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ScienceHideout
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Making Sodium Cyanide
Hello everyone!
I am planning a reaction on making NaCN from NaOH and urea. This will prevent the scary encounter with HCN.
My thinking is to add NaOH in a test tube, and add a stoiciometric amount of urea. I will heat this in a fume hood with a bunsen burner.
Here are where my problems come in-
Will the NaOH safely react without eating the glass?
What IS the stoiciometry between these substances?
I don't have too much experience with urea, and all my molten NaOH I've encountered before I used steel. Any thoughts?
Thanks in advance!
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hkparker
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Please be careful, and reconsider trying this.
What is your source that NaOH reacts with Urea to form NaCN? Another thread perhaps? If you saw a source then I'm sure they gave you a reaction,
from which stoichiometry could be calculated.
I've looked around online and cant find a reference for this. From a google result I get:
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The hydrolysis of urea proceeds like normal base-catalyzed amide hydrolysis, giving first sodium carbamate and ammonia. The carbamate readily
undergoes a second hydrolysis reaction to give sodium carbonate and another equivalent of ammonia.
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Not NaCN. This was in reference to a (I believe wet) reaction between urea and Sodium Hydroxide. <a target="tab"
href="http://www.scienceforums.net/topic/38367-what-happens-when-you-add-sodium-hydroxide-to-urea/">Link here</a>.
Also, molten NaOH eats glass fast, so it could not be done in glass.
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ScienceHideout
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I have heard of people doing the same with KOH, and I know that is MUUCH more corrosive than NaOH.
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hkparker
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How is KOH more corrosive then NaOH? At least, "MUUCH more corrosive"?
Once again, where did you hear people doing this?
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Endimion17
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Molten sodium hydroxide eats glass for breakfast. Urea, if heated alone, yields something I despise - a mixture that is nearly impossible to remove.
AFAIK, it contains cyanuric acid, biuret and some polymerized stuff. Essentially, you get an almost inert, rock hard polymer that ruins glassware. You
can pound it with a hammer if you like.
I have no idea whether that polymer is soluble in molten sodium hydroxide. But glass is, so chances are your tube will be gone before urea.
I don't really know will urea gently dissolve in molten NaOH, to give a homogenous reaction mixture.
And I don't recall cyanides having to do anything with this.
[Edited on 18-9-2011 by Endimion17]
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ScienceHideout
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I read on this forum of a person claiming that he did this reaction with KOH. The topic was about him claiming that KOH is less corrosive than NaOH,
but from experiments and knowledge I know otherwise.
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hkparker
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A link it what I had in mind. But looks like s/he was wrong, this won't work. And KOH is not more corrosive in a any significant way that I know of.
It is slightly more soluble, so there's that, but the potassium ion is larger and I would image less % of KOH is actually hydroxide ions then NaOH.
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ScienceHideout
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http://www.sciencemadness.org/talk/viewthread.php?tid=15633
Sodium Hydroxide is stronger than lithium hydroxide, but not as strong as rubidium hydroxide, so potassim hydroxide would be stronger than sodium
hydroxide, right?
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hkparker
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Thanks for the link. Read the whole thread. blogfast25 points out how in solution KOH is only slightly more corrosive (Im guessing because K+ is a
weaker conjugate acid?). However, <a target="tab" href="http://www.springerlink.com/content/n5523871x634l523/">this link</a> says that
NaOH is more corrosive specifically to glass.
Either way, The thread says heating KOH and Urea with cyanuric acid will make KOCN (no source backing it up). Doesn't mean NaOH and urea will make
NaCN if thats what you were going off of.
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ScienceHideout
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Well, chemical reactions tend to go in 'families'. example: you can make fluoroform, chloroform, bromoform, and iodoform all with the same reaction,
but different reactions.
BTW: I realized just then he said cyanate, not cyanide.... but NaOCN would still be as useful.
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hkparker
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For what? Whats your goal with making cyanide/cyanate?
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plante1999
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Does anyone already make the famous polymeric material from pyrolisis of urea , if yes does it melt , I Supose it is melamine. Simply by curiosity , I
also want cyanide for making gold sol.
I never asked for this.
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Formatik
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Cyanate can be obtained by route of alkali base and urea, but decomposition of it (at least for KCNO) only gives partial yield cyanide at higher
temperatures. This and cyanate preparation was mentioned here.
I mentioned my experience of attempting to obtain cyanate here, but for some reason got something containing cyanide, even though I was only using a bunsen burner to heat, and I believe used
stoichiometric amounts.
If you are heating aq. NaOH, Na2CO3, etc. with urea, then you will split off all nitrogen as NH3. I've done this as well (primordial chemicals
thread).
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Nicodem
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Thread Moved
18-9-2011 at 02:37 |
ScienceHideout
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I am planning on making a little bit of cyanate/cyanide salt for synthesis of inorganic (and some organic) compounds. I always love adding another
polyatomic ion to my lab. 
