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Author: Subject: Preparation of cyanides
Engager
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[*] posted on 3-2-2012 at 01:51


Yes. Actually you can use hydrate. Just heat it up on the frying pan, it looses water at about ~130C and became lighter in colour. You can as well control completeness of dehydration by measuring mass loss, just heat up on the pan until mass loss will become theoretical. Dry fusion of pure K4Fe(CN)6 is a bit tricky, if you will try to do this on air contact you will end with with cyanate and cyanogen beeing evolved. To prevent oxidation process must carried out out of air contact, that's why method witch K2CO3 and carbon works the best - you don't need protecting atmosphere you just must cover reaction vessel with lid to reduce free air flow, reaction products CO and CO2 will form protecting buffer of gas under the cover and prevent oxidation of product to cyanate, remember you don't need completely airtight vessel (reaction gases must evolve freely) just cover crucible with ceramic lid and heat it up in electric furnace. I made K4Fe(CN)6 + K2CO3 + C process for many times now and produced a lots of cyanide using this method, temperature program i've used ~30 min to 600C, then 1 hour at this temp, rise to 650 in 30 minutes, and one more hour at 650. If your crucible is high and you sit it long enough cyanide separates from Fe and carbon particles and solidifies as shiny snow white layer at the top layer, however if this has't happened and resulting mass is black and feromagnetic this is fine too, you can separate cyanide by dissolving and filtering. I've used such cyanide for the benzoin condensation 2 or 3 times, each time from new batch and always got good yields of benzoin.


[Edited on 3-2-2012 by Engager]
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[*] posted on 3-2-2012 at 09:11


I have always thought that the reduction of cyanate to cyanide would need simuler conditions as the reduction
of nitrate too nitrite.

In the ionic nitrites thread taoiseach has posted a link too the german forum that describes the use
of calcium formate for the reduction of nitrate.

I was thinking of lead tartrate before but with this prep laid out for us I would think this would be an
easier task.

thread to taoiseach's post
http://www.sciencemadness.org/talk/viewthread.php?tid=52&...

german thread too nitrite synthesis with calcium formate
http://www.versuchschemie.de/topic,13865,-Herstellung+von+Ni...




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[*] posted on 3-2-2012 at 18:17


Quote: Originally posted by Engager  
I made K4Fe(CN)6 + K2CO3 + C process for many times now and produced a lots of cyanide using this method,
Will this carbon work? http://www.onlinesciencemall.com/carbon-lumps-15-grams.html

Quote: Originally posted by Engager  
resulting mass is black and feromagnetic this is fine too, you can separate cyanide by dissolving and filtering
How exactly do you do that?

[Edited on 4-2-2012 by RisingSun96815]
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[*] posted on 3-2-2012 at 21:29


Here is a preparation for HCN or its salts that uses only household products (scary). The reference is a bit dated but I suspect basically accurate. Source: "The Pharmaceutical journal and transactions", by Pharmaceutical Society of Great Britain on December 24, 1887, page 530:

"When the ammonia and iodine are first mixed, an explosive compound, the so-called iodide of nitrogen, is precipitated, but soon splits up again and dissolves. Disregarding this reaction, the steps of the process may be made clear by the following equations, which are not given as an exact representation of what is probably a more complicated reaction, but rather as an explanation of the results detailed above. Schbnbein (Watts' 'Dictionary,' vol. iii., p. 297) has found that hypoiodite of ammonium is formed by the action of iodine on excess of ammonia. The reactions may, therefore, be represented as follows:—

1. Iodide and hypoiodite of ammonium are formed thus :—

6 NH4HO + 3 I2 = 3 NH4I + 3 NH2IO + 3 H2O

2. The hypoiodite reacts with the alcohol to form iodoform and iodide and formate of ammonium, thus:—

2C2H60 + 8NH4IO = CHI3 + 3 NH4CHO2 + 5 NH4I + 4H20

3. The iodoform reacts with the free ammonia to form iodide and formate of ammonium thus :—

CHI3 + 4 NH4HO = 3 NH4I + NH4CH02 + 2 H20, so that ultimately the tincture contains iodide and formate of ammonium, free ammonia and spirit.

http://books.google.com/books?pg=PA529&lpg=PA529&dq=...

