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kmno4
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[*] posted on 14-2-2011 at 15:54


Long time ago I performed similar experiment.
My product was hard, crystalline grey mass, smeling like bitter ... + ferromagnetic particles (however much weaker than Fe)
But this "result" gives no information about what it is.
I took a sample of this product (after purification) as catalyst for benzoin condensation.
And I had to boil mixture for very long time to obtain visible amounts of benzoin :mad:
The same amount of pure KCN gave sudden formation of benzoin after 1/10 of time needed for "pyrolytical KCN" synth.

This:
K4[Fe(CN)6] + K2CO3 + C => 6KCN + Fe + CO2 + CO
is only theory (wishful thinking).
Have you tried to do some tests for your product (carbonates, KCN content, yield) ?
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[*] posted on 14-2-2011 at 22:21





I have done only qualitive test for cyanide, without quantitative analysis of the sample, however i will do this some time later in the lab, because i don't want to work with cyanogen nasties at home conditions. Images above are from "Cyanide Industry". Pyrolityc method of cyanide production is known for the long time, it surely works and was even used in industry, only thing to ensure here is that time about ~3 hours is enough to complete conversion of source products.

Here is also a description of cyanide production by Leibig's method from "The Practical Metal-Worker's Assistant", by Oliver Byrne:

This substance may be prepared by exposing ferrocyanide of potassium (yellow prussiate of potash) to a red heat in an iron crucible; then pounding the mass, and boiling it in alcohol of about spec. grav. 0.900: cyanide of potassium crystallizes on cooling the resulting solution. It is now, however, almost universally prepared for electro-metallurgical purposes, by a process which was first suggested by Messrs. F. and E. Rodgers. but afterwards more fully explained by Professor Liebig, and hence called "Liebig's Process:" it is at once both simple and easy of performance.

Ferrocyanide of potassium rounded fine, is dried over a slow fire (we have found an iron plate, or clean shovel, to serve the purpose very well): it must be constantly stirred to prevent its forming a cake upon the hot iron; when perfectly free from moisture, 8 parts must be thoroughly well mixed with three parts of carbonate of potash, also well dried: put a cast-iron crucible into the fire, and, when it is red hot, nearly fill it with the mixture, and keep up the heat by occasional augmentations of fuel: the crucible should be kept covered as much as possible. In a short time the whole fuses into a beautiful liquid with the evolution of gas. It should be kept in this state for 10 or 15 minutes, being occasionally stirred with an iron rod: the portion adhering to the red should be examined from time to time, and when the liquid on it cools white, it is an indication that it is ready to be removed from the fire; but the first time a cast-iron crucible is used, this test will not be so accurate, the salt having then a light gray color. When the crucible is removed from the fire, it should be placed upon a stone, the mass stirred, and then allowed to settle for a short time, after which the clear, or liquid part, is to be poured off into a clean iron vessel. The sediment should be scraped clean out of the crucible while it is hot, as the crucible will do to use again several times; but if the mass at bottom be allowed to cool it will be difficult to remove it from the crucible afterwards. The clear liquid poured off is cyanide of potassium, having from 25 to 30 per cent, of cyanate of potash, and other impurities generally contained in commercial yellow prussiate of potash: 80 per cent. of cyanide of potassium is the greatest proportion that this process can give. We have occasionally obtained it at 78 per cent. from commercial materials, but more generally at 70 and 72 per cent; and we have found cyanide of potassium in the market containing as little as 49 per cent. of pure cyanide.

[Edited on 15-2-2011 by Engager]




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[*] posted on 14-2-2011 at 22:44


Quote: Originally posted by kmno4  
Long time ago I performed similar experiment.
My product was hard, crystalline grey mass, smeling like bitter ... + ferromagnetic particles (however much weaker than Fe)
But this "result" gives no information about what it is.
I took a sample of this product (after purification) as catalyst for benzoin condensation.
And I had to boil mixture for very long time to obtain visible amounts of benzoin :mad:
The same amount of pure KCN gave sudden formation of benzoin after 1/10 of time needed for "pyrolytical KCN" synth.

This:
K4[Fe(CN)6] + K2CO3 + C => 6KCN + Fe + CO2 + CO
is only theory (wishful thinking).
Have you tried to do some tests for your product (carbonates, KCN content, yield) ?