Heating sodium carbonate seems a lot easier than hydroxide- but- it always seems like it would be difficult to melt- especially because it is so...
dry! I've melted many a chemical before, but, alas, CO3^2's weren't one of them!
I guess I could try the alkali carbonate... again I know that I will not get a good yeild, but I might aswell try! That's why it's called an
experiment!
I will post my results!
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barley81
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There's a whole thread on cyanide preparation here:
http://www.sciencemadness.org/talk/viewthread.php?tid=23
The process involved fusing alkali carbonate with urea/cyanuric acid (giving cyanate), adding charcoal and heating to red heat or higher (producing
cyanide and CO), dissolving/filtering the residue, and precipitating with alcohol.
Relatively pure (at least free-flowing) potassium carbonate can be bought cheaply from pottery supply stores if you want to make KCN and don't want to
use more expensive KOH.
For high temp. stuff, you can make a crude furnace from an empty paint can, a hairdryer, and cheap charcoal briquettes. It worked for me for some
crude aluminum casting.
Don't use glass as your reaction vessel with the furnace, it may crack. Use a metal crucible (a soup can, an iron pipe cap/nipple, or a stainless
steel cup).
Also it is very, very, very, very helpful to use the search function before starting new threads.
[Edited on 18-9-2011 by barley81]
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ScienceHideout
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Thanks so much! I will let you know of my results...
hey, if you are reading this, I can't U2U, but you are always welcome to send me an email!
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cyanureeves
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there was a video on youtube for a while that got took down of a guy heating potassium carbonate or hydroxide,i forget which, with potassium
ferrocyanide in a test tube. potassium cyanide formed like a beach around the mixture. it was in german so i had to use google translater on his
notes. he didnt say how he kept away from the hcn gas though.careful.
oh! and the test tube was tilted just above horizontal while heating.
[Edited on 18-9-2011 by cyanureeves]
[Edited on 18-9-2011 by cyanureeves]
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mr.crow
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Speaking of Germans, here is a thread. Translation
Don't die
Double, double toil and trouble; Fire burn, and caldron bubble
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Melgar
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Oh, hey, that was my thread.  I know KOH can corrode glass, but my point was that
you can do the KOH/urea reaction in glass without noticeably damaging it, probably because once molten, the reaction proceeds rather quickly.
For making NaCN, it would probably be best to heat a stochiometric mixture of sodium carbonate/hydroxide, urea, and charcoal to red hot, probably in a
good-sized charcoal fire. This reaction does give off lots of ammonia, which will react with red-hot charcoal to form hydrogen cyanide, so watch out
for that.
Oh, and you know what makes an excellent crucible? Empty disposable propane tanks with the top sawed off. They're clean, thick enough to stand up to
high temperatures, and most of us probably have a few laying around already. Of course, you do need to make DAMN sure, they're actually empty before
actually sawing the top off one.
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AndersHoveland
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Often times you can find good tutorials for making cyanide on suicide forums. I found an interesting method of making hydrogen sulfide this way.
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testimento
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For this topic, I would like to continue.
Could NaCN be produced by following method:
-Burn calcium carbonate into calcium oxide at 1000C
-Mix 3 moles of urea and 1 moles of calcium oxide at urea melting, when calcium cyanate is formed
-Calcinate calcium cyanate at 700-900C protected from oxygen to produce Calcium Cyanamide
-Mix 1 mole of calcium cyanamide, 1 mole of sodium carbonate and 2 moles of carbon at 900C temperature, where carbonate will melt and reaction will
produce molten sodium cyanide, carbon monoxide and calcium oxide and the sodium cyanide could be poured out in molten stage in ceramic container where
it can be cooled and smashed into powder and put into proper container.
Sources:
https://en.wikipedia.org/wiki/Calcium_cyanamide
http://www.sciencemadness.org/whisper/viewthread.php?tid=142...
If this process works, it looks the most straightforward and OTC to me, apart from the trouble of making the furnace. I suggest using clay flowerpot
or SS cooking pot with clay coating and 0.5mm nichrome wire installed inside clay surface with dimmer(triac) to get over 1000C tempes. The pot could
be insulated with quite thick layer of clay, cement or other stuff too.
Another process is to blow ammonia through glowing coal, but IDK about this process a lot, sounds like PITA to get HCN out from CO2, CO and soot
created by the coal, and the heating of it would be another PITA, maybe a shitload of nichrome around quartz tube, but can you get it glowing without
reacting air with it too?
[Edited on 6-7-2013 by testimento]
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AJKOER
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OK, a possibly cheap and relatively easy path to a cyanide that I have been considering. Take safety precautions as this preparation can still
accidentally lead to exposure to deadly gases including both CO and HCN.