Now, allow the tincture to evaporate leaving I2 and Ammonium formate, then followed the process outlined by Madscientist on page 1 of this thread , but allow the Iodine to collect at the top of the heated vessel by cooling that area. Per Madscientist:

"PREPARATION OF POTASSIUM CYANIDE (KCN):
The ammonium formate crystals are heated by flame in an environment containing as little oxygen gas as possible. The ammonium formate decomposes into formamide (HCONH2) which then decomposes into hydrogen cyanide.

[HCOO-][NH4+] --} HCONH2 + H2O
HCONH2 + H2O --} HCN + 2(H2O)

The gas given off is condensed in in a rubber, plastic, or, preferrably, glass tube that has one end immersed in a beaker containing a solution of potassium hydroxide (KOH). The tube should be positioned so that any liquids forming in it will run off into the beaker of potassium hydroxide. Some of the gas given off may not be condensed..."

If one effectively recycles the Iodine, then this process is relatively inexpensive consuming just NH3 and alcohol. However, a potential issue is the creation of any NI3 (from any residual Ammonia and/or a side reaction, per Wiki noted below, plus Iodine) from the heating of the Iodine/ammonium formate, which should be guarded against, as its detonation could spread deadly HCN gas.

Note, per wikipedia:
"When heated, ammonium formate eliminates water, forming formamide. Upon further heating it forms to HCN and H2O. A side reaction of this is the decomposition of formamide to CO and NH3."


[Edited on 4-2-2012 by AJKOER]
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[*] posted on 4-2-2012 at 07:13


Why use iodine to make ammonium formate ?

I have made this before with just formic acid and ammonia gas.
The formic was made via oxalic acid and glycerol then turned to salt with sodium bicarbonate.

The formate can be made into an acid which is strong enough to be gassed with 80 too 85% sulfuric acid
if the formate is added to the acid when it is cooled below 0C. if the temp is above 0C it will crack your formic
acid and make carbon monoxide.

waist of iodine.

I would do my best not to work with HCN having had a dose of it in the past.
It was far from pleasent and ive been poisoned by quite a few of my stupid endevours when I was younger.
HCN was up there with the worst the post about it is probably here somewere.

I think you should listen to some of the warnings posted by the people here HCN is as bad as they say.






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[*] posted on 4-2-2012 at 09:32


Ephoton:

I definitely agreed do not attempt this synthesis (in case it actually does work).

The positive aspect of the thread is letting kids known that Nitrogen tri-iodide, a novelty explosive, cannot safely be prepared adding ammonia to tincture of iodine and heating the product. This could, instead, lead to a tragic poisoning by way of Hydrogen Cyanide gas fumes.

So don't do it!
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[*] posted on 4-2-2012 at 14:08


Quote: Originally posted by AJKOER  
The positive aspect of the thread is letting kids known that Nitrogen tri-iodide, a novelty explosive, cannot safely be prepared adding ammonia to tincture of iodine and heating the product. This could, instead, lead to a tragic poisoning by way of Hydrogen Cyanide gas fumes.

So don't do it!
Do you really believe that this reaction will make significant amounts of HCN?
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[*] posted on 4-2-2012 at 16:03



OK, if we net these two reactions (per the source):

2C2H60 + 8NH4IO = CHI3 + 3 NH4CHO2 + 5 NH4I + 4H20
CHI3 + 4 NH4OH = 3 NH4I + NH4CH02 + 2 H20
-------------------------------------------------------------------------
2C2H60 + 8NH4IO + 4 NH4OH = 4 NH4CHO2 + 8 NH4I + 6 H20

or, dividing through by 2:

C2H60 + 4 NH4IO + 2 NH4OH = 2 NH4CHO2 + 4 NH4I + 3 H20

So, for each mole of alcohol, we form two moles of ammonium formate. Per its decomposition reaction, one mole of ammonium formate produces one mole of HCN. So, if we are not limited by the available Iodine & Ammonia (that is, plan the experiment with an excess of I2 and NH3), each mole of alcohol can produce 2 moles (or 44.8 liters) of HCN gas. However, there is a side reaction:

NH4CHOO ---Heat Secondary Reaction--> NH3 + H2O + CO

so if the yield is reduced by 40% (a significant side reaction), each mole of alcohol still produces over a mole of HCN (as .6 X 2 = 1.2 mole).

