Sciencemadness Discussion Board

Preparation of cyanides

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Paddywhacker - 4-10-2009 at 11:50

Would fusing ferrocyanide or ferricyanide with KOH, or with KOH/NaOH eutectic mixture free up the cyanide to be distilled off as HCN with H2SO4?

kmno4 - 4-10-2009 at 12:55

Quote: Originally posted by entropy51  

How you figure 5.5 gm of distillate is 50% without titrating the CN?
Not bullshit, with CuCl I can get 80% of the CN from ferrocyanide. That's by titration.
It didn't work for you because your CuCN wasn't dissolved.

I obtained this amount by collecting all vapour coming below 95 C.
Generally distillation stops at ~85 C (temp. of vapour) and I had to increase heating to force temperature rise.
I wanted to collect HCN, not H2O.
I posted here HCN-H2O diagram and this 5,5g is mainly HCN. That is why I wrote ~50 % not strictly 50% and in reality it is little less than 50%.
"It didn't work for you because your CuCN wasn't dissolved."
??
It did not work because it cannot work.
I use CuCl in my last experiment. I do not know what happens later - mixture is not homogenous. The only difference is colour (pinky), probably this is caused by CuCN.
In conditions I presented, CuCN or CuCl has no effect on yield of HCN.
That is why I am still interested in conditions of your experiment with recovery of 80% CN from K4...
If you cannot give these conditions, we have nothing to discuss.

entropy51 - 4-10-2009 at 14:09

Quote:
If you cannot give these conditions, we have nothing to discuss


I used the procedure given in Brauer, scaled down to 10 gm of ferrocyanide and using twice as much H2SO4. One run without CuCl, one run with CuCl. I used 0.6 gm CuCl dissolved in the minimum amount of 1:1 HCl. The HCN was absorbed in ice cold 1 N NaOH and an aliquot titrated with AgNO3 solution.

Since you have decided that it cannot work, discussion seems pointless.

I wonder why (or if) chemists would spend the money necessary to file a patent for a method that they know doesn't work.

[Edited on 4-10-2009 by entropy51]

[Edited on 4-10-2009 by entropy51]

S.C. Wack - 4-10-2009 at 14:56

Quote: Originally posted by kmno4  

Williams' book says about patent (in case of use CuCl), not about practical method


The procedure that starts on the page that I linked to references his Chem. Ind. article, not the patent. If those aren't practical details, I don't know what practical details are.

A 1929 article in Analyst describes the bullshitness of Williams thusly:

"Under the first head the cyanogen of the ferrocyanide is distilled off as hydrocyanic acid either by the method of W. Feld (J. Soc. Chem. Ind., 1903, 1068), in which the ferrocyanogen radicle is broken up by boiling with mercuric chloride and the cyanogen converted into mercuric cyanide, which is then distilled with an acid; or by the method of H. E. Williams (J. Soc. Chem. Ind., 1912, 315), in which the ferrocyanide and acid is distilled with a small quantity of cuprous chloride, the latter acting catalytically in breaking up the ferrocyanide and converting the cyanogen contents into hydrocyanic acid.

The hydrocyanic acid evolved is absorbed into dilute caustic soda solution, and the resulting cyanide solution titrated with standard silver nitrate solution after the addition of a few drops of a 10 per cent. solution of potassium iodide.

Both these methods are accurate if performed with care, but the results are liable to be somewhat low, particularly the former, owing to the fact that slight losses may occur in the different operations, which are accumulative and appreciable when estimating material for 100 per cent. purity.

They have the advantage that the cyanogen content is finally titrated by a solution which may be accurately standardised by known and accepted methods, instead of by standardisation with what may or may not be pure ferrocyanide. On the other hand, while the cuprous chloride method is comparatively simple, both methods require considerable skill and practice, and are therefore not suitable for general analytical practice."

If you're using the method for analysis, that is. Simply distilling off the HCN is a little simpler.

entropy51 - 4-10-2009 at 17:20

Quote: Originally posted by kmno4  

I took 25g of K4[Fe(CN)6], 52g of 96% H2SO4, ~160g of H2O and 0,7g of CuCN (small granules, 1-2 mm).
After 5-hours heating (boiling) I still had lots of light green shit in a flask.....
Yield of NaCN: ~6g. A few grams remain in ethanolic/water solution (~200 ml) . So it is close to 50% recovery of cyanide from ferrocyanide.


According to the paper by Adie and Browning posted abovethread, a dilute solution of H2SO4 such as this should give nearly 100% recovery of CN from ferrocyanide, yet you only found 50%.

kmno4 - 5-10-2009 at 00:19

Quote: Originally posted by entropy51  
Quote: Originally posted by kmno4  

I took 25g of K4[Fe(CN)6], 52g of 96% H2SO4, ~160g of H2O and 0,7g of CuCN (small granules, 1-2 mm).
After 5-hours heating (boiling) I still had lots of light green shit in a flask.....
Yield of NaCN: ~6g. A few grams remain in ethanolic/water solution (~200 ml) . So it is close to 50% recovery of cyanide from ferrocyanide.


According to the paper by Adie and Browning posted abovethread, a dilute solution of H2SO4 such as this should give nearly 100% recovery of CN from ferrocyanide, yet you only found 50%.

I know what I obtained. I also posted this article. I also know what is written there. But I cannot find this "according".
Could you post some attachment or citation where recovery of near 100% of CN can be obtained when reagents are used in proportions given above ?

Quote: Originally posted by S.C. Wack  
Quote: Originally posted by kmno4  

Williams' book says about patent (in case of use CuCl), not about practical method


The procedure that starts on the page that I linked to references his Chem. Ind. article, not the patent. If those aren't practical details, I don't know what practical details are.

A 1929 article in Analyst describes the bullshitness of Williams thusly: (...)


Quote: Originally posted by kmno4  
Volume ~130 ml, 0,5g K4..... and ~48-fold mole excess of H2SO4 is not interesting for me. On this proportions it works also without any Cu salt, as it is described in previously cited paper from JChemSoc.

Paper by Adie and Browning of course :P
I have read many articles about "analytical decomposition" of ferrocyanides. In some article is given reference and its authors investigate various salts for this purpose and most active are salts of : Pt, Pd, Ag, Hg... but Cu is not even mantioned. Unfortunately, this reference (in german) is unavailable in electronic form.

[Edited on 5-10-2009 by kmno4]

entropy51 - 5-10-2009 at 14:35

Quote:
But I cannot find this "according".
Could you post some attachment or citation where recovery of near 100% of CN can be obtained when reagents are used in proportions given above ?


Compare your H2SO4 concentration to the table on page 154 of Adie and Browning, specifically the column labelled "HCN (calc as 6HCN per mol. K4Fe(CN)6) which corresponds to your reaction conditions (sulfuric conc and reaction time). Your sulfuric concentration looks like approximately H2SO4 17H2O in their terminology (molar ratio). You distilled for 5 hours. Their yield of HCN for those conditions is 98 or 99% of 6HCN from their table. Thus your yield seems only about half that of Adie and Browning.

Thus my use of the word "according", which I think is fairly accurate.

I was just wondering if you had noticed that, but I guess you had not compared your result to theirs.

kmno4 - 6-10-2009 at 01:29

Quote: Originally posted by entropy51  
Quote:
But I cannot find this "according".
Could you post some attachment or citation where recovery of near 100% of CN can be obtained when reagents are used in proportions given above ?


Compare your H2SO4 concentration to the table on page 154 of Adie and Browning, specifically the column labelled "HCN (calc as 6HCN per mol. K4Fe(CN)6) which corresponds to your reaction conditions (sulfuric conc and reaction time). Your sulfuric concentration looks like approximately H2SO4 17H2O in their terminology (molar ratio). You distilled for 5 hours. Their yield of HCN for those conditions is 98 or 99% of 6HCN from their table. Thus your yield seems only about half that of Adie and Browning.

