Heptane

Heptane
	Skeletal formula of heptane
	Skeletal formula of heptane of all implicit carbons shown, and all explicit hydrogens added
	Ball and stick model of heptane
	IUPAC name Heptane
Identifiers
CAS number	142-82-5 7px
PubChem	8900
ChemSpider	8560 7px
UNII	456148SDMJ 7px
EC number	205-563-8
UN number	1206
MeSH	n-heptane
ChEBI	CHEBI:43098 7px
ChEMBL	CHEMBL134658 7px
RTECS number	MI7700000
Beilstein Reference	1730763
Gmelin Reference	49760
Jmol-3D images	Image 1
	SMILES CCCCCCC <p><p style="word-wrap: break-word;"> ;
	InChI InChI=1S/C7H16/c1-3-5-7-6-4-2/h3-7H2,1-2H3 7px; Key: IMNFDUFMRHMDMM-UHFFFAOYSA-N 7px ;
Molecular formula	C7H16
Molar mass	100.2 g mol−1
Thermochemistry
Std enthalpy of; formation ΔfHo298	−225.2–−223.6 kJ mol−1
Std enthalpy of; combustion ΔcHo298	−4.825–−4.809 MJ mol−1
Standard molar; entropy So298	328.57 J K−1 mol−1
Specific heat capacity, C	224.64 J K−1 mol−1
Hazards
GHS pictograms	The flame pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) The exclamation-mark pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) The health hazard pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) The environment pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word	DANGER
GHS hazard statements	H225, H304, H315, H336, H410
GHS precautionary statements	P210, P261, P273, P301+310, P331
EU Index	601-008-00-2
EU classification	Flammable F Harmful Xn Dangerous for the Environment (Nature) N
R-phrases	R11, R38, R50/53, R65, R67
S-phrases	(S2), S16, S29, S33
NFPA 704	75px 3 1 0
Flash point	−4.0 °C
Autoignition; temperature	223.0 °C
Explosive limits	1.05–6.7%
Related compounds
Related alkanes	Hexane; Octane;
	14px (verify) (what is: 10px/10px?); Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
	Infobox references

{{#if:PetrolicPetrolicColourless liquid679.5 mg mL⁻¹4.2745.33 kPa (at 20.0 °C)12 nmol Pa⁻¹ kg⁻¹1.387386 μPa s0.0 D182.2183.0167|! style="background: #F8EABA; text-align: center;" colspan="2" | Properties

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.

Uses

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 the zero point of the octane rating scale. It is undesirable in petrol, because it burns explosively, causing engine knocking, as opposed to branched-chain octane isomers, which burn more slowly and give better performance. It was 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.

Isomers and enantiomers

Heptane has nine isomers, or eleven if enantiomers 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),
2,2-Dimethylpentane, (H₃C)₃–C–CH₂–CH₂–CH₃,
2,3-Dimethylpentane, (H₃C)₂–CH–C^*H(CH₃)–CH₂–CH₃ (chiral),
2,4-Dimethylpentane, (H₃C)₂–CH–CH₂–CH–(CH₃)₂,
3,3-Dimethylpentane, H₃C–CH₂–C(CH₃)₂–CH₂–CH₃,
3-Ethylpentane, H₃C–CH₂–CH(CH₂CH₃)–CH₂–CH₃,
2,2,3-Trimethylbutane, CH₃–C(CH₃)₂–CH(CH₃)–CH₃, this isomer is also known as pentamethylethane and triptane.^[2]

References

↑ "n-heptane – Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 16 September 2004. Identification and Related Records. http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=8900&loc=ec_rcs. Retrieved 2 January 2012.
↑ Isomers. Members.optushome.com.au. Retrieved on 2012-03-04.