Potassium thiocyanate (potassium thiocyanate)
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Potassium thiocyanate (potassium thiocyanate) - potassium sulphocyanate.
Potassium thiocyanate (potassium thiocyanate) — chemical compound, potassium salt of thiocyanic acid,
Chemical formula — KSCN.
By sight — the colourless crystals of monoklinny system blurring in humid air. Have no smell. Are hygroscopic.
Potassium thiocyanate reacts with bromine water with formation of cyanogen bromide and potassium sulfate, with iron with formation of potassium cyanide and iron sulfide. Decays when heating above 250 °C — to potassium sulfide and cyan, it is above 300 °C — disulfide of potassium and potassium cyanide.
Synonyms: Potassium thiocyanate, potassium sulphocyanate, Potassium rhodanate, Potassium sulphocyanate, Potassium thiocyanate, potassium thiocyanate, KCNS
- in the textile industry;
- in the photo;
- in organic synthesis (for example, for receiving thiourea, artificial mustard oil or dyes),
- for receiving thiocyanates, cooling mixtures, insecticides, etc.
Potassium sulphocyanate can be received at interaction of ammonium rhodanide with potassium hydroxide:
NH4NCS + KOH = KNCS + Nh3b + H2O
In hot (70 °C) solution of 500 g NH4NCS (h and. ) in 250 ml of water flow (under draft) when hashing solution of 368 g of KOH (p. ) in 400 ml of water. Mix is heated at 80 - 85 °C to full removal of NH3 (test of solution when heating with KOH should not allocate NH3 found on smell). Upon termination of reaction solution is filtered via the double folded filter. The filtrate is boiled out before film formation of crystals and cooled. The dropped - out crystals suck away on Buchner filter and dry at 30 - 40 °C. Exit of 400 - 440 g (62 - 70% ) of the preparation corresponding to reactant of qualification of h and. From mother solution evaporation and crystallization it is possible to receive 100 - 140 more g of salt.
If as raw materials the technical product of NH4NCS containing considerable impurity of sulfates, then technique of preparation of KNCS a bit different apply.
To 50 ml of water add Ba(OH)2 before full sedimentation of SO42 - to the solution of 175 g NH4NCS heated to 80 °C. To solution allow to be defended and filter. The filtrate is heated to 80 °C and added in the small portions of K2CO3 (p. ) before alkalescent reaction to phenolphthalein. Then reactionary solution is boiled by 10 - 12 h before removal of NH3, bring 2 g of active coal and boil out until density of solution does not become equal 1,45 (at 110 °C). Solution is filtered and cooled. The dropped - out crystals suck away on Buchner filter and dry at 30 - 40 °C.
Exit of 100 g (47% ). Using mother solution, it is possible to raise preparation exit considerably.