Thus my use of the word "according", which I think is fairly accurate.

I was just wondering if you had noticed that, but I guess you had not compared your result to theirs.

I knew that you recall table on 154 page :D
You have missed one very important thing (missing) in this article.
I give you 2 days for reading this article as many times as it is necessary for fully understanding why you cannot compare their results to my results.
Have a nice reading.
:P

entropy51 - 6-10-2009 at 05:28

Quote: Originally posted by kmno4  
[I knew that you recall table on 154 page :D
You have missed one very important thing (missing) in this article.
I give you 2 days for reading this article as many times as it is necessary for fully understanding why you cannot compare their results to my results.
Have a nice reading.
:P
I don't need to read the article again to understand what you did differently. They had glassware and chemicals and actually performed an experiment. On the other hand, I've seen your fantastic equipment here and dodgy reports.

I did my homework asignments when I was in school. Now that I've had my doctorate since before you were born, I don't need homework assignments from wee lads like you. Find some kids your own age to play games with. I hope you had a nice reading.

[Edited on 6-10-2009 by entropy51]

[Edited on 7-10-2009 by entropy51]

kmno4 - 8-10-2009 at 08:18

Wow. Doctor. Fenced doctor. I know such doctors very well :mad:
I am almost going down on my knees saying " I am sorry for my experiments".
"I've seen your fantastic equipment here and dodgy reports"
My equipment seems not fantastic to me and I am sorry that you cannot afford for equally good one. Dodgy reports - I report (from time to time) effects of my experiments, that is all.
Unfortunately no-one else wants to report effects of H2SO4/K4... experiments. Effects determined by weight, not by visual observations.

As I see, you were too lazy to do your homework, although you had two days and only 11 pages of reading :mad:

The table on p. 154 contains a summary of the results obtained, using as neariy as possible the same weight of potassium ferrocyanide and a large excess of sulphuric acid, so as to keep the concentration of the acid nearly constant.

This is very important note from page 6 of mentioned article.
Because of unknown (but large) amount of H2SO4 solution, reported results are almost useless. The only information is that the larger dilution of H2SO4, the larger extent of K4... decomposition, under condition of large excess of acid solution.
This is very similar to "analytical" procedures posted earlier but not to procedures which I implemented.

End of homework.

ps. you have mentioned procedure from Brauer with 10g of K4... x3H2O and twice H2SO4.
So I am going to try this: 20g K4... x3H2O, 32g H2SO4 (96%), 25g H2O, 1,2g CuCl in minimal amount of 1:1 HCl.
Then I will see if you are a plain liar (like I suspect) or not.
Of course I will post my dodgy results here ;)

watson.fawkes - 8-10-2009 at 16:26

Quote: Originally posted by kmno4  
As I see, you were too lazy to do your homework, although you had two days and only 11 pages of reading :mad:
Pardon my interruption, but you're acting the ass here, just like that fellow who was all up about ORMUS a few months ago. In both your case and his, you somehow seem to think that the responsibility for proving claims relies on someone else other than you. The difference, admittedly, is that you can eventually do so and he can't. Nonetheless, the more important of these, the taking of responsibility, is the one you've failed at. You've achieved no moral high ground, rather instead painting yourself as somewhat delusional about your own status.

So just stop, and let it pass as a folly, hopefully of youth.

entropy51 - 8-10-2009 at 17:28

Quote: Originally posted by kmno4  
Unfortunately no-one else wants to report effects of H2SO4/K4... experiments. Effects determined by weight, not by visual observations.
Ok, you weighed something, but what was it?
Quote: Originally posted by kmno4  
I wanted to collect HCN, not H2O.
I posted here HCN-H2O diagram and this 5,5g is mainly HCN.
OK, you think it was HCN, but was it really?
Quote: Originally posted by kmno4  
Solution should be heated up to boiling. In r.t. or even warmer, reaction is very slow.
Green precipitate (FeK2[Fe(CN)6]), turning blue on air is normal thing. It very, really very slowly reacts with H2SO4 even on boiling.
So you heated an aqueous solution to boiling and distilled something out, and you just know that it was mainly HCN and you determined your yield by weighing it? I captured HCN in cold aqueous NaOH and titrated it with AgNO3 using the standard procedure.

And you have the nerve to call me a liar?


[Edited on 9-10-2009 by entropy51]

kmno4 - 9-10-2009 at 00:11

Quote: Originally posted by watson.fawkes  
Pardon my interruption(..)

Sorry, I do not understand this gibberish but it seems to have nothing with "preparation of cyanides". If you have something to say to me personally, do it via U2U.

To entropy51:
I am not going to discuss with you in this way, beacuse you can find answers for all these questions, in this thread. I am not going to quote myself for eternity. My posts are clear enough even for "doctors".

[Edited on 9-10-2009 by kmno4]

watson.fawkes - 9-10-2009 at 05:35

Quote: Originally posted by kmno4  
Sorry, I do not understand this gibberish but it seems to have nothing with "preparation of cyanides". If you have something to say to me personally, do it via U2U.
My condolences that you don't understand what "acting the ass" means, and no, I won't do this in private. You've been demanding that other people confirm whatever it is you've been doing. This is counter to the way that science works, which is that people who claim something carry the burden of proof. If you are unwilling or unable to carry the burden of proof, then don't make such claims in the first place.

Your challenger is not an idiot and has legitimate concerns about your experimental procedure. Rather than answer these concerns or concede them, you've gotten defensive, which I have previously ignored. You crossed the line when you demanded that someone else take undue effort and then upbraided them for not doing so. That is the veritable territory of cranks. And this is the reason that this is in public, that this kind of behavior is not respectable, and you have earned my disrespect.

If someone has a concern about something you've claimed, then you answer it. If you've already answered the exact question, such that reading a single previous answer is sufficient, then you may answer by reference. Otherwise, even when there is partial overlap in a previous question, then you partially repeat myself. It is not the obligation of a questioner to defend your claim and convince themselves. It is your responsibility.

entropy51 - 9-10-2009 at 06:39

Quote: Originally posted by kmno4  
[I am not going to discuss with you in this way, beacuse you can find answers for all these questions, in this thread. I am not going to quote myself for eternity. My posts are clear enough...
Reality check:
Quote: Originally posted by kmno4  
I wanted to collect HCN, not H2O.
I posted here HCN-H2O diagram and this 5,5g is mainly HCN.
The only diagram posted by kmno4 in this thread (he did say "this thread") is a plot of pH vs HCN/CN- which says nothing about how much (if any) HCN is contained in his distillate. So weighing the distillate proves nothing.
Quote: Originally posted by kmno4  
I think that the only way to obtain pure (>98%) cyjanides is introducing mixture HCN+H2O to akoholic solution KOH or NaOH. I have made many grams of KCN using this methode (more than 1kg :o)
Mixture HCN/H2O was obtained by heating K4[Fe(CN)6]+H2O+H2SO4 or H3PO4. Both acids work good and concentration(%) has no special meaning: 30%-60% is ok.
Reaction is:
2K4[Fe(CN)6]+3H2SO4 -> 6HCN + FeK2[Fe(CN)6]+3K2SO4
With a simple distilling aparaturus, during haeting, at about 50*C (temperature of vapors) the mixture HCN/H2O starts to evolute, and after condesation it is introduced into KOH/C2H5OH solution.
KCN starts to precipitate,the solution is getting warm, but there is no need to to cool it. This mixture MUST be continual stirrig by magnetic stirrer - in another case a "cake" is collecting at the surface and there is no full reaction between HCN and KOH - it is a little dangerous.
The distillation is interputted at about 95*C - just too many water is then evoluted.
But in this post, kmno4 says that if you heat above 95 that too much water comes over! And he says that HCN/H2O distills! Not mainly HCN.

