Acetic Acid
Glacial acetic acid, made from methanol and carbon monoxide. Freezes at 16.6 °C, which is where the name comes from and why heated storage is normal.
Molecular Structure
What is Acetic Acid?
Acetic acid is a methyl group attached to a carboxyl group. The carboxyl carbon carries both a double-bonded oxygen and a hydroxyl, and the two share electron density, which is what makes the O–H acidic — pKa 4.76 — where an ordinary alcohol is not.
It hydrogen-bonds strongly enough that molecules pair into cyclic dimers, even in the vapour phase. That association is why acetic acid boils at 117.9 °C and freezes at 16.6 °C, which is high for a 60 g/mol molecule and close enough to room temperature that the pure acid solidifies in cool weather. The solid resembles ice, and that is where 'glacial' comes from.
Around three quarters of world production comes from carbonylating methanol with carbon monoxide over a rhodium or iridium catalyst — the Monsanto and Cativa processes. Both feedstocks come from synthesis gas, which is what places acetic acid in the C1 family rather than the olefins chain.
Chelora supplies glacial acetic acid at ≥99.85 wt% with freezing point, formic acid, acetaldehyde, iron and permanganate time certified. Heated or insulated transport arranged where ambient temperatures approach the 16.6 °C freezing point.
Quick Reference
Key Physical & Chemical Properties
Structure & Bonding
The carboxyl group does everything here. It makes the molecule acidic, it makes it hydrogen-bond into dimers, and it is the handle for the esterification and carbonylation chemistry that the derivative chain is built on.
Structure — methyl group attached to a carboxyl group
Structural Identity
- IUPAC NameAcetic acid (ethanoic acid)
- Molecular FormulaC₂H₄O₂ (CH₃COOH)
- Molecular Weight60.05 g/mol
- Functional groupCarboxylic acid
- Bond lengths1.21 Å C=O; 1.31 Å C–OH
- AciditypKa 4.76 at 25 °C
- AssociationForms cyclic hydrogen-bonded dimers
- Freezing point16.6 °C — hence 'glacial'
- SolubilityFully miscible with water
- CAS Number64-19-7
- InChI KeyQTBSBXVTEAMEQO-UHFFFAOYSA-N
Product Specifications
Chelora supplies Acetic Acid in standard and custom grades. Contact us for specification sheets tailored to your process.
| Chemical name | Acetic acid, glacial |
|---|---|
| CAS Number | 64-19-7 |
| Molecular formula | C₂H₄O₂ |
| Molecular weight | 60.05 g/mol |
| Purity (min) | ≥ 99.85 wt% |
| Freezing point (min) | ≥ 16.35 °C |
| Water (max) | ≤ 0.15 wt% (Karl Fischer) |
| Formic acid (max) | ≤ 0.05 wt% |
| Acetaldehyde (max) | ≤ 0.05 wt% |
| Iron (max) | ≤ 1.0 ppm wt |
| Heavy metals as Pb (max) | ≤ 0.5 ppm wt |
| Chloride (max) | ≤ 1.0 ppm wt |
| Sulphate (max) | ≤ 1.0 ppm wt |
| Permanganate time (min) | ≥ 30 min |
| Residue on evaporation (max) | ≤ 0.01 wt% |
| Colour | ≤ 10 Pt-Co (Hazen) |
| Density at 20 °C | 1.048 – 1.051 g/cm³ |
| Flash point | 39 °C (closed cup) |
| Autoignition temperature | 485 °C |
| Flammable limits | 4.0 – 19.9% v/v in air |
| UN Number | UN 2789 (Acetic acid, glacial) |
| IMDG / ADR Class | Class 8 (Corrosive), subsidiary risk 3, PG II |
Downstream Applications & Derivatives
Key derivative chains and industrial uses of Acetic Acid.
Vinyl Acetate Monomer
Reaction with ethylene and oxygen over a palladium catalyst gives VAM — the largest acetic acid outlet — polymerised to PVA and EVA for adhesives, paints, packaging film and solar encapsulant.
PTA Process Solvent
Acetic acid is the reaction solvent in the liquid-phase oxidation of para-xylene to terephthalic acid. It is recovered and recycled, but consumption through losses makes PTA a major demand centre.
Acetic Anhydride & Cellulose Acetate
Dehydration gives acetic anhydride, used to acetylate cellulose into acetate tow and film, and as an acetylating agent in pharmaceutical synthesis including aspirin.
Acetate Ester Solvents
Esterification with alcohols gives ethyl, butyl and propyl acetate — medium-evaporating solvents for coatings, printing inks, adhesives and nail care.
Monochloroacetic Acid
Chlorination gives MCAA, the route to carboxymethyl cellulose, glycine, thioglycolates and the glyphosate herbicide chain.
Food, Textile & Technical
Diluted to vinegar as an acidity regulator and preservative, used as a pH regulator in textile dyeing and leather processing, and as a general acidulant across industry.
Why source Acetic Acid through Chelora Petrochem?
Verified Origin
Full origin certification and asset-backed supply chain documentation — no grey-market supply.
Grade Flexibility
Glacial grade supplied as standard, with food-grade and low-metals options. Iron, chloride and permanganate time can be tightened for catalyst-sensitive or food-contact applications.