What are exact conditions of your pyrolysis experiment? Have you added carbon to reduce cyanate? How much care was taken to protect mixture from the air? What is the temperature scheme used?




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[*] posted on 15-2-2011 at 02:23


Quote:

What are exact conditions of your pyrolysis experiment? Have you added carbon to reduce cyanate? How much care was taken to protect mixture from the air? What is the temperature scheme used?

These data are not available :P
Just it was performed long time ago, in much simpler way than your experiment.
Synthesis via K4[Fe(CN)6] + K2CO3 + C methode is mentioned many times in books and even in this topic.
The most important to me is real amount of KCN prepared from given amount of K4[Fe(CN)6], not very nice looking equations.
If something is crystalline and sweet - it does not mean that it is pure sugar.
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[*] posted on 16-2-2011 at 06:02


What about the reaction of chloroform with amines to yield isocyanides?

CHCl3 + amine + base --> isocyanide

Now, if we use ammonia instead of amine?

CHCl3 + NH3(g) + base --> cyanide salt?
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[*] posted on 16-2-2011 at 07:32


Quote: Originally posted by Random  
What about the reaction of chloroform with amines to yield isocyanides?

CHCl3 + amine + base --> isocyanide

Now, if we use ammonia instead of amine?

CHCl3 + NH3(g) + base --> cyanide salt?


This is a well documented reaction. The only drawback is the fact the NH3+base and CHCl3 are imiccible and so a PTC is required.
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[*] posted on 16-2-2011 at 10:13


Do you know some PTC which is easy available or easy to make? I think this route is a lot easier than those other high temperature reactions.
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[*] posted on 16-2-2011 at 10:41


You have to use a very strong basis eg potassium hydroxide and it is hard to keep the ammonia in solution at normal pressure.
A lot of chloride is produced as well so it is hard to fish the potassium cyanide out of the reaction mixture at the end.
Balance the equation and allow for formate etc formed by hydrolysis and you will see how disgusting it is! :(
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[*] posted on 16-2-2011 at 12:34


Quote: Originally posted by Random  
Do you know some PTC which is easy available or easy to make? I think this route is a lot easier than those other high temperature reactions.


It is no where as good as the other outlined methods.... yields are crap and as affore mentioned high pressures are needed for good yields....
benzyltrimethylammonium chloride should work fine!
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[*] posted on 16-2-2011 at 14:42


It sounds hard to do then. But, maybe cyanides could be made from organic isocyanides which could be made from amine+chloroform+base?

Also there is formamide decomposition route.
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[*] posted on 16-2-2011 at 15:05


Quote: Originally posted by Random  
Also there is formamide decomposition route.
Please don't post random misinfformation before at least using the search function to see if it's already been randomly posted by random newbies:
Quote: Originally posted by Nicodem  
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.
There's a whole frickn thread on this nonsense.
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[*] posted on 16-2-2011 at 16:03


The ways of making potassium or sodium cyanide on a laboratory scale have been exhaustively explored and documented including detailed preparations.

The best way to go about it is to research the recipes, buy the reagents for your chosen method and then execute the preparation using the appropriate safety precautions and scale. Test your product and if it contains significant amounts of free cyanide anion store and use it with the appropriate precautions.

Making sodium thiosulphate by boiling up sodium metabisulphite, sodium hydroxide and sulphur is OK.
It is really not poisonous so making up your own recipe is OK, but DIY cyanide is nuts unless you have serious experience!
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[*] posted on 17-2-2011 at 04:16


I didn't say to use hydroxides, formamide on strong heating decomposes into water and HCN, on slow into ammonia and carbon monoxide.

Check more on wikipedia about Hydrogen Cyanide.

I also read on some page that HCN was successfully synthesized from formamide in history, just I don't remember who did it first..

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[*] posted on 17-2-2011 at 10:26


I haven't read the whole thread, but I was curious if sodium hydroxide/carbonate could be mixed with cyanuric acid, then heated to like 800C in a cast iron (or refractory clay) crucible to get sodium cyanide. I'm assuming it'd work with urea, which would give the cyanate first. And 800C is maybe too hot for me to get it to. I'm guessing 600 or 700 would probably work?

