Sciencemadness Discussion Board - K4[Fe(CN)6] Making Prussiate of Potash Starting With KNO3

K4[Fe(CN)6] Making Prussiate of Potash Starting With KNO3

Diablo - 7-3-2016 at 10:19

I'm trying to find a process to synthesise Prussiate of Potash with chemicals I already have. I have potassium nitrate and chloride as potential potassium sources. I've been looking into the compound and it seems like it should be doable, somehow.

Daffodile - 7-3-2016 at 12:23

I would mix it (KNO3) with Carbon, and heat to redness to make Potassium Carbonate, and then that with Iron filings, a Nitrogen source (ie: leather, etc), and more charcoal. That is supposed to form Ferrocyanide when heated to redness for an extended period of time, at which point you cool, dissolve in water, and evaporate to collect product. I've tried this reaction several times, and I've managed to make it work exactly once. The product is a pale yellow, a colour that reminds me of Potassium Nitrite. It might be more distinct if your product is better than mine.

[Edited on 7-3-2016 by Daffodile]

Diablo - 12-3-2016 at 13:04

Quote: Originally posted by Daffodile

I would mix it (KNO3) with Carbon, and heat to redness to make Potassium Carbonate, and then that with Iron filings, a Nitrogen source (ie: leather, etc), and more charcoal. That is supposed to form Ferrocyanide when heated to redness for an extended period of time, at which point you cool, dissolve in water, and evaporate to collect product. I've tried this reaction several times, and I've managed to make it work exactly once. The product is a pale yellow, a colour that reminds me of Potassium Nitrite. It might be more distinct if your product is better than mine.

[Edited on 7-3-2016 by Daffodile]

I may try this when I can find a good nitrogen source. Would urea work maybe?

Daffodile - 12-3-2016 at 15:00

I think that would leave you with Potassium Cyanide and Iron. Not sure where the reaction would proceed to from there.

Daffodile - 13-3-2016 at 18:00

Okay I tried the synthesis and I got tiny amounts of Potassium Ferrocyanide. I added 5g Iron to 15g Potassium Carbonate, and 10g Charcoal powder. Then, I heated it to a bright red. Light purple flames appeared and lingered over the coals. I dissolved everything in water, and evaporated it to get a whitish powder. I tested the powder with Ferrous Sulfate in Hydrochloric Acid. The product was mostly Carbonate.

[Edited on 14-3-2016 by Daffodile]

[Edited on 14-3-2016 by Daffodile]

[Edited on 14-3-2016 by Daffodile]

MeshPL - 15-3-2016 at 06:56

You omitted the nitrogen part! I guess even dumb things like stale meat, dried blood etc. should work as N sources. I'm not sure but I think I read that atmospheric N2 also works, however your setup may not exposed to the air enough.

Do you happen to have mice or rats in your cellar?

They contain nitrogen...

Daffodile - 15-3-2016 at 08:56

Quote: Originally posted by MeshPL

You omitted the nitrogen part! I guess even dumb things like stale meat, dried blood etc. should work as N sources. I'm not sure but I think I read that atmospheric N2 also works, however your setup may not exposed to the air enough.

Do you happen to have mice or rats in your cellar?

They contain nitrogen...

I'll use leather instead...

MeshPL - 19-3-2016 at 09:27

I may try it soon with gelatin as nitrogen source. Should be fairly pure. My only concern is that I may not manage to heat it enough, but I'll see.

MeshPL - 26-3-2016 at 03:54

Meh. Gelatin turns into liquid, foamy black mess when heated and spilled upon every attempt. To make anything sensible with it, you must use a small amount or a big crucible.

I tried without gelatin but faileded too.

chipwit - 2-8-2016 at 21:36

Hair and feathers are good nitrogen sources too. Bloodmeal is another available source. I tried the synthesis once with hair and feathers but after boiling the result and reducing the liquor, I only got a gray ashy powder with iron and carbonate. I think I need to keep the reactants covered next time.

Cryolite. - 2-8-2016 at 22:43

Can you obtain cyanuric acid? This is sold as a pool chlorine controlling chemical. If so, it would likely work as the nitrogen source-- heating it with potassium hydroxide and charcoal makes potassium cyanide.

If you can't, you could always try collecting your urine