Prepd by saturating with HCl a soln of resorcinol and anhydr hydrocyanic acid in abs ether and boiling the precipitated resorcylaldimide-HCl with water: Gattermann, K"obner, Ber. 32, 278 (1899); DE 106508; Chem. Zentralbl. 1900, I, 742. By adding POCl3 to a soln of resorcinol and formanilide in ether, then boiling with dil NaOH, acidifying with H2SO4 and extracting with ether: Dimrath, Z"oppritz, Ber. 35, 995 (1902); by passing HCl into a mixture of resorcinol, ether, anhydr zinc chloride and cyanogen bromide, then boiling the precipitate with water: Karrer, Helv. Chim. Acta 2, 92 (1919).