And dissolving in RT methanol then filtering and evaporating would give fairly pure NaCN, right? I'm guessing water could be used too, but it might be a little harder to evaporate away without decomposing the NaCN, right?

[Edited on 2/17/11 by Melgar]
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[*] posted on 18-3-2011 at 16:31


Quote: Originally posted by kmno4  
Quote:

What are exact conditions of your pyrolysis experiment? Have you added carbon to reduce cyanate? How much care was taken to protect mixture from the air? What is the temperature scheme used?

These data are not available :P
Just it was performed long time ago, in much simpler way than your experiment.
Synthesis via K4[Fe(CN)6] + K2CO3 + C methode is mentioned many times in books and even in this topic.
The most important to me is real amount of KCN prepared from given amount of K4[Fe(CN)6], not very nice looking equations.
If something is crystalline and sweet - it does not mean that it is pure sugar.


Ok... May be this is not sugar. However, recently i made a larger batch of cyanide using method i've described. Although i haven't made precise analysis, i've observed mass loss and it was consistent with equation from the book. A batch of product was flushed with water, and filtered. Unsoluble impurities were metallic Fe and some carbon. Obtained solution was used for benzoin condensation. Procedure i've used was taken from http://www.orgsyn.org/orgsyn/prep.asp?prep=cv1p0094, refluxing period was 1 hour instead of 30 min proposed by the procedure. Benzoin was obtained with 82% yield. :) So purity of product remain unknown, but it is proved to be useful for benzoin condensation.


[Edited on 19-3-2011 by Engager]




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[*] posted on 21-8-2011 at 11:47


Quote: Originally posted by Nicodem  
Wouldn't polyethylene start "cracking" at the temperature required? Most of it might escape in form of vapors of higher olefins.

If using pre-prepared tripotassium cyanurate the powder is fine enough (and chemicaly homogenous = as much as it can be) to form KOCN at lower temperatures (250-350°C).* This yields a highly homogenous and very fine product. Perhaps such product would be more ready to react with something like polyethylene at somewhat lower temperatures.
Perhaps the reduction would work even better with thoroughly homogenized crude KOCN with sugar:D, which then carbonizes to some fine carbon that should do the job. However, at the begining there would be a lot of annoying froating due to evolved H2O and CO2 from such a "caramel candy". Starch does not melt, so perhaps it would be more apropriate even though it would be less homogenous.

* This is how I once supposedly prepared some KOCN: I prepared "tripotassium cyanurate" (due to pKa3, I doubt one can prepare it stoichiometricaly pure from KOH) from cyanuric acid and 3 eq of KOH in IPA solution, vacuum filtered the white voluminous paste and while still wet (to avoid CO2 absorption) heated it on a hotplate well covered with alu-foil until up to some 250-350°C and left there for about 2h. There was some cracking of the powder at the beginning and later no more notable change. I haven't analyzed the product but given that no cyanuric acid precipitated after acidification with HCl of an aqueous solution of the product, I assume only KOCN could have formed. This was a modification based on GB710143 where Na2CO3 with cyanuric acid is used to produce NaOCN. If someone is terribly curious if this was truly KOCN, I might bother to check with IR (if someone is so kind to provide a reference spectra:P).


Pardon my digression concerning a parallel interest with regards to cyanuric acid possibly having other usefulness as well. I will go out on a limb here somewhat with speculation
since this seems possible but complete references are not available for having certainty about this possible scheme.

What would be more interesting for me than the IR spectra
would be an experiment to find out about the feasability of further reaction of the KOCN with additional KOH or NaOH either as a subsequent addition, or provided in excess sufficient from the beginning of the reaction, to accomplish the reaction described by Dreschel leading to the dibasic salt of cyanamide and a carbonate. This would be interesting not in regards to production of cyanides so much as it would be interesting as a path to guanidine and also to aminoguanidine.

