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kmno4
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Because its impossible to obtain given amount of HCN from given amounts of substrates under given conditions.
I wrote too many posts on this topic and I am just bored with it, I do not want to explain the same things another time.
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Zan Divine
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I'll bet you're fixating on the acid concentration. I didn't bother mentioning that I add additional water during the foaming stage to keep it out of
the condenser. Never realized it helped.
Anyway, I'm telling you as a flat-out fact that this was done, multiple times with consistent yields.
You can actually watch a similar prep. with H3PO4 on youtube
(http://www.youtube.com/watch?v=K5NuqpdYDhE). He gets 10 g of NaCN (after crystallization) from 22.7 g ferrocyanide. You should know how
low the recovery is when crystallizing it out of alcohol. He probably had 8 or 9 g of HCN to get 10 g of crystallized NaCN.
That would scale up to him getting a bare minimum of ~148 g HCN from 420 g ferrocyanide, and possibly over 160 g. Very much in line with my results.
You can doubt me if you want, and then doubt your own eyes.
Maybe you are referring to the (incorrect) assertion that only half the HCN comes out without catalysis by copper salts/copper metal?
Working chemists tend to learn early on that just because it says somewhere that something proceeds in this or that yield, your mileage may vary...
(and, if you're working from a patent, sometimes it's just fiction).
Writing many posts is certainly valuable, however I tend to view actual experimental results with more regard.
[Edited on 7-6-2012 by Zan Divine]
He who makes a beast of himself gets rid of some of the pain of being a man. --HST
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AJKOER
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A simple direct and proven approach (but gaseous requiring precautions and use of an expensive catalyst), try to replicate the industrial Andrussow
process either on a micro scale or larger. Per Wiki, to quote:
"The Andrussow process is an industrial process for the production of hydrogen cyanide from methane and ammonia in the presence of oxygen and a
platinum catalyst.[1][2]
CH4 + NH3 + 1.5 O2 → HCN + 3 H2O
Side Reactions
This reaction is very exothermic. The change of Enthalpy of this reaction is equal to -481.06 kJ[3]. The heat provided by the main reaction serves as
a catalyst for other side reactions.
CH4 + H2O → CO + 3 H2
2 CH4 + 3 O2 → 2 CO + 4 H2O
4 NH3 + 3 O2 → 2 N2 + 6 H2O
This side reactions can be reduced by only short exposures to the catalyst."
Link: http://en.wikipedia.org/wiki/Andrussow_process
The created HCN could be immediately be reacted with NaOH (or perhaps more ammonia). Obviously, this reaction should only be attempted with
appropriate safety equipment and ventilation being a gases reaction process.
Also, I suspect one may be able to successfully substitute C2H6 for CH4 with increasing air/O2 flow.
So, if one made a home-made Pt catalyst (Platinum jewelry turned into powder, or better, dissolved and freshly precipitated), even though less than
the perfect catalyst, the reaction is reported as exothermic and best with "only short exposure to the catalyst", so a home-made low efficiency Pt
catalyst may work. One may be able also to use a Ag/Al2O3 based catalyst (see full thesis at http://research.cems.umn.edu/schmidt/schmidtpapers/thesis/Sa... ). I would make such a Silver catalyst by the thermal decomposition of Silver
oxalate (Aluminium oxalate).
However, further research does indicate that the process is intricate requiring a heat exchanger (see "Alternative catalyst supports for hydrogen
cyanide synthesis and ammonia oxidation" by DA Hichkman, M Huff and LD Schmidt, published in Ind. Eng. Chem. Res., 1993, 32 (5), pp 809–817. Link:
http://pubs.acs.org/doi/abs/10.1021/ie00017a007 ) to avoid a thermal decomposition of the highly unstable HCN:
HCN + H2O --> NH3 + CO
[Edited on 30-8-2012 by AJKOER]
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carlos_souza
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Quote: Originally posted by Polverone  | I know I've told some people about it, but I can't seem to find my more refined NaCN preparation writeup here.
