Hydrogen cyanide is a highly toxic clear to pale blue liquid or gas with
the odor of bitter almonds. It melts at -14 C and boils at 25.6 C. It is
miscible in water or ethanol and is slightly soluble in ether. Its water
solution, called hydrocyanic acid, is a weak acid. Hydrogen cyanide is mainly
obtained by the reaction of ammonia with carbon
monoxide (Andrussow process) or with natural gas (methane) in the presence of rhodium/platinum catalyst at approximately 1100
C. Very short contact time (milliseconds) is required
to obtain the optimum yield and consequently a high operating temperature is required to reach equilibrium.
It can be
prepared also by the reaction of cyanide salts, e.g., calcium cyanide, with a
strong acid (sulfuric acid). Hydrogen cyanide is obtained as a by-product from
acrylonitrile production. But the portion is small. It is used as a fumigant in
agriculture. The principal use of hydrogen cyanide is in the manufacturing of
acrylates, synthetic fibers (as a starting material for nylon 66), plastics and
cyanide salts, especially sodium cyanide to extract gold from ore. It is used in the manufacturing of organic chemicals; acrylonitrile,
metal
polishes, dyes, rodenticides, pesticides, synthetic fibers, plastics, and
electroplating solutions. Cyanide salts are utilized in metal cleaning, tempering of steel,
gardening, in ore-extracting
processes, dyeing, printing and photography, electroplating (gold and silver bath), various organic
reactions (Organic
cyanide and nitrile synthesis) manufacture of adiponitril for nylon production. Also used for production of monomers (e.g. acrylates)
as well as in fumigants and pesticides. |