2-Methylhexane

2-Methylhexane

Names
IUPAC name 2-Methylhexane
Identifiers
CAS Number	591-76-4 Y
Beilstein Reference	1696856
ChemSpider	11094 Y
EC Number	209-730-6
Jmol 3D model	Interactive image
PubChem	11582
RTECS number	MO3871500
UN number	3295
InChI InChI=1S/C7H16/c1-4-5-6-7(2)3/h7H,4-6H2,1-3H3 Y Key: GXDHCNNESPLIKD-UHFFFAOYSA-N Y
SMILES CCCCC(C)C
Properties
Chemical formula	C7H16
Molar mass	100.21 g·mol−1
Appearance	Colorless liquid
Odor	Odorless
Density	679 mg ml−1
Melting point	−119.0 to −117.8 °C; −182.3 to −180.1 °F; 154.1 to 155.3 K
Boiling point	89.6 to 90.6 °C; 193.2 to 195.0 °F; 362.7 to 363.7 K
Vapor pressure	15.7 kPa (at 37.7 °C)
Henry's law constant (kH)	19 nmol Pa−1 kg−1
Refractive index (nD)	1.384
Thermochemistry
Specific heat capacity (C)	222.92 J K−1 mol−1
Std molar entropy (So298)	323.34 J K−1 mol−1
Std enthalpy of formation (ΔfHo298)	−231.1–−228.5 kJ mol−1
Std enthalpy of combustion (ΔcHo298)	−4.8127–−4.8103 MJ mol−1
Vapor pressure	{{{value}}}
Related compounds
Related alkanes	2-Methylpentane 3-Methylpentane 3-Ethylpentane 3-Methylhexane 2-Methylheptane 3-Methylheptane
Related compounds	2-Ethyl-1-butanol Valnoctamide 2-Ethylhexanol Valpromide 2-Ethylhexanoic acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

2-Methylhexane (C₇H₁₆, also known as isoheptane, ethylisobutylmethane) is an isomer of heptane. It is structurally a hexane molecule with a methyl group attached to its second carbon atom. It exists in most commercially available heptane merchandises as an impurity but is usually not considered as impurity in terms of reactions since it has very similar physical and chemical properties when compared to n-heptane (straight-chained heptane).

Being an alkane, 2-methylhexane is insoluble in water, but is soluble in many organic solvents, such as alcohols and ether. However, 2-methylhexane is more commonly considered as a solvent itself. Therefore, even though it is present in many commercially available heptane products, it is not considered as a destructive impurity, as heptane is usually used as a solvent. Nevertheless, by concise processes of distillation and refining, it is possible to separate 2-methylhexane from n-heptane.

Within a group of isomers, those with more branches tend to ignite more easily and combust more completely. Therefore, 2-methylhexane has a lower Autoignition temperature and flash point when compared to heptane. Theoretically 2-methylhexane also burns with a less sooty flame, emitting higher-frequency radiation; however, as heptane and 2-methylhexane differ by only one carbon atom, in terms of branching, both burn with a bright yellow flame when ignited.

Compared to n-heptane, 2-methylhexane also has lower melting and boiling points. A lower density of liquid is found in 2-Methylhexane than heptane.

On the NFPA 704 scale, 2-methylhexane is listed as a reactivity level-0 chemical, along with various other alkanes. In fact, most alkanes are unreactive except in extreme conditions, such as combustion or strong sunlight. At the presence of oxygen and flame, 2-methylhexane, like heptane, combusts mostly completely into water and carbon dioxide. With UV-light and mixed with halogens in solvents, usually bromine in 1,1,1-trichloroethane, a substitution reaction occurs.

See also

• 3-Methylhexane