Heptane

Heptane is a hydrocarbon in the alkane series with seven carbon atoms and the formula C7H16. It exists as a family of structural isomers; the straight-chain form is n-heptane, while branched isomers include variations such as 2-methylhexane and others. The term heptane is commonly encountered in petroleum refining and organic chemistry.

It is obtained from petroleum fractions such as naphtha and during distillation of crude oil. It is widely used as a nonpolar solvent in laboratories and industry for cleaning, degreasing, and preparing samples; it is also used in chromatography as a mobile phase component. In fuel chemistry, n-heptane is used as a reference compound in octane rating systems (assigned an octane number of 0), with higher octane components like iso-octane assigned higher numbers.

At room temperature, heptane is a colorless, extremely flammable liquid with a characteristic odor. It is less dense than water and immiscible with it; it dissolves in many organic solvents. The boiling point of n-heptane is about 98°C, while the melting point is around -90°C. It has a relatively low vapor pressure at room temperature, but its vapors can form flammable mixtures with air.

Heptane vapors are primarily a hazard by inhalation; exposure can cause dizziness, headaches, and irritation. It is flammable; proper storage in tightly closed containers away from heat and oxidizers is required. It is a volatile organic compound and can contribute to air pollution; disposal should follow local hazardous waste regulations; spills should be contained to prevent environmental contamination.