Snakeplisken - 21-9-2008 at 11:38
Hello everyone first excuse me for my english i speak better french my question is , if we have a solution of glucose obtained from the kiliani
fischer reaction wich involved cyanhydric acid , and if we want to taste the obtained sugar , is there a way to separate pure glucose after the
reaction without the risk to taste traces of cyanhydric acid in the same time ( and then dying few minutes later 
) ?
[Edited on 21-9-2008 by Snakeplisken]
12AX7 - 21-9-2008 at 11:51
Never taste anything made in the lab. Sounds like an excellent example why not to.
Hydrocyanic acid = hydrogen cyanide you mean?
Tim
Snakeplisken - 21-9-2008 at 11:57
Hi 12AX7 , yes hydrogen cyanide and they use it to make glucose by the kiliani fischer reaction , don't you think sodium hypochlorite can be usefull
to neutralise hydrogen cyanide ?
woelen - 21-9-2008 at 12:00
It indeed neutralized the hydrogen cyanide, but it also has some really nasty side reactions with the sugar. Do not taste such solutions, they
probably are as toxic as the solution with the hydrogen cyanide (carcinogenic partially chlorinated organic compounds).
Probably the only way is to boil the entire stuff to dryness and then dissolve the solid material in a suitable organic solvent, which dissolves the
sugar, but leaves any ionic salt-like matter behind.
Snakeplisken - 21-9-2008 at 12:05
thanks woelen , what kind of solvent do you propose to do this job ? can you describe the process in wich you boil the solution ? -thanks a lot
zed - 21-9-2008 at 20:22
HCN is both an acid and a gas. It's a weak acid, not unlike carbonic acid in some regards. Boil it off, from an acidified solution, making sure you
vent or trap the gas. Then when you are done, and you are quite sure all of the HCN is gone. Please do what I would do. Flush it down the toilet,
and buy some sugar at the store.
raiden - 21-9-2008 at 21:58
Yeah don't eat it, it's not worth the risk.
woelen - 23-9-2008 at 09:33
Sugar is soluble in isopropanol, while most salts are only marginally soluble. After this process, perform another recrystallization from water or
ethanol and then you should be fairly safe.
Just to be sure, test your stuff for cyanide, before anything is tasted!! A good test is to add some acidified FeSO4 or FeCl2 to the solution and add
a single drop of H2O2. A blue color appears when cyanide is present (formation of the complex [FeFe(CN)6](-)).