1. A possible source of HCN is by burning a nitrogen containing plastic as per Wikipedia (http://en.wikipedia.org/wiki/Hydrogen_cyanide ):
"and in smoke from burning nitrogen-containing plastics"
An important point is precisely which plastic, however, as a low nitrogen content is not desirable. This source (http://answers.yahoo.com/question/index?qid=20101104220951AA... ) may provide an answer as it states:
"HCN forms when synthetic fibers containing Orlon® or Acrilan® burn. Acrilan® has an empirical formula of \rm CH_2CHCN, so HCN is 50.9% of the
formula by mass. A rug in the laboratory measures 12.0 times 15.0 ft and contains 30.0 oz of Acrilan® fibers per square yard of carpet. If the rug
burns, what mass of HCN will be generated in the room? Assume that the yield of HCN from the fibers is 20.0% and that the carpet is 36.0 % consumed"
Acrilan is a brand name for acrylic fiber which contains essentially Acrylonitrile (formula C3H3N, see discussion at http://en.wikipedia.org/wiki/Acrylonitrile).
I have long known that a fire in a building having plastic rugs, curtains,...can produce HCN, which is perhaps equally dangerous as is the CO and the
fire itself.
2. Direct the smoke using an air flow into a scrubbing solution of iced NH4OH (other choices include NaOH, KOH, but NH4OH also does dissolve CO).
That's it. The scrubbing solution will contain NH4CN (see http://en.wikipedia.org/wiki/Ammonium_cyanide for more details) along with some nitrite and nitrate along with some exit gas of toxic CO. I have
chosen this unstable cyanide as it decomposes readily (permitting cyanide separation) as follows, per Wikipedia:
"Ammonium cyanide decomposes to ammonia and hydrogen cyanide, often forming a black polymer of hydrogen cyanide:
NH4CN → NH3 + HCN "
and I speculate that adding some H2O2, CO2 and Cu (or no Copper as with Hydrogen peroxide the safer cyanate (CNO-) could be formed from the cyanides
if pH 9-10, see http://www.h2o2.com/industrial/applications.aspx?pid=106&... ) to the aqueous cyanide/nitrite/nitrate mix would, in time, release N2, NO (see
my comments at http://www.sciencemadness.org/talk/viewthread.php?tid=6381#p... ), previously dissolved CO and possible HCN. The latter could be re-absorbed
leaving only a solution of HCN and some CuCN/Cu(CN)2.
[EDIT] I would consider adding a secondary scrubbing solution of fine Fe in a suspension of ammonia water to address excess CO. In all cases, this
preparation should be performed in a fume hood or outdoors.
[Edited on 8-7-2013 by AJKOER]
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Clan-destined
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Can you ppl please dispense with this urea talk for preparation of sodium cyanide? This shit is a no-brainer:
1. Sodium hydroxide
2. Equal amounts of potassium ferrocyanide (yes, you may use sodium ferrocyanide--geez... Using potassium ferrocyanide gives the identical potassium
cyanide. In fact, it's been said that the only difference between the two molecules is that one bottle has a label that reads "potassium" before the
cyanide and the other reads a "sodium" before the cyanide.).
3. A clean metal vessel (tablespoon; lid to a jar of spaghetti sauce, etc).
4. Propane and a match.
Now mix the ferrocyanide in with the hydroxide. Apply lots of heat. Don't worry about cyanide poisoning; your propane burns off the evolving hydrogen
cyanide gas. But to satisfy the weenies on this board, I declare a warning: DON'T TRY THIS WITHOUT A FUME HOOD OR RISK CERTAIN DEATH BY INHALING EVEN
A BIT OF THE GAS THAT EVOLVES! IT'S BEEN SAID THAT EVEN A CUBIC CENTIMETER OF THIS STUFF IS FATAL! Ok, the weenies are now happy...
As you continue to heat, the mixture turns from a faint yellow, coarse powder to a black bubbling viscous liquid. The flames you see shooting out is
your hydrogen cyanide gas. You can't keep heating it much beyond this or risk losing all the cyanide part of your sodium cyanide! Total heat time
can't run for over 5 minutes for a small cook. You're done when the sodium cyanide begins to precipitate out as a white liquid that floats on top.
Turn off the heat, you're done!
Let this substance cool into a hard, crusty material.
The ferro in ferrocyanide precipitated out of the reaction, and it's now time for you to separate it from the goods. Simply dissolve the moonrock in a
small quantity of warm water (the purpose of which is to dissolve your sodium cyanide, while leaving all other ingredients behind). Decant the rust
from the sodium cyanide solution.
You may now remove the water from your sodíum cyanide using any means available. The white, crystalline crusty stuff left is crude sodium cyanide.
Proof: drop a small chunk in some HCL. Prussian blue? Check! The stench of hydrogen cyanide immediately filling the garage? Check!
Do we have our sodium cyanide? Check...
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Mabus
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Unfortunately neither ferro nor ferricyanides are not something you can just find at the local store, while urea and KOH is something you do. Also,
both urea and alkali hydroxides are much cheaper, so there's also the cost to be considered.
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S.C. Wack
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The urea method does not use hydroxides esp. KOH w/10% water. It requires the most anhydrous carbonate you got. Same with the ferrocyanide.
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