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Author: Subject: Potassium Ferrocyanide synthesis and purification?
Amos
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[*] posted on 22-8-2014 at 18:56
Potassium Ferrocyanide synthesis and purification?


For those of you looking for a clean step-by-step synthesis, sorry to disappoint you; this was makeshift at best. I decided to use my chemistry skills to start making my own pigments to use in paints (I also do some art!), and found online that one can make prussian blue (Iron(III) hexacyanoferrate(II), or Fe7(CN)18) by treating sodium or potassium ferrocyanide solutions with FeCl3. Not wanting in any way to deal with the synthesis from hydrogen cyanide, I stumbled upon an admittedly dubious post here, and decided to entertain the idea that it might work: http://bitnest.ca/Rhodium/chemistry/cyanide.html

It describes strongly heating a fine mix of carbon(charcoal), iron oxide, and anhydrous sodium carbonate in a normal air atmosphere(largely nitrogen) to produce modest ammounts of sodium ferrocyanide. I carried this out in crucible within my old brick furnace at just over 1000 degrees Fahrenheit for an hour, and did indeed obtain a light yellow solution upon leaching the resulting burnt mixture. Adding a few drops of ferric chloride solution formed a dark blue-grey precipitate in suspension, which I assumed would have been some of the prussian blue with very large contamination of iron carbonates/hydroxides, a result of most of the sodium carbonate being unreacted and coming into solution. Is there any creative way I can either separate the sodium carbonate and sodium ferrocyanide, or separate the two end products? I know it's a crude synthesis, so I'm not expecting much.

[Edited on 8-23-2014 by No Tears Only Dreams Now]

[Edited on 8-23-2014 by No Tears Only Dreams Now]




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Amos
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[*] posted on 23-8-2014 at 15:36


All right, I'm dumping the solution. I'd like to do another run with purer chemicals and more calculation, and for a longer time, but purification is still going to be necessary if I want some nice prussian blue.



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