The way I do it now, for making larger quantities, is to mix powdered urea or cyanuric acid with NaHCO3 and heat, covered, until it's melted...
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Hi Polverone.
Actually, do you not heat the sodium bicarbonate to produce sodium carbonate before mix with the cyanuric acid?
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robertstar
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My report
I needed some grams of NaCN for an experience of coating of copper, then I tried to produce it, boiling potassium ferrocyanide with phosphoric acid,
but it did not work because I used a makeshift apparatus. The mixture was boiled in a kitasato flask whose nozzle was closed with a rubber stopper.
The output of kitasato was connected through a silicone tube to an improvised condenser done with two turns of copper pipe in a bucket full of ice
water. The condenser output was dripping in a flask with concentrated solution of NaOH.
My heating source was a gas cooking stove. It was impossible to control the temperature. The result was that too water was evaporated, the solution
dried soon and I was with very dilute NaOH solution, and besides, the HCN was not condensed, which came in the form of gas at the end of the
condenser. The ambient temperature was 30° C.
I concluded that it is not possible to distillate HCN with improvised apparatus unless the ambient temperature is very low.
I then decided to try the method described by the author of this topic, Polverone.
I built a small furnace with bricks stacked.
In my first attempt, I used a can of 20 cm length by 8 cm in diameter. The coal involved the can until its half.
I bought sodium bicarbonate in the pharmacy where it is sold as a stomach antacid. I bought acid isocyanuric in a store of products for treatment of
pools, as chlorine stabilizer, but I suspect that he was with the expiry date. He came grainy and I turned 50 g powder gradually putting inside a
small plastic bag, beating with a hammer and passing through a fine sieve.
I lit the coal, put 50 g of sodium bicarbonate in the can and left waiting for a few minutes until it was converted into sodium carbonate. Not knowing
whether or not the conversion had been completed, I added the acid isocyanuric.
After a few minutes, everything was turned into a boiling liquid. At this point, I added about 10 g of powdered charcoal. To transform coal into
powder, I used a sandpaper, after passing through a fine sieve.
To close the can, I used a metal plate. After some time, the can was red and began to bend due to the weight of the metal plate. After 2 hours the can
disintegrated at half its height. Then, I removed the bottom of the can from the fire and let it cool. It was possible to feel the smell of HCN in
solid contained in the bottom of the can. The solid was scraped from the bottom of the can and placed inside a glass jar, covered with 100 mL of water
at room temperature and stirring occasionally for 2 hours. The liquid also emitted the odor of HCN.
After that, the liquid was filtered out with filter paper coffee. I didn’t do any test with this filtrate.
I added 200 mL of ethanol and mixed. At that moment, it was possible to see a remnant of coal that escaped filtering. It was formed a colorless
biphasic liquid solution with the bottom phase with a volume much smaller than water that was there before. There was no crystallization. The ambient
temperature was about 30° C.
The solution was filtered. I believed that the lower phase was not to pass the filter, but it was a mistake, as I could see on the second try. I have
lost most of their product. When filtering was too slow, I spilled the contents of the filter into a bowl of steel. I heated the bowl with a heat gun
until result in a white salt. The mass of this salt was about 4 g. I kept in a closed bottle of 100 ml. Later, when opening the bottle, I felt the
odor of ammonia.
Some of this salt was dissolved in water and then mixed with a slightly acidic solution of iron sulphate and showed a light blue color. I poured the
rest of the solution in a vinegar solution and it was bubbled.
We conclude that this attempt I got a bit of cyanide and a lot of impurity, probably because I had to stop the warming.
For the second attempt, I searched a container that resists heat. I bought an old fire extinguisher of 8 cm diameter, 30 cm height and steel plate 4
mm thick. I cut it at a height of 20 cm and I got a container of 1 L. As it is rounded background, I used a piece of metal shaped ring to stop him
standing. I tried to remove as much rust inside it. To cap it I used the same metal plate.
As I suspected that my isocyanuric acid was expired, I bought granulated urea in a store as fertilizer and turned 150 grams powder with the aid of a
hammer.
