Adipic Acid
A six-carbon diacid with one dominant customer. Roughly two-thirds is condensed with hexamethylenediamine to make Nylon 66, and most of the rest becomes polyester polyols for polyurethane.
Molecular Structure
What is Adipic Acid?
Adipic acid is hexanedioic acid — a straight six-carbon chain with a carboxyl group at each end. The even chain length is not incidental. It allows the chains of Nylon 66 to pack with every amide hydrogen bond aligned across neighbouring chains, and that alignment is why Nylon 66 melts around 260 °C, well above Nylon 6, and holds its stiffness closer to that melting point.
Almost all of it is made by oxidising cyclohexane to KA oil — a cyclohexanone and cyclohexanol mixture — and then oxidising that with nitric acid. The nitric acid step co-produces nitrous oxide, a greenhouse gas roughly 270 times as potent as carbon dioxide over a hundred-year horizon. Abatement is now standard practice at well-run plants and is a genuine point of difference between producers rather than a technicality.
Beyond nylon, adipic acid is a building block for polyester polyols in polyurethane, a plasticiser precursor as dioctyl adipate, and a food acidulant approved as E355. It is a mild, non-hygroscopic solid acid that is straightforward to handle, and its principal physical hazard is dust rather than toxicity.
Ask your supplier about nitrous oxide abatement. Adipic acid production is one of the largest single industrial sources of N₂O, and the gap between an abated and an unabated plant is wide enough to dominate the cradle-to-gate carbon footprint of everything made downstream of it.
Quick Reference
Key Physical & Chemical Properties
Structure & Bonding
Two carboxyl groups on a straight six-carbon chain. The even chain length is what lets Nylon 66 pack tightly and melt high; the two acid groups are what make adipic acid a polyester polyol building block and a plasticiser precursor.
Skeletal structure — a six-carbon chain with terminal carboxyls
Structural Identity
- IUPAC NameHexanedioic acid
- Common namesAdipic acid, E355
- Molecular FormulaC₆H₁₀O₄
- Molecular Weight146.14 g/mol
- Functional groupsTwo terminal carboxylic acids
- AciditypKa₁ 4.43, pKa₂ 5.41
- Chain lengthSix carbons — even, which sets PA66's melt
- Polymerises withHexamethylenediamine → Nylon 66
- Made fromCyclohexane → KA oil → HNO₃ oxidation
- CAS Number124-04-9
- InChI KeyWNLRTRBMVRJNCN-UHFFFAOYSA-N
Product Specifications
Chelora supplies Adipic Acid in standard and custom grades. Contact us for specification sheets tailored to your process.
| Chemical name | Adipic acid |
|---|---|
| CAS Number | 124-04-9 |
| Molecular formula | C₆H₁₀O₄ |
| Molecular weight | 146.14 g/mol |
| Purity (min) | ≥ 99.80 wt% |
| Melting point (min) | ≥ 151.5 °C |
| Colour, molten or 10% aqueous (max) | ≤ 10 APHA |
| Ash (max) | ≤ 5 ppm wt |
| Iron (max) | ≤ 0.50 ppm wt |
| Water (max) | ≤ 0.20 wt% |
| Nitric acid & nitrates as HNO₃ (max) | ≤ 3 ppm wt |
| Total nitrogenous compounds as N (max) | ≤ 15 ppm wt |
| Oil & grease (max) | ≤ 5 ppm wt |
| Lower dibasic acids (max) | ≤ 0.15 wt% |
| Heavy metals as Pb (max) | ≤ 5 ppm wt |
| Bulk density | ≈ 600 – 750 kg/m³ |
| Flash point | 196 °C (closed cup) |
| Autoignition temperature | 420 °C |
| Dust explosion class | St 1 — combustible dust |
| Transport classification | Not regulated as dangerous goods |
Downstream Applications & Derivatives
Key derivative chains and industrial uses of Adipic Acid.
Nylon 66 (PA66)
The dominant outlet. Reacted with hexamethylenediamine to form nylon salt and then polymerised, giving a polyamide that melts near 260 °C — airbag fabric, tyre cord, engineering resin and apparel fibre.
Polyester Polyols
Adipate polyols for polyurethane: flexible and microcellular foams, shoe soles, coatings, adhesives and elastomers with better mechanical strength than polyether at equivalent hardness.
Plasticisers
Dioctyl and di-isononyl adipate for PVC that has to stay flexible in the cold — automotive interior trim, refrigeration gaskets, outdoor cable and film.
Food Acidulant (E355)
A tart, non-hygroscopic acidulant used where a slow-dissolving acid is wanted: powdered drink mixes, gelatine desserts, baking powders and confectionery.
Polyester & Powder Coatings
A chain-length modifier in saturated and unsaturated polyester resins and in powder coating resins, where it adds flexibility and impact resistance to otherwise brittle systems.
Synthetic Esters
Adipate diesters as synthetic lubricant base stocks and refrigeration oils, plus adipic acid as a precursor route to adiponitrile and speciality polyamides.
Why source Adipic Acid through Chelora Petrochem?
Verified Origin
Full origin certification and asset-backed supply chain documentation — no grey-market supply.
Grade Flexibility
Nylon, polyol and food grades supplied. Where colour, nitrogenous compounds or iron govern your process, we specify against them rather than accepting the assay alone.
Full Documentation
CoA, SDS, REACH compliance, food-grade and kosher or halal certification where required, and destination-market documentation with every shipment.
Logistics Support
Experienced in bulk solids logistics — 25 kg bags, jumbo bags and bulk trucks with dust control and moisture protection, for Indian and international delivery.
Storage & Handling Guidelines
Always refer to the full SDS before handling. The following is a summary of key requirements.
