Safer and Convenient Synthesis of 3,4-Dicyanofuroxan

A safer, convenient,
cost-effective, and scalable synthesis for
3,4-dicyanofuroxan (C4N4O2) is described.
Dropwise treatment of a well-stirred suspension of cyanoacetic acid
in dichloromethane with concentrated mixed acid (HNO3/H2SO4) affords dicyanofuroxan in 72% yield and in
84% purity after liquid chromatography analysis. Single crystal X-ray
diffraction studies further confirm the product and yield its molecular
conformation and crystal packing. During the dropwise addition of
mixed acid, self-heating occurs, and this event is necessary for the
reaction to adequately proceed. However, such self-heating is limited
to the refluxing temperature of dichloromethane. This new method supersedes
the previous methods used to synthesize dicyanofuroxan, which were
low-yielding and of significantly lower purity, irreproducible, relied
on expensive reagents, and suffered from dangerous exothermic profiles.