Chemical Properties
Sodium thiocyanate, a white rhombic system crystal, is soluble in water, ethanol, acetone; Relative density is 1.735. Melts at approx. 287℃. Decomposes on heating and under influence of light producing toxic fumes of sulfur oxides,nitrogen oxides and cyanides. Reacts violently with acids,strong bases and strong oxidants.
Uses
Sodium thiocyanate is a valuable chemical raw material and has important uses in various sectors of the national economy. Sodium thiocyanate is mainly used as a solvent for spinning acrylic fibers, chemical analysis reagents, color film film rinses, certain plant defoliants, and airport road herbicides. Sodium thiocyanate is also used in pharmaceuticals, printing and dyeing, rubber processing, black nickel plating, and artificial mustard. Oil, etc. The main industrial production processes are: separation of sodium thiocyanate from waste liquid in coke oven gas, synthesis of sodium thiocyanate with sodium cyanide and sulfur, and production of sodium thiocyanate by metathesis reaction of ammonium thiocyanate and sodium hydroxide. The synthesis of sodium thiocyanate requires high purity HCN as raw material, which is costly and harsh.
Chemical Properties
white crystalline powder
Physical properties
Colorless crystals or white powder; deliquescent; melts at 287°C; very soluble in water; soluble in alcohol.
Uses
Sodium Thiocyanate is used widely in chemical synthesis as source of thiocyanate anion such as in the conversion of alkyl halides to alkylthiocyanates.
Uses
manufacture of other thiocyanates, especially organic.
Definition
ChEBI: An organic sodium salt which is the monosodium salt of thiocyanic acid.
Preparation
Sodium thiocyanate is prepared by boiling an aqueous solution of sodium cyanide with sulfur: NaCN + S → NaSCN.
Reactions
Sodium thiocyanate is an analytical reagent for measuring iodide. Other uses are dyeing and printing textiles, preparing thiocyanate salts, and nickel plating. Used in titrimetry.
General Description
Odorless white solid. Sinks and mixes with water.
Air & Water Reactions
Water soluble.
Reactivity Profile
Nitric acid violently oxidized a thiocyanate solution [Bretherick 1979 p. 121]. Caution should be exercised in treating a thiocyanate with an oxidizing agent such as a peroxide or chlorate as such mixtures have been known to explode. Special Hazards of Combustion Products: Irritating oxides of sulfur and nitrogen may form in fire [USCG, 1999]. Carbonyl sulfide is produced in a violent reaction by the mixture of sulfuric acid and Sodium thiocyanate.
Health Hazard
Inhalation of dust causes irritation of nose and throat. Ingestion of large doses causes vomiting, extreme cerebral excitement, convulsions, and death in 10-48 hrs.; chronic poisoning can cause flu-like symptoms, skin rashes, weakness, fatigue, vertigo, nausea, vomiting, diarrhea, confusion. Contact with eyes causes irritation. Prolonged contact with skin may produce various skin eruptions, dizziness, cramps, nausea, and mild to severe disturbance of the nervous system.
Fire Hazard
Special Hazards of Combustion Products: Irritating oxides of sulfur and nitrogen may form in fire.
Flammability and Explosibility
Non flammable
Safety Profile
Poison by ingestion, intravenous, and subcutaneous routes. Moderately toxic by intraperitoneal route. Large doses taken internally cause vomiting, convulsions. Chronic poisoning is manifested by weakness, confusion, diarrhea, and skin rashes. When heated to decomposition it emits very toxic fumes of NOx, SOx, and Na2O. See also THIOCYANATES.
Purification Methods
It is recrystallised from EtOH or Me2CO, and the mother liquor is removed from the crystals by centrifugation. It is very deliquescent and should be kept in an oven at 130o before use. It can be dried in a vacuum at 120o/P2O5 [Partington & Winterton Trans Faraday Soc 30 1104 1934]. Its solubility in H2O is 113% at 10o, 178% at 46o, 225.6% at 101.4o; in MeOH 35% at 15.8o, 51% at 48o, 53.5% at 52.3o; in EtOH 18.4% at 18.8o, 24.4% at 70.9o; and in Me2CO 6.85% at 18.8o and 21.4% at 56o [Hughes & Mead J Chem Soc 2282 1929]. Sodium thiocyanate has also been recrystallised from water, acetonitrile or from MeOH using Et2O for washing, then dried at 130o, or dried under vacuum at 60o for 2days. [Strasser et al. J Am Chem Soc 107 789 1985, Szezygiel et al. J Am Chem Soc 91 1252 1987.] (The latter purification removes material reacting with iodine.) Sodium thiocyanate solutions can be freed from traces of iron by repeated batch extractions with Et2O.