- Store in a cool, dry, well-ventilated area away from moisture. Adipic acid cakes when it takes up water, which is a handling problem rather than a chemical one but an expensive one at scale.
- Manage dust as an explosion hazard. Adipic acid dust is combustible with a St 1 dust explosion class — earth and bond conveying equipment, control accumulation on surfaces, and assess explosion protection on silos, mills and dust collectors.
- Keep ignition sources and hot surfaces away from any area where a dust cloud can form, including during bag tipping and silo filling.
- Use stainless steel for wetted parts in solution and melt service. Hot aqueous adipic acid attacks carbon steel, and the resulting iron pickup drives colour in the finished polymer.
- Keep food-grade material entirely separate from technical grade, with dedicated conveying, storage and cleaning records.
- Segregate from strong oxidisers, strong bases and reducing agents.
- Control airborne dust with local extraction rather than relying on respirators; nuisance dust exposure limits apply and are easily exceeded at open transfer points.
- Protect bags from ground moisture and direct sunlight, and rotate stock — extended storage in humid conditions is the usual cause of caking.
- Provide eyewash and washing facilities at handling points; the acid is a recognised eye irritant even though its general toxicity is low.
Hazard Summary
Classification: Eye Irrit. 2 (H319) under CLP, and nothing further. Adipic acid has low acute toxicity by all routes and is approved as a food additive, so its hazard profile is unusually benign for a bulk intermediate.
Dust explosion is the real hazard: like most fine organic solids, adipic acid dust forms explosible clouds. It is classed St 1, which means an explosion is credible and protective measures are required — grounding, bonding, housekeeping and protection on enclosed equipment. This, not toxicity, is what drives the handling regime.
Eye irritation: causes serious eye irritation on direct contact with dust or solution. Eye protection is required at all open handling points.
Corrosion to equipment: hot aqueous solutions attack carbon steel. This is primarily a product quality issue — dissolved iron drives colour in polyamide and polyester — but it also shortens equipment life where the wrong metallurgy has been specified.
Caking: moisture uptake in storage causes caking and bridging in silos. Not a safety hazard, but the most common practical complaint and readily prevented by dry storage and stock rotation.
Fire: a combustible solid with a flash point of 196 °C and autoignition at 420 °C. Molten material burns, and combustion produces carbon monoxide and carbon dioxide.
Carbon footprint: conventional production co-produces nitrous oxide, a very potent greenhouse gas. Abatement status varies between producers and is worth confirming if you are reporting Scope 3 emissions on the downstream product.
PPE minimum: safety goggles, gloves and dust protection where dust clouds can form; nothing beyond routine good practice for closed handling.
Consult the full SDS for exposure limits, spill containment, emergency response and disposal before any use.
Frequently Asked Questions
Technical and commercial questions about Adipic Acid sourcing and specifications.
What is adipic acid used for?
Around two-thirds goes into Nylon 66, where it is combined with hexamethylenediamine to form nylon salt and then polymerised for airbag fabric, tyre cord, engineering resin and apparel fibre. Most of the remainder becomes polyester polyols for polyurethane foams, elastomers and coatings. Smaller volumes go into adipate plasticisers for cold-flexible PVC, food acidulant use as E355, polyester and powder coating resins, and synthetic ester lubricants.
Why does Nylon 66 melt higher than Nylon 6?
Because of how the chains pack. Nylon 66 is built from two six-carbon monomers, adipic acid and hexamethylenediamine, and the even chain lengths mean every amide group on one chain lines up with an amide group on the neighbouring chain when the polymer crystallises. Every hydrogen bond forms. Nylon 6 is made from a single monomer that polymerises head to tail, so the amide groups only align when chains run antiparallel, and a proportion of the potential hydrogen bonds go unformed. The result is roughly a 40 °C difference in melting point and noticeably better heat resistance for PA66.
Why does adipic acid have a carbon footprint issue?
The final oxidation step uses nitric acid, and it co-produces nitrous oxide as an unavoidable by-product. N₂O has a global warming potential around 270 times that of carbon dioxide over a hundred years, so even modest volumes matter a great deal in emissions terms. Adipic acid production was historically one of the largest industrial sources of N₂O worldwide. Thermal and catalytic abatement units now destroy the great majority of it at well-run plants, but coverage is not universal, and the difference between an abated and an unabated source is large enough to dominate the footprint of the downstream polymer.
What grades of adipic acid are there?
In practice the assay is similar across grades and the distinctions lie in the trace specification and the handling regime. Nylon grade is held tightly on colour, iron and nitrogenous compounds, because those carry through into polymer colour and thermal stability. Polyol and plasticiser grades are somewhat more tolerant. Food grade is tested against food additive purity criteria for E355 and requires segregated handling, cleaning documentation and, where the customer needs it, kosher or halal certification.
Why does adipic acid cake in storage and what prevents it?
Adipic acid is only moderately soluble in cold water but it does take up moisture from humid air. Water condenses at the contact points between crystals, dissolves a little material, and then re-crystallises as bridges when conditions dry out, welding the mass together. The prevention is entirely practical: keep the material dry, store bags off the ground and away from external walls, avoid large temperature swings that drive condensation inside packaging, keep silos dry-air purged where the climate demands it, and rotate stock rather than holding it through a humid season.
What documentation does Chelora provide?
Every shipment includes a Certificate of Analysis covering purity, melting point, colour, ash, iron, water, nitric acid and nitrates, total nitrogenous compounds, oil and grease, lower dibasic acids and heavy metals; a Safety Data Sheet to GHS and REACH format; confirmation that the material is not regulated as dangerous goods; an origin certificate; and food-grade, kosher, halal or destination-market certificates where the application requires them.
Request a quote or specification sheet
Talk to Chelora's sourcing team about Adipic Acid grade, volume, logistics, documentation, and lead times. We respond within one business day.