3 KOCN + 3 KOH ------> K2CN2 + 2 K2CO3 + NH3

This is the reaction of Dreschel corrected to show the evolution of ammonia reported in the attached article, see page 11 of the pdf The Ammono Carbonic Acids Franklin, JACS 44

What I have thought about is the sum of the reactions

(HOCN)3 + 3 KOH ----> K3(OCN)3 + 3 HOH ---->

3 KOCN + 3 KOH ----> K2CN2 + 2 K2CO3 + NH3 =

--------------------------------------------------------------------

(HOCN)3 + 6 KOH ----> K2CN2 + 2 K2CO3 + NH3

Doubling the amount of hydroxide for the formation of the tripotassium cyanurate could then lead to dipotassium cyanamide. Curiosity exists whether or not this entire reaction sequence may occur in DMSO under reflux, so that byproduct H2O and NH3 is volatilized.

Subsequent treatment of the completed reaction mixture
with hydrazine sulfate could lead to aminoguanidine.
Nitrosation in situ could produce guanyl azide and cyclization to 5-aminotetrazole would seem convenient as a possible one pot synthesis.

Alternatively the completed reaction mixture might be acidified for isolation of cyanamide or cyanoguanidine
or be used as an intermediate for production of guanidine.

It remains unclear what sort of reaction condition is required for the Dreschel reaction to proceed, and with what efficiency does that described reaction occur. But the implications are certainly interesting for these other possible end products obtainable from cyanuric acid, under whatever reaction conditions, and most interesting if indeed such reactions can occur under relatively milder conditions of temperature than the pyrolytic decomposition schemes, especially if it would occur in DMSO.

Now there is a qualitative analysis approach that you know very well is more interesting than an IR spectrum :D

Dreschel article also attached see pae 13 of pdf

Attached also is some data about the level of hydration of
alkali cyanurates. Evidently the tripotassium cyanurate has been reported difficult. The disodium cyanurate and trisodium cyanurate reportedly crystallize in anhydrous form. So it may go equally well to work with the less expensive sodium salts.

GB710143 also attached

Attachment: The Ammono Carbonic Acids JACS.pdf (1.1MB)
This file has been downloaded 1119 times

Attachment: Dreschel article.pdf (1.9MB)
This file has been downloaded 787 times

Attachment: GB710143 Cyanates from Cyanurates.pdf (791kB)
This file has been downloaded 850 times

Attachment: Alkali Cyanurates thermochemical properties JOCS 70.pdf (214kB)
This file has been downloaded 1139 times

There is some additional discussion regarding the cyanate in a cyanate specific thread
http://www.sciencemadness.org/talk/viewthread.php?tid=9128

[Edited on 22-8-2011 by Rosco Bodine]
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[*] posted on 26-9-2011 at 21:48


Here's an idea I haven't seen, though it seems obvious.
Adding TCCA to an alkaline solution of amino acids has been shown to give high yields of the corresponding nitrile and CO2. Other sources indicate that glycine yields HCN from reacting with hypochlorite.
So why not just gradually add TCCA to the glycine solution, keeping glycine in excess in order to prevent the TCCA from destroying the cyanide?
Separation of cyanide from the cyanurates and chlorides shouldn't be hard right?
Doesn't get much easier than that...

[Edited on 27-9-2011 by 497]




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[*] posted on 27-9-2011 at 14:53


Quote: Originally posted by Rosco Bodine  

Alternatively the completed reaction mixture might be acidified for isolation of cyanamide


Since you happen to mention GB710143 and an interest in cyanamide, perhaps I can mention here the amine version of cyanuric acid, melamine, and bell-ringer US2656253. Both patents are known here due to trying to find a use for it, since it's on hand (but not larger tubing, yet. Or the pressure apparatus for the GB).




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[*] posted on 17-1-2012 at 15:52


Quote: Originally posted by Polverone  
YIKES! I found the following information on another site:

a patent on making metal cyanides from nitrates or nitrites and
carbon; US patent 579988.
KNO3 + 4C -> KCN + 3CO
KNO2 + 3C -> KCN + 2CO

I was unable to access the patent since I'm temporarily banned from the database for running too many queries (oops).

So I decided to try just forming a pyrotechnic mixture with the right ratios. 10 grams KNO3, 4.8 of charcoal, place in stainless steel vessel and ignite with gas heating from below...

As expected, the mass of what remained was much reduced, from loss of gas, solid particulates, things flung from the vessel by the reaction, etc. There was little material left in the bottom. I figured there had to be more to the method than this; after all, nobody talks about pyrotechnic formulas leaving cyanide lying around, and this is pretty much the same thing.

