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Skeletal formula of heptane
Skeletal formula of heptane of all implicit carbons shown, and all explicit hydrogens added
Ball-and-stick model of the heptane molecule
IUPAC name
142-82-5 YesY
ChEBI CHEBI:43098 YesY
ChEMBL ChEMBL134658 YesY
ChemSpider 8560 YesY
EC Number 205-563-8
Jmol 3D model Interactive image
MeSH n-heptane
PubChem 8900
RTECS number MI7700000
UNII 456148SDMJ YesY
UN number 1206
Molar mass 100.21 g·mol−1
Appearance Colourless liquid
Odor Petrolic
Density 0.6795 g mL−1
Melting point −91.0 to −90.1 °C; −131.7 to −130.3 °F; 182.2 to 183.0 K
Boiling point 98.1 to 98.7 °C; 208.5 to 209.6 °F; 371.2 to 371.8 K
0.0003% (20 °C)[2]
log P 4.274
Vapor pressure 5.33 kPa (at 20.0 °C)
12 nmol Pa−1 kg−1
Viscosity 386 μPa s
0.0 D
224.64 J K−1 mol−1
328.57 J K−1 mol−1
−225.2–−223.6 kJ mol−1
−4.825–−4.809 MJ mol−1
Vapor pressure {{{value}}}
Related compounds
Related alkanes
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
YesY verify (what is YesYN ?)
Infobox references

n-Heptane is the straight-chain alkane with the chemical formula H3C(CH2)5CH3 or C7H16. When used as a test fuel component in anti-knock test engines, a 100% heptane fuel is the zero point of the octane rating scale (the 100 point is a 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 dispensed in the United States and internationally.


Heptane (and its many isomers) is widely applied in laboratories as a totally non-polar solvent. As a liquid, it is ideal for transport and storage. In the grease spot test, heptane is used to dissolve the 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.[citation needed]

Aqueous bromine may be distinguished from aqueous iodine by its appearance after extraction into heptane. In water, both bromine and iodine appear brown. However, iodine turns purple 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 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.

Octane rating scale

n-Heptane is defined as the zero point of the octane rating scale. It is undesirable in gasoline, because it burns explosively, causing engine knocking, as opposed to branched-chain octane isomers, which burn more slowly and give better performance. 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 of Jeffrey pine and from the fruit of Pittosporum resiniferum. Other sources of heptane and octane, produced from crude oil, contain a mixture of different isomers with greatly differing ratings, and do not give as precise a zero point. ChevronPhillips Specialty Chemical produces a specialized grade of high purity n-heptane (>99.0%) from crude oil through precision refining and distillation, that is used in the measurement of octane rating for fuels.[citation needed]

Isomers and enantiomers

Heptane has nine isomers, or eleven if enantiomers are counted:

Health risks

Acute exposure to heptane vapors can cause dizziness, stupor, incoordination, loss of appetite, nausea, dermatitis, chemical pneumonitis, or unconsciousness.[2]


  1. "n-heptane – Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 16 September 2004. Identification and Related Records. Retrieved 2 January 2012. 
  2. 2.0 2.1 Cite error: Invalid <ref> tag; no text was provided for refs named PGCH
  3. Isomers. Members.optushome.com.au. Retrieved on 2012-03-04.

External links