[aerosam]

Hi i am trying to carry out the following reaction, with formamide and KOH.
HCONH2 + KOH → KCN + 2H2O
I plan to use the product for a Von-Richter reaction.

But having added the 2 reactants(Potassium Hydroxide and Formamide), i don't get any precipitate. I am not sure of whether a reaction has occurred, or whether KCN is in solution.
How do i tell?

Thanks
Sam

[Dan]

If you didn't expect KCN to be soluble in water you should probably not be playing with it.

You should do this under the supervision of a chemist. You could kill yourself.

[aerosam]

If you didn't expect KCN to be soluble in water you should probably not be playing with it.

You should do this under the supervision of a chemist. You could kill yourself.

I realized that KCN is probably in the solution. To be on the safe side, i didn't even want to heat it. So i just left the beaker out in the open(safe and partially covered) for a week. I didn't want to risk heating it.
The volume of water reduced from about 50ml to approx 7ml, but no sign of precipitation. Initial concentrations were about .1Moles of both reactants.

This leads me to suspect that maybe there is a side-reaction that decomposed the KCN or that maybe the above reaction was wrong. I found it on wikipedia.

[Dan]

The volume of water reduced from about 50ml to approx 7ml, but no sign of precipitation. Initial concentrations were about .1Moles of both reactants.

Moles is not a measure of concentraton. Do you mean that you started with 0.1 mol (moles) in 50 mL, or that you started with 50 mL of solution at a concentration of 0.1 M (molar)?

The solubility of KCN in water is about 11 M at RT. So for 0.1 mol, it should start to precipitate at <9 mL. If you started with 50 mL of a 0.1 M solution, ie 5 mmol, you shouldn't expect a precipitate until you're down to <0.45 mL.

Do you have any evidence that the reaction has worked? Are you following a literature procedure or did you just read the equation on Wikipedia?

I still think you should get some experience with safer reactions before attempting this.

Note that cyanide salts may be controlled substances in some parts of the world, so at least make sure you're not breaking the law.

[aerosam]

I had .1 moles of reactants to begin with, in about 50ml of solution. Now i am down to about 7-10ml of solution, thanks to evaporation, no clear signs of precipitation.
I suspect the reaction was a dud. But how do i tell? I don't want to just pour it down the drain. I believe i detected a scent of Ammonia initially.
Where i am it's legal to make small quantities of cyanides for lab use, without a permit.

[discodermolide]

I had .1 moles of reactants to begin with, in about 50ml of solution. Now i am down to about 7-10ml of solution, thanks to evaporation, no clear signs of precipitation.
I suspect the reaction was a dud. But how do i tell? I don't want to just pour it down the drain. I believe i detected a scent of Ammonia initially.
Where i am it's legal to make small quantities of cyanides for lab use, without a permit.

I agree with Dan, leave this alone, you obviously do not know what you are doing. You are doing this on a relatively large scale.
If you wish to dispose of the reaction mixture treat it with an excess of bleach (10-15% solution), then dilute with water and pour it away with lots of running water.

[aerosam]

Considering that i am down to less than 10ml of water, would it help if i evaporated the remaining water by heating? Could a mass spectrometer be used to see if the residue is kcn?

In general, what other way is there to determine whether a reaction has occurred?

[discodermolide]

Considering that i am down to less than 10ml of water, would it help if i evaporated the remaining water by heating? Could a mass spectrometer be used to see if the residue is kcn?

In general, what other way is there to determine whether a reaction has occurred?

It looks as if you have a mess.
I would start again, very carefully. Too strong a base or forcing conditions will hydrolyze the amide to the acid and ammonia.
Please read up about the properties and the precautions one needs to take when using or generating cyanide before you start. Have the appropriate cyanide antidotes available near you , to be used if required.

[aerosam]

Considering that i am down to less than 10ml of water, would it help if i evaporated the remaining water by heating? Could a mass spectrometer be used to see if the residue is kcn?

In general, what other way is there to determine whether a reaction has occurred?

It looks as if you have a mess.
I would start again, very carefully. Too strong a base or forcing conditions will hydrolyze the amide to the acid and ammonia.
Please read up about the properties and the precautions one needs to take when using or generating cyanide before you start. Have the appropriate cyanide antidotes available near you , to be used if required.

Could you suggest a reference about the forcing conditions to prevent amide hydrolysis as well as the cyanide precautions.

I was kind of suspecting that this might happen. A preliminary thought that i had was to dilute the KOH solution to begin with. That would make it less basic. But that would mean, so much more water to eliminate. I toyed with the idea of dissolving KOH in a lot of ethanol, since KCN is practically insoluble in ethanol, as well as conducting the reaction in an ice-bath.

[discodermolide]

Considering that i am down to less than 10ml of water, would it help if i evaporated the remaining water by heating? Could a mass spectrometer be used to see if the residue is kcn?

In general, what other way is there to determine whether a reaction has occurred?

It looks as if you have a mess.
I would start again, very carefully. Too strong a base or forcing conditions will hydrolyze the amide to the acid and ammonia.
Please read up about the properties and the precautions one needs to take when using or generating cyanide before you start. Have the appropriate cyanide antidotes available near you , to be used if required.

Could you suggest a reference about the forcing conditions to prevent amide hydrolysis as well as the cyanide precautions.

I was kind of suspecting that this might happen. A preliminary thought that i had was to dilute the KOH solution to begin with. That would make it less basic. But that would mean, so much more water to eliminate. I toyed with the idea of dissolving KOH in a lot of ethanol, since KCN is practically insoluble in ethanol, as well as conducting the reaction in an ice-bath.

Sorry I have no references available. Cyanide antidotes you should be able to find on Google.
Forcing conditions means for me heating the reaction, when it's perhaps not required.
Certainly reflux with base is required for amide hydrolysis, so your suggestion of employing lower temperatures is ok.

[aerosam]

I am beginning to think that the reaction
HCONH2 + KOH → KCN + 2H2O
is wrong. Could wikipedia be wrong
I can't seem to find a reference to this reaction anywhere.
Have attached a reference on common synthesis techniques, but none of them mention the above route. What am i missing? Is there some other reference for this reaction. If not i intend to correct the wiki article.

Edit: Attachment removed for copyright infringement

[Dan]

No, the Wikipedia article is not wrong.

The fact that you have posted copyright protected material on a public forum makes this easy. Topic locked, 30 day ban.

Stop playing with cyanide, you clearly do not have the knowledge and skills to handle it safely.