Sciencemadness Discussion Board

the journal of irreproducible results presents: KCN from KOH and formamide

mario840 - 20-1-2010 at 10:33

Hello

I have a question how about making HCN form formamide and P2O5 ??

Drop slowly formamide into P2O5 and this makes HCN as white smoke then bubbling gas into solution KOH in water or ethanol ?? I heard that's works well

In wikipedia says they made KCN form formamide and KOH ?? Maybe that will works ?

Myfanwy - 27-1-2010 at 07:18

you can make KCN directly from potassium hydroxide and formamide. no hydrogen cyanide fumes and you mustnt waste your phosphorus pentoxide :)

then pour the new solution into ethanol and the KCN crystalls appear.

mario840 - 27-1-2010 at 07:25

thanks for reply ..... so i must have formamide and then pour solution KOH in ethanol but how much concentration % i must have, and how much formamide i need, how much KOH solution for example 100 ml formamide and 100 ml 40% KOH in ethanol ?? please tell me more about this process because it's much safer than the others ... and how about yield ??? for any information thx :)

Myfanwy - 29-1-2010 at 02:46

CH3NO + KOH -> KCN + 2H2O

For 20g KCN u need 13,8g Formamide and 17,2g KOH. Then u get 20g KCN and 11g Water.
but formamide is unfortunately not that easy to make. you can make it by ammonolysis of formate esters. lets say with ethyl formate and ammonia. send a stream of ammonia by ammonium salt and sodium hydroxide through the ester. no ammonia solution, because ethyl formate hydrolysis very fast.
with an ammonia solution i got nearly no formamide.

i think the formamide can also made by the reaction of Ammonium formate with urea.
and formic acid and an acid amide? what are u thinking guys?


i would use concentrated potassium hydroxide solution. but it will also work with dilute.

some more questions?

mario840 - 29-1-2010 at 03:10

so let's close up this reaction ... i need like you said 13,8 g formamide (no problem for me easy to get pure :) ) and then i dissolved ??? 17,2 g KOH or make solution KOH in 96% ethanol ??? which one is good ??? KOH disoles in formamide easily or not???
If not disolve then i must do solution in ethanol and then should immediately KCN crystals appers or i must heat up the reaction solution ?? tell me all that and i'm done ;)

Myfanwy - 29-1-2010 at 04:26

lol where you get this stuff^^

okay i would dissolve it in 20g water and then adding the alcohol,when the reaction is done, because KOH isnt that good soluble in alcohol.
but at first try it in a test tube. i dont even know,if potassium hydroxide dissolves in formamide, but this reaction is done in the indstry, to get potassium cyanide, so im sure this will work =P

all thecrystalls will appear, when u add the alcohol. i think u dont have to heat it.

mario840 - 29-1-2010 at 05:04

form the store :P:)

Hey but i have read that formamide is easily hydrolized by acids and base ??? so it's really works with KOH ??? because this really worried me

Myfanwy - 29-1-2010 at 05:14

jes we want to hydrolyze it xDD

bases form cyanide salts and acids will make hydrogen cyanide.

mario840 - 29-1-2010 at 05:29

ohhhh :) that's sound great!!

tell me more about your methods of preparation of cyanides .... :)

Myfanwy - 29-1-2010 at 09:50

mh making cyanides is legal in germany.
youre right. HCN in air isnt that poisonous as many think.

mario840 - 29-1-2010 at 10:30

don't be scared ... do everything easy and carefully and photos and movie will be fantastic knowlege to me how to do it in the future, as you finished experiment write did it works , how yield you got :)

@S.C. Wack .... yes but heating this to 600 C ??? i'd prefer simple adding CH3NO to P2O5 without any heat and other stuff .. of course if you heat that mixture formamide/P2O5 at the end you will get much more HCN and KCN :) so i prefer this metod or metod of Myfanwy :)

kmno4 - 29-1-2010 at 14:52

Quote: Originally posted by Myfanwy  

CH3NO + KOH -> KCN + 2H2O

okay i would dissolve it in 20g water and then adding the alcohol,when the reaction is done, because KOH isnt that good soluble in alcohol.
but at first try it in a test tube. i dont even know,if potassium hydroxide dissolves in formamide, but this reaction is done in the indstry, to get potassium cyanide, so im sure this will work =P

all thecrystalls will appear, when u add the alcohol. i think u dont have to heat it.

