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Heptane



Heptane
Identifiers
CAS number 142-82-5
RTECS number MI7700000
SMILES CCCCCCC
Properties
Molecular formula C7H16
Molar mass 100.21 g/mol
Appearance colorless liquid
Density 0.684 g/ml, liquid
Melting point

−90.61 °C (182.55 K)

Boiling point

98.42 °C (371.58 K)

Solubility in water Immiscible
Viscosity 0.386 cP at 25 °C
Hazards
EU classification Flammable (F)
Harmful (Xn)
Dangerous for
the environment (N)
NFPA 704
3
1
0
 
R-phrases R11, R38, R50/53,
R65, R67
S-phrases (S2), S9, S16, S29, S33,
S60, S61, S62
Flash point −4 °C
Autoignition
temperature
285 °C
Related Compounds
Related alkanes Hexane
Octane
Related compounds Methylcyclohexane
Cycloheptane
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

Heptane (also known as dipropyl methane, gettysolve-C or heptyl hydride) is an alkane with the chemical formula H3C(CH2)5CH3. Heptane has nine isomers, or eleven if enantiomers are counted:

  • Heptane (n-heptane), H3C–CH2–CH2–CH2–CH2–CH2–CH3, straight chain of seven carbon atoms.
  • 2-Methylhexane, H3C–CH(CH3)–CH2–CH2–CH2–CH3, chain of six carbon atoms, and a methyl group attached to the second.
  • 3-Methylhexane, H3C–CH2–C*H(CH3)–CH2–CH2–CH3 (chiral), chain of six carbon atoms, and a methyl group attached to the third.
  • 2,2-Dimethylpentane, (H3C)3–C–CH2–CH2–CH3, chain of five carbon atoms, and two methyl groups attached to the second.
  • 2,3-Dimethylpentane, (H3C)2–CH–C*H(CH3)–CH2–CH3 (chiral), chain of five carbon atoms, and methyl groups attached to the second and third.
  • 2,4-Dimethylpentane, (H3C)2–CH–CH2–CH–(CH3)2, chain of five carbon atoms, and methyl groups attached to the second and fourth.
  • 3,3-Dimethylpentane, H3C–CH2C(CH3)2–CH2–CH3, chain of five carbon atoms, and two methyl groups attached to the third.
  • 3-Ethylpentane, H3C–CH2–CH(CH2CH3)–CH2–CH3, chain of five carbons, and an ethyl group attached to the third.
  • 2,2,3-Trimethylbutane, (H3C)3–CH(CH3)–CH3, chain of four carbon atoms, with two methyl groups attached to the second, and one to the third.[1]

Additional recommended knowledge

The straight-chain isomer n-heptane is the zero point of the octane rating scale. It is undesirable in petrol, as it burns explosively, causing engine knocking, as opposed to branched-chain octane isomers, which burn more slowly and give better performance. Its choice for the zero point of the scale was due to the availability of very high purity n-heptane, unmixed with other isomers of heptane or other alkanes, distilled from the resin of Jeffrey Pine. Other sources of heptane and octane, produced from crude oil, contain a mixture of different isomers with greatly differing ratings, so do not give a precise zero point.

Uses

Heptane, as well as its many isomers, are widely applied in laboratories as a totally non-polar solvent. Being 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.

Heptane is also used as a medium to distinguish bromine from iodine from aqueous mixtures. While both bromine and iodine appear brown in aqueous media, bromine remains brown when dissolved in heptane, while iodine turns purple when mixed with heptane.

Heptane is commercially available as the rubber cement solvent Bestine.

References

     
    This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Heptane". A list of authors is available in Wikipedia.
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