Chemical synthesis Aqueous KSCN reacts almost quantitatively with
Pb(NO3)2 to give Pb(SCN)2, which has been used to convert
acyl chlorides to isothiocyanates. KSCN converts
ethylene carbonate to
ethylene sulfide. 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 and
KOCN. : KSCN is also the starting product for the synthesis of
carbonyl sulfide.
Special effects Dilute aqueous KSCN is occasionally used for moderately realistic blood effects in film and theatre. 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.
Laboratory The reaction with Fe3+ mentioned above is used as a
test for Fe3+ ions in the
laboratory.
Law enforcement Approximate
cocaine purity can be determined using 1 mL 2% cupric sulphate pentahydrate in dilute HCl, 1 mL 2% potassium thiocyanate and 2 mL of
chloroform. The shade of brown shown by the chloroform is proportional to the cocaine content. This test is not cross sensitive to heroin, methamphetamine, benzocaine, procaine and a number of other drugs but other chemicals could cause false positives. ==References==