element109 (Hive Bee)
01-16-02 18:51
No 257249
      What to do with old NaCN?  Bookmark   

Suppose someone has two vials of NaCN that's probably 20 years old, one is really yellow and grey, the other is even worse containing black chunks .

Does someone know what NaCN is decomposed to? I assume the grey/black stuff is carbon.
What would be the best way to clean this? I was thinking dissolving in EtOH, careful filtration and evaporation.

(Hive Bee)
01-16-02 19:05
No 257255
      Re: What to do with old NaCN?  Bookmark   

NaCN is purified by recrystallization.
(Hive Bee)
01-16-02 19:11
No 257258
      Re: What to do with old NaCN?  Bookmark   

Alkali cyanides should be very stable over time without any contaminants, maybe the vial seal has started rotting. If they are medical vials (like the one seen in "JAWS") where you draw out the cyanide with a needle syringe, then maybe a needle broke off in the vial once ?

Are they screw cap vials ?
Does the seal look ok on them ?
Describe the vial, can you post an image ?

One day I'll understand everything !
(Hive Bee)
01-19-02 02:42
No 258150
      Re: What to do with old NaCN?  Bookmark   

They are screw-cap, the label is real brown and there's "NaCN" written on it. Could it be the poor storage conditions for 20 years? I don't own a scanner so i can't post an image.

Are there any analytical tests for alkali cyanides (except releasing HCN crazy) ?

(Master Whacker)
01-19-02 20:27
No 258375
      Re: What to do with old NaCN?  Bookmark   

NaCN does discolor and degrade over time with exposure to air.  Even if the coloration is fairly extreme, it can still be used for many purposes as is.  For example, a 50 year old bottle of grey-brown degraded material sealed with a dry rotted cork and bakelite cap reacted fine with a certain substituted benzyl chloride.  An excess was used to compensate for possible decomposition.

I know you probably know this but I'm going to say it anyway. This shit is rediculously toxic and dangerous to work with in basement laboratory conditions.  If you decide to risk it, remember that most reactions involving NaCN will emit HCN fumes.  Many authors neglected to report this fact in much existing reference material using this reagent.  If you do decide to live dangerously and work with this shit, make sure you have some of those amyl nitrite poppers around.  If you get a face full of HCN (trust me, you'll know if this happens- it has a horrible smell and smacks you in the face like a ton of bricks) inhaling 2 or three of those poppers over a several minute period may save your life.  If you spill a solution of that stuff on you, you're in deep shit.   The antidote is sodium thiosulfate and sodium nitrite solution, but it must be administered intravenously.  I dont think oral absorbtion would be quick enough to save your ass.