Anyway, not having an analytical method for detecting cyanides at hand and being too stupid to look one up (and also expecting failure), I added a bit of vinegar to the residue left in the bottom. It fizzed vigorously and I caught the distinct odor of almonds... At which point I backed the heck away from there. I now intend to find a method for assaying KCN that is not so suicidal, and also to try making some more and purifying it (I have no idea what purity I obtained with this first test.) This method seems to be a vastly superior route to cyanides for the home experimenter, compared to the laborious steps given in the PMJB and the 19th century texts from which they were derived. I hope to view that patent soon and see if it contains any additional refinements (compared to crude ignition).


I gave this a shot. It seemed to be the most simplistic method listed in this thread.

The reaction vessel I used was a small stainless steel camping pan 1/2 full with heavy duty foil over the top. The reagents occupied an approximate volume of 350 ml. The carbon was activated carbon from the pet store fish isle which I ground finely in a coffee grinder. The NaNO2 was free flowing and fine. I placed the reaction vessel over very low gas heat. Nothing happened for few mins as the mixture came up to temperature. A violent reaction occured. The foil lid blew off the small pan. It looked like a small volcano erupting. The reaction reminded me of gunpowder burning. It made a big mess. There were little black crystalline pebbles of the partially reacted mixture everywhere. A decent amount of smoke was created. It looked like there was a fire. The cleanup was painstaking because I didn't know if the reaction had succeed and there was potentially NaCN all over everything in a 5 foot radius from the cup. There was indeed a blackened crystalline fused mass in the bottom of the cup. I was so preoccupied with the mess and smoke I had made, I neglected to test the remaining product on some silver. I called it a day.

I'm interested in trying this again. This time, in a much less full heavy duty stainless steel pot with a weighted lid on top to keep the spatter down. After the reaction, do you suggest that I continue heating it? Should I just allow it to cool and go from there? It seems to me that any continued heating would be irrelevant because the mixture has already literally burned on it's own.


[Edited on 1.18.2012 by slinky]
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[*] posted on 17-1-2012 at 16:19


Quote: Originally posted by slinky  
Quote: Originally posted by Polverone  
YIKES! I found the following information on another site:

a patent on making metal cyanides from nitrates or nitrites and
carbon; US patent 579988.
KNO3 + 4C -> KCN + 3CO
KNO2 + 3C -> KCN + 2CO

I was unable to access the patent since I'm temporarily banned from the database for running too many queries (oops).

So I decided to try just forming a pyrotechnic mixture with the right ratios. 10 grams KNO3, 4.8 of charcoal, place in stainless steel vessel and ignite with gas heating from below...

As expected, the mass of what remained was much reduced, from loss of gas, solid particulates, things flung from the vessel by the reaction, etc. There was little material left in the bottom. I figured there had to be more to the method than this; after all, nobody talks about pyrotechnic formulas leaving cyanide lying around, and this is pretty much the same thing.

Anyway, not having an analytical method for detecting cyanides at hand and being too stupid to look one up (and also expecting failure), I added a bit of vinegar to the residue left in the bottom. It fizzed vigorously and I caught the distinct odor of almonds... At which point I backed the heck away from there. I now intend to find a method for assaying KCN that is not so suicidal, and also to try making some more and purifying it (I have no idea what purity I obtained with this first test.) This method seems to be a vastly superior route to cyanides for the home experimenter, compared to the laborious steps given in the PMJB and the 19th century texts from which they were derived. I hope to view that patent soon and see if it contains any additional refinements (compared to crude ignition).


I gave this a shot. It seemed to be the most simplistic method listed in this thread.

The reaction vessel I used was a small stainless steel camping pan 1/2 full with heavy duty foil over the top. The reagents occupied an approximate volume of 350 ml. The carbon was activated carbon from the pet store fish isle which I ground finely in a coffee grinder. The NaNO2 was free flowing and fine. I placed the reaction vessel over very low gas heat. Nothing happened for few mins as the mixture came up to temperature. All at once, a violent reaction happened. The foil lid blew off the small pan. It looked like a small volcano erupting. The reaction reminded me of gunpowder burning. It made a big mess. There were little black crystalline pebbles of the partially reacted mixture everywhere. A decent amount of smoke was created. It looked like there was a fire. The cleanup was painstaking because I didn't know if the reaction had succeed and there was potentially NaCN all over everything in a 5 foot radius from the cup. There was indeed a blackened crystalline fused mass in the bottom of the cup. I was so preoccupied with the mess and smoke I had made, I neglected to test the remaining product on some silver. I called it a day.