This is inconsistent with his earlier claim that his distillate is "mainly HCN". Kmno4 does have nerve claiming that he's the only one who has posted solid claims.
Quote: Originally posted by kmno4  
Solution should be heated up to boiling.


Kmno4 says that the concentration of H2SO4 has no influence on CN yield, but we do know better than that don't we? Based on the Adie and Brown article that kmno4 assigned as my homework.

How could anyone make sense out of kmno4's inconsistent and dodgy posts?

Kmno4 seems to have a surplus of mouth until someone points out his egregious errors, then he shuts up.

kmno4 - 12-10-2009 at 12:48

I have just done experiment according to Brauer, with double amount of H2SO4, 20g K4...x3H2O + 2g CuCl in 1:1 HCl (~10 cm3).
Results are very interesting but predictable, according to literature.
After 4 hours boiling less than 0,8 g of low-boiling condensate was colected.
Reaction was very slow and few last droplets of condensate were colored. Loss of weight of input material was almost the same.
Now I am sure that entropy51 is just a liar, like I suspected from the very beginning :P

He has never even touched equipment to test this reaction, with or without CuCl or any other shitty catalyst. His only contribution to this thread is entropy and noise.
That is all I have to say in question of Doctor Entropy and Cu salts. And patents about it.

* liquid-vapour diagram for HCN-H2O is available from Ullmann's Encyclopedia in "Cyanides" chapter. I posted this picture here long time ago but now it's gone ( probably I removed it)
** at last I got standard sample of AgNO3 and titrated freshly prepared and dried NaCN. Result was a pleasure: 99.6 %. My old sample of NaCN gave 95,6%.

[Edited on 12-10-2009 by kmno4]

entropy51 - 12-10-2009 at 14:07

The Scientific Method
(according to kmno4)


1. All patents are bullshit

2. Peer-reviewed literature is to be taken with grain of salt

3. Anybody who questions his methodology is to be given a homework assignment.

4. If he cannot reproduce their results, they are liars.

5. One of his experiments is worth ten of anybody elses.

6. If anybody asks for details, he says he has already told that many times.

7. His distillations give the product that he says they do, even if he said they give something else another time.

8. His $ 12 scale is better than any foolish titration.

entropy51 - 12-10-2009 at 14:27

Quote: Originally posted by kmno4  
at last I got standard sample of AgNO3 and titrated freshly prepared and dried NaCN. Result was a pleasure: 99.6 %.


Congratulations on your pleasure. Other chemists on the forum have found their samples to titrate at 85%. There is usually some Na2CO3 contamination from atmospheric CO2 and sometimes the reaction itself gives CO and CO2. Somebody may be lying again!

Quote:
I am not going to discuss with you in this way, beacuse you can find answers for all these questions, in this thread. I am not going to quote myself for eternity.
Now you see it, now you dont!
Quote: Originally posted by kmno4  
liquid-vapour diagram for HCN-H2O is available from Ullmann's Encyclopedia in "Cyanides" chapter. I posted this picture here long time ago but now it's gone ( probably I removed it)
More magic tricks by the Amazing Purple One.

[Edited on 13-10-2009 by entropy51]

UnintentionalChaos - 12-10-2009 at 17:42

Quote: Originally posted by entropy51  
Quote: Originally posted by kmno4  
at last I got standard sample of AgNO3 and titrated freshly prepared and dried NaCN. Result was a pleasure: 99.6 %.


Congratulations on your pleasure. Other chemists on the forum have found their samples to titrate at 85%. There is usually some Na2CO3 contamination from atmospheric CO2 and sometimes the reaction itself gives CO and CO2. Somebody may be lying again!

Quote:
I am not going to discuss with you in this way, beacuse you can find answers for all these questions, in this thread. I am not going to quote myself for eternity.
Now you see it, now you dont!
Quote: Originally posted by kmno4  
liquid-vapour diagram for HCN-H2O is available from Ullmann's Encyclopedia in "Cyanides" chapter. I posted this picture here long time ago but now it's gone ( probably I removed it)
More magic tricks by the Amazing Purple One.

[Edited on 13-10-2009 by entropy51]


Do us all a favor. Next time you feel the need to type, let it go.

entropy51 - 12-10-2009 at 18:05

Us? All?

Engager - 19-10-2009 at 16:51

Recently i've found interesting method to produce cyanide without too high temperatures or HCN involved. This simple process was discovered by Playfair and even was offered for idustial use:

Then Playfair tried the use of metals at first lead and zinc, for these only appeared suitable. The metals decomposed the sulphocyanide either in fusion or in solution according to the reaction

KSCN + Zn = ZnS + KCN

After many experiments, Playfair adopted the following procedure : He used a receiver made of black lead, whose form is that of an inverted muffle and which is provided with a tightly fitting lid. This apparatus is placed in a furnace in such a way that the top of the receiver extends 2 to 5 centimeters above the upper border of the furnace so that it becomes heated only at the bottom and the sides. Zinc is then melted in the presence of a small quantity of pulverized charcoal, which maintains a reducing atmosphere in the crucible. When the zinc is completely fused dry sulphocyanide is added, either cold or even in a melted state.

The mass is kept stirred and the reaction continued till the mass becomes quite thick and begins to redden. At this point the reaction is complete. The mass is then allowed to cool, protected from the air. When cold, the mass is easily removed from the crucible, which does not appear at all attacked. The color of the mass should be pearly gray, if the reaction has been successful, in which case its solution will be entirely free of soluble sulphides. But if the mass has been superheated, which happens especially when too large crucibles are used, it has a brownish and sometimes even a reddish color, and the solution may contain as much as 15% of alkaline sulphide.

As a rule one must assume a loss of about 5%, due partly to moisture and partly to the formation of small quantities of cyanate and carbonate. One should add also to the above loss that which may result from the formation of the double cyanide of zinc and potassium or sodium in consequence of a too high temperature, but this loss may be easily avoided by the use of a slight excess of sulphocyanide.

The melted mass is subjected to a systematic lixiviation in a series of vats. The alkaline cyanide solution is separated from the insoluble zinc sulphide by decantation. This latter substance constitutes about 65% of the fused mass. The solutions thus obtained vary considerably in concentration; that is, from 4 grams of sodium cyanide per liter to 220-240 grams. These latter solutions are evaporated in vacuum to the consistency of a thick paste, which on cooling crystallize. The following is an analysis, made by Playfair, of one of these solutions. The figures represent the amounts per 100 cc. of solution to be evaporated.

Sodium cyanide 22.00 gm.
Cyanate 3.06
Double cyanide of zinc and sodium 1.55
Sodium carbonate 0.71
Sodium sulphocyanide 1.80

Playf air's process marks a real progress; it can be applied industrially, since, according to the inventor, the yield is about 70% of the theoretical amount. This result is obtained if care be taken to concentrate the solutions in a vacuum of 66 centimeters, using solutions containing at least 22% of cyanide, so as to avoid loss of cyanogen.

Dr. Hans Luttke's Process. This process is based on the same principle. It consists in melting sulphocyanide with zinc powder. In an iron crucible are fused together

97 kg. sulphocyanide of potassium,
65 zinc powder.

The mass is stirred while being heated, and from the moment it fuses, the crucible is removed from the fire. The reaction then goes on by itself. When the fused mass is treated with water it yields about 60 kg, of cyanide, i.e., 90% of the theoretical amount. The sulphide of zinc which is obtained as a by-product may be profitably used as a mineral color.

The reaction takes place between 360 and 400; this temperature may be lowered by an addition of 1% to 2% caustic alkali, which at the same time, increases the yield of cyanide.

Various other metals have been tried. Lead, which was also recommended by Playfair, has the advantage of not forming double cyanide of lead and potassium, but on account of its high atomic weight, three times as much lead as zinc are required to perform the same work, while, at the same time, it has a tendency of falling to the bottom of the crucible without remaining mixed with the sulphocyanide.

