Hexamine · methenamine · urotropine · Powder, granules and crystals
Hexamethylenetetramine is the odd one out in any list of amines. It is not a chain with amino groups on the ends — it is a rigid cage of four nitrogens bridged by six methylene groups, with no N–H bond anywhere on the molecule. That structure makes it almost inert at room temperature and a generous source of both formaldehyde and ammonia when heated or acidified, which is exactly what a novolac phenolic resin needs to crosslink. It is also a reportable explosives precursor in the European Union and controlled in a number of other markets, so it is supplied against a confirmed end use. Chelora Amines supplies HMTA as powder, granules and crystals, with a batch-wise COA and SDS on every dispatch.
72.06 + 12.10 + 56.03 = 140.19 g/mol
Hexamethylenetetramine — hexamine, methenamine, urotropine, HMTA — is a white crystalline solid, odourless to faintly amine-like, freely soluble in water and giving a mildly alkaline solution. It does not melt: heated strongly it sublimes and decomposes from around 260 °C. It burns readily with an almost smokeless flame, which is both why it is classified as a flammable solid and why it has been used for decades in solid fuel tablets.
Chemically it behaves nothing like the amines it sits alongside. There is no N–H bond on the molecule, so it does not cure epoxy, does not react with isocyanates as an amine and is a very weak base. What it does instead is store formaldehyde and ammonia in a stable, free-flowing solid and release them on heating or in acid. That is the whole basis of its biggest use: mixed into a novolac phenolic resin, it supplies the methylene bridges that crosslink the resin when the part is cured.
It also has a serious regulatory profile that has nothing to do with toxicity. Hexamine is listed in Annex II of the EU explosives precursors regulation as a reportable substance, which places duties on suppliers and users around suspicious transactions, disappearances and thefts, and a number of other jurisdictions impose their own controls. We supply it for industrial and professional use against a confirmed end use.
| Chemical name | Hexamethylenetetramine |
| Common synonyms | HMTA, hexamine, methenamine, urotropine, 1,3,5,7-tetraazaadamantane, formin |
| CAS number | 100-97-0 |
| EC / EINECS number | 202-905-8 |
| HS / HSN code | 2933 69 (heterocyclic compounds with nitrogen hetero-atoms only; HSN 2933 69 90 on Indian invoices) |
| Molecular formula | C₆H₁₂N₄ ((CH₂)₆N₄) |
| Molecular weight | 140.19 g/mol |
| Appearance | White crystalline powder, granules or crystals |
| Odour | Odourless to faintly amine-like |
| Melting behaviour | Does not melt; sublimes and decomposes from about 260 °C |
| Density | About 1.33 g/cm³ |
| Solubility in water | Freely soluble — roughly 85 g per 100 mL at 20 °C |
| pH, 10% aqueous solution | About 7–10 |
| Basicity | Very weak base — no N–H, tertiary nitrogens only |
| Decomposition products | Formaldehyde and ammonia, on heating or in acid |
| UN number | UN 1328, Hexamethylenetetramine, Class 4.1 (flammable solid), Packing Group III |
| Regulatory status | EU Regulation 2019/1148 Annex II — reportable explosives precursor; controls vary by jurisdiction |
Figures are typical values for the technical grade. Pharmacopoeial and food-grade material is tested against its own monograph. All values for the material you order are stated on its Certificate of Analysis and Safety Data Sheet.
Almost everything hexamine does industrially comes back to one fact: the cage is stable until you heat it or acidify it, and then it gives up formaldehyde and ammonia.
Blended into a novolac resin, hexamine decomposes at cure temperature and supplies the methylene bridges that link the phenolic chains — with the ammonia released acting as catalyst.
novolac + HMTA → cured resole networkIn acid the cage breaks down cleanly to formaldehyde and ammonium salt. This is the basis of its analytical determination and of its action as a urinary antiseptic.
(CH₂)₆N₄ + acid → 6 HCHO + 4 NH₄⁺On heating it sublimes and breaks down rather than melting, releasing formaldehyde and ammonia — the behaviour exploited in resin cure, foundry binders and refractory systems.
heat → HCHO + NH₃Paired with resorcinol and silica in the classic three-part bonding system, hexamine provides the methylene donor that builds the resin in situ during vulcanisation.
methylene donor in HRH bondingFormylates activated aromatic rings ortho to a phenolic hydroxyl — a standard laboratory and fine-chemical route to salicylaldehyde derivatives.
ArOH + HMTA → ortho-aldehydeConverts benzylic halides to the corresponding aldehydes through the quaternary hexaminium salt, under mild conditions and without over-oxidation.