Also, it is perhaps not unusual to employ an excess of NH3 (it is cheap) and we are attempting to recycle the Iodine.





[Edited on 5-2-2012 by AJKOER]
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[*] posted on 4-2-2012 at 16:47


Quote: Originally posted by AJKOER  
The reference is a bit dated but I suspect basically accurate. Source: "The Pharmaceutical journal and transactions", by Pharmaceutical Society of Great Britain on December 24, 1887, page 530:
I suspect it is hokum. And 1887 is more than "a bit dated". You can't believe everything you read. Unless you're an arm chair chemist who doesn't own any glssware or chemicals to verify what you read.
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[*] posted on 6-2-2012 at 13:53


Quote: Originally posted by entropy51  
Quote: Originally posted by AJKOER  
The reference is a bit dated but I suspect basically accurate. Source: "The Pharmaceutical journal and transactions", by Pharmaceutical Society of Great Britain on December 24, 1887, page 530:
I suspect it is hokum. And 1887 is more than "a bit dated". You can't believe everything you read. Unless you're an arm chair chemist who doesn't own any glssware or chemicals to verify what you read.


Actually, if you know or even looked at some of the reactions, in light of today's knowledge, your comment "hokum' is really misplaced.

For your edification, the 1st reaction is based on the classic disproportionation of a halogen in water. For Iodine:

I2 + H2O <===> HI + HIO

and adding NH3 reacts forming NH4I and NH4IO, a reaction correctly referenced back to Watt's.

Next, the creation of Iodoform is also a classic reaction. For example per "Chemistry, inorganic and organic: with experiments' By Charles Loudon Bloxam, page 636:

"Iodoform, CHI3 or tri-iodo-methane, is a product of the action of iodine upon alcohol in an alkaline solution, the immediate agent being probably a hypo-iodite, whilst chloroform is produced by a hypo-chlorite. To prepare it, dissolve 32 parts of potassium carbonate in 80 parts of water, add 16 parts of alcohol of 95 per cent, and 32 parts of iodine; heat gently till the colour of the iodine has disappeared, when iodoform will be deposited on cooling.

CH3-CH2OH + 6KOH + I8 = CHI3 + HCOOK + 5KI + H2O.

To recover the iodine left as KI, the filtrate from the iodoform is mixed with 20 parts of HC1 and 2.5 parts of potassium dichromate, which liberates the iodine. The liquid is neutralised with potassium carbonate, and 32 parts more of that salt are added, together with 6 parts of iodine and 16 of alcohol; the operations of heating and cooling are then repeated.

Iodoform is deposited in yellow shining hexagonal plates, smelling of safi'ron. It fuses at 120° C, and may be sublimed with slight decomposition. It is insoluble in water, but dissolves in alcohol and ether. When boiled with potash, it is partly volatilised with the steam, and partly decomposed, yielding potassium iodide and formate. The production of CHI3, on adding iodine and dilute KOH and stirring, is a very delicate test for alcohol, but many other substances also yield it. "

link:
http://books.google.com/books?pg=PA662&dq=ammonia+and+et...
IvT4zQHcbv0gGxxJXnCg&id=ogtDAAAAIAAJ#v=onepage&q=ammonia%20and%20ethyl%20iodide&f=false

Also, another source:

"An introduction to chemical pharmacology: pharmacodynamics in relation to ....", page 7 of 30 by Hugh McGuigan:

"IODOFORM AND PHYSIOLOGICAL SUBSTITUTES

Iodoform, or triodomethane, was the first solid antiseptic known. It is prepared by the action of iodine upon alcohol or acetone, in the presence of an alkali or an alkaline carbonate. Its formation is also used to test for the presence of alcohol or acetone. A solution of I in KI is added to the solution of alcohol, or acetone, and warmed, then dilute NaOH or KOH is added, drop by drop until the color has disappeared. Iodoform is formed :