The reduction of sulphocyanide may be well carried on with the use of tin, but tin sulphide dissolves in rather appreciable quantities in the alkaline cyanide. The use of copper is no more successful, for it gives rise to cuprocyanides.


[Edited on 20-10-2009 by Engager]

Engager - 19-10-2009 at 17:12

Now some personal experience. I've prepared mixture from 32g zinc dust and 5g of finely grounded charcoal, those are added to fused 50g of potassium thyocyanate (KSCN). Addition was carried out by portions with stirring. After all zinc has been added iron crucible was heated further using flame from propane gas oven, with eventual mixing. After some time mixture begun to increase it's volume showing some very slight foaming, heating was continued, mixture was setteled down and gradualy begun to thicken, at this moment bottom of the crucible was at red heat. Then mixture almost solidified, heat source was shut down and mixture is allowed to cool, then crushed to lumps and liquified with 100 ml of warm water. Lumps we quickly dissolved leaving black solution containing large ammount of solid (some unreacted charcoal and zinc sulphide), it was filtered to obtain very slightly yellowish solution with strong alkaline reaction. Sample of solution was tested for presence of cyanide by double decomposition with zinc chloride, imidately after mixing amorphous precipitate of zinc cyanide was precipitated from solution (zinc thyocyanate is perfectly soluble so not gives precipitate in same test). To differ precipitate with grey zinc sulphide witch can also precipitate due to sulphides present in product solution, excess of product solution is added to solid sample - most of it dissolved due to formation of soluble zinc-potassium double cyanide, showing that some small of sulphide present, but solution contained mainly potassium cyanide.

[Edited on 20-10-2009 by Engager]

entropy51 - 19-10-2009 at 17:53

Interesting prep, Engager. Have you tried something quantitative such as titration to see how much KCN is in the product? Thanks.

halogenstruck - 20-10-2009 at 09:18

if it works then
why not this:
NaCNO+Zn--->NaCN+ZnO
or NaCNO+C--->NaCN+CO
ACTUALLY when u heat KNO3& C then U have NaCNO at first step then is reduced to NaCN
and sodium cyanate can be made from just urea

Jor - 20-10-2009 at 10:38

I will give this a try when I'm home. Shame I have only a few tens of grams of KSCN, and I have zinc shavings only, but as it will melt in the progress it shouldn't matter.

However, I will extract the KCN with methanol, it dissolves about 5g per 100mL at 20C. Much easier.

Myfanwy - 28-10-2009 at 10:25

Hi im new in this forum and this is my first post :P

I also made Hydrogen cyanide by destilling K4[Fe(CN)6] with 25% Sulfuric Acid.
I condensed the Fumes with Ice-cold Water.My HCN was a little bit yellow, because of polymerization.
You can`t store it, if you don`t have H3PO4.

Now i want to make sodium cyanide in a different way.

Will Ammonium formiate and a ethanolic solution of sodium hydroxide will give some sodium cyanide?!
HCOONH4 + NaOH -> NaCN + 3H2O?

one weak ago i attemped to make Formamide by the decomposition of Ammonium formiate, but it mostly sublimes and decomposes to Ammonia and Carbon monoxide

Next weak i try ethyl formiate and ammonia! Ethyl formiate you get from sodium bisulfate and sodium formiate in ethanol.

If anyone have Urea, you can heat this with Formic Acid to become some Formamide.
This will produce a large amount of ammonia.
------------------------------------------------------------------------------

Ammonium formiate and sodium hydroxide won`t work to form cyanide.
It will form Ammonia, water and sodium formiate...

[Edited on 28-10-2009 by Myfanwy]

JohnWW - 29-10-2009 at 20:20

You were lucky to live to tell the tale!

slyder - 4-12-2009 at 11:37

i was wondering if is posible to obtain liquid Hydrogen cyanide throught pigment PRUSSIAN BLUE ? (its easy to obtain pigment without any restriction) :p

and heat PRUSSIAN BLUE pigment up to 300 degress C or applying strong conc. H2SO4 on prussian blue and then fractional distillete it to obtain liquid HCN ?

what do you think ?

Picric-A - 4-12-2009 at 12:08

It scares me when new members ask questions regarding the preperation of 'liquid hydrogen cyanide'....
not to mention asking stupid questions which could be answered in about 30secs by google...

Engager - 15-12-2009 at 07:41

Recently i have discovered info on other possible way to cyanides through weakly studied substance called Formaldoxime. Reference states the following:

"Our knowledge of this compound, the first member of the series of paraffinic aldoximes, is very limited, being in fact represented only by the observations made a few years ago br Scholl (Bey., 24, 573), who found that the chief product of the interaction of formaldehydeand hydroxylamine was a white amorphous solid, which behaved as a polymeride of formaldoxime. The aldoxime itself Scholl was only able to study as a solution, obtained by heating the polymeride withcertain liquids, and as a gas obtained by heating the dry polymeride. He showed that the substance in these two forms has a molecular weight corresponding with the formula CH2=NOH, that it is a powerful reducing agent, and in its other properties behaves as an aldoxime.

The authors have obtained formaldoxime as a colourless, highly refractive liquid, boiling between 84-85C, by extracting with ether a, warm, freshly prepared mixture of aqueous formaldehyde and hydroxylamine (hydroxylamine hydrochloride with the calculated amount of sodium carbonate), and then fractionally distilling the ethereal solution. All attempts to crystallise the liquid have failed.When cooled it quickly changes into the solid polymeride, and even at the ordinary temperature it cannot be kept for long without polymerisation taking place. It has a slight curious odour, which is difficult to describe, and it burns with a livid yellow flame, producing much hydrogen cyanide, CH2NOH = H2O + HCN. A determinationof the molecular weight of the liquid by Raoult's method,using acetic acid as the solvent, gave a result corresponding with the formula CH2=NOH.

Formaldoxime undergoes quantitative hydrolysis into formaldehyde and hydroxylamine when it is digested with cold concentrated hydrochloric acid, but when it is heated with dilute acids, formic acid and ammonia are also produced, owing to the previous conversion of some of the aldoxime into formamide, HCONH2, a mode of isomeric change which is characteristic of these aldoxirnes. Formaldoxime readily decomposes into its nitrile (hydrogen cyanide) and water when it is heated with aqueous alkalis, or when it is acted on by acetic chloride. It forms unstable derivatives with the alkali metals ; the sodium derivative, CH2NONa, is crystalline ; it explodes when heated, and very readily loses water, becoming sodium cyanide.

When warmed with aqueous solutions of salts of silver, gold, copper, and mercury, formaldoxime acts as a powerful reducing agent. With cold aqueous copper sulphate it furnishes a dark green solution, which soon deposits crystals of a remarkable copper salt,and these, when kept, spontaneously evolve nitric oxide.

When dry hydrogen chloride is led into the well dried ethereal solution of formaldoxime, the hydrochloride separates as an amorphous solid, which, however, may be readily crystallised from its solution in a mixture of alcohol and ether. When analysed, the well defined prismatic crystals (m. p. 136C) furnished data corresponding with the formula CH2=NOH*HCl.

This remarkable salt, which can easily be obtained pure, constitutes a convenient source for the preparation of pure formaldoxime. It dissociates into the aldoxime and hydrochloric acid when it is dissolved in water, and if the solution is neutralised, pure formaldoxime may be recovered by distillation. The salt dissolves when warmed with aniline, and the formaldoxime can then be distilled from the mixture. A similar crystalline hydrobromide, CH2NOH*HBr, m. p. 120°C, have been prepared."

Full version of ref from JCS is attached to this message.

