Potassium thiocyanate

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Potassium thiocyanate
Potassium thiocyanate.png
Other names
Potassium sulfocyanate
Potassium isothiocyanate
Potassium thiocyanide Potassium rhodanide
3D model (JSmol)
ECHA InfoCard 100.005.792
RTECS number XL1925000
Molar mass 97.181 g mol−1
Appearance Colorless deliquescent crystals
Odor Odorless
Density 1.886 g/cm3
Melting point 173.2 °C (343.8 °F; 446.3 K)
Boiling point 500 °C (932 °F; 773 K) (decomposes)
177 g/100 mL (0 °C)
217 g/100 mL (20 °C)
Solubility in acetone 21.0 g/100 mL
−48.0·10−6 cm3/mol
Safety data sheet ICSC 1088
Toxic (T)
R-phrases (outdated) R20/21/22 R32 R52/53
S-phrases (outdated) (S2) S13 S61
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Lethal dose or concentration (LD, LC):
854 mg/kg (oral, rat)[1]
Related compounds
Other anions
Potassium cyanate
Potassium cyanide
Other cations
Sodium thiocyanate
Ammonium thiocyanate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Potassium thiocyanate is the chemical compound with the molecular formula KSCN. It is an important salt of the thiocyanate anion, one of the pseudohalides. The compound has a low melting point relative to most other inorganic salts.

Use in chemical synthesis[edit]

Aqueous KSCN reacts almost quantitatively with Pb(NO3)2 to give Pb(SCN)2, which has been used to convert acyl chlorides to thiocyanates.[2]

KSCN converts ethylene carbonate to ethylenesulfide.[3] For this purpose, the KSCN is first melted under vacuum to remove water. In a related reaction, KSCN converts cyclohexene oxide to the corresponding episulfide.[4]

C6H10O + KSCN → C6H10S + KOCN

KSCN is also the starting product for the synthesis of carbonyl sulfide.

Other uses[edit]

Dilute aqueous KSCN is occasionally used for moderately realistic blood effects in film and theater. It can be painted onto a surface or kept as a colorless solution. When in contact with ferric chloride solution (or other solutions containing Fe3+), the product of the reaction is a solution with a blood red colour, due to the formation of the thiocyanatoiron complex ion. Thus this chemical is often used to create the effect of 'stigmata'. Because both solutions are colorless, they can be placed separately on each hand. When the hands are brought into contact, the solutions react and the effect looks remarkably like stigmata.[citation needed]

Similarly, this reaction is used as a test for Fe3+ in the laboratory.


  1. ^ http://chem.sis.nlm.nih.gov/chemidplus/rn/333-20-0
  2. ^ Smith, P. A. S.; Kan, R. O. (1973). "2a-Thiohomophthalimide". Org. Synth. ; Coll. Vol., 5, p. 1051 
  3. ^ Searles, S.; Lutz, E. F.; Hays, H. R.; Mortensen, H. E. (1973). "Ethylenesulfide". Org. Synth. ; Coll. Vol., 5, p. 562 
  4. ^ van Tamelen, E. E. (1963). "Cyclohexenesulfide". Org. Synth. ; Coll. Vol., 4, p. 232