CH3COCH8 + 3KI0 = CH3COCI3 + 3K0H
CH3COCI3 + KOH = CH3COOK + CHI3

The potassium hypoiodite KIO is formed when dilute KOH is added to the I in KI solution : 2 KOH + I2 = KIO + KI + H2O. The hypoiodites are easily decomposed into iodides, and iodates:

3 KIO = KIO3 + 2KI.

Both the iodate and iodide are usually formed in the solution with the iodoform, even when KI has not been added. Strong alkalies cause the formation of the iodate; and, therefore, if a too strong alkali is added, it interferes with the reaction. For this reason, sodium carbonate or potassium carbonate instead of the hydrate is sometimes recommended in making the iodoform test. From alcohol, iodoform is prepared, possibly according to the following reaction:

C2H6OH+I8+6KHCO3 = CHI3+5KI + KCOOH+6CO2+5H2O

Ethyl iodide, acetic ether, and other compounds are probably also produced. The result appears to be greatly influenced by the temperature, and the relative amounts of the materials used."

Please note the last sentenced as I do not mean to say that careful attention to detail is not needed for a successful reaction here.

LINK:
http://www.ebooksread.com/authors-eng/hugh-mcguigan/an-intro...

With respect to the creation of any Ethyl iodide, which, per Bloxam, page 633:

"In a large number of cases the mere treatment of an alcohol with halogen hydride, particularly in the presence of a dehydrating agent, will produce the halogen substitution product, the reaction being of the type ROH + HX = EX + HOH." Note, we are not directly employing a dehydrating agent, but the overall reaction does consume water. To best understand how to proceed with these multi-step reactions, also note in the reaction:

I2 + H2O <===> HI + HIO

clearly having an excess of conc. NH3 to remove the HI and HIO would be good as otherwise a possible disproportionation into iodate (noted above as unfavorable):

3 HIO --> 2 HI + HIO3

Other factors, mild heat (say 90 C), KI to add to the solubility of the Iodine, and working in a sealed chamber (to prevent ammonia loss). Heat and water loss would also increase the reactivity of the HI in the creation of iodides.

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

Per research, I also can across the Tollens Reagents test, which could also form NH4HCO2. In general, for an aldehyde, RCOH:

RCOH + 2 Ag2(NH3)2OH ---> 2 Ag(s) + NH4(+)RCO2(-) + H2O + 3 NH3

which, in our case of interest, R is a single hydrogen (H) and the synthesis is thus based on formaldehyde, H2CO.

LINK:
http://opencourseware.kfupm.edu.sa/colleges/cs/chem/chem303/files%5C3-Lecture_Notes_CHEM-303_(Classification_Tests).pdf

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



[Edited on 6-2-2012 by AJKOER]
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[*] posted on 16-2-2012 at 09:22


I made the following attempt this morning: I heated wet potassium ferrocyanide until it was lighter in color, assuming it changed to anyhydrous. I then combined it with potassium carbonate and a little carbon, added a lid to the crucible, and heated it in my gas-powered fireplace for 2 hours. The result was a black solid with a few white crystals on the edge of the black mass. I'm assuming the white crystals are actually potassium carbonate. What am I doing wrong here? Is the temp of my fireplace too low? I checked periodically, and I never got any liquid.
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[*] posted on 16-2-2012 at 09:32


Temperature schedule to be used in K4[Fe(CN)6] + K2CO3 + C: about 1 hour to 600C, 30 min to 650-700, and 1 hour at 650-700C. And actually yes, mixture should be liquid at this temp since KCN melts around 630C. Correctly prepared product after cooling is fused black ferromagnetic mass with smell of bitter almond. I guess that your temperature was too low for the process.

[Edited on 16-2-2012 by Engager]
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[*] posted on 16-2-2012 at 12:41


I would treat that black mass you took out of your fireplace with a lot of respect. Ie, there may be more cyanide there than you think. I suggest you test it using a Prussian Blue test as follows:

1.Place about 1 mL of water in a small test tube.
2. Add a smidgen (few mg) of FeSO4*7H20 or other soluble ferrous salt and stir until dissolved.
3. Acidify with a few drops of 1M HCl.
4. Add a smidgen of your product and stir.

An intense dark blue color indicates the presence of cyanide.