Attachment: PL8941.PDF (1.5MB)
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[Edited on 15-12-2009 by Engager]

Engager - 15-12-2009 at 08:07

Taking to account information from post above leads to idea to produce sodium cyanide by reacting formaldehyde with hydroxylamine, adding sodium hydroxide and subsequent evaporation off water to dryness. I'm sure that process will proceed through formation of sodium formaldoximate intermediate witch will loose water on heating to form sodium cyanide:

CH2=NONa => NaCN + H2O

Seems like this is a good idea to try, but regretably currently i don't have hydrohylamine available to try this prep. Someone up to try this?

Original article by Sholl from Ber. and US Patent for production of formaldoxime trimer are attached to this message.

[Edited on 15-12-2009 by Engager]

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Attachment: US4680394 (Method of preparing formaldoxime trimer).pdf (330kB)
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Myfanwy - 9-1-2010 at 05:49

To distill HCN from ferrocyanides you must take conc. H3PO4 ,instead of dilute H2SO4.
Conc H2SO4 will produce (CN)2 and dilute will hydrolyse the HCN in the boiling water to Formamide and Ammonium formiate.

Next week i will try with 75% H3PO4 and K4[Fe(CN)6] and post the results.
3K4[Fe(CN)6] + 6H3PO4 -> 18HCN + 4K3PO4 + Fe3(PO4)2
1692,96g on the left and 1693g on the right.

Okay, i will take 22,7g K4[Fe(CN)6], 15g 75% H3PO4, and distiling the resulting 10g HCN into an solution containing 15g NaOH. Then pour alcohol 96% into the solution and filtering the appeared crystals.

Theoreticly this will result 18g of Sodium cyanide.

EDIT :
But some Dicyane will hydrolyse to form sodium oxalate, whats non soluble in Ethanol.


[Edited on 9-1-2010 by Myfanwy]

anotheronebitesthedust - 10-1-2010 at 15:38

Does anyone know of any synthesis of Sodium Cyanoborohydride without the use of HCN?

I found this website:

http://designer-drugs.com/pte/12.162.180.114/dcd/chemistry/c...

DJF90 - 10-1-2010 at 16:43

*That* site gives instructions using NaCN and also the reference from which they pertain. I suggest you open your eyes!

crazyboy - 10-1-2010 at 17:36

Quote: Originally posted by DJF90  
*That* site gives instructions using NaCN and also the reference from which they pertain. I suggest you open your eyes!


All the reactions detailed in that paper which use NaCN use diborane an extremely toxic, flammable, reactive gas which is also very expensive and nearly impossible to procure.

According to Wikipedia sodium cyanoborohydride can also be made by reacting sodium borohydride and mercury cyanide. Mercury cyanide can be made by reacting Mercury(I) nitrate and potassium cyanide. This path is also quite dangerous as mercury cyanide is also extremely toxic but not as dangerous as diborane and probably easier to handle than HCN.

It's up to you, pick your poison, (literally) just be sure to have adequate safety equipment and a backup plan in case something goes wrong.

anotheronebitesthedust - 12-1-2010 at 08:50

http://en.wikipedia.org/wiki/Mercury_cyanide
Quote:

It rapidly decomposes in acid to give off hydrogen cyanide. Samples also decompose when exposed to light, becoming darker in color. It reacts vigorously with oxidizing agents; fusion with metal chlorates, perchlorates, nitrates, or nitrites can cause a violent explosion.


It also mentions that Mercury(II) cyanide is one of the most toxic poisons, and requires quite stringent safety precautions according to http://www.analytyka.com.mx/tabla%20periodica/MSDS/Hg/mercur...

500 grams of Mercury Cyanide is only $388.19 at VWR. I wonder how much Sodium Cyanoborohydride could be synthed from 500 grams of Mercury Cyanide? Not that I would ever attempt an advanced technique, since I am such a chemical newbie. Not to mention my fumehood is not quite done.

50 grams of Sodium Cyanoborohydride is listed at VWR for $123.14 Speaking of which, if anyone knows of a cheap Sodium Cyanoborohydride supplier, I'd very much appreciate a lead in the right direction. I have accounts with most of the major chemical suppliers, but many of their prices can be way overpriced. I tend to use Chinese or Indian suppliers, but the Borohydrides are classified as flammables/explosives and most of my overseas suppliers refuse to mislabel what they consider to be dangerous/flammable/explosive chemicals.

[Edited on 12-1-2010 by anotheronebitesthedust]

anotheronebitesthedust - 12-1-2010 at 10:01

Some more quotes from Wikipedia which may deter newbie chemists from attempting dangerous syntheses involving Cyanide and Cyanide salts without professional equipment or at least some experience in a qualified lab.
Quote:

Cyanide salts are among the most rapidly acting of all known poisons. Cyanide is a potent inhibitor of respiration, acting on mitochondrial cytochrome oxidase and hence blocking electron transport. This results in decreased oxidative metabolism and oxygen utilization. Lactic acidosis then occurs as a consequence of anaerobic metabolism.

Quote:

Sodium cyanide is an inorganic compound with the formula NaCN. This highly toxic colourless salt is used mainly in gold mining.

Quote:

Because the salt is derived from a weak acid, NaCN readily reverts back to HCN by hydrolysis: the moist solid emits small amounts of hydrogen cyanide, which smells like bitter almonds (not everyone can smell it—the ability thereof is due to a genetic trait[6]). Sodium cyanide reacts rapidly with strong acids to release hydrogen cyanide. This dangerous process represents a significant risk associated with cyanide salts



But of course I'm preaching to the choir aren't I? Oh well, I figure it's better to err on the side of caution.

Ahh... The beauty of copy and paste. Nowadays anyone can act like lie an experienced expert with the use of Wikipedia. lol.

[Edited on 12-1-2010 by anotheronebitesthedust]

Myfanwy - 29-1-2010 at 06:34

well i try to make sodium cyanide this weekend by passing gaseous HCN (from H3PO4 and K4[Fe(CN)6]) into a concentrated lye.

if u have a good burner, try CO(NH2)2 with K2CO3 and C.

mario840 - 29-1-2010 at 06:56

tell me more men :)

did it work??? how many g KCN you made ???

mario840 - 29-1-2010 at 06:57

sorry NaCN :P :)

Myfanwy - 29-1-2010 at 07:21

:D
nope i tried it not yet.
i will make it tomorrow or so...

then i`ll tell you

[Edited on 29-1-2010 by Myfanwy]

mario840 - 29-1-2010 at 08:02

ok i'll wait ... i hope for tomorrow :P:) as soon as you can :P

mario840 - 29-1-2010 at 08:46

i have better idea ... if you want too .... make photos by your phone and past them into word document you know what i mean like in drug forum in pdf .... "scenario" of experiment and wirte the most important thing like for example ... to 100g ferrocyanide we add hmmm 45 ml of 60% H3PO4 .... many people doing that thing and make life easy to many users ... i will be very greatfully if you do that ... and pst here like or something ... it's just idea but i bet it will be fantastic work .... then no-one ask how to make cyanide ... just a few picture of most important part of experiment that's all

Myfanwy - 29-1-2010 at 09:29

mh i make a video + photos + description with my digicam and post it on youtube, if i dont die :D :(

mario840 - 29-1-2010 at 09:41

yesssssssssssssssssssssss :)

please do that , but seriously ... i don't recomend youtube .. cyanide is higly poision as you know :) and Your movie will be very quick delete .... make photo past into word file or make pdf or whatever you like :) make video and paste this into hmmmm rapidshare you know some not "invigilated" servis and give here to us link :)

ohhh i'm sure you not die ... it's not that poision as there write ... :)
make in high resolution picts :P:) and of course make photo of final substance

mario840 - 29-1-2010 at 09:54

ohhh it's very good :) so post it in youtube and send link
and as I said please do that experiment as soon as you can , finally i will be know 100% working synth of cyanide :)

Myfanwy - 29-1-2010 at 10:02

jop i make it definitively tomorrow, but im a little bit scared from this shit, because im a pussäy^^

mh but i think all HCN will be bond by the lye and not released into the air.
i use a 100ml roundbottom flask and a liebig condenser for the distilling.

