Melamine

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15 atoms, 15 bonds.

IUPAC name: 1,3,5-triazine-2,4,6-triamine
Molar mass: 126.123(13) g/mol
Atoms: 15
SMILES: C1(=NC(=NC(=N1)N)N)N
InChIKey: JDSHMPZPIAZGSV-UHFFFAOYSA-N
PubChem CID: 7955

Made of

Structural formula of melamine. Each unlabelled corner is a carbon atom. It shows which atoms are joined to which, not the shape. The model above shows the shape.

Melamine is approved in the United States for making some cooking utensils, plates, paper, paperboard and industrial coatings, according to the US Food and Drug Administration (FDA). It may not be added directly to human food or animal feed. The compound is C₃H₆N₆, built from carbon, hydrogen and nitrogen, with a molar mass of 126.12 g/mol. Its IUPAC name describes a ring of three carbon and three nitrogen atoms, 1,3,5-triazine, carrying three amino groups, NH₂. Its high nitrogen content, singled out by FDA, later drew it into food fraud.

Melamine forms colourless to white crystals or a white powder that sublimes, passing straight to vapour, when warmed gently, in CAMEO Chemicals’ description. On the International Chemical Safety Cards (ICSC) it has no melting point and decomposes above 345 °C. Its melting point is 354 °C in the Hazardous Substances Data Bank (HSDB).

Structure and bonding

In melamine, carbon and nitrogen take turns around a six-membered ring, and each carbon carries an NH₂ group pointing outward. The Labels button marks three C, six N and six H; half the nitrogens sit in the ring, half in the amino groups. Turned edge-on, the model thins to a line: PubChem’s computed conformer keeps every atom within 0.002 Å of one plane. The Stick view shows the same flat, three-cornered frame, and the Space-filling view fills it out into a single slab.

The ring is drawn with three double bonds alternating with three single ones, one of two equivalent ways to place them. Yet in the model’s coordinates all six ring bonds measure 1.343 Å, against 1.412 Å for each bond to an amino group. Stephen Lower’s Chem1 text treats a structure with two equivalent bond arrangements as a resonance hybrid, the idea the benzene page sets out.

The model shows the neutral molecule. ChEBI, the database of Chemical Entities of Biological Interest, calls melamine the conjugate base of melamine(1+), the cation it forms by taking up a hydrogen ion. CAMEO notes that it neutralises acids, forming salts.

Where it turns up

Industry makes melamine from urea, by a low-pressure or a high-pressure process, according to HSDB. The carbon dioxide and ammonia given off go back into urea production. More than 95 per cent of world output becomes thermosetting resins for laminates, moulding compounds, protective coatings, paper coatings and textile finishes. Once such a resin has set, the idea of a separate molecule largely loses its meaning, so in Chem1’s account the resin has no melting point. FDA describes melamine tableware as melamine-formaldehyde resin shaped under heat.

Most of the remainder serves, as crystals or salts, in flame-retardant and moisture-resistant products. Its resins also go into adhesives for wood-based panels, and melamine or its resins into flame-retardant additives for foam mattresses, according to FDA’s guidance on melamine contamination. HSDB records the resin soaked into plaster of Paris bandages so that casts set faster.

Why it matters

In 2007 cats and dogs began falling ill and dying after eating certain pet foods. FDA traced the cause to melamine in wheat gluten and rice protein shipped from China. By 2008 the recalls that followed were the most numerous in FDA history, the agency reported. The animals had kidney failure, with crystals inside the kidney tubules made mostly of melamine-cyanurate. Melamine and cyanuric acid assemble through hydrogen bonding into a complex that barely dissolves in most solvents. FDA names this the probable cause of the pet food’s unexpectedly high toxicity.

In 2008 Chinese manufacturers put melamine into infant formula so that it would seem to contain enough protein. One way to estimate protein is to measure nitrogen, and a nitrogen test could not tell melamine from protein, FDA explains. Babies suffered kidney failure; FDA’s food-fraud page cites news reports of more than 300,000 illnesses, 50,000 hospitalisations and at least six deaths. FDA’s guidance on melamine contamination records thousands of hospital admissions for kidney trouble and at least three deaths.

Properties

Properties of melamine Molar mass summed from IUPAC/CIAAW 2024 standard atomic weights; formula, atom and bond counts and PubChem's molecular weight from PubChem CID 7955.
Property	Value	Unit	Source
Molecular formula (Hill order)	C₃H₆N₆
Molar mass	126.123(13) g/mol	g/mol	IUPAC/CIAAW 2024
Carbon atoms	3
Hydrogen atoms	6
Nitrogen atoms	6
Bonds	15
Single bonds	12
Double bonds	3
PubChem molecular weight	126.12 g/mol	g/mol	PubChem

Safety

The European Union classifies melamine as suspected of causing cancer and as able to harm organs through prolonged or repeated exposure, under the signal word Warning. A Japanese classification names the urinary organs as the target. On heating or burning it decomposes, giving off toxic and irritating fumes that include hydrogen cyanide, nitrogen oxides and ammonia, according to the ICSC. Workplace exposure limits exist, and the PubChem Laboratory Chemical Safety Summary for melamine sets out the full classification.

Questions

What is the chemical structure of melamine?

Melamine, C₃H₆N₆, is a six-membered ring in which three carbon atoms alternate with three nitrogen atoms, and each carbon holds an NH₂ group. ChEBI, the database of Chemical Entities of Biological Interest, calls it a trimer of cyanamide: three cyanamide units joined on a 1,3,5-triazine skeleton. In PubChem's computed 3D model, every one of the 15 atoms lies almost exactly in one plane.

Why did melamine fool protein tests?

One way to estimate a food's protein is from how much nitrogen it holds, and FDA describes melamine as a nitrogen-based compound with a high nitrogen content: six of the 15 atoms in C₃H₆N₆ are nitrogen. In the nitrogen assay FDA describes, every nitrogen atom in a sample ends up as ammonia, which is then measured. A buyer relying on that test, FDA explains, could not have told melamine apart from real protein.

Is melamine dinnerware safe to eat from?

Melamine plates and bowls are moulded from melamine-formaldehyde resin, and FDA explains that a small amount of melamine left over from making the resin stays in the plastic. That residue can creep very slowly into food touching the tableware. In the tests FDA reports, it did not migrate into most foods; the only measured migration was into acidic foods, under exaggerated conditions.

Does melamine cause cancer?

In a 1983 feeding study by the US National Toxicology Program, melamine caused bladder cancer in male rats, and all but one of those rats also had bladder stones. Melamine did not cause cancer in female rats or in mice of either sex. The EU classifies melamine as suspected of causing cancer, and California's Safe Cosmetics Program lists it among the Group 2B carcinogens of the International Agency for Research on Cancer (IARC).

Made of the same elements

C₅H₅N₅ Adenine 15 atoms, 16 bonds.
C₄H₁₁N₅ Metformin 20 atoms, 19 bonds.
C₅H₉N₃ Histamine 17 atoms, 17 bonds.
(CH₃)₃N Trimethylamine 13 atoms, 12 single bonds.
C₁₀H₁₄N₂ Nicotine 26 atoms, 27 bonds.