What Hexadecylamine Is
Hexadecylamine, also written 1-hexadecylamine or cetylamine, is a primary alkylamine with a straight 16-carbon chain and a terminal amino group. Its molecular formula is C16H35N and its molecular weight is 241.46 g/mol. It appears as a white to pale yellow powder or waxy solid with a mild, characteristic amine odour and melts in the range of 46-50 °C, so it stays solid under normal storage and transport conditions.
The compound is practically insoluble in water but dissolves in ethanol, ether and chloroform. Its structure pairs a long hydrophobic hexadecyl chain with a hydrophilic amino head, which gives it strong surface activity and makes it valuable wherever a durable hydrophobic layer or a cationic charge is needed.
Typical Specification
| Parameter | Typical value |
|---|---|
| CAS number | 143-27-1 |
| Molecular formula | C16H35N |
| Molecular weight | 241.46 g/mol |
| Appearance | White to pale yellow powder or waxy solid |
| Assay (total amine, titrimetric) | 98% minimum |
| Melting range | 46-50 °C |
| Water content | 0.3% maximum |
| Solubility | Insoluble in water; soluble in ethanol, ether and chloroform |
| Packaging | 25 kg lined fibre drum, 160 kg steel drum or 800 kg intermediate bulk container |
Surfactant and Personal Care Intermediates
1-Hexadecylamine is widely used to build cationic surfactants. Because the C16 chain is longer than the C12 analogue, the resulting surfactants deposit a softer, more substantial film on fibres and hair, which is exactly what conditioning products require.
Cationic surfactants: reaction with acids or with alkylating agents yields amine salts and quaternary ammonium compounds used in fabric softeners, hair conditioners and antistatic agents.
Substantivity: the positively charged head adsorbs on the negatively charged surface of hair and textiles, while the long chain lubricates the surface and reduces friction and static.
Emulsifiers: the amine and its ethoxylates stabilise oil-in-water and water-in-oil emulsions in creams, lotions and industrial formulations.
Corrosion Inhibition
Hexadecylamine acts as an excellent corrosion inhibitor for metals. The polar amino group chemisorbs on steel, copper and other metal surfaces, and the C16 chains pack side by side into a dense, water-repellent film that keeps moisture, oxygen and corrosive ions away from the metal.
Cooling water and closed circuits: low continuous dose rates protect carbon steel and copper alloys in recirculating systems.
Oil tanks and pipelines: as a filming amine it limits internal corrosion of wet pipelines, tank bottoms and cargo tanks.
Metal processing equipment: it extends the service life of pickling lines, rinse stages and machining equipment exposed to aqueous media.
Comparison with shorter chain amines: the longer C16 tail gives a thicker and more persistent barrier, so lower treat rates are often sufficient.
Lubricant Additives and Tribological Use
In lubricants, hexadecylamine functions as an additive that improves performance at the metal interface. The amino group adsorbs on the rubbing surface and the alkyl chains create a boundary layer that carries part of the load.
Friction modification: the adsorbed film lowers friction between moving metal parts in machinery and automotive assemblies.
Antiwear behaviour: by separating asperities it reduces wear and scoring under boundary lubrication conditions.
Adhesion improvement: it helps the lubricant itself cling to metal surfaces, which is useful in chains, open gears and wire drawing.
Mining, Agriculture and Other Uses
Flotation collector: in mining it renders target silicate and oxide minerals hydrophobic so they attach to air bubbles and rise for collection in the froth.
Pesticide formulations: it serves as an emulsifier that helps oil-based actives disperse in water, and it improves the adhesion of the spray deposit to plant surfaces.
Pigment and bitumen additives: it acts as a dispersing and adhesion-promoting agent in coatings, inks and asphalt systems.
Intermediate chemistry: it is a building block for amine oxides, betaines and specialty quaternary salts.
Quality Control, Handling and Storage
Typical release testing covers appearance, total amine value by titration, melting range, colour and water content by Karl Fischer titration. Because the material is a solid with a relatively high melting point, it is normally supplied as powder or flakes and needs no heated handling.
Store in a cool, dry, well-ventilated area in tightly closed containers, away from acids, oxidising agents and direct sunlight.
Wear gloves, safety goggles and dust respiratory protection where powder or dust is generated; provide local exhaust ventilation at transfer points.
Keep the material dry: moisture uptake causes caking, which complicates dosing and blending.
Frequently Asked Questions
Q: What is hexadecylamine used for?
A: Its main uses are the production of cationic surfactants for conditioning and softening products, corrosion inhibition of metals, lubricant additives, minerals flotation and agricultural emulsifiers.
Q: Is hexadecylamine soluble in water?
A: No. It is insoluble in water but soluble in organic solvents such as ethanol, ether and chloroform, and it becomes water dispersible after conversion to an acid salt.
Q: How does it differ from dodecylamine?
A: The C16 chain is longer than the C12 analogue, giving a higher melting point, a thicker adsorbed film, stronger conditioning performance and lower treat rates in corrosion service.
Q: What is the melting point?
A: Commercial hexadecylamine melts in the range of 46-50 °C, so it remains a solid powder or waxy solid throughout normal storage and shipping.
Q: Which parameters should a buyer specify?
A: Assay as total amine value, melting range, colour and water content are the key parameters, together with particle form and packing configuration.
Q: Is it used in lubricants?
A: Yes. It improves lubricant adhesion to metal, reduces friction and wear between moving parts and is used in machinery and automotive applications.