Sciencemadness Discussion Board

Sodium cyanate from cyanuric acid

Organikum - 2-11-2004 at 09:18

Thats a question.

Anybody done this?

Cyanuric acid decomposes by heating to cyanic acid, venting this into a solution of NaOH or sodium carbonate will yield sodium cyanate.

Thats right?
Think so at least.

Any advise for purification and extraction?

Cyanates and such

chloric1 - 2-11-2004 at 09:44

Well, I would recommend putting excess cyanuric acid into a ball mill with anhydrous soda ash and mix well. Then I would melt them together and you should have your cyanate. The reason I suggest Excess Cyanuric acid is to allow for decomposition to carbon dioxide and ammonia. I got this idea from some thread on cyanide synthesis. The cyanate should react with pure carbon above 1000 degrees C to make the cyanide which can be remelted and poured through Insulation cloth or dissolved in water, passed through diatamasous earth and flash evaporated in a shallow pyrex dish. Let me know where your experiments take you :)

Polverone - 2-11-2004 at 11:17

Quote:
First, I found a British patent, (710143), that relates a method of preparing cyanates from cyanuric acid. In the patent they are concerned about avoiding cyanide, but I am obviously NOT.

Quick summary of the patent: powdered alkali carbonates are mixed with powdered cyanuric acid and heated to about 520 C. If this is done in a carbon dioxide atmosphere, there is no detectable amount of cyanide formed. The reaction is carried out in a closed steel vessel at atmospheric pressure. Only about 2/3 of the stoichiometric amount of alkali carbonate should be used. If more carbonate is used, some remains unconverted to cyanate. If less is used, some ammonium carbonate and other products form.


This is from the old "preparation of cyanides" thread. I know that I did obtain sodium cyanate at least as an intermediate, but of course I was heating much more strongly, and longer, with charcoal, to convert as much as possible to sodium cyanide.

I don't think aqueous methods are best for cyanate production. Cyanate easily hydrolyzes in warm water near neutral or in acid conditions, though I believe it is more stable under strongly alkaline conditions. The classic lab preparation is fusing powdered alkali carbonates or hydroxides with powdered urea. The cyanuric acid seemed to work well also and was easier to powder.

Organikum - 3-11-2004 at 05:48

Made the cyanate from recrystallized urea and sodium carbonate, worked well.

Purification ideas?

I know this is already here and on the HIVE - I plain ask for some spoonfeeding here as I am pressed on time.

regards
ORG

[Edited on 3-11-2004 by Organikum]

S.C. Wack - 3-11-2004 at 10:25

Recrystallization from water is recommended both by Inorg Syn (available for months now) and the Perrins' and Armarego's Purification of Laboratory Chemicals (coming soon). It seems that the K salt is a better choice to make if one wants a pure product, due to recrystallization losses of the Na salt by their method.

Inorg Syn uses alcohol precipitation of the aq. sol'n after neutralization with acetic acid, with the K salt. They didn't want to use a large amount of alcohol to precipitate the Na salt, but that's them.