philippines and Mount Kinabalu of ...
''. Other sources of heptane and octane, produced from
crude oil Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crude ...
, contain a mixture of different isomers with greatly differing ratings, and do not give as precise a zero point.


Isomers and enantiomers

Heptane has nine
isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Iso ...
s, or eleven if
enantiomer In chemistry, an enantiomer ( /ɪˈnænti.əmər, ɛ-, -oʊ-/ ''ih-NAN-tee-ə-mər''; from Ancient Greek ἐνάντιος ''(enántios)'' 'opposite', and μέρος ''(méros)'' 'part') – also called optical isomer, antipode, or optical ant ...
s are counted: * Heptane (''n''-heptane), H3C–CH2–CH2–CH2–CH2–CH2–CH3, * 2-Methylhexane (isoheptane), H3C–CH(CH3)–CH2–CH2–CH2–CH3, * 3-Methylhexane, H3C–CH2–C*H(CH3)–CH2–CH2–CH3 (
chiral Chirality is a property of asymmetry important in several branches of science. The word ''chirality'' is derived from the Greek (''kheir''), "hand", a familiar chiral object. An object or a system is ''chiral'' if it is distinguishable from ...
), * 2,2-Dimethylpentane (neoheptane), H3C–C(CH3)2–CH2–CH2–CH3, * 2,3-Dimethylpentane, H3C–CH(CH3)–C*H(CH3)–CH2–CH3 (
chiral Chirality is a property of asymmetry important in several branches of science. The word ''chirality'' is derived from the Greek (''kheir''), "hand", a familiar chiral object. An object or a system is ''chiral'' if it is distinguishable from ...
), *
2,4-Dimethylpentane 2,4-Dimethylpentane is an alkane with the chemical formula H3C)2CHsub>2CH2. This colorless hydrocarbon is produced in large quantities in oil refineries. It results from the alkylation of isobutane by propylene Propylene, also known as prop ...
, H3C–CH(CH3)–CH2–CH(CH3)–CH3, * 3,3-Dimethylpentane, H3C–CH2–C(CH3)2–CH2–CH3, * 3-Ethylpentane, H3C–CH2–CH(CH2CH3)–CH2–CH3, * 2,2,3-Trimethylbutane, H3C–C(CH3)2–CH(CH3)–CH3, this isomer is also known as pentamethylethane and triptane.


Preparation

The linear ''n''-heptane can be obtained from
Jeffrey pine ''Pinus jeffreyi'', also known as Jeffrey pine, Jeffrey's pine, yellow pine and black pine, is a North American pine tree. It is mainly found in California, but also in the westernmost part of Nevada, southwestern Oregon, and northern Baja Califo ...
oil.Graham Edgar, George Calingaert, and R. E. Marker (1929): "The preparation and properties of the isomeric heptanes. Part I. Preparation". ''Journal of the American Chemical Society'', volume 51, issue 5, pages 1483–1491. The six branched isomers without a quaternary carbon can be prepared by creating a suitable secondary or tertiary
alcohol Alcohol most commonly refers to: * Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom * Alcohol (drug), an intoxicant found in alcoholic drinks Alcohol may also refer to: Chemicals * Ethanol, one of sev ...
by the
Grignard reaction The Grignard reaction () is an organometallic chemical reaction in which alkyl, allyl, vinyl, or aryl-magnesium halides ( Grignard reagent) is added to a carbonyl group in an aldehyde or ketone. This reaction is important for the formation of ...
, converting it to an
alkene In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond. Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic, an ...
by
dehydration In physiology, dehydration is a lack of total body water, with an accompanying disruption of metabolic processes. It occurs when free water loss exceeds free water intake, usually due to exercise, disease, or high environmental temperature. Mil ...
, and hydrogenating the latter. The 2,2-dimethylpentane isomer can be prepared by reacting ''tert''-butyl chloride with ''n''-propyl magnesium bromide. The 3,3-dimethylpentane isomer can be prepared from ''tert''-amyl chloride and ethyl magnesium bromide.


Health risks

Heptane can affect a person when breathed in. Acute exposure to heptane vapors can cause
dizziness Dizziness is an imprecise term that can refer to a sense of disorientation in space, vertigo, or lightheadedness. It can also refer to disequilibrium or a non-specific feeling, such as giddiness or foolishness. Dizziness is a common medical c ...
, stupor, incoordination, loss of appetite, nausea, dermatitis, chemical pneumonitis, unconsciousness, or possible peripheral neuropathy. In a
CDC The Centers for Disease Control and Prevention (CDC) is the national public health agency of the United States. It is a United States federal agency, under the Department of Health and Human Services, and is headquartered in Atlanta, Georgi ...
study, it was found that prolonged exposure to heptane may also cause a state of
intoxication Intoxication — or poisoning, especially by an alcoholic or narcotic substance — may refer to: * Substance intoxication: ** Alcohol intoxication ** LSD intoxication ** Toxidrome ** Tobacco intoxication ** Cannabis intoxication ** Cocaine i ...
and uncontrolled hilarity in some participants and a stupor lasting for 30 minutes after exposure for others. According to information from the New Jersey Department of Health and Senior Services, n-heptane can penetrate through the skin and further health effects may occur immediately or shortly after exposure to it. Exposure to n-Heptane may lead to: a)      Short term health effects like irritation of the eyes, nose, or throat, headache, dizziness, or loss of consciousness. b)     Chronic health effects that may last for months or years, like reduced memory and concentration, sleep disturbance, or reduced coordination due to its effects on the nervous system.


References


External links


International Chemical Safety Card 0657
(''n''-heptane)

(2-methylhexane)




Phytochemical database entry
{{Authority control Alkanes Hydrocarbon solvents