Heptane

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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
Identifiers
CAS number142-82-5 YesY
PubChem8900
ChemSpider8560 YesY
UNII456148SDMJ YesY
EC number205-563-8
UN number1206
MeSHn-heptane
ChEBICHEBI:43098 YesY
ChEMBLCHEMBL134658 YesY
RTECS numberMI7700000
Beilstein Reference1730763
Gmelin Reference49760
Jmol-3D imagesImage 1
Properties
Molecular formulaC7H16
Molar mass100.20 g mol−1
AppearanceColourless liquid
OdorPetrolic
Density0.6795 g mL−1
Melting point−91.0 to −90.1 °C; −131.7 to −130.3 °F; 182.2 to 183.0 K
Boiling point98.1 to 98.7 °C; 208.5 to 209.6 °F; 371.2 to 371.8 K
log P4.274
Vapor pressure5.33 kPa (at 20.0 °C)
kH12 nmol Pa−1 kg−1
Refractive index (nD)1.387
Viscosity386 μPa s
Dipole moment0.0 D
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, C224.64 J K−1 mol−1
Hazards
GHS pictogramsThe 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 wordDANGER
GHS hazard statementsH225, H304, H315, H336, H410
GHS precautionary statementsP210, P261, P273, P301+310, P331
EU Index601-008-00-2
EU classificationFlammable F Harmful Xn Dangerous for the Environment (Nature) N
R-phrasesR11, R38, R50/53, R65, R67
S-phrases(S2), S16, S29, S33
NFPA 704
NFPA 704.svg
3
1
0
Flash point−4.0 °C; 24.8 °F; 269.1 K
Autoignition temperature223.0 °C; 433.4 °F; 496.1 K
Explosive limits1.05–6.7%
Related compounds
Related alkanes
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references
 
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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
Identifiers
CAS number142-82-5 YesY
PubChem8900
ChemSpider8560 YesY
UNII456148SDMJ YesY
EC number205-563-8
UN number1206
MeSHn-heptane
ChEBICHEBI:43098 YesY
ChEMBLCHEMBL134658 YesY
RTECS numberMI7700000
Beilstein Reference1730763
Gmelin Reference49760
Jmol-3D imagesImage 1
Properties
Molecular formulaC7H16
Molar mass100.20 g mol−1
AppearanceColourless liquid
OdorPetrolic
Density0.6795 g mL−1
Melting point−91.0 to −90.1 °C; −131.7 to −130.3 °F; 182.2 to 183.0 K
Boiling point98.1 to 98.7 °C; 208.5 to 209.6 °F; 371.2 to 371.8 K
log P4.274
Vapor pressure5.33 kPa (at 20.0 °C)
kH12 nmol Pa−1 kg−1
Refractive index (nD)1.387
Viscosity386 μPa s
Dipole moment0.0 D
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, C224.64 J K−1 mol−1
Hazards
GHS pictogramsThe 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 wordDANGER
GHS hazard statementsH225, H304, H315, H336, H410
GHS precautionary statementsP210, P261, P273, P301+310, P331
EU Index601-008-00-2
EU classificationFlammable F Harmful Xn Dangerous for the Environment (Nature) N
R-phrasesR11, R38, R50/53, R65, R67
S-phrases(S2), S16, S29, S33
NFPA 704
NFPA 704.svg
3
1
0
Flash point−4.0 °C; 24.8 °F; 269.1 K
Autoignition temperature223.0 °C; 433.4 °F; 496.1 K
Explosive limits1.05–6.7%
Related compounds
Related alkanes
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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.

Uses[edit]

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[edit]

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[edit]

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

References[edit]

  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. ^ Isomers. Members.optushome.com.au. Retrieved on 2012-03-04.

External links[edit]