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Metacelsus
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The first reaction is a good way to get killed. Nitrogen trichloride AND hydrogen cyanide?!? 
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WGTR
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I tried the "HCN by chloroform and ammonia in base" reaction a few years back, and it worked the first time (Thanks,
Polverone). An excess of concentrated ammonia was used, and alcohol was the main solvent. I noticed that no reaction
occurred if the solution was stirred at room temperature, but somewhere close to 40°C the reaction kicked off, and a sharp
exotherm was noted. At the same time, the KCl and KCN precipitated out quickly (when an excess of KOH was used).
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Dan Vizine
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Have done it numerous times. Although, for obvious reasons, CH2Cl2 was far more preferable. No reaction occurs in a few minutes or longer at room
temp. Considering the emulsions such mixtures form, that's a good thing. Aq. NaOH/chlorinated solvent emulsions are among the most troublesome for
your typical synthetic chemist.
[Edited on 16-4-2014 by Dan Vizine]
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DoctorZET
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I think the best way to get HCN in a home-lab is the proces involving chloroform and ammonia... 
As Cheddite Cheese says, hydrogen cyanide is toxic enough ... and if you're doing the first process (involving nitrogen trichloride & methane) in
a closed environment ... you will certainly have some very bad health issues after this.
Good thing I have do that outside 
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The Volatile Chemist
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If I needed it, I always have extra Ferri- and Ferro-cyanides I could decompose by heat or acidification, but I'm a bit young to try it (14) and don't
feel like I'm mature enough  As well as being at a slight lack of glassware
re-condensing stuff...
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Dan Vizine
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It isn't even debatable, HCN via acidification & heating of aq. K4Fe(CN)6 is unrivaled by any other method.
Always remember HCN is en endothermic compound, and explosive polymerization can be initiated by excess CN anions. Stabilize with 1% H2SO4.
It's beautiful and mesmerizing, looks very much like water. I love the smell in high dilutions. I'm one of the group that smells it, some people
don't. It's a genetic thing.
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DoctorZET
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You should not smell it too much... it's highly toxic , remember O_o ?
Now I think about next process (starting from ammonium formate):
NH4OOC (ammonium formate)(solid) --(thermal decomposition)--> OCH-NH2 (formamide)(gas) + H2O (vapors) --(excess of powdered calcium oxide,
300-350*C)--> Ca(CN)2 (solid) + 2H2O(vapors)
I think is also a good process...
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Mildronate
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ScienceHideout asked dG for reaction:
NH3 + CHCl3 + 4 NaOH ---> NaCN + 3 NaCl + 4 H2O
, sorry i calculated for KCN
From my calculation dG must be -740.1 kJ/mol*K at 298K (see atachment)
[Edited on 18-4-2014 by Mildronate]
Attachment: dgkcn.xlsx (9kB)
This file has been downloaded 479 times
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AJKOER
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Here is a possibly small scale route based on photolysis that may be theoretically feasible. Comments invited as I suspect there are fine points of
the procedure that may need refinement.
1. Gradually create some CHCl3 and other compounds including CH2Cl2, CCl4,.. by exposing a mixture of methane with an excess of chlorine to diffused
daylight at 298 K. A finer point, direct sunlight as confirmed by Mellor (see "Modern Inorganic Chemistry" page 693 at http://books.google.com/books?id=1iQ7AQAAMAAJ&pg=PA694&a... ) with an excess of Cl2 should be avoid due to explosion hazard. The later can
actually be expected based on the known explosive chain reaction of hydrogen and chlorine. Per this source (http://www.google.com/url?sa=t&rct=j&q=photolysis%20... ) some expected uv radical formation reactions:
Cl2 + uv = Cl + Cl
CH4 + uv = CH3 + H
H + Cl = HCl
CH3 + Cl = CH3Cl
For a net reaction:
Cl2 + CH4 + uv = HCl + CH3Cl
and similar progression of the chain for the creation of CH2Cl2, CHCl3 and CCl4. Note, per Wikipedia, there is a commercial production method for
chloroform by directly heating CH4 and Cl2 between 400 C and 500 C (see
http://en.m.wikipedia.org/wiki/CHCl3). Also, given the associated poisoning of the H2/Cl2 chain reaction by O2 (see http://books.google.com/books?id=nirXFo1S9VkC&pg=PA120&a... ), I would similarly avoid the presence of any oxygen. Also, no CO2 as, per the
prior cited source:
CO2 + uv = CO + O
or possibly water vapor, again liberating some oxygen in the presence of uv.
2. Lastly, the formation of some HCN with the introduction of NH3, again in the presence of uv light, most likely near 100 C.