I heated baking soda in a bowl of steel in the kitchen stove, stirring continuously until it ceased gas emissions, to turn it into sodium carbonate.
I mixed 150 grams of urea powder with 100 grams of sodium carbonate and 50 grams of coal powder, placed the mixture in the container and heated it in
the same furnace with some modifications.
After half an hour, the mixture powder was completely melted and boiling. When the lid was removed to check on, the gas into the container was burned.
Even it was closed, sometimes a jet of yellow fire went out underneath the lid.
After the coal was burning, it was easy to keep it, just every 15 minutes to put some coal in it.
As time passed, the mixture was becoming thicker, but still bubbling.
I decided to leave until the bubbles ended, which occurred after 6 hours. I left it 1 more hour to finish burning the coal that was in the furnace.
A total of seven hours of heating has been consumed 7.5 kg of charcoal. The container took 1 hour to cool. It suffered no apparent damage.
The black product that resulted in the bottom of the container was very hard. In the interior side of the container, just above the bottom, was formed
a crystalline solid. Not knowing what was this salt that was formed on the side, I removed it separately from the background layer. The bottom layer
was very difficult to remove. I used a large screwdriver hitting the cable with a rubber hammer. I removed about 20 g of product of the side and
somewhere around 100 g from the background that were placed in different vials. The odor of HCN was strong in both.
After turn them powder with the aid of a hammer, I added 100 ml of water to the 20 g and 300 mL to 100 g. The water, that was cold, has warmed. I
stirred the solutions sometimes for about 1 hour. The solutions were separately filtered out using filter paper coffee. The solutions were a slightly
yellowish color. Both solutions gave off smell of HCN.
I added, separately, a few drops of each solution in a green slightly acidic solution of iron sulfate and mixed, getting a dark blue solution, very
different from that obtained with the solution of my first attempt.
I poured vinegar on the filtered solutions and they not bubbled.
I heated the solutions and felt no ammonia odor.
After these tests, I mixed the solutions and added 800 mL of ethanol. It was formed a liquid heterogeneous solution of two phases. The low phase was a
volume of approximately 200 mL. There was no crystallization. The ambient temperature was around 30 ° C.
At this time, I not filtered out, as on the first try, because I realized that both phases passed through the filter. I just put the solution in the
freezer. After 1 hour, the part corresponding to bottom liquid phase were crystallized. I poured the liquid into another container and with a steel
spoon I removed the crystallized salt, putting it on a few sheets of paper towel. I spread salt on paper towel and put other leaves on top, pressing.
I did it until the paper towel absorbs the most of the liquid.
The salt was exposed to air for about 1 hour until the smell of alcohol has disappeared, but the salt was still wet.
After that, I wrapped the salt on a filter paper and put it in a closed glass jar with poured about 100 g of silica gel in the bottom of it.
In the next day, the top of the salt was dry, but the background was still wet. I mixed the salt and closed the bottle again.
I dropped it into the glass drying for five days stirring once a day.
After that time, the salt apparently was dry and its mass was 53 grams.
The salt remains exhaling odor of HCN. I believe that my product is mostly NaCN, although I do not know which its purity is.
Some pictures of the experiments can be see in the following links.
First try:
http://s1293.beta.photobucket.com/user/robertstar1971/librar...
Second try:
http://s1293.beta.photobucket.com/user/robertstar1971/librar...
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Hexavalent
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You may be able to recrystallize your crude NaCN if necessary to further purify it, and you could filter over diatomaceous earth or a similar material
to remove the suspended carbon.
How well did the covers fit over the containers?
BTW, you repeatedly mention that you "smell" HCN (almonds?). If you can smell it, you are inhaling it - be careful.
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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robertstar
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I believe it will not be necessary to purify the NaCN. The lid just rested on top of the container. When I smell the HCN, I take away the source,
preventing most aspire.
