The Complete Guide to n-Heptane: Grades, Properties, Industrial & Laboratory Applications
Table of Contents
What you will learn
Complete technical guide to n-heptane — ACS vs Technical grade, boiling point, safety (UN1206), and top industrial & laboratory applications.
💡 Frequently Asked Questions
Find quick answers to common questions about the complete guide to n-heptane: grades, properties, industrial & laboratory applications.
n-Heptane, in 30 seconds
- What it is: n-Heptane (CAS 142-82-5, C₇H₁₆) is a straight-chain, non-polar alkane solvent with a boiling point of 98.4 °C and a flash point of −4 °C. It's the reference zero-octane fuel, a safer replacement for n-hexane in many labs, and a workhorse solvent for adhesives, extractions, and GC/HPLC.
- Which grade to buy: 99% ACS for chromatography, kauri-butanol testing, and analytical work; 99% Technical for degreasing, adhesive removal, and industrial cleaning.
- Why it matters: n-Heptane lacks the chronic neurotoxicity of n-hexane, making it the preferred non-polar solvent in modern laboratories and extraction facilities. Every shipment ships with a Certificate of Analysis (COA) from our in-house QC lab.
n-Heptane is one of the most misunderstood solvents on the shelf. It sits next to its more famous cousin hexane and its blended relative petroleum ether, and it quietly does work the other two can't — from ASTM reference-fuel blending to HPLC mobile-phase prep to KB-value rubber cement testing. This guide covers everything our technical team gets asked about n-heptane, in one place.
What is n-Heptane?
n-Heptane is the straight-chain isomer of heptane — seven carbon atoms in an unbranched line, saturated with hydrogen. Its molecular formula is C₇H₁₆, molecular weight 100.21 g/mol, and CAS registry number 142-82-5. It is colorless, volatile, water-insoluble, and emits a characteristic gasoline-like odor.
The "n-" prefix is important. "Heptane" without the prefix refers to any of the nine structural isomers of C₇H₁₆. "n-Heptane" refers specifically to the linear isomer, which has distinct physical properties — a higher boiling point and different octane rating than the branched isomers. When an ASTM method or a USP monograph specifies "n-heptane," branched isomers are not acceptable substitutes.
The pure linear structure is what makes n-heptane the reference zero-point on the research octane number (RON) scale, against which isooctane (2,2,4-trimethylpentane) defines the 100 point. Every octane rating at the pump is traceable back to this solvent.
Physical & Chemical Properties
Quick-reference values for design, handling, and storage calculations:
n-Heptane is strongly non-polar (log P ≈ 4.5), which explains why it dissolves oils, greases, waxes, and most non-polar organic matter but is essentially immiscible with water, methanol, and glycerol. It is miscible with most other non-polar organics — benzene, toluene, ether, chloroform, and carbon tetrachloride. For more detail on physical data, the NIST Chemistry WebBook entry for heptane is the authoritative primary source.
Grades: ACS 99% vs Technical 99%
Alliance Chemical stocks two grades, and the difference is not the purity headline — both are "99% minimum." The difference is in the residual specification and the paperwork.
| Specification | 99% ACS | 99% Technical |
|---|---|---|
| Assay (n-heptane, GC) | ≥ 99.0 % | ≥ 99.0 % |
| Color (APHA) | ≤ 10 | ≤ 20 |
| Water content | ≤ 0.01 % | ≤ 0.05 % |
| Residue after evaporation | ≤ 0.001 % | ≤ 0.005 % |
| Acidity (as acetic) | Pass ACS test | Not specified |
| Sulfur compounds | Pass ACS test | Not specified |
| Thiophene | ≤ 0.4 ppm | Not specified |
| Per-lot COA | Yes (full ACS panel) | Yes (assay + color) |
| Typical use | HPLC, GC, KB value, reference fuel, extraction | Degreasing, adhesive work, cement, coatings |
n-Heptane vs n-Hexane: Why Labs Are Switching
For decades, n-hexane was the default non-polar extraction and chromatography solvent. Cheap, effective, ubiquitous. Then toxicology caught up.
n-Hexane is metabolized in the human liver to 2,5-hexanedione, a potent neurotoxin. Chronic exposure — the kind that happens in a botanical-extraction facility or an adhesive factory over years — causes peripheral neuropathy: numbness, weakness, and in severe cases permanent nerve damage in the hands and feet. The condition was first documented in sandal-glue workers in Japan and has been confirmed in shoe, printing, and cleaning workers worldwide. OSHA's PEL for n-hexane is 500 ppm, but the ACGIH TLV is a much lower 50 ppm, reflecting the toxicology.