[Edited on 16-2-2012 by Magpie]




The single most important condition for a successful synthesis is good mixing - Nicodem
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[*] posted on 16-2-2012 at 16:51


i second magpie because i bubbled hcn into potassium hydroxide/ water solution by distilling potassium ferrocyanide with sulfuric acid.i then added cold ethanol to precipitate the salt and it all turned to ammonia in a day but to make a long story short,i mostly had cyanate because of the water or excess potassium hydroxide.i forgot about the salt which i stored in a jar with a dessicant but last month i took it out and added a bit of water and dropped a piece of gold in it and now i got a yellowish looking solution which i did never before could produce.i know gold cyanide is white but where is the gold color coming from.i think i always had cyanide in the mix because it plates out gold beautifully and boy had i been careless with the stuff.definitley wear a mask when you break the hard black mass.
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[*] posted on 16-2-2012 at 17:13


Perhaps assumptions were made about the ease of completely dehydrating the salt?



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[*] posted on 16-2-2012 at 18:41


the salt is very very difficult to dry, it actually never did even in the texas summer heat. just when it was about to dry off it kept grabbing moisture from the air like a freaking gecko.this salt was stored with baked epsom salt in a jar for over six months. the little piece of gold is sitting at the bottom of a tiny jar covered in crystal clear salt covered by a spongy looking stuff then the yellow solution.i did the method engager is doing and also the urea,charcoal and carbonate method and got the salt to dissolve copper and silver but only when adding 3% hydrogen peroxide. the copper just melts like butter on the outside and bleeds off but the silver breaks up into particles.i should've weighed the gold before i dropped it in the salt.
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[*] posted on 21-2-2012 at 07:56


Today I replaced my thick-walled crucible with a steel soup can, and sure enough I got liquid. I let it cook for an hour, and had a black mass. So how exactly do I filter this to extract any KCN that is there?
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[*] posted on 21-2-2012 at 23:31


Is it safe to buy Potassium Ferrocyanide? I mean the lab guys will ask a million questions as to why you need the compound, right? And what will you reply?

PS: I'm not interested in making this stuff. Just curious after seeing the amount of enthusiasm in here. :)
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[*] posted on 22-2-2012 at 10:58


Yes. Ferrocyanides/ferricyanides are not that toxic because the cyanide ligands are tightly bound to the iron core. Perfectly safe to buy, and not that expensive too.
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[*] posted on 22-2-2012 at 19:04


Quote: Originally posted by RisingSun96815  
Today I replaced my thick-walled crucible with a steel soup can, and sure enough I got liquid. I let it cook for an hour, and had a black mass. So how exactly do I filter this to extract any KCN that is there?
i think the next step is crush the mass to a powder and throw it in a container with warm water.swish it around and invert it totally over and flush on a filtered funnel that is taped to a jar or glass.as the stuff is pouring quickly cover the whole thing with plastic wrap and tape it tightly around the glass.when it is all poured out inject ice cold ethanol into the container through the plastic.you rapidly see the white precipitate out like a gel looking stuff and more so if you shake it.avoid oxygen is a key also. this precipitate is what dissolved copper and silver in my experiment when i added peroxide but as of yet it did not dissolve gold. this stuff is so hard to dry too.
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[*] posted on 22-2-2012 at 19:11


Quote: Originally posted by madmanhere  
Is it safe to buy Potassium Ferrocyanide? I mean the lab guys will ask a million questions as to why you need the compound, right? And what will you reply?

PS: I'm not interested in making this stuff. Just curious after seeing the amount of enthusiasm in here. :)
yes it is and i have bought some.its safe as heck because photographers use it also and i read that it is also added to food to keep it from caking up. ferrycyanide is also safe to buy but its more expensive.both can release hcn and become deadly though if acid is added to them but hell ,bullets are deadly.
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[*] posted on 23-2-2012 at 08:26


Thanks for the replies.

I went through myfanwy's video on NaCN preparation and is intrigued by a few basic things. Searched on Google, but couldn't find an answer.

1. If room temperature is ~30'C, HCN will be in gaseous form. To convert into liquid, one should pass chilled water through the condenser. Assuming HCN indeed comes out in liquid form at the other end of the condenser, how do you ensure it is collected as a liquid? Should we immerse the receiving flask in chilled water too?

