Melamine cyanurate

Melamine cyanurate, also known as melamine–cyanuric acid adduct or melamine–cyanuric acid complex, is a crystalline complex formed from a 1:1 mixture of melamine and cyanuric acid. The substance is not a salt despite its non-systematic name melamine cyanurate. The complex is held together by an extensive two-dimensional network of hydrogen bonds between the two compounds, reminiscent of the guanine–cytosine base pairs found in DNA.^[2] Melamine cyanurate forms spoke-like crystals from aqueous solutions ^[3] and has been implicated as a causative agent for toxicity seen in the Chinese protein export contamination and the 2007 pet food recall.^[3] This complex is cited as an example of supramolecular chemistry.^[4]

Melamine-cyanuric acid complex^[1]

Names
Preferred IUPAC name 1,3,5-Triazinane-2,4,6-trione—1,3,5-triazine-2,4,6-triamine (1/1)
Other names Melamine–cyanuric acid compound, melamine–cyanuric acid adduct, melamine cyanurate, melamine isocyanurate
Identifiers
CAS Number	37640-57-6 Y 70371-20-9 N
3D model (JSmol)	Interactive image
ChemSpider	84141 N
ECHA InfoCard	100.048.687
MeSH	melamine+cyanurate
PubChem CID	93198
CompTox Dashboard (EPA)	DTXSID3068043
InChI InChI=1S/C3H6N6.C3H3N3O3/c4-1-7-2(5)9-3(6)8-1;7-1-4-2(8)6-3(9)5-1/h(H6,4,5,6,7,8,9);(H3,4,5,6,7,8,9) N Key: ZQKXQUJXLSSJCH-UHFFFAOYSA-N N
SMILES c1(nc(nc(n1)N)N)N.c1(=O)[nH]c(=O)[nH]c(=O)[nH]1
Properties
Chemical formula	C6H9N9O3 (C3H6N6·C3H3N3O3)
Molar mass	255.19 g/mol
Solubility in water	none
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Uses

Melamine cyanurate is used as a flame retardant, most commonly in polybutylene terephthalate (PBT), polyamide 6 (nylon 6) and polyamide 6,6 (nylon 6:6).^[5] It is also used to fireproof in polyester fabrics.

Toxicity

It has been considered to be more toxic than either melamine or cyanuric acid alone.^[6]

LD₅₀ in rats and mice (ingested):

• 4.1 g/kg – Melamine cyanurate
• 6.0 g/kg – Melamine^{[clarification needed]}
• 7.7 g/kg – Cyanuric acid

A toxicology study conducted after recent pet food recalls concluded that the combination of melamine and cyanuric acid in diet does lead to acute kidney injury in cats.^[7] A 2008 study produced similar experimental results in rats and characterized the melamine and cyanuric acid in contaminated pet food from the 2007 outbreak.^[8]

Section of the extensive two-dimensional hydrogen bond network (dashed) between melamine (blue) and cyanuric acid (red)

See also

• 1,3,5-Triazine
• Hydrogen bonding

References

1. EPA: Substance : Archived 2008-09-22 at the Wayback Machine
2. Perdigão LM, Champness NR, Beton PH (2006). "Surface self-assembly of the cyanuric acid-melamine hydrogen bonded network". Chem. Commun. (5): 538–540. doi:10.1039/b514389f. PMID 16432575.
3. Lili He; Yang Liu; Mengshi Lin; Joseph Awika; David R Ledoux; Hao Li; Azlin Mustapha (2008). "A new approach to measure melamine, cyanuric acid, and melamine cyanurate using surface enhanced Raman spectroscopy coupled with gold nanosubstrates". Sens. & Instrumen. Food Qual. 2: 66–71. doi:10.1007/s11694-008-9038-0. S2CID 93425738.
4. Lehn, J. M. (1995). Supramolecular Chemistry: Concepts and Perspectives. Weinheim: VCH.
5. Gijsman, Pieter; Steenbakkers, Rieky; Fürst, Christian; Kersjes, Joyce (2002). "Differences in the flame retardant mechanism of melamine cyanurate in polyamide 6 and polyamide 66". Polymer Degradation and Stability. 78 (2): 219–224. doi:10.1016/S0141-3910(02)00136-2.
6. A.A. Babayan, A.V.Aleksandryan, "Toxicological characteristics of melamine cyanurate, melamine and cyanuric acid", Zhurnal Eksperimental'noi i Klinicheskoi Meditsiny, Vol.25, 345-9 (1985). Original article in Russian.
7. Puschner et al. (November 2007). Assessment of melamine and cyanuric acid toxicity in cats. Journal of Veterinary Diagnostic Investigation. Retrieved on 2007-11-16.
8. Dobson; et al. (August 2008). "Identification and characterization of toxicity of contaminants in pet food leading to an outbreak of renal toxicity in cats and dogs". Toxicological Sciences. 106 (1): 251–62. doi:10.1093/toxsci/kfn160. PMID 18689873.