A compound containing the —CN group, for example, potassium cyanide, KCN; calcium cyanide, Ca(CN)₂; and hydrocyanic (or prussic) acid, HCN. Chemically, the simple inorganic cyanides resemble chlorides in many ways. Organic compounds containing this group are called nitriles. Acrylonitrile, CH₂CHCN, is an important starting material in the manufacture of fabrics, plastics, and synthetic rubber.