ArCH₂X → ArCHOConverts alkyl halides to primary amines through the same quaternary salt followed by acid cleavage — a clean alternative to direct ammonia alkylation.
RX → RNH₂Adsorbs on steel surfaces in acid, slowing attack on the metal while leaving scale dissolution largely unaffected — hence its use in pickling and acidising inhibitor packages.
inhibitor film on steel in acidHexamine is a formaldehyde source, and that has two consequences worth planning for. In the process, the formaldehyde and ammonia it releases have to go somewhere — cure ovens, presses and foundry lines need extraction sized for it. In the product, residual free formaldehyde may be subject to emission limits depending on where the finished article ends up. Both are easier to design for than to retrofit.
Discuss your processHexamine is made in one step, by reacting formaldehyde with ammonia. The chemistry is simple; the work is in crystallisation and in keeping the product dry and free-flowing.
Aqueous formaldehyde and ammonia, in the ratio the stoichiometry demands — six molecules of formaldehyde to four of ammonia.
Ammonia is absorbed into formalin under controlled temperature and pH; the cage assembles directly, with water as the only by-product.
The solution is evaporated under vacuum, keeping temperature low enough that the product does not begin to decompose.
Crystals are grown, separated by centrifuge and washed; crystal size here sets whether the product behaves as a dusty powder or free-flowing granules.
Material is dried to specification, screened to the grade's particle size and bagged or filled into bulk bags in a dust-controlled plant.
Particle size is not a cosmetic choice with hexamine, and it is the specification most often left off an enquiry. Fine powder disperses quickly and evenly into a novolac resin or a friction compound, which is what a moulding or brake pad formulator wants, but it dusts badly and dust is both a nuisance and a flammability consideration. Granular and crystalline grades flow cleanly, charge with far less airborne dust and suit automated weighing, but they take longer to disperse and can leave unreacted hexamine in a short mixing cycle. Pick on the mixing time you actually have, and if you are moving from one form to another, expect to re-check your cure profile rather than assuming it carries across.
Hexamine is stable in storage if it is kept dry and away from acids. Moisture causes caking and, over time, slow hydrolysis releasing formaldehyde; acid contact does the same thing quickly, so it must be segregated from acids in both storage and spill planning. It is a flammable solid that ignites readily and burns with an almost invisible flame, so ignition sources need controlling and a fire in a hexamine store will not look like a fire until you are close to it. Keep packs sealed, palletised and under cover, store below about 30 °C, and treat the material as dust-explosive in handling design where the powder grade is used in quantity.
Assay and ash separate the industrial grades from each other; particle size separates them in practice.
Powder, granular or crystal for phenolic resins, friction materials, abrasives, foundry binders and rubber bonding systems.
Tighter ash, chloride and heavy metal limits for electronic-grade resins, analytical use and demanding resin systems.
Material tested against the applicable pharmacopoeial or food-additive monograph, supplied with the corresponding documentation.
| Parameter | Test method | Typical specification |
|---|---|---|
| Appearance | Visual | White crystalline powder, granules or crystals |
| Assay, dry basis | Acid back-titration | ≥ 99.0% w/w |
| Loss on drying | 105 °C, 4 h | ≤ 0.5% w/w |
| Residue on ignition (ash) | Gravimetric | ≤ 0.03% w/w |
| pH, 10% solution | pH meter | 7.0 – 10.0 |
| Chlorides | Turbidimetric | ≤ 0.015% w/w |
| Sulphates | Turbidimetric | ≤ 0.02% w/w |
| Heavy metals (as Pb) | Colorimetric | ≤ 10 ppm |
| Particle size | Sieve analysis | To the grade ordered |
Indicative specification for planning. The controlling document is the Certificate of Analysis issued for your batch. State the particle size you need at enquiry stage — it is the parameter most often omitted and the one most likely to affect your process.
Phenolic resin chemistry takes most of the volume, and a surprisingly wide tail takes the rest.
The dominant outlet. Blended into novolac phenolic resins as the crosslinker for moulding compounds, laminates, binders and composite systems.
The hardener in phenolic-bonded brake pads, brake linings and clutch facings, where the cured resin has to hold its strength hot.
Resin-bonded grinding wheels, cutting discs and coated abrasives, and phenolic-bonded refractory shapes and ramming masses.
The hardener in resin-coated sand for shell moulding and core making, giving fast, reliable cure on a hot pattern.
The methylene donor in resorcinol-based bonding systems for steel cord and textile adhesion, and a secondary accelerator in some compounds.
Used in pickling and acidising inhibitor packages, where it slows attack on steel while leaving scale removal largely unaffected.