n-Heptane is one carbon longer. That seemingly trivial difference means it is metabolized through a different pathway and does not produce 2,5-hexanedione. It is not classified as a neurotoxin. Physical properties are close enough that most methods port directly: boiling point is 29 °C higher, polarity is marginally lower, evaporation rate is similar. For HPLC, GC, and botanical extraction, n-heptane has become the default at most modern facilities.
| Property | n-Heptane | n-Hexane |
|---|---|---|
| Boiling point | 98.4 °C | 68.7 °C |
| Flash point | −4 °C | −22 °C |
| Density (20 °C) | 0.684 g/mL | 0.659 g/mL |
| Chronic neurotoxin? | No | Yes (via 2,5-hexanedione) |
| ACGIH TLV | 400 ppm | 50 ppm |
| Typical use today | Modern lab, extraction, HPLC | Legacy methods, commodity scale |
See our companion guide, The Science of Botanical Extraction, for a deeper dive on n-heptane's role in replacing hexane for essential oil and cannabinoid workflows.
Industrial Applications
1. Reference fuel for octane testing
n-Heptane defines the zero point of both the Research Octane Number (RON) and Motor Octane Number (MON) scales, under ASTM D2699 and D2700. Every gasoline at every pump is rated by direct comparison to reference blends of n-heptane and isooctane. When a refinery QC lab orders 99% ACS n-heptane, this is almost always why.
2. Adhesive removal and natural-rubber cement
n-Heptane is one of the best solvents for natural rubber — it dissolves latex, rubber cement, and many pressure-sensitive adhesives without attacking polar substrates like paper or most cured finishes. Shoe factories, book restorers, and auto-upholstery shops use it where mineral spirits are too weak and toluene is too aggressive or too regulated.
3. Degreasing and metal surface prep
For wax removal, oil cleanup, and pre-paint surface prep, n-heptane's fast evaporation and clean residue profile make it competitive with VM&P naphtha and chlorinated solvents. With new TCE restrictions coming into force, heptane has picked up much of the slack in precision degreasing.
4. Flavor, fragrance, and cannabinoid extraction
n-Heptane is the non-polar solvent of choice for essential-oil and cannabinoid separations where n-hexane is being phased out for occupational-health reasons. It strips lipophilic molecules cleanly, evaporates at a workable 98 °C, and leaves negligible residue when paired with a proper vacuum-oven finish step.
5. Coatings and paint thinning
In low-polarity coatings — alkyd primers, synthetic rubber cements, and some specialty urethanes — n-heptane functions as a viscosity modifier and flash aid. It pairs well with xylene and toluene in multi-solvent blends.
6. Polymer and plastics cleaning
When a polyethylene or polypropylene surface needs to be cleaned without swelling or crazing, n-heptane's short contact time and non-polar character usually pass. For polystyrene or polycarbonate, keep contact brief — n-heptane will slowly attack amorphous polymers given enough dwell time.
Laboratory Applications
Non-polar mobile phase in chromatography
In HPLC normal-phase separations, n-heptane is now the dominant non-polar component, having largely displaced n-hexane. In gas chromatography, it appears as a calibration standard, a dilution solvent for aromatic analytes, and a component in residual-solvent testing per USP <467>. Our 99% ACS grade is specified tight enough (thiophene ≤ 0.4 ppm, residue ≤ 0.001 %) for both applications.
Kauri-Butanol value reference solvent
The Kauri-Butanol (KB) test, ASTM D1133, measures a solvent's aromatic strength by titrating it into a saturated solution of kauri gum in n-butanol. n-Heptane is the lower reference point (KB = 25–30); toluene defines the upper reference (KB = 105). Any industrial solvent buyer specifying an aromatic replacement will eventually land on the KB chart, and that chart lives in n-heptane units.
Sample prep, extraction, and liquid-liquid partition
For lipid extraction, wax isolation, and polymer fractionation, n-heptane is paired with more polar partners — methanol, acetone, or ethyl acetate — to tune selectivity. Its long carbon chain gives it better phase separation than hexane against polar phases.
Cleaning glassware and instruments
Between runs, n-heptane rinses non-polar contaminants (oils, silicone, aromatic residues) from glassware without leaving a film. Many labs finish with a polar rinse (ACS IPA, then deionized water) to remove the heptane.
