General Description
Odorless white solid. Sinks and mixes with water.
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(540-72-7).
Air & Water Reactions
Water soluble.
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.
Physical properties
Colorless crystals or white powder; deliquescent; melts at 287°C; very soluble in water; soluble in alcohol.
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.
Flammability and Explosibility
Nonflammable
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.
