What is "cyanoform"

n. (context organic compound English) The compound CH(CN)₃ analogous to the haloforms

Cyanoform (tricyanomethane) is a cyanocarbon and derivative of methane with three cyano groups. For many years, chemists have been unable to isolate this compound as a neat, free acid. However, in September 2015, reports surfaced of a successful isolation.

Dilute solutions of this acid, as well as its salts, have long been well known. Cyanoform ranks as one of the most acidic of the carbon acids with an estimated pK of -5.1 in water and measured pK 5.1 in acetonitrile. The reaction of sulfuric acid with sodium tricyanomethanide in water (a reaction first tried by H. Schmidtmann in 1896 with inconclusive results) is reported to result in the formation of the hydrate (NC)CHO or the formation of (Z)-3- amino-2-cyano-3-hydroxyacrylamide (HN)(OH)C=C(CN)CONH depending on the precise conditions. The reaction of HCl gas with sodium tricyanomethanide dissolved in THF is reported to yield 1-chloro-1-amino-2,2-dicyanoethylene ((NC)C=C(NH)Cl) and its tautomer.