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ktcd
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I don't understand, if CNCl + H2O -> HOCl + HCN (which I would think thermodynamically unfavorable, but anyways , shouldn't HOCN + HCl -> HOCl + HCN
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UnintentionalChaos
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| Quote: Originally posted by ktcd | | I don't understand, if CNCl + H2O -> HOCl + HCN (which I would think thermodynamically unfavorable, but anyways, shouldn't HOCN + HCl -> HOCl + HCN |
Because CNCl + H2O does not form HCN and hypochlorous acid. It form HOCN and HCl.
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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Zan Divine
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Every time I have prepared NaCN by leading liquid/gaseous HCN directly from my sulfuric acid-ferrocyanide reactor into aqueous NaOH I end up with a
brown-black product.
If I collect the HCN as liquid (stabilized w/ H2SO4) and then drop that into aqueous NaOH it stays almost colorless. Even when I collected
unstabilized liquid HCN, it too gave no brown-black products.
I'm assuming you guys know that unstabilized HCN may undergo spontaneous polymerization. Be aware that a tiny trace of the CN anion in the form of a
dissolved speck of NaCN will catalyze this.
Anyway, this is obviously a polymerization problem. Anybody else seen the same thing?
He who makes a beast of himself gets rid of some of the pain of being a man. --HST
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kmno4
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These brown matters are known issues for very long time.
I also noticed this and can confirm it.
It is easy way to avoid this - introduce HCN to solution of KOH (NaOH) in ethanol.
NaOH is better because nice, crystalline hydrate of NaCN separates. It is unstable and must be quickly dried (vacuum or very quick drying in steel pot
at ~90 C with continuous stirring with a spoon). Snow-white product, strongly hygroscopic can be obtained.
Слава Україні !
Героям слава !
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Zan Divine
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That's the classical method for isolating KCN or NaCN.
Absolute ethanol is very difficult to come by here in the US. The best most can find is about 90% (as Everclear alcohol I guess). Any road to absolute
EtOH from there is laborious. I've never needed my cyanide salts as crystalline solids, fortunately.
The thing I find striking is that collection of the neat HCN and then subsequent addition to aqueous base circumvents the brown-black horror.
Presumably, the HCN contains the same components as the vapor it is condensed from. But that can't really be true. Short lived transient species?
He who makes a beast of himself gets rid of some of the pain of being a man. --HST
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franklyn
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All Cyanide compounds may be derived from Cyanogen. NΞC-CΞN
Cyanogen is produced by dry distillation of Ammonium Oxalate
(NH4)2C2O4 => 4H2O + NC-CN
done in a glycol or glycerine to sequester the water produced.
Google this => "Ammonium Oxalate" Cyanogen
From : Commercial Organic Analysis - 1896
http://books.google.com/books?id=ppDPAAAAMAAJ&pg=PA424&a...
It is an old preparation , confirmed on the second page
From : The Chemistry of Cyanogen Compounds - 1915
http://books.google.com/books?id=vW86AAAAMAAJ&pg=PA2&...
From : Theoretical organic chemistry - 1916
http://books.google.com/books?id=c8wQAQAAMAAJ&pg=PA210&a...
From : A Textbook of Organic Chemistry - 1921
http://books.google.com/books?id=bkQAAAAAYAAJ&pg=PA409&a...
.
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robertstar
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Hello, I described my experience of producing NaCN few posts ago.
Due to the strong odor of HCN, I believed that its purity was considerable, but it did not work satisfactorily in the process of electroplanting.
Anyone knows any indicator for the titration of cyanide with silver nitrate that can be used to replace the rhodanine?
I tried with potassium iodide, but did not work.
[Edited on 20-2-2013 by robertstar]
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Magpie
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| Quote: Originally posted by robertstar |
Anyone knows any indicator for the titration of cyanide with silver nitrate that can be used to replace the rhodanine?
I tried with potassium iodide, but did not work.
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I would recommend the Liebig method, as I have used it before with apparent success. I found it in "Quantitative Analysis," by Pierce and Haenisch,
3rd ed. You may also be able to find it by searching Google Books.