Safety, Storage & Handling
Exposure limits
- OSHA PEL (8-hour TWA): 500 ppm / 2,000 mg/m³
- ACGIH TLV (8-hour TWA): 400 ppm
- ACGIH STEL (15-min): 500 ppm
- NIOSH IDLH: 750 ppm
Full OSHA chemical data is published at osha.gov/chemicaldata/84.
Personal protective equipment
- Gloves: Viton or 4H laminate. Nitrile offers only short-duration protection; butyl and latex are unsuitable.
- Eye protection: Chemical splash goggles; face shield for transfer operations.
- Respiratory: Organic-vapor cartridge respirator above the TLV; supplied air for confined-space work or above IDLH.
- Clothing: Flame-resistant outer wear when working near open handling of bulk quantities.
Storage
Store in tightly-sealed original containers, away from oxidizers and ignition sources, between 5 °C and 30 °C, in a ventilated flammable-liquids cabinet. Ground all drums and totes. Do not store near chlorinated solvents or strong acids. Shelf life is 24+ months when containers are sealed and stored correctly.
Aspiration hazard
n-Heptane is classified as a Category 1 aspiration toxicant — if swallowed and aspirated into the lungs, it can cause chemical pneumonitis. Do not induce vomiting; get immediate medical attention. Always include this hazard statement on secondary labels.
Spill response
For small spills, absorb with inert material (vermiculite, dry sand) and place in a grounded, sealed container for disposal as hazardous waste. Eliminate all ignition sources. For large releases, evacuate the area, use explosion-proof ventilation, and follow your facility's emergency-response plan. Report releases above the CERCLA reportable quantity (1 lb for many hydrocarbons) as required.
Regulatory Status
| Jurisdiction / Regulation | Status |
|---|---|
| DOT (US domestic shipping) | UN1206, Heptanes, Class 3, PG II — Flammable Liquid |
| IATA (air) | UN1206, PG II — limited quantity provisions apply; most common sizes ship Dangerous Goods |
| TSCA Inventory (US) | Listed — active |
| EPCRA / SARA Title III | Section 313 reportable above de minimis; plan for Tier II if storing bulk |
| California Prop 65 | Not listed |
| REACH (EU) | Registered |
| IARC carcinogen classification | Not classified |
| EPA VOC status | Exempt in some state regulations (CARB rule 1113 context); check local authority |
For hazmat shipping questions, our customer service team will confirm the appropriate mode (LTL / ground / air) for your quantity and destination.
How to Choose the Right Grade
A simple decision tree that resolves 95 % of "which heptane do I need?" questions:
- Does the method reference ACS reagent grade or cite residue/thiophene limits? → Buy 99% ACS.
- Is this HPLC or GC work, or a USP/EPA/ASTM analytical method? → Buy 99% ACS.
- Are you running Kauri-Butanol value testing or octane reference fuel blending? → Buy 99% ACS.
- Is this industrial degreasing, adhesive removal, coatings blending, or rubber cement manufacture? → Buy 99% Technical — the cost savings are meaningful at drum and tote volumes.
- Still unsure? Email the technical team with your end use; we'll confirm before you order.
Packaging & Shipping
n-Heptane is stocked in UN-rated hazmat packaging across all standard industrial volumes:
| Size | Container type | Typical buyer |
|---|---|---|
| 1 gallon | UN-rated metal can or HDPE jug | Lab, small shop, R&D |
| 5 gallon pail | UN-rated steel pail with bung | Mid-scale extraction, QC lab |
| 55 gallon drum | UN-rated steel drum | Manufacturing, degreasing line, mid-volume extraction |
| 270 gallon tote (IBC) | UN-rated IBC with metal cage | Continuous processing, refinery QC |
Pricing is volume-tiered. Bulk, contract, and purchase-order arrangements are available — contact sales@alliancechemical.com or call for a drum or tote quote. Ground LTL is standard for drum and tote orders; 1-gallon and 5-gallon can ship parcel (UN specification packaging required). See also the full Hydrocarbons collection and Solvents collection.
Frequently Asked Questions
Is n-heptane the same as heptane?
No. "Heptane" is the general name for any C₇H₁₆ isomer — there are nine. "n-Heptane" specifies the straight-chain (linear) isomer. ASTM methods, USP monographs, and most analytical specifications require n-heptane specifically, because branched isomers have different boiling points, octane numbers, and chromatographic behavior.