:D
It will work only in your dreams.
It is time to wake up and go to school.

mario840 - 29-1-2010 at 23:43

@kmno4 so you telling that reaction is wrong ... and only way to get KCN from formamide is dehydration with P2O5 and then "gassing" lye ????? tell me more and don't be rude because it nothing change and just wanna know

Myfanwy - 30-1-2010 at 01:45

okay kmno4 tell me whats wrong at this reaction.
i think it must work -> indutrial method

Myfanwy - 30-1-2010 at 01:50

only saying it wont work is a little bit dumb, sry.
i need a explanation :)

mario840 - 30-1-2010 at 02:00

ohhhhh but i hope you don't change your mind about experiment today ... :)

kmno4 - 30-1-2010 at 02:18

Quote: Originally posted by Myfanwy  

i think it must work -> indutrial method

It is your industrial method, not working in reality.
Try to read more scientific literature than Wikipedia.

Myfanwy - 30-1-2010 at 03:16

jes i will make the experiment today. i just made the photos of the chemicals and of the glasswear.
i take 41g H3PO4, this is an massive overkill. I just need 15g.

even my chemical database says,that formamide forms cyanides with bases. hydrolysis in aqueous soltions in presence of acids or bases.

kmno4 - 31-1-2010 at 04:16

Quote: Originally posted by Myfanwy  
ok i done the experiment. i made 64 pictures and movies.
i got about 10g of sodium cyanide (55,6%).

It seems to me that your NaCN is not dried (> 100 C) and yield of dry product may be even below 5 g.
Quote: Originally posted by Myfanwy  
my chemical database says,that formamide forms cyanides with bases.

Can you write from what database/book/encyclopedia/article/paper you have this information ?

Myfanwy - 31-1-2010 at 04:30

yes its not dried. but 5g are better than nothing ;)

Taoisearch it was under 0°C outside and i used 2Kg Ice to cool it.
But even with this cooling most HCN just gassed away.

If i made it again i would use an ethanolic solution of NaOH.

kmno4 i have it from a german database called "gestis".


[Edited on 31-1-2010 by Myfanwy]

[Edited on 31-1-2010 by Myfanwy]

S.C. Wack - 31-1-2010 at 07:22

There is obviously no way that NaCN is going to be produced by hydrolysis.
They obviously use NaOH to absorb the HCN.
This is obviously not the same.

Really wish y'all would raise your standards instead of bringing us down to yours.

CH3NO + KOH ---> Gas

ramual - 6-2-2010 at 02:01

I've read at lot of sites and books, that Formamide + Potassium Hydrooxide will give Potassium Cyanide + water

CH3NO + KOH --> KCN + H2O


but i am getting = CH3NO + KOH --> GAS + Some thing

May be the out put is reacting again

KCN + H2O -> HCN + KOH

as the output gas smell like HCN

I tried to cool it and convert it to liquid HCN but failed. So i doubt if i m correct.

can some one guide me


[Edited on 6-2-2010 by ramual]

S.C. Wack - 6-2-2010 at 10:59

So we're going to let this continue then. Wow. The sheeple have been trained well, and are probably looking forward to more.

Myfanwy - 6-2-2010 at 11:29

the mixture becomes hot by its own.

Polverone - 6-2-2010 at 13:03

Real chemical processes need a little more to be plausible than the faint praise of "it wouldn't violate the conservation of mass."

Foss_Jeane - 6-2-2010 at 13:16

Oh for the love of God! Didn't anyone notice the title of the initial post?

"the journal of irreproducible results presents: KCN from KOH and formamide"

It's a joke. Formamide + base/acid + water= ammonium formate + formic acid + ammonia Back before the Haber Process, it was easier to make cyanides than ammonia, and that's how they made ammonia: by passing steam over red hot NaCN or KCN, giving the corresponding formate as a by-product they could sell for extra profit.

I have yet to see any process that produced cyanides that wasn't a hot process: Nitrates or nitrites or metallic amides + carbon, and lots of heat (think arc heating here) or passing the nitrogen or ammonia over carbon brought to orange heat, or passing gaseous precursors through an electric arc.