S.C. Wack - 29-1-2010 at 10:03

Quote: Originally posted by Myfanwy  
you can make KCN directly from potassium hydroxide and formamide.


http://moronail.net/img/1156_Its_time_to_stop_posting_lolcat...

formamide can however be

DEHYDRATED

without P2O5 with copper gauze in a tube heated to 600C or any number of catalysts in the patent and etc. literature.


mario840 - 30-1-2010 at 03:41

ok do your thing and remeber making photos during the reaction in the most imporant moments ... when you add acid when destill and when crystallize from ethanol .... i'll be waiting for results ... good luck ....

Myfanwy - 30-1-2010 at 06:13

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

the yield could be better. i think to much HCN leaved the Flask gaseous and didnt react with the Lye. I done it outside. The smell of the bitter almonds was really amazing^^love it.

now i will make the movie. i think its ready in 3 hours.

mario840 - 30-1-2010 at 06:20

shit , dude that's fantastic :)

write in movie how many you use ferrocyanide, concentration of acid , and how many NaOH you disolved in ethanol or water write it all and send a link :)

BTW. send link to photos too :)

Myfanwy - 30-1-2010 at 09:15

http://www.youtube.com/user/Myfanwy94#p/a/u/0/K8C2lqzcGhg

here it is. not the best.

mario840 - 30-1-2010 at 09:27

can i ask you to upload all your photo the best will be in rar files and send link :)

BTW. The video is very nice , well done :)

Myfanwy - 30-1-2010 at 09:38

okay tomorrow i will upload them^^

mario840 - 30-1-2010 at 10:04

how much water (ml) did you use to dissolved 17g NaOH ???

Myfanwy - 30-1-2010 at 10:06

i used 17 or 20ml

[Edited on 30-1-2010 by Myfanwy]

mr.crow - 30-1-2010 at 16:31

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

the yield could be better. i think to much HCN leaved the Flask gaseous and didnt react with the Lye. I done it outside. The smell of the bitter almonds was really amazing^^love it.

now i will make the movie. i think its ready in 3 hours.


So you let enough HCN gas escape to kill 100 people :p

Definitely need a second bottle of NaOH to bubble the gas through. The video also doesn't mention you put the NaOH solution into the receiver first.

I love the little swirlies when the distillate hits the solution.


Myfanwy - 31-1-2010 at 02:09

yes they look strange^^ never saw this before.

mario840 - 31-1-2010 at 02:57

please upload this photo as fas as you can i'll be very greatfully .. because i'm in hurry little :P:)

Taoiseach - 31-1-2010 at 04:09

AWESOME :)

Thx for uploading. Please make more videos like that... love it :D

One question: Why didn't you make an ethanolic solution of NaOH? It dissolved quite well in EtOH.

It looks quite wintery in your area (noticed the frost and snow on the ground), so you should use a good bunch of snow to cool your receiver flask to minimize HCN loss.

Myfanwy - 31-1-2010 at 09:57

@mario

http://rapidshare.com/files/343951606/DSC00380.JPG.html

http://rapidshare.com/files/343952359/DSC00397.JPG.html

http://rapidshare.com/files/343953040/DSC00420.JPG.html

these are the first 3. dont want to upload more today. this is boring =D

slyder - 31-1-2010 at 11:22

nice work Myfanwy :)

i have just question would it work if i would use potassium ferrocyanide and dilute H2SO4 50% w/w ? or do i have only to use phosphoric acid if i want to obtain HCN ?

[Edited on 31-1-2010 by slyder]

[Edited on 31-1-2010 by slyder]

Myfanwy - 31-1-2010 at 12:11

H2SO4 will work too, but some Cyanide will be oxidized to cyanogen (poisonous gas). (CN)2 is very interesting. i just made it one time by heating potassium ferrocyanide with sulfuric acid (96%).
the gas burns with a nice purple-red flame and smells not like bitter almonds.
carl willhelm scheele made it with sulfuric acid. it will work, i tried it 3 times this way.

[Edited on 31-1-2010 by Myfanwy]

slyder - 31-1-2010 at 12:15

thanks =)

if i use it in concentration H2SO4 50% throught ferrocyanide way is ok ?


and yet something did you use K4[Fe(CN)6]•3H2O or did you use K4[Fe(CN)6] ?

is it important to use it anhydrous or is not matter ?

[Edited on 31-1-2010 by slyder]

Myfanwy - 31-1-2010 at 12:22

i used the trihydrate. doesnt matter if its anhydrous or not.
you can dry your trihydrate at 100°C and you get your anhydrous salt.

i think 50% is a little bit to high concentrated.
i used 38%.

but unfortunately HCN decomposes in hot boiling water(like cyanide salts), so you will lose some.

mario840 - 4-2-2010 at 05:34

i have a big problem ... i mix ferocyanide 24 g with diluted sulfuric acid 40 ml 40% and heat it ... everything was fine ... the bubbles appers and gas condansate and drop into solution 16 g KOH in 20 ml water but after about 20 - 30 minutes the whole solution turned into YELLOW!!!!! when i add ethanol 95% 100 ml nothing appears :( what I do wrong ???????????????

vassili78 - 5-2-2010 at 12:56

what happens if i make the HCN bubbling trough a solution of NaOH without cooling it?

The cooling procedure is not a problem where i leave but maybe the yield could be better without this step.

ScienceSquirrel - 6-2-2010 at 11:24

If I was planning on making hydrogen cyanide or potassium cyanide I would find a published procedure and follow it to the letter taking appropriate precautions.
Heating up mixtures of chemicals that may produce hydrogen cyanide or potassium cyanide on the scale that some posters seem to be attempting strikes me as rash or even incredibly foolish.

ScienceSquirrel - 6-2-2010 at 18:58

And if you need a www.youtube.com video detailing the preparation then maybe you should not be tackling the preparation anyway.
Hydrogen cyanide, cyanogen, sodium cyanide and potassium cyanide are very poisonous.
I worked with cyanide in a research lab in the distant past and I had to account for the potassium cyanide that I used and there was a special system for signing off my cyanide related experiments.
I weighed out the potassium cyanide and then wrote the new gross weight on the potassium cyanide bottle so I could account for the potassium cyanide consumed within a few grams, also I had to submit experimental procedures to my research supervisor in advance of the experiment.
But I was using a lot of potassium cyanide!

Jor - 6-2-2010 at 19:51

Ofcourse it is a dangerous chemical, but with care it can be used safely. The bookkeeping of the amount of KCN used is done because of liability issues, not indicating how dangerous is it. There are much more dangerous chemicals used in research, it's just that this is such a easy way to poison someone.

Watching your videos on youtube, I see you handling whole blocks of white P, wich is a FAR more dangerous substance than KCN, 5 times as toxic, and an serious fire/burn hazard. But you did work with it quite responsibly, without any fume hood, are very serious gloves. This is also true for KCN, work with care and you'll be fine.

Yes HCN is extremely poisonous, but you still need quite large ppm values to kill. It is fatal at 300ppm for 10 minutes, that is still 300mL of pure HCN gas per m3. So even if you release 3L of HCN gas in a very small 10m3 room, without ventilation, you would need to stay there at least 5 minutes to go down.
So good ventilation like wind or fume hood isn't gonna kill if you work with care.
Liquid HCN is another story, a few drops on your skin might be fatal I think.

ScienceSquirrel - 6-2-2010 at 21:14

Quote: Originally posted by Jor  
Ofcourse it is a dangerous chemical, but with care it can be used safely. The bookkeeping of the amount of KCN used is done because of liability issues, not indicating how dangerous is it. There are much more dangerous chemicals used in research, it's just that this is such a easy way to poison someone.