What is the boiling point of n-heptane?
98.4 °C (209 °F) at 760 mmHg. The melting point is −90.6 °C. Its higher boiling point relative to n-hexane (68.7 °C) makes it easier to handle at room temperature with less evaporative loss, but also requires slightly higher rotovap temperatures to strip from a sample.
Is n-heptane safer than n-hexane?
Yes, for chronic-exposure neurotoxicity. n-Hexane is metabolized to 2,5-hexanedione, which causes peripheral neuropathy with long-term exposure. n-Heptane is not metabolized through the same pathway and is not classified as a neurotoxin. Both remain flammable hydrocarbons with significant acute and fire hazards — PPE, ventilation, and grounding practices are identical.
Is n-heptane suitable for food-contact use?
Alliance Chemical does not certify n-heptane for food-contact or food-additive applications. It is stocked as an industrial and laboratory solvent. For any use that contacts food, flavor, or fragrance, the buyer is responsible for verifying suitability against FDA 21 CFR 173.270 (residual solvents in spice oleoresins) or the applicable specification. Our ACS grade meets the residue and purity limits referenced by many of those specifications, but certification for food-contact applications is the user's responsibility.
What's the shelf life of n-heptane?
24 months minimum in sealed original containers stored between 5 °C and 30 °C away from sunlight and ignition sources. Because n-heptane is a saturated hydrocarbon with no reactive functional groups, it does not form peroxides the way ethers do, and it does not hydrolyze. Color and residue after evaporation are the two properties most likely to drift with long storage in vented containers.
Can I ship n-heptane ground, LTL, or by air?
Ground and LTL — yes, under UN1206, Class 3, Packing Group II. Quart and 1-gallon sizes in UN packaging can ship parcel (FedEx, UPS) with Hazmat accessorial fees. Drums and totes ship LTL freight with a certified hazmat carrier. Air shipments are possible under IATA PG II rules but expensive; most buyers default to ground. Our customer service team confirms the right mode before we ship.
What grade of n-heptane do I need for botanical extraction?
For any extract that will be consumed or inhaled, use 99% ACS grade — the tight residue-after-evaporation spec (≤ 0.001 %) minimizes residual solvent carry-through. Pair the extraction step with a proper winterization, vacuum-oven purge, or rotary-evaporator strip to drive residuals below your state's testing limit. Technical grade is appropriate for upstream equipment cleaning, not for direct product contact.
Does n-heptane form peroxides like ethers do?
No. Saturated straight-chain alkanes like n-heptane do not have the α-carbon-to-oxygen chemistry that produces peroxides in diethyl ether, THF, or diisopropyl ether. Peroxide testing is not part of the normal n-heptane QC panel, and peroxide-scavenging additives are not required for storage.
Related Reading
- Petroleum Ether: The Complete Chemistry, Grades, and Applications Guide — for the lower-boiling hydrocarbon fraction
- The Complete Guide to Ethyl Acetate — polar aprotic solvent, often paired with n-heptane for liquid-liquid partitions
- The Science of Botanical Extraction: Solvents, Methods, and Quality Control
- The Ultimate Guide to Industrial Solvents — the overview, with n-heptane in context
- The D-Limonene Deception — why grade paperwork matters for solvent-in-product contexts
- TCE Ban Explained — regulatory shift driving heptane and other solvent switches
- Collection: Alcohols, Ketones, Lab Chemicals, Industrial & Automotive
Buy n-Heptane Direct From Alliance Chemical
COA per lot. SDS with every order. UN-packaged hazmat. Bulk, PO, and contract pricing available.
Primary references
- NIST Chemistry WebBook, n-heptane entry: webbook.nist.gov
- OSHA Chemical Data for n-heptane: osha.gov/chemicaldata/84
- ASTM D2699 — Standard Test Method for Research Octane Number of Spark-Ignition Engine Fuel
- ASTM D1133 — Standard Test Method for Kauri-Butanol Value of Hydrocarbon Solvents
- ACGIH TLVs and BEIs (current edition)
- 49 CFR 172.101 — DOT Hazardous Materials Table entry for UN1206
For industrial use only. Not for human consumption. Follow all applicable safety guidelines. Consult the current SDS before handling. This guide is informational; always confirm grade, specification, and regulatory status with Alliance Chemical's technical team before finalizing your procurement. Alliance Chemical has been supplying industrial and laboratory chemicals since 1998 — CAGE Code 1LT50.