Full Documentation
CoA, SDS, UN transport docs, REACH compliance, and destination-market certificates with every shipment.
Logistics Support
Experienced in corrosive liquid logistics — stainless steel ISO tanks and lined vessels, heated or insulated movements where ambient approaches the 16.6 °C freezing point, and full UN 2789 documentation.
Storage & Handling Guidelines
Always refer to the full SDS before handling. The following is a summary of key requirements.
- Keep storage and lines above 20 °C — glacial acetic acid freezes at 16.6 °C, and a frozen line or valve will not be discovered until you try to move product.
- Use 316L stainless steel, or lined or high-alloy equipment; acetic acid attacks carbon steel and picks up iron, which discolours the product and fails specification.
- Bear in mind that dilute acetic acid is more aggressive to many metals than the glacial acid, so water ingress makes the corrosion problem worse rather than better.
- Treat it as both corrosive and flammable — flash point 39 °C means bonding, earthing and ATEX-rated equipment are required alongside corrosive-handling controls.
- Provide safety showers and eyewash within immediate reach of all transfer points; glacial acetic acid causes severe burns and serious eye damage.
- Fit local exhaust ventilation at sampling and drumming points; the vapour is irritating well below concentrations that would be obvious as a hazard.
- Keep away from strong oxidisers, strong bases, chromic acid, peroxides and permanganates — all react vigorously.
- Have absorbent and neutralising material available for spills, and never wash residues to drain without pH control.
Hazard Summary
Classification: Flam. Liq. 3 (H226) · Skin Corr. 1A (H314) · Eye Dam. 1 (H318).
Corrosivity: Glacial acetic acid causes severe skin burns and serious eye damage. It is a strong contact hazard rather than a systemic one — the injury happens where it lands, and eye splashes can cause permanent damage.
Dual hazard: The combination of corrosive and flammable is easy to under-plan for. A flash point of 39 °C means a warm warehouse or a hot day can bring the material close to producing an ignitable vapour, so corrosive-handling controls alone are not sufficient.
Exposure limits: ACGIH TLV 10 ppm 8-hour TWA with a 15 ppm STEL; OSHA PEL 10 ppm TWA. Confirm the limit in force in your jurisdiction.
Freezing: The acid solidifies below 16.6 °C and expands on thawing. Never apply direct flame or localised heat to thaw a frozen container or line — use controlled warm-water or steam tracing.
PPE minimum: Chemical splash goggles and face shield, butyl or neoprene gloves, acid-resistant apron or suit for transfer work, and organic-vapour respiratory protection where ventilation cannot hold exposure below the limit.
Consult the full SDS for exposure limits, spill containment, emergency response, and disposal before any use.
Frequently Asked Questions
Technical and commercial questions about Acetic Acid sourcing and specifications.
What is acetic acid used for?
Vinyl acetate monomer is the largest outlet, going into PVA and EVA for adhesives, paints, packaging film and solar encapsulant. Acetic acid is also the reaction solvent for PTA production, and it feeds acetic anhydride for cellulose acetate and pharmaceutical acetylation, the acetate ester solvents, and monochloroacetic acid for the CMC and glyphosate chains. Food-grade material is diluted to vinegar.
Why is it called glacial acetic acid?
Because pure acetic acid freezes at 16.6 °C into a colourless crystalline solid that looks like ice. That is only just below normal room temperature, so the pure acid will solidify on a cold day — which is a genuine operational problem, not a curiosity. 'Glacial' distinguishes the essentially water-free acid from the dilute aqueous solutions.
How is acetic acid produced?
Roughly three quarters of world capacity is methanol carbonylation — reacting methanol with carbon monoxide over a rhodium catalyst in the Monsanto process, or an iridium catalyst in BP's Cativa process, which is now the dominant technology. The remainder comes from acetaldehyde oxidation, direct ethylene oxidation, and bacterial fermentation for food-grade vinegar.
Why does the specification include a freezing point?
Because it is a sensitive and quick purity check. Water and other impurities depress acetic acid's freezing point measurably, so a minimum freezing point of around 16.35 °C confirms the material is genuinely glacial without waiting for a full chromatographic assay. It is reported alongside the water content on most certificates.
What materials are suitable for acetic acid service?
316L stainless steel is the normal choice, with lined or higher-alloy equipment for more demanding duty. Carbon steel is not suitable — it corrodes and contaminates the product with iron, which shows up as colour and fails specification. An important and counter-intuitive point: dilute acetic acid is more corrosive to many metals than the glacial acid, so water ingress makes the situation worse. Confirm material compatibility for your actual concentration and temperature.
What documentation does Chelora provide?
Every shipment includes a Certificate of Analysis covering purity, freezing point, water, formic acid, acetaldehyde, iron, heavy metals, chloride, sulphate, permanganate time, residue on evaporation and colour; a Safety Data Sheet (GHS/REACH); UN 2789 Class 8 with subsidiary risk 3, PG II transport documentation; an origin certificate; and any destination-market or food-contact certificates required.
Request a quote or specification sheet
Talk to Chelora's sourcing team about Acetic Acid grade, volume, logistics, documentation, and lead times. We respond within one business day.
