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Author: Subject: NaBH3CN workup
Klute
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[*] posted on 21-1-2010 at 11:43
NaBH3CN workup


I'm planning on trying some reductions with NaBH3CN, notably reductive aminations.

I'm very weary of doing the traditional workup ei acidifying to quench the hydride, wash with solvent, basify and extract, because not having a hood I can't take the risk of evolving HCN.. It seems that if I want to quench the hydride, I need to take the pH low enough to protonate the cyanide ions (pKa ~9)..

So how can I proceed? I was thinking of basifying the reaction mixture after removing as much MeOH as possible, extracting everything, and then doing an A/B on the amine to remove the neutral impurities. So then I can dispose of the hdyride solution without acidifying.
Or, remove MeOH, directly wash the residu with solvent to remove neutrals (the amine should be under the hydrochloride form), basify and extract.

Any suggestions, comments?

BTW, what is the best way of destroying cyanide ions? Hypochlorite?





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Picric-A
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[*] posted on 21-1-2010 at 11:51


Quote: Originally posted by Klute  

BTW, what is the best way of destroying cyanide ions? Hypochlorite?



Hypochlorite or alkaline H2O2 will oxidise CN- to cyanate
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