Watching your videos on youtube, I see you handling whole blocks of white P, wich is a FAR more dangerous substance than KCN, 5 times as toxic, and an serious fire/burn hazard. But you did work with it quite responsibly, without any fume hood, are very serious gloves. This is also true for KCN, work with care and you'll be fine.

Yes HCN is extremely poisonous, but you still need quite large ppm values to kill. It is fatal at 300ppm for 10 minutes, that is still 300mL of pure HCN gas per m3. So even if you release 3L of HCN gas in a very small 10m3 room, without ventilation, you would need to stay there at least 5 minutes to go down.
So good ventilation like wind or fume hood isn't gonna kill if you work with care.
Liquid HCN is another story, a few drops on your skin might be fatal I think.


To my knowledge I do not have any videos on youtube and certainly none showing me handling white phosphorous.
My white phoshorous days preceded camera phones and the internet!
There are plenty of more dangerous chemicals used in research but most labs like to keep an eye on cyanides, white phosphorous, carbon monoxide, phosgene etc.
Cyanides are listed poisons within the UK and any unlisted really toxic material is watched if you use it in sufficient quantity.

Jor - 7-2-2010 at 03:37

Correction that was ScienceGeek. My mistake :P

vassili78 - 7-2-2010 at 10:18

what happen ? yeasterday there was 187 reply in 16 pages, now there are 171 messages in 15 pages?

ScienceSquirrel - 7-2-2010 at 10:49

Some of them have been taken and put over here in their own thread.

http://www.sciencemadness.org/talk/viewthread.php?tid=13376

vassili78 - 8-2-2010 at 13:46

what about my question? Does the yield will be better if i make the HCN bubble into the NaOH solution ?

Myfanwy - 9-2-2010 at 06:50

no. much hydrogen cyanide will just gas out and does not react.

anyway my vid was deleted on youtube.
maybe i will reupload it.




[Edited on 9-2-2010 by Myfanwy]

vassili78 - 9-2-2010 at 12:18

try metacafe.com to upload your videos. it is less controled that youtube, you can find lot of chemistry videos or other thing like that.

your video was very nice. if i liquify completely the HCN, the yield will be better?

i tried today with no good results, i will try to cool it with the same system you used but instead of a baker containing NaOH solution, i will put an empty baker surrounded with water, salt and ice to be sure that the HCN will be liquid and then i will put it into a solution of NaOH.


Nicodem - 9-2-2010 at 13:04

Quote: Originally posted by vassili78  
i will put an empty baker surrounded with water, salt and ice to be sure that the HCN will be liquid and then i will put it into a solution of NaOH.

It is not like I will shed a tear if there will be one less kewl on this world, but still I take it as my duty to ask you if you have enough intelligence to imagine what happens if you pour liquid HCN into a caustic solution?

How about reading some chemistry books first?

Myfanwy - 9-2-2010 at 13:16

what would happen if you pour all the HCN into the lye? Such an exothermic reaction, that all the HCN just gas out again?

vassili78 - 10-2-2010 at 11:45

i think the HCN will polymerize with a violent reaction...

vassili78 - 10-2-2010 at 11:53

that's what happen to MARIO840, his solution turn to yellow but he didnt' describes any violent reaction. may be i'm wrong...

KnooBill - 12-2-2010 at 13:47

Your solution turning yellow is probably due to polymerization of the triple bond between the carbon and nitrogen. I did not neutralize HCN with ethanol and KOH immediately but did it after the ferrocyanide finished reacting with H2SO4. It was kept in an ice bath instead with an one way valve to keep the pressures equal (HCN takes volume in the bottle hence air must go out). However you need explerience to practise the experiment, and youtube is no chemistry tutor.

evil_lurker - 7-3-2010 at 11:07

Here lately it has occurred to me that rather than simply attempting to bubble HCN thru a base and try and isolate pure cyanide salts it should be possible to instead utilize commonly found weak base anion exchange resins which adsorb and form complexes with HCN.

If that is the case, then HCN can be safely sequesterd onto the surface of the polymer, and NaCN could easily be eluted in stoichemetric amounts simply by subjecting the resin to a solution of NaOH.

Will definately have to do more research into which resin would produce the best results.


Picric-A - 7-3-2010 at 12:19

Quote: Originally posted by evil_lurker  
Here lately it has occurred to me that rather than simply attempting to bubble HCN thru a base and try and isolate pure cyanide salts it should be possible to instead utilize commonly found weak base anion exchange resins which adsorb and form complexes with HCN.

If that is the case, then HCN can be safely sequesterd onto the surface of the polymer, and NaCN could easily be eluted in stoichemetric amounts simply by subjecting the resin to a solution of NaOH.

Will definately have to do more research into which resin would produce the best results.



One problem with this is it would be difficult to recover 100% of the cyanide from the resin and this would leave you with a highly toxic resin to dispose of.

Taoiseach - 7-4-2010 at 22:01

I recently mixed together potassium ferricyanide (or was it ferro - well the yellow stuff anyways) with ammonium chloride and heated small amounts. There was a strong smell of HCN and the mixture turned a nice blue color.

I have not yet dared try to distill ammonium cyanide from a larger amount but it looks to be possible. Ammonium cyanide is less volatile than HCN (altough still volatile enough to kill you with its vapours!) and reacts with ethanolic KOH solution to form KCN. The latter should precipate immediately due to its insolubility in EtOH.

DJF90 - 8-4-2010 at 04:56

Nice work Taoiseach, what kind of temperature did you heat them to? I didn't realise Ammonium cyanide was that volatile, wikipedia says bp of 36C, which is about the same as Ether. Heavy cooling will be required for distillation, but it's still a nicer material to distil than HCN. Good find!

Not sure about heavy cooling... it appears ammonium cyanide is a solid, and it would clog the condenser... any idea as to the mp of NH4CN?

[Edited on 8-4-2010 by DJF90]

Taoiseach - 9-4-2010 at 07:47

I didnt control temperature. Literature says it can be destilled from the mixture at 100°C. Also that it is very soluble in ethanol. I would try to catch it in ice-cold ethanol.


Sydenhams chorea - 16-5-2010 at 04:54

According to his youtube page (http://www.youtube.com/user/Myfanwy94) the user known as "Myfanwy" has recently passed away at the age of 16. I can only hope this was not the result of his recent experiments with cyanides.

Quote:

just2diy (2 weken geleden)
I miss him, he has always loved the chemistry and now they killed him.
I was in the same class as he saw and now I teach every day the place. I'm so sorry about him.

In memory of:
Myfanwy94 (Max Klempke)
04/19/2010


Taoiseach - 17-5-2010 at 09:11

I recently tried the C reduction of potassium cyanate, made by fusing K2CO3 with urea. The fused mass, after cooling, was extracted with warm water (30°C). After adding EtOH and cooling in a freezer, a few crystals of KCN precipated but the yield was neglible. The solution supersaturated and only started to crystallize after vigorous shaking. The stench of HCN was barely tolerable; I was really suprised how pungent and penetrating it smells. Even the next day the smell was clearly noticable in my home lab.

Lessons learned: The entire procedure has to be done outside or under a good fume hood. CO2 from the air liberates a lot of HCN from the solution - enough to give a numb and weird feeling in the throat. You can only smell the first wiff as it numbs the sense of smell, then after a while at fresh air you can smell it again :) Hot water has to be used for extraction - this however causes hydrolysis of the cyanide. Idea: Filtrate the hot extract into a cooled flask filled with ice-cold EtOH. The reaction vessel must be free of rust or ferrocyanide will be formed, evidenced by a distinct yellow coloration of the filtrate.

Any other ideas of how to extract KCN from the melt?

