Is n-Heptane an Organic Compound?
Yes. n-Heptane is an organic compound. It is a hydrocarbon, meaning its molecules consist only of carbon and hydrogen atoms joined by covalent bonds. It belongs to the alkane family, so every carbon-to-carbon bond is a single bond and the molecule is fully saturated. Its chemical formula is C7H16 and its straight-chain structure is CH3-CH2-CH2-CH2-CH2-CH2-CH3, with no branching and therefore no isomers of the same skeleton.
The distinction matters commercially. Because the material is organic, it is supplied as a petrochemical solvent rather than an inorganic chemical, and it is manufactured, packed and classified accordingly, including for transport as a flammable liquid.
Chemical Identity and Typical Properties
| Parameter | Value |
|---|---|
| CAS number | 142-82-5 |
| Molecular formula | C7H16 |
| Molecular weight | 100.20 g/mol |
| Appearance | Colourless liquid with faint gasoline-like odour |
| Boiling point | 98.4 °C |
| Melting point | -90.6 °C |
| Density at 20 °C | About 0.684 g/cm3 |
| Flash point | -4 °C, closed cup |
| Polarity | Non-polar, immiscible with water |
Grades and Purity Specifications
Commercial n-Heptane is offered in industrial, laboratory and pharmaceutical grades that differ mainly in assay, distillation range and residue limits. Industrial grade is the normal choice for cleaning, adhesives and rubber work, while laboratory and pharmaceutical grades are controlled more tightly for non-volatile residue, water content and trace impurities. Certain analytical applications also require a defined content of the branched isomer to keep retention behaviour reproducible.
Purchasers should specify the assay, distillation range, water content and residue limits that their process actually needs, and confirm the flash point and dangerous goods classification on the safety data sheet. Over-specifying purity raises cost without improving performance, so the grade should be matched to the duty.
Main Industrial and Laboratory Applications
Laboratory solvent: a non-polar medium for reactions, extractions and chromatography.
Pharmaceutical processing: carrier and crystallisation medium for active ingredients.
Adhesive manufacturing: a key component of rubber and plastics bonding formulations.
Rubber and plastics: dissolving elastomers before compounding and shaping.
Aerosols and paint thinners: fast, even evaporation for smooth coatings.
Fuel testing: the zero reference point of the octane rating scale.
Electronics and printing: cleaning precision parts and formulating inks.
Flammability, Handling and Storage
n-Heptane is highly flammable. Its vapour is heavier than air, can travel along the ground to a distant ignition source and can form explosive mixtures, so ventilation design is critical. The liquid defats the skin and irritates the eyes, and inhaling high vapour concentrations may produce dizziness, headache or drowsiness. Operators should work with explosion-proof ventilation, chemical-resistant gloves, eye protection and protective clothing, and transfer operations should use bonded and earthed equipment.
Store the material in tightly sealed containers in a cool, well-ventilated area, separated from oxidisers and all ignition sources, and keep spill kits and appropriate extinguishing media available in the storage and handling zones. Drums and tanks should be kept closed when not in use, and empty packaging must be treated as still hazardous.
Supply, Packaging and Selection Checklist
n-Heptane is normally supplied in 200 litre drums, smaller cans for laboratory use and bulk tankers or ISO tanks for larger programmes. When selecting a supplier, check the declared assay and analytical method, the residue and water limits, the batch certificate of analysis, the packing and labelling under dangerous goods rules, and the consistency of the distillation range between lots. A stable distillation range is often the clearest indicator of a dependable supply.
Frequently Asked Questions
Q: Is n-Heptane organic or inorganic?
It is organic. n-Heptane is a saturated hydrocarbon built only from carbon and hydrogen atoms.
Q: What is the chemical formula of n-Heptane?
The formula is C7H16, and the CAS number is 142-82-5.
Q: What is n-Heptane used for?
It serves as a laboratory and industrial solvent in adhesives, paint thinners, rubber processing and electronics cleaning, and as the zero reference for octane ratings.
Q: Is n-Heptane the same as hexane?
No. Hexane has six carbon atoms and the formula C6H14, while n-Heptane has seven and the formula C7H16, so their boiling points and solvent strength differ.
Q: Is n-Heptane flammable?
Yes. It is a flammable liquid with a closed-cup flash point of about -4 °C and must be stored away from ignition sources.
Q: Is n-Heptane miscible with water?
No. It is non-polar and practically insoluble in water, although it mixes readily with most organic solvents.