Hydrocyanic acid flammability limits

Hydrogen cyanide, HCN or hydrocyanic acid, is a remarkably versatile Q building block for the modern synthetic chemist today. Its use, however, has been limited by its relatively difficult synthesis/purification as well as by its high flammability, its tendency toward base-catalyzed explosive polymerization, and its toxicity. Most of the recent hydrocyanation literature comes from industry rather than academic laboratories. 

---