If it sounds too good to be true, then it probably is.

Polverone - 6-2-2010 at 13:20

Actually, I gave that title to the thread after I split it off from the larger cyanide thread.

un0me2 - 7-2-2010 at 01:30

K3wl;)

S.C. Wack - 7-2-2010 at 14:44

Here is your ref for formamide and NaOH giving NaCN. I am shocked, shocked to find that it involves hot formamide vapor ("Die Zersetzungstemperatur wird am besten möglichst hoch genommen.") and is a little vague.
DE108152

EDIT: This was the only ref in Beilstein anywhere close, same for google's books on cyanide manufacture.

[Edited on 8-2-2010 by S.C. Wack]

bbartlog - 7-2-2010 at 16:57

Neat patent. Basically says that if you want to go straight from ammonium formate to cyanide, you need to send the gas through a molten alkali solution at minimum 360 deg C, whereas if you first go to the trouble of distilling formamide from the ammonium formate you can get by with temperatures as low as 200C (but still *piping the gas into the alkali*, not just mixing and heating). The vagueness in my opinion comes in because molten alkali at 200C sounds like a hydrate melt though this is not explicitly specified. Anyway, it does clear up some confusion.

kmno4 - 7-2-2010 at 23:49

Quote: Originally posted by S.C. Wack  
Here is your ref for formamide and NaOH giving NaCN

Thanks. I was looking for any scientific informations about it but is turns out an old german patent. Definitely not scientific material, probably equally irreproducible like other "wonderful" cyanide patents.

Nicodem - 8-2-2010 at 03:02

My skill in reading German sucks and I don't really want to be a party breaker, but that patent does not really claim that NaCN is formed from the reaction of formamide and sodium hydroxide directly. Actually this patent is not only vague, but it does not even go to a chemical interpretation of the process (kind of understandable given its age).
In my understanding, the formamide is thermolysed at >360°C and the products (containing HCN among other stuff) absorbed directly at this temperature over potassium or sodium hydroxides to give NaCN or KCN. The formamide feed into the process is formed from the thermolysis of ammonium formate in an autoclave at 200-300°C, with or without an acid catalyst (Chlorzinkammoniak). In the presence of the catalyst a little HCN forms already in the autoclave, especially at higher temperatures. The patent even tells us that if the formamide vapours are being carried over the hydroxides at a temperature lower than the one needed for the thermolysis then the hydroxide reacts with formamide by the usual manner yielding only hydrolysis products:

"Kaltes oder mäfsig warmes Alkali zersetzt Ammoniumformiat oder Formamid zu Alkaliformiat und Ammoniak; geschmolzenes Alkali dagegen spaltet Wasser ab und bildet glatt Blausäure, mit der es sich sofort zu alkali verbindet. Die Zersetzungstemperatur wird am besten möglichst hoch genommen. Arbeitet man mit reinem Formamiddampf, so genügt allerdings schon eine Temperatur von 200° zur Zersetzung; ist aber noch Ammoniumformiatdampf oder Wasserdampf zugegen, somufs man über 360° erhitzen."

As far as I could understand, this is also the only passage that mentions that the alkali hydroxides decompose formamide into HCN. But if you read carefully it says that molten alkali does that, indicating that it is the heat that causes the decomposition of formamide into HCN and not the reaction with the alkali hydroxide. Hence it says that the cyanide forms only at high enough temperature, preferably over 360°C. If the alkali hydroxide would somehow react with the formamide, then HCN could not be a product, because HCN reacts with hydroxides to give cyanides and water (obviously the authors were aware of this and if they would have believed the KCN/NaCN formed from the reaction of HCONH2 with KOH/NaOH, they would have not be mentioning HCN as intermediate).
So what this patent is describing is actually only the usual thermolytical elimination of water from formamide and the neutralization of the so formed HCN over molten hydroxides. The only difference from the other related HCONH2 -> HCN processes is in that they do not use alumina or any other dehydration catalyst for the formamide decomposition into HCN. Since the reaction HCONH2 <-> H2O + HCN is highly reversible at the required temperatures (300-500°C), there might be a rational reason for performing it over molten hydroxides. Namely, the HCN is absorbed as it forms, therefore forcing further conversion. At such high temperatures (>360°C) the vast majority of formamide is probably in the gas phase and only tiny amounts may be absorbed in the melt, the very high temperature thus paradoxically preventing hydrolysis (while gaseous acids react very rapidly with molten hydroxides, the hydrolysis requires absorption, because the reaction can not occur easily just via an interphase boundary reaction like is the case with proton exchanges). However, given that HCONH2 is itself a very weak acid it can be chemisorbed in molten NaOH by forming the sodium amide salt and this then slowly hydrolysed. But if the temperature is high enough for the rapid formation of HCN (it being many thousand times stronger acid than HCONH2), this will be competing at the phase boundary preventing the hydroxide from taking up formamide. Another reason for keeping the temperature as high as possible.