Polverone - 17-5-2010 at 11:30

You should have got more than a few crystals unless the reduction was very incomplete or you didn't use enough alcohol. Freezer cooling is not necessary. There should be an obvious precipitation (not visibly crystalline) after just a few seconds when the leach solution is poured into ethanol and stirred.

I have found that reduction can be visible monitored by evolution of gas bubbles during the heating process, after the full mass has melted. I believe the bubbles are CO because they will burn as they pop if the surface of the melt is exposed to air.

I used charcoal or propane heat to do the reductions. It can be a while before the evolution of bubbles slows down. Higher heat makes the reaction go much faster. If the melt has free access to air the re-oxidation of cyanide to cyanate may prevent realization of a high cyanide content product.

I will admit that of my few dozen trials and production runs that I ever made while experimenting with this method I only made a few with potassium compounds instead of sodium, and those before I had much experience optimizing conditions. Still, I would be rather surprised if the choice of cation made a dramatic difference.

Taoiseach - 17-5-2010 at 21:31

Thx for the answer Polverone. How much water/EtOH did you use and what temperature? I calculated the theoretical yield of cyanide and the amount of 30°C water needed to dissolve it, then doubled the volume. An equal volume of EtOH was used.


Polverone - 18-5-2010 at 08:58

The water was at "room temperature" -- I actually didn't take its temperature. The quantity of water you're using sounds ok to me. I added enough to make fluid and leach the rather thick mass of cyanide-impregnated charcoal fragments that were an inevitable part of my production process. I let the mixture stir for maybe 45 minutes before filtration in hopes of leaching most of the cyanide from the charcoal.

However, I'd say that I stirred my cyanide solution into something like 3 or 4 times its volume of 95% ethanol, which seems to be a considerably higher ratio than what you used. 95% ethanol is fairly expensive for me so I've also used the painter's "denatured alcohol" that contains methyl isobutyl ketone and (according to the MSDS) up to about 50% methanol. That seemed to work ok too. I had to wash the wet solid with a little 95% ethanol after precipitation to get rid of that MIBK odor.

Taoiseach - 18-5-2010 at 10:39

Well NaCN is slightly more soluble in water than KCN so maybe I should try the sodium salt next time. Could be its easier to crystallize also.

What yields did you achive? Did you analyze the product's purity or use it in any subsequent synthesis?


Polverone - 18-5-2010 at 11:39

My analytical methods were extremely crude. I did a qualitative cyanide test (not that I really needed it, given the smell) preparing prussian blue from mixed iron II/III salts. I also checked for carbonate contamination by adding a small quantity of the cyanide to ice cold dilute hydrochloric acid -- absence of bubbling indicated little or no carbonate. I searched for a simple method to analyze mixed cyanate/cyanide, as I suspected cyanate would be the greatest remaining impurity, but did not find anything at the time.

I subsequently used my cyanide with success to prepare a few different copper and nickel complexes, dissolve gold foil, plus (of course!) prepare a larger quantity of the lovely prussian blue.

I suspect production could be more elegant, and done on a larger scale, by using an electric furnace instead of combustion based heating. However I never needed it on a large scale and so had little incentive to scale up. Making 20 grams or less at a time was fine for me.

Thermal decomposition of ferricyanides or ferrocyanides is probably simpler. I do like the carbon reduction of cyanate because the raw materials are so very inexpensive and widely available.

Formatik - 18-5-2010 at 18:13

This reminds me of my first preparation of cyanide, which was incidental. I wasn't trying to make CN-. I melted alkali carbonate and urea in an open ceramic dish. Then applied stronger heat. I removed the heat after enough gas release, when cool, a strong bitter almond odor was emanating from the solids. Letting it stand longer in air caused a powerful bitter almond odor to form. Cyanide can be smelled before it kills you, and like Taoiseach says, it can be smelled once but then not continuously. Don't get too sniff happy. I was trying to form cyanate! I must have heated too strongly and despite being in open air, it still formed a significant amount of CN-. I found the maximal yield possible by thermal decomposition of potassium cyanate, and mentioned it here. I destroyed it with aq. permangante.

Measuring Cyanide in any solution

grains4me - 18-5-2010 at 19:01

Hi Poverone
You are a few years ahead of me. I am doing a lot of reading about Cyanide before making a bit to disolve gold from my many prospecting trips and mountain climbing. The best info besides your experiment has come from a website by Dr. A. K. Williams from San Pedro, Costa Rica. He has a huge website: http://www.prospectorsparadise.com where he gives excellent instructions in plain english on "Determination of Free Cyanide in Solution" using 13.07g of Silver Nitrate and a Titration setup. You have to get a 25 or 50cc burette in 0.1cc divisions and do the thing with the eye dropper, watching for the point where one drop forms a cloud which does not dissolve. He does all the math for you including Molar Mass and buffering which is way beyond my skills! Anyway, you can then know your exact Cyanide amount in percent and produce no extra toxic chemicals to worry about (5mg = Lethal Dose!).

Dr. Williams quit working in the USA and tries to educate the people who burn "Dore"-Mercury amalgum gold/silver globs in town resturants to show off the purity of their gold panning claims in South America, releasing all kinds of toxic Mercury fumes. Read through the entire website, its awsome!

Another website suggests a thiosulfate solution is best to destroy slight traces of Cyanide before throwing away those burnt soup tins etc.

mario840 - 1-12-2010 at 09:52

People always amaze me how can they make life so difficult, 16 pages and almost eveything is trash , melting something with something , cyanohydrin ?? when we want kcn who is need to synthesis cyanohydrin. WTF ? Buy ? so buy kcn. Ok there is no easiest way to obtain pure (99%) kcn then HCN introducing into alcoholic solution of koh , here you have:




no title.JPG - 73kB

If someone want to say is dangerous so maybe quit chemistry at all

entropy51 - 1-12-2010 at 14:46

Good Lord. Posting Jared Ledgard's crap on Science Madness. Have you no shame?

madscientist - 1-12-2010 at 15:34

mario840, it's really easy with the cyanate process Polverone discovered.

Simply melt urea with sodium hydroxide to yield cyanate, grind it finely with charcoal, load into a steel can, cover the top with loose aluminum foil, and blast it with a hot charcoal fire until flames (burning carbon monoxide produced by reduction of cyanate) cease to spew out from under the foil. I used a pair of hair dryers, bathing the can in sheets of brilliant white flame; probably overkill, but it did the job.

I believe I extracted the cyanide with cool water and then crashed it into a large volume of cold isopropanol to precipitate it.

An aqueous solution of said precipitate did not bubble on addition of citric acid at 10C. It did at something like 30C. Took that as evidence enough it was successful - I lacked the facilities for further analysis, and was not about to do a smell test!

As Polverone said, be careful about leaving it exposed to air, especially while still hot. Don't leave it in water for long periods of time either, particularly hot water - it will hydrolyze.

[Edited on 1-12-2010 by madscientist]

cyanureeves - 1-12-2010 at 19:49

i tried the method mario840 posted . i used distilled water and koh as recipient. it turned to ammonia after a day and precipited a salt. still at the bottom right now after 2 or 3 months. i then tried ethanol and koh. it did not turn to ammonia. i tried to dehydrate it slowly and it never dried after days of warming but turned to paste.both turn dark blue with iron sulfate. both make good plating solutions but niether will dissolve gold on their own. i tried the sodium carbonate and urea method but only got as far as making the cyanate and did not heat the precipitate with charcoal as mad scientist states. i missed this part in the 16 pages of literature . so i will try again. i also have gone through these posts for month and obviously im missing something. polverone states his salt dissolves gold leaf. that is my goal! i tried to contact my dear boy myfanwy and almost came to tears as i watched his channel.the boy actually succeeded and made a video. he was a MAD SCIENTIST.
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