As methenamine and its salts, a long-established urinary antiseptic that works by releasing formaldehyde in acidic urine. Requires monograph-grade material.
The reagent behind the Duff, Sommelet and Delépine reactions, and a standard buffer and reagent in analytical chemistry.
From brake pads to grinding wheels — the value chain downstream of hexamethylenetetramine.
| Application | What hexamine does | End product |
|---|---|---|
| Novolac moulding compounds | Supplies methylene bridges and catalytic ammonia at cure temperature | Electrical components, closures, handles, engineering mouldings |
| Friction materials | Cures the phenolic binder that holds the friction formulation together | Brake pads, brake linings, clutch facings |
| Resin-bonded abrasives | Hardens the phenolic bond that holds the grain | Grinding wheels, cutting discs, coated abrasives |
| Shell moulding sand | Cures the resin coating on hot pattern contact | Foundry shells and cores for metal casting |
| Rubber bonding systems | Acts as the methylene donor alongside resorcinol and silica | Steel cord and textile adhesion in tyres and belting |
| Methenamine salts | Salt formation with hippuric or mandelic acid | Urinary antiseptic pharmaceutical products |
| Synthetic intermediates | Formylating, aminating and oxidising reagent in named reactions | Aldehydes, primary amines and fine-chemical intermediates |
Every container carries the Chelora Amines label with product name, grade, net weight, batch number, manufacturing date, UN number and hazard pictograms, including the flame pictogram. Packs are sealed against moisture.
PE-lined paper or polywoven bags, heat-sealed and palletised under shrink wrap. The standard pack for resin and compound producers.
Lined FIBCs with a discharge spout for contained charging — the better option wherever the powder grade is used in quantity.
Lined fibre or steel drums where a rigid moisture-tight pack is wanted, and 500 g to 5 kg containers for laboratory and trial use.
Two things to tell us at enquiry stage that buyers routinely leave out: the particle size you need, and the end use. The first decides whether the material disperses properly in your mix; the second we are required to establish before accepting an order. Export consignments are packed in UN-specification packaging with full dangerous goods documentation for a Class 4.1 flammable solid, and shipped FOB, CIF or CFR through Nhava Sheva and Mundra.
Plan my supplyHexamine is a flammable solid and may cause an allergic skin reaction. It is not corrosive and not acutely toxic in the way most amines on this site are, but it burns readily with an almost invisible flame, the powder grade presents a dust hazard, and contact with acid releases formaldehyde. The notes below are a summary for planning only; always work to the Safety Data Sheet and your own site risk assessment.
Regulatory status. Hexamine is listed in Annex II of Regulation (EU) 2019/1148 as a reportable explosives precursor, because it can be diverted into the manufacture of military explosives. Annex II status does not restrict sale to professional users, but it does create duties: economic operators must inform the supply chain, and suspicious transactions, disappearances and thefts must be reported to the national contact point. Several other jurisdictions impose their own licensing, record-keeping or reporting requirements. We confirm the end use before accepting an order, keep records of supply, and expect buyers to control and reconcile stock on their own sites. Check the position that applies where you operate rather than relying on a page like this one.
Confirm compliance| Parameter | Specification | Result |
|---|---|---|
| Appearance | White crystalline solid | Complies |
| Assay, dry basis | ≥ 99.0% | Complies |
| Loss on drying | ≤ 0.5% | Complies |
| Residue on ignition | ≤ 0.03% | Complies |
| pH, 10% solution | 7.0 – 10.0 | Complies |
| Heavy metals (as Pb) | ≤ 10 ppm | Complies |
Hexamine is checked before dispatch. Each consignment leaves with the paperwork your QC, EHS, stores and accounts teams need on day one — and, for this product, the records that the precursor obligations expect.
Five steps for a first order of hexamine. The end-use check in step two is specific to this product.
Grade, particle size, quantity, pack size, intended application and your delivery location.
We confirm the intended use and the regulatory position in the destination market before an order is accepted — this is a precursor obligation, not a formality.
We quote, then the batch is tested — assay, moisture, ash, pH and particle size — and the COA and SDS are prepared.
Sealed, labelled bags, FIBCs or drums move under dangerous goods documentation for a Class 4.1 flammable solid.
Material reaches your gate and repeat dispatches are scheduled to your usage, with supply records kept on both sides.
Buyers who order hexamine usually source these from the same list. See the full product range for the complete picture.
Short answers to what purchase, lab, EHS and plant teams ask us most. Anything else, ask us directly.
Send the grade, particle size, quantity, pack size, intended end use and your delivery address or destination port. We come back with a price, the documents that go with the batch and a dispatch or shipping plan, usually within 24 hours.