[Edited on 20-4-2014 by AJKOER]
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Mildronate
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yeah CH4+Cl2 + UV= BANG!
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DoctorZET
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Well ... it's very possible to get a "bang" if you mix in a baloon Cl2 and CH4 (remember that H2+Cl2+UV=>2HCl+energy)
But think about mixing Cl2 and CH4 in a long and thin glass tube illuminated with UV and , as the input gases you have a continuos flux of Cl2 and
methane. If you try this, is very probable to get a lot of heat instead of a "bang" (perhaps the tube must be submerged in water).
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Mildronate
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Anyway its much easier to make HCN from K3[Fe(CN)6 and sulfuric acid.
[Edited on 24-4-2014 by Mildronate]
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DoctorZET
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Agree, but only if you have access to a hexacyanoferrate salt (just like K3Fe(CN)6).
And, by the way, hexacyanoferrates it happens to be illegal substances in my country... so I need to produce HCN in my home lab from usual chemicals.
And that's our discussion about.
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Mildronate
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Why its illegal?
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Pickardjr
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potassium ferrocyanide is not a toxic cyanide metal salt. Its in table salt to keep it from clumping, and road salt for same reasons. Why would it be
illegal?
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Dan Vizine
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It causes damage to aquatic ecosystems if I recall correctly.
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Pickardjr
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ah, yea I see that now. question retracted.
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plastics
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These posts on the original 'Preparation of cyanides' page (http://www.sciencemadness.org/talk/viewthread.php?tid=23&...) using only ferricyanide and KOH have always intrigued me
Densest:
One approach which I saw appeared to work:
To a cold saturated solution of KOH was added K4Fe(CN)6 crystals until no more would dissolve. The flask was sealed with plastic film to exclude CO2
and O2. Over a period of some days, Fe hydroxides and oxides precipitated, and the color of the solution changed from yellow-green to clear. The
supernatant was decanted. On further chilling, transparent square plates and small cubes crystallized. Filtered quickly, washed with a minimum of very
cold distilled water, a very small amount (milligrams) gave a very strong blue reaction with FeSO4 solution.
I believe it took several weeks overall, using an outdoor shed during autumn. It would seem to depend on KCN being somewhat less soluble than KOH or
K2CO3 and very little O2 being available to destroy the KCN. Perhaps the air in the flask could be displaced with something else to improve the yield.
According to an old Chem Rubber handbook, the only likely substance in that solution which crystallizes to a square or cubic form would be KCN giving
a second reason to believe the process worked.
len1:
Thanks for the info SC Wack. But none of the links work. The first two only give me the title pages the last hangs the computer.
ANYONE WHO WORKS WITH CYANIDES INCLUDING MYSELF MUST WEAR A GAS MASK, GLOVES and GLASSES!. Even in this case when theoretically no HCN is generated
KCN spilled on a stray drop of HCl, can generate enough HCN to kill, especially if you are like myself and cant smell it. Grinding or picking KCN can
stray particles into your face and mouth - also enough to kill. A mask will guard against all of this. Gloves give protection against KCN dissolving
in skin moisture and penetrating though cuts etc. Glasses protect against KCN particles flicked into the eye dissolving in tears, being absorbed, and
killing. Symptoms of mild CN poisoning resemble symptoms of fear of having been poisoned (anxiety).
Ive done the Ksp calculations, and the KOH method must work and it must work even better with K3FeCN6 since its last cyanide is weakly bound (making
it poisnous) so that it can be substantially separated even in boiling water
[Fe(CN)6]3- + OH- -> [Fe(CN)5OH]3- + CN-; [Fe(CN)6]3- + H2O -> [Fe(CN)5H2O]2- + CN-
Removal of all the cyanides if you check the K's proceeds because of the low Ksp of iron hydroxide. BUT its all very slow and inefficient. In
practice my method is better: simplest method imaginable - no mixing, weighing etc; takes a few hrs; directly gives pure KCN; is safe for
non-specialist labs - no HCN at any stage
Yiled can be improved, but at the expense of a lot more dangerous work. At this level I think this method is perfect.
[Edited on 24-2-2009 by len1]
Anyone else tried this method?
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lysander
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I have a hard time believing you love the smell. I smell it but find it unquestionably unpleasant and somewhat nauseating. I wonder if
maybe I got cyanide poisoning once and that gave me a bad association? I'm a supertaster who can also smell asparagus metabolites. Maybe there are
genetic variations among HCN smellers?
Actually it would be neat to do a poll thread on cyanide, but I can't see that polls are possible with this forum:
Can't smell it
Don't like its smell
Like the smell
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