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Author: Subject: I want some cyanide, should I choose NaCN or KCN?
fusso
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[*] posted on 6-12-2018 at 17:26
I want some cyanide, should I choose NaCN or KCN?


Which should I choose, concerning factors like solubility, hygroscopicity, cost (per mol!), etc?



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[*] posted on 6-12-2018 at 18:27


For what reason, exactly, do you want cyanide for?

KCN is cheaper on Sigma-Aldrich.
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DoctorOfPhilosophy
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[*] posted on 6-12-2018 at 18:45


I can think of some use cases where it wouldn't matter :P For gold extraction, Wikipedia suggests calcium cyanide
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fusso
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[*] posted on 6-12-2018 at 18:52


Quote: Originally posted by myr  
For what reason, exactly, do you want cyanide for?

KCN is cheaper on Sigma-Aldrich.
One rxn I want to try is making nitriles. Also I'm worried new legislations may be made to ban them in my country so I want to get some ASAP before they are banned. I favour other suppliers over SA as it's the most expensive.



Useful sites:
Balance Chemical Equation: http://www.webqc.org/balance.php
Molecular mass and elemental composition calculator: https://www.webqc.org/mmcalc.php
Solubility table: https://en.wikipedia.org/wiki/Solubility_table
Azeotrope table: https://en.wikipedia.org/wiki/Azeotrope_tablesIt's not crime if noone finds out - Nyaruko
List of materials made by ScienceMadness users: https://docs.google.com/spreadsheets/d/1nmJ8uq-h4IkXPxD5svnT...
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clearly_not_atara
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[*] posted on 6-12-2018 at 18:57


I would consider CuCN or Zn(CN)2 as they're much safer to handle and, IIRC, cyanide can be recovered by dissolving in ammonia and reducing with Mg. In particular, Zn(CN)2 can be used directly in the Gattermann reaction.



[Edited on 04-20-1969 by clearly_not_atara]
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fusso
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[*] posted on 6-12-2018 at 18:58


Quote: Originally posted by DoctorOfPhilosophy  
I can think of some use cases where it wouldn't matter :P For gold extraction, Wikipedia suggests calcium cyanide
So is Ca cyanide the cheapest cyanide salt? If yes then I can see why is Ca cyanide used to extract gold.



Useful sites:
Balance Chemical Equation: http://www.webqc.org/balance.php
Molecular mass and elemental composition calculator: https://www.webqc.org/mmcalc.php
Solubility table: https://en.wikipedia.org/wiki/Solubility_table
Azeotrope table: https://en.wikipedia.org/wiki/Azeotrope_tablesIt's not crime if noone finds out - Nyaruko
List of materials made by ScienceMadness users: https://docs.google.com/spreadsheets/d/1nmJ8uq-h4IkXPxD5svnT...
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DoctorOfPhilosophy
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[*] posted on 6-12-2018 at 19:33


I dug deeper into this. Apparently it started during WWI when the European supply of NaCN was cut off and we started making it locally but with calcium instead (https://dr.library.brocku.ca/handle/10464/9781?show=full). The manufacturing process also seems easier, being a continuous one step process (https://www.911metallurgist.com/blog/cyanide-gold-dissolutio...).
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ninhydric1
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[*] posted on 6-12-2018 at 20:49


Calcium cyanide can be easily converted to NaCN or KCN using sodium or potassium sulfate, filtering out the calcium sulfate and boiling down the filtrate, so it is pretty versatile.



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Herr Haber
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[*] posted on 7-12-2018 at 04:14


I'd go straight for the salt that I need for what I want to do.
If several options are available then my other criteria would be solubility.

I am not concerned about using the salt or a solution but I'd rather avoid unnecessary manipulation in this case.
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