I think we should all wait our funny cyanide kewls to provide the reference for their illogical claim that alkali cyanides can be made by reacting formamide with alkali hydroxides. This patent is surely not what they had in mind (considering the required reaction conditions and all). It should not be so difficult telling us where they read about a reaction so kewl that goes against chemical theory and against experimental data confirming that formamide reacts with KOH and NaOH in the usual manner.

bbartlog - 8-2-2010 at 08:06

'It should not be so difficult telling us where they read about a reaction so kewl...'

Surely you could have guessed :-) -

http://en.wikipedia.org/wiki/Potassium_cyanide

ramual - 8-2-2010 at 10:42

CH3NO + KOH -> KCN + 2H2O

CH3NO (CN- , H30+) + ( K+, OH- ) -> KCN + 2H20

This is what happen when formamide(acid) reacts with Potassium hydrooxide(Base) -> KCN (Salt) + water

after that a second reaction occurs due to heat produced by first reaction

KCN + H20 -> HCN + KOH

The problem is How to convert HCN (Gas) into liquid or solid

bbartlog - 8-2-2010 at 11:13

Ah, really? That first equation is a reasonable gloss of the discussion to date, though I believe the question at this point is just how hot the KOH needs to be in order for gas-phase formamide to react as described. Maybe you'd like to show us where you found that second reaction, where heat decomposes potassium cyanide into hydrogen cyanide and potassium hydroxide. Because last time I checked KCN (with or without H2O) doesn't decompose under heating in anything less than an electric furnace (and even then I doubt it splits neatly into acid and base).
Quote:
The problem is How to convert HCN (Gas) into liquid or solid


The problem is that you can't be bothered to learn chemistry or read the entire contents of the thread. It sounds like you've seen gas coming off of some KOH and formamide mix and erroneously concluded that since the formamide *must* have been turned into KCN and water, the vapors couldn't be anything except cyanide. Chemically this makes about as much sense as boiling salt water to produce lye and hydrochloric acid (which is to say no sense at all).

Panache - 8-2-2010 at 19:46

A great source of acidic or caustic vapour is simply produced by boiling water
H2O ---> OH-(g) + H+(g),
the trick is of course how do you manage to isolate those suckers before they find each other again.
I believe if you achieve this you will move science forward quite dramatically and after your work on this is complete you should move onto producing an antigravity beam or trying to locate where the holy trinity hangout.

Paddywhacker - 9-2-2010 at 00:24

Quote: Originally posted by Panache  
A great source of acidic or caustic vapour is simply produced by boiling water
H2O ---> OH-(g) + H+(g),
the trick is of course how do you manage to isolate those suckers before they find each other again.
I believe if you achieve this you will move science forward quite dramatically and after your work on this is complete you should move onto producing an antigravity beam or trying to locate where the holy trinity hangout.


Isn't OH- seventeen times heavier than H+ ? So I'd say blowing on it would separate them nicely.

ramual - 16-2-2010 at 03:55

I've tried the same reaction with sodium hydroxide. but the result is same.


CH3NO + NaOH --> Gas + Something

????

DJF90 - 16-2-2010 at 10:39

The "gas and something" will be ammonia and sodium formate.

ramual - 18-2-2010 at 02:47

I think the we got a conclusion

Formamide + Pottassium Hydroxide -- > Pottasium Formate + Amonia
CH3NO + KOH --> CHOOK + NH3


Formamide + Sodium Hydroxide -- > Sodium Formate + Amonia
CH3NO + NaOH --> CHOONa + NH3



[Edited on 18-2-2010 by ramual]