Melamine Cyanurate (CAS: 37640-57-6)

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 to that seen in DNA base pairing.[2] Melamine cyanurate forms spoke-like crystals from aqueous solutions and has been implicated as a causative agent for toxicity seen in the Chinese protein export contamination and the 2007 pet food recall.

Chemistry

The substance is best described as a melamine-cyanuric acid co-crystallate, complex, or non-covalent adduct. The two compounds do not form a salt as suggested by its non-systematic trivial name melamine cyanurate.

Melamine and cyanuric acid form a jigsaw puzzle-like two-dimensional hydrogen bonding network because of the complementarity of the two compounds, similar to DNA base pairing.

Uses

Melamine cyanurate is commonly used as a fire retardant.

Toxicity

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

LD50 in rats and mice (ingested):

•     4.1 g/kg – Melamine cyanurate

•     6.0 g/kg – Melamine

•     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 renal failure in cats. A 2008 study produced similar experimental results in rats and characterized the melamine and cyanuric acid in contaminated pet food from the 2007 outbreak.