If yes, another question. If the climate is very humid- say 80%, atmospheric water vapour will condense on the inner walls of the receiving flask. Is there any problem if HCN mixes with this water?

2. Instead of using an empty receiving flask, why can't we just dip one end of the condenser tube into NaOH? Is it safe (bubbling)? Is there any chance for NaOH to get sucked up into the heating flask?

3. How is NaCN extracted from NaOH solution? Heating is not safe, right?

I don't plan to conduct the experiment any time soon (chemistry noob + know the dangers). Would love to do it after a while though.




[Edited on 23-2-2012 by madmanhere]
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[*] posted on 23-2-2012 at 08:59


Its so viscous! Pretty :D



BOLD

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[*] posted on 23-2-2012 at 12:29


"If yes, another question. If the climate is very humid- say 80%, atmospheric water vapour will condense on the inner walls of the receiving flask. Is there any problem if HCN mixes with this water?"

It probably hydrolizes, so yes.

"Instead of using an empty receiving flask, why can't we just dip one end of the condenser tube into NaOH? Is it safe (bubbling)? Is there any chance for NaOH to get sucked up into the heating flask?"

One should never risk a suck-back when working with such awefully dangerous substances. If suckback happens and ice-cold NaOH solution is sucked back into the hot reaction vessel, chances are the glass will crack, releasing deadly HCN fumes.

"How is NaCN extracted from NaOH solution? Heating is not safe, right?"

Heating wet cyanide is one of the fastest ways to destroy it. It could be precipated with ice-cold ethanol but I would rather evaporate under vacuum at a low temperature until it starts to crystallize.

Personally I would not conduct this experiment even when someone offered me 1000$ to do it. There are much easier and far less dangerous ways to make cyanide which have been posted already. I would prefer decomposing dry potassium ferrocyanide in a charcoal furnace and then boil the resulting mass in MeOH to dissolve all cyanide. The MeOH is then filtered and destilled until dry canide is obtained.
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[*] posted on 24-2-2012 at 11:14
ferro+carbonate+c method


Yes. Actually you can use hydrate. Just heat it up on the frying pan, it looses water at about ~130C and became lighter in colour. You can as well control completeness of dehydration by measuring mass loss, just heat up on the pan until mass loss will become theoretical. Dry fusion of pure K4Fe(CN)6 is a bit tricky, if you will try to do this on air contact you will end with with cyanate and cyanogen beeing evolved. To prevent oxidation process must carried out out of air contact, that's why method witch K2CO3 and carbon works the best - you don't need protecting atmosphere you just must cover reaction vessel with lid to reduce free air flow, reaction products CO and CO2 will form protecting buffer of gas under the cover and prevent oxidation of product to cyanate, remember you don't need completely airtight vessel (reaction gases must evolve freely) just cover crucible with ceramic lid and heat it up in electric furnace. I made K4Fe(CN)6 + K2CO3 + C process for many times now and produced a lots of cyanide using this method, temperature program i've used ~30 min to 600C, then 1 hour at this temp, rise to 650 in 30 minutes, and one more hour at 650. If your crucible is high and you sit it long enough cyanide separates from Fe and carbon particles and solidifies as shiny snow white layer at the top layer, however if this has't happened and resulting mass is black and feromagnetic this is fine too, you can separate cyanide by dissolving and filtering. I've used such cyanide for the benzoin condensation 2 or 3 times, each time from new batch and always got good yields of benzoin. [Edited on 3-2-2012 by Engager]

1.Can porcelain crucible be used ?
2.Can carbon rode be used to stir the mass?
3.If not porcelain or iron , can regular stainless steel cooking ware can be used ?
4.How the temp. variation can be done in a domestic cooking gas range ?
5.The regular wook burnt will work or need to buy activated charcoal from amazon or so ?

I used first a regular cooking ware (stainless steel) and then a porcelain.None worked.But I didnt regulate the air and due to fear of toxic gas i had the windows open and exhaust fan on all the time.I didnt add carbon either.I should have made the ventilation clear but the pan kept closed it seems ?
Anyway what I ended up with is a dark ,dry sediment.Need to try next after getting ur response..
Thanks !




alchemist
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