Liebig Method for Cyanides
To the dissolved sample, which should contain 6-8 mmol of cyanide ion, add 30-40 mmol of ammonium hydroxide and 0.1-0.2g KI, and dilute to a volume of
200mL. Titrate with standard 0.1M AgNO3 until the addition of 1 drop of reagent causes the appearance of a permanent turbidity in the solution.
Prior to the stoichiometric point, a soluble silver cyanide complex ion is formed:
Ag+ + 2CN- -----> Ag(CN)2-
The single most important condition for a successful synthesis is good mixing - Nicodem
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robertstar
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Thank you Magpie.
I didn't found the book on google, but I found this document:
http://nvlpubs.nist.gov/nistpubs/jres/7/jresv7n5p913_A2b.pdf
As I understand it was originally used only silver nitrate and the indication of the end of the titration occurred when the solution became turbid. I
decided to test ...
I dissolved 1 g of my product in 100 ml of distilled water. The obtained solution was colorless. Next, I removed 10 mL and added 90 ml of distilled
water to obtain 100 mL of a solution with 1 g/L of concentration. I used 20 ml of this solution to the titration. In this solution I instilled a drop
of solution of 0.5 N sodium hydroxide to avoid the presence of HCN.I used a 0.01 N silver nitrate solution.
The problem is that even just a drop of the silver nitrate solution becomes the solution turbid. For turbid I mean it ceases to be transparent,
assuming a brownish. However, after only about 5 mL there was precipitation of a gray solid.
With potassium iodide, the solution takes on a yellowish color after receiving the first drop of the solution of silver nitrate.
I'll still read the document carefully and perhaps make other attempts titration ...
I believe that my product is mostly sodium carbonate.
You know some form of separating the sodium cyanide from sodium carbonate without involving distillation?
[Edited on 21-2-2013 by robertstar]
[Edited on 21-2-2013 by robertstar]
[Edited on 21-2-2013 by robertstar]
[Edited on 21-2-2013 by robertstar]
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Magpie
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| Quote: Originally posted by robertstar |
The problem is that even just a drop of the silver nitrate solution becomes the solution turbid. For turbid I mean it ceases to be transparent,
assuming a brownish. |
I think this is because you have no (or very little) cyanide.
Here's a picture of what the endpoint looks like for a cyanate titration w/AgNO3. IIRC that for the cyanide titration is very
similar.
| Quote: Originally posted by robertstar |
I believe that my product is mostly sodium carbonate.
You know some form of separating the sodium cyanide from sodium carbonate without involving distillation?
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You are probably right. The best yield that I got was 36.7%. I didn't attempt to purify it as my application did not require that.
To purify it you would likely have to first convert it to HCN. I took pains in my preparation not to mess with that bad boy.
The single most important condition for a successful synthesis is good mixing - Nicodem
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robertstar
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Thank you very much Magpie.
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robertstar
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I tried to produce sodium cyanide by heating sodium carbonate and urea as I reported behind.
Due to the strong odor of HCN exalate from the product, I believed that he had got a product with a purity appreciable.
But a titration with silver nitrate, showed me I got a negligible amount of cyanide.
I'm reporting my failure to alert anyone who tries to use the same method.
[Edited on 18-3-2013 by robertstar]
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testimento
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Ok, so far we have the following reactions:
NaCO3+Fe3O4+C+N2+hell of a heat = Ferrocyanide
Chloroform + ammonia distilled through 300C glass tube = ammonium cyanide and hydrochloric acid (shouldnt the NH4CN react with HCL to form NH4CL and
HCN?)
sodium metal + molten urea or zinc(oxide) + molten urea = cyanides? could this work with lead oxide?
And then this:
http://www.sciencemadness.org/talk/viewthread.php?tid=14267
The making of calcium cyanamide from calcium oxide(caco3+hell of a heat) and molten urea = calcium cyanate + 700-900C = calcium cyanamide?
This article states that cyanamide will form hydrogen cyandie in alkali environment. I have understood that one will need acid to liberate the HCN,
not alkali.
- WHAT CYANIDES (CYANATE, CYANAMIDE, CYANIDE?) can be used to form HCN gas upon reaction with acid or alkali?
