Malononitrile is an organic compound nitrile with the formula . It is a colorless or white solid, although aged samples appear yellow or even brown. It is a widely used building block in organic synthesis.
It can be prepared by dehydration of cyanoacetamide.[1] This method is mainly practiced in China where environmental rules are lax. Most commonly malononitrile is produced by the gas-phase reaction of acetonitrile and cyanogen chloride:[2]
About 20,000,000 kg are produced annually (2007). Important outlets include the synthesis of thiamine, the drug triamterene and minoxidil, and the dyes disperse Yellow 90 and disperse Blue 354.[2]
Malononitrile is relatively acidic, with a pKa of 11 in water.[3] This allows it to be used in the Knoevenagel condensation, for example in the preparation of CS gas:
Malononitrile is a suitable starting material for the Gewald reaction, where the nitrile condenses with a ketone or aldehyde in the presence of elemental sulfur and a base to produce a 2-aminothiophene.[4]