I'm interested in trying this again. This time, in a much less full heavy duty stainless steel pot with a weighted lid on top to keep the spatter down. After the reaction, do you suggest that I continue heating it? Should I just allow it to cool and go from there? It seems to me that any continued heating would be irrelevant because the mixture has already literally burned on it's own.

[Edited on 1.17.2012 by slinky]



Did you read the whole thread? What about the patent mentioned?

Quote: Originally posted by Polverone  


Oh, BTW, that patent I mentioned in the 2nd post in this thread? It involves using electrified carbon rods in molten KNO3/KNO2, so it's still not the easiest thing ever...


[Edited on 18-1-2012 by Bot0nist]




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[*] posted on 17-1-2012 at 16:22


He himself didn't use electrified carbon rods. I did read the patent he cited a few times.
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[*] posted on 17-1-2012 at 16:31


I don't think his reaction lead to confirmed formation of metal cyanides either. He even implied that him smelling almonds was not conclusive, and no attempts where made to determine yield. Two things you have also not done.

I would love if it was that easy, but I have attempted to make NaNO<sub>2</sub> via C and NaNO<sub>3</sub> in a similar fashion, albeit with different proportions. Keep experimenting though. Try and find a way to accurately confirm the formation of metal cyanides and then isolate and quantify your yield. This would be the best place to focus efforts, IMHO.

[Edited on 18-1-2012 by Bot0nist]




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[*] posted on 31-1-2012 at 17:03


Here is the method I'm planning to follow:
Quote:

To convert the ferro to cyanide do this (please note that these instructions were for the potassium not sodium salt. I'm assuming that the ratios are similar for both); Mix thoroughly 8 parts of dry sodium ferrocyanide and 3 parts dry sodium carbonate (pool pH adjuster), heat them in a steel container (cleaned oil filter can works nicely), with constant stirring (use clothes hanger, straightened out), with a propane torch or other intense heat source till it melts into a clear liquid. Heating is continued until the mix no longer fizzes and the fluid portion is colorless. After a few minutes rest, to allow the contents to settle, the clear portion is poured from the heavy black sediment (iron) at the bottom of the crucible and onto to a clean slab or steel bowl. It's then broken up while still warm and stored in airtight bottles. This will be almost pure cyanide.

K4Fe(CN)6•3H2O + K2CO3 --> 6KCN + CO2 + FeO + 3H2O

Is the above possible in my backyard?
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cyanureeves
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[*] posted on 31-1-2012 at 18:20


i've done this but with sodium carbonate and never could tell the clear liquid from the rest of the fused stuff. i used a swiping motion when i poured the liquid in hopes that the liquid portion would run out first then the sediment would follow afterwards and so i could separate the solid from the liquid. what i got was a grey rocklike stuff. it made good prussian blue with iron sulphate but so did the ferrocyanide.i never got it to dissolve gold but did use it for a gold plating solution but it was not satisfactory. i think oxygen is absorbed to quickly when pouring the molten stuff out and turns to cyanate instead. i dont know but i want to try with potassium carbonate because it melts faster. this time i would cover it immediately with a huge pot with plumbers putty on the rim to make a seal so as to starve it of oxygen. this liquid hardens fast too but it can be done in the backyard,now to make the ferrocyanide or cyanide like the german site shows requires lots of heat,i had to use a leaf blower and tons of charcoal and still didnt get it hot enough to thoroughly fuse.i could'nt see crap because i had snot and tears running all the way down to my belly.
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seashell1982
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[*] posted on 1-2-2012 at 18:02


Is there some way to turn wet potassium ferrocyanide into the dry version? Like this:

K4Fe(CN)6•3H2O --> K4Fe(CN)6 + 3H2O

Apparently I need the anhydrous, but the chemical supply stores seem only to sell the trihydrate version.
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