What is the easiest way to make hydrogen cyanide gas(only to be intercepted in a solution of NaOH in EtOH to form suitable pure NaCN) with NO
cyanide compounds of any kind available, only urea(as ammonia) and other common chemicals that can be made?
From my point of view, the cyanamide process and the chloroform+ammonia sounds most feasible, and I dont know would the Bucher(of whatever) process
with C+Fe+N2+NaCO work, but anyways.
[Edited on 3-7-2013 by testimento]
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Random
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I have always wondered if we could use a better nitrogen source like urea, which would decompose to biuret and ammonia, then leave biuret and it's
decomoposition products as a source of nitrogen at high temperatures. It would be more reliable, safe and easier than stiring to use N2 from air. I
have read somewhere I think they used animal parts like hair and leather as a nitrogen source for ferrocyanide production, but haven't found the
actual procedure.
On another note, is the reaction fairly safe? Does it produce any cyanide at all? I would love to try it in the future but don't wanna fool myself and
get like 30% cyanide along ferrocyanide.
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testimento
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I could try it. I have a place and equipment(steel reactors and industrial grade protective gear), but I lack the urea which I got to find in small
quantity first. Originally I planned to use an air pump to inject atmospheric air into the container and, if necessary, use excess of carbon since
oxygen would scavenge it.
I have the following formula:
-1kg C powder
-1kg NaCO3
-500g Fe2O3
I could try like 500 grams of urea with this mix and see what happens. My goal is to acquire sodium ferrocyanide which I will directly use for
production of hydrogen cyanide gas with acid(HCl, citric, etc.) and inject it into solution of KOH in EtOH. I need to recover the iron from the
remnants.
The next promising subject is molten urea + calcium oxide, which is expected to produce calcium cyanate and burned in high temp to get corresponding
cyanamide and then release the HCN with acid. I have understood that HCN cannot be obtained from cyanate so cyanamide needs to be manufactured first.
[Edited on 3-7-2013 by testimento]
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math
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I've got a question about the preparation of sodium cyanide from cyanuric acid, NaHCO3 and charcoal.
From what I've read in this thread, things should go like that (starting from available compounds):
[A] 3 HCl (l) + C3Cl3N3O3 (s) ---> [C(O)NH]3 (s) + 6 Cl (g)
[B] 2 NaHCO3 + heat ---> Na2CO3 (s) + H2O (g) + CO2 (g)
Then
[C] Na2CO3 (s) + 2/3 [C(O)NH]3 ---> 2 NaOCN + CO2 + H2O
[D] NaOCN (s) + C (s) ---> NaCN (s) + CO (g)
At which temperature are reaction [B], [C] and [D] carried out? Can I expect to reach them on charcoal fire?
Do I need any catalyst for [C] or [D] to occur? Can I carry them in a porcelain/ceramic crucible? Do I need to use a specialty sealing crucible with
two lids (one nested on top of each other) or would this be counterproductive?
Thank you
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bfesser
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Thread Bumped
17-7-2013 at 11:30 |
testimento
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I could expect that the reaction temperature for the carbonic reduction is about 550C, which is the melting point of the sodium cyanate. The
decomposition point is not cited, but its boiling point says it decomposes so the reaction should take place immediately upon melting.
The reaction is supposedly possible to carry out in ceramic crucible (porcelain, flower pot?).
Im gonna try this out. Cyanuric acid can be made from urea by heating it up to 175C and saving the ammonia from it and the rest can be done as
previous poster said.
[Edited on 21-7-2013 by testimento]
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S.C. Wack
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Some have found otherwise. I was speaking of the usual methods in the manuals.
http://www.sciencemadness.org/talk/viewthread.php?tid=9543&a...
BTW preparation of HCN or CO from cyanide, more convenient than formic acid if you have cyanide or live in a gold mining area...
Preparation of dry hydrogen cyanide and carbon monoxide
John Wade and Laurence C. Panting
J. Chem. Soc., Trans., 1898,73, 255-258
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