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Magpie
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I just called my local coin dealer. His price today is $15.90 for a 1 troy ounce silver coin. This equates to $15.90/31.1g = $5.10/10g. Did you
slip a decimal point?
My 2 quantitative analysis books don't talk about interferences other than halides, so I can't help you there.
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len1
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Thanks Magpie.
No I didnt make a mistake, and I generally post only info that I actually know. AgNO3 is not readily available to my home lab (and I have none at
work, plus it would be immoral to use an expensive chemical not directly for work purposes). So the only work around I could think of is bying a hand
bracelet at the jewler. The best weight/price ratio was for a thick Streling silver bracelet, which at home weighed 10gms. So here you are. I dont
think we have scrap silver dealers here.
The cyanate, although the quantitative test showed there is no great amount of it, quantitatively I think will interfer with the test you propose as
AgCNO is more soluble than AgCN. The standard method of acidifying, decomposing, absorbing NH3 in acid, neutralising, is not only tedious, but due to
the many steps likely inaccurate in the home lab.
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Magpie
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Len1, I don't know if you have seen this or not but a good reference on cyanates is Allen's "Commercial Organic Anaysis," vol. VII, 1913. This is
available on the internet.
On p. 539:
"Cobalt potassium cyanate, K2Co(CNO)4 is precipitated in dark blue quadratic crystals on adding a solution of cobalt acetate (or cobalt
nitrate with potassium acetate) to a solution of potassium cyanate. The reaction has been applied to detection of cyanate in commercial potassium
cyanide."
Further down:
"Silver nitrate forms a white cheese-like precipitate which is soluble in ammonia and nitric acid, thus differeing from silver cyanide."
Based on this last statement it seems that the Liebig method for determining cyanide may be protected from cyanate interference via NH4OH.
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len1
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Thanks Magpie.
If K2Co(CNO)4 is insoluble the procedure is to add enough cobalt ions to a CN-/CNO- solution until no more percipitate forms. We either need cobalt
cyanide to be soluble - or a soluble Co(CN)6 to form preferentially. On checking www.1911encyclopedia.org/Cobalt I find thats only true in a certain concentration range.
If there is a large excess of cyanide one adds the cobalt ions until the percipitate ceases to form. The trouble is knowing when that happens - its
would be possible to add too much cobalt so the cyanide is no longer in excess, possibly precipitating the cyanide.
The silver test is also a bit tedious, you have to precipitate the AgCN, filter, dry, weigh the small amount. Then dissolve what you can in nitric
acid and repeat, and take the difference - its all prone to error.
The iodine reaction is promissing. No filtration and weighing of precipitates required. I dont know if iodine interacts with CNO.
[Edited on 27-2-2009 by len1]
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kmno4
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In "References" I have posted article from Berichte.
This article contains some procedure for determination/detection OCN(-) in the presence of CN(-) by reaction with Co<sup>2+</sup>. It is
in german and - generally - not clear for me. Unfortunately no-one wants to transtale it. I have an impression it could be interesting.
[Edited on 1-3-2009 by kmno4]
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len1
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KMnO4 - Why not post it here? Is there a particular reason why not post it in the open?
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kmno4
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| Quote: | Originally posted by len1
KMnO4 - Why not post it here? Is there a particular reason why not post it in the open? |
1. Because it is not "wanted translation" section.
2. Because I do not want to post article of unknown (for me) content.
3. Because all contributors of this "cyanide topic" have access to References.
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garage chemist
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I have the Berichte article and will provide an overview of the important sections. Please, if you want an article translated, send me a PN, I don't
frequent the Wanted References thread.
If cobalt acetate solution is added to a solution of KOCN, an intense blue color is produced, and slowly large dark blue crystals of a complex salt
with the composition "Co(OCN)2 + 2 KOCN" separate.
However, cyanide interferes with this reaction by precipitating sparingly soluble cobalt cyanide in a form that is difficult to filter, and the
cyanate reaction in the filtrate becomes uncertain.
Cobalt acetate requires at least 0,5% KOCN in water in order to give the cyanate reaction, upon stronger dilution with water, the blue color vanishes.
Cobalt nitrate is even less sensitive, it requires 1% KOCN in water.
But in alcohol, the reaction is much more sensitive: in 90-95% alcohol as reaction medium, down to 0,0033g KOCN in 100ccm can be detected with cobalt
acetate.
As cyanide strongly interferes with the reaction, it has to be removed first, and this is best accomplished by bubbling a brisk stream of CO2 through
the solution to effect formation and purging of HCN.
3g KCN, as a 10% solution in water, were found to completely lose their cyanide content upon bubbling with CO2 for 45 minutes.
The resulting solution is the diluted with alcohol to precipitate potassium carbonate and the filtrate tested with cobalt acetate.
If larger amounts of KCN are to be tested this way, most of the cyanide is to be precipitated form the concentrated aqueous solution by adding
alcohol, the filtrate sparged with CO2, filtered from K2CO3 and again sparged with CO2 until completion of the cyanide removal.
Then more alcohol is added and the solution tested with cobalt acetate.
With those methods, 1% to 0,35% can be detected in KCN.
The less water one uses for the initial dissolution of the KCN, the more sensitive the cyanate test will be.
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Magpie
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Thanks kmno4 and garage chemist. I think that information is going to be very useful. I tested my KCN solution for OCN- using Co(NO3)2 and KCH3COO
and only saw a wispy white ppt.
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kmno4
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Thanks to G-C for translation.
Unfortunately this procedure requires removing of CN(-) ions 
If somebody is interested in more "sophisticated" methods of detection/determination of OCN(-) ion - few articles on 4shared.
This is all I could find in chemical databases.
3 articles from Analytical Chemistry, 1 from The Analyst, 2 from Fresenius' Journal of Analytical Chemistry (Z. anal.
Chem.) and 1 article from Analytica Chimica Acta (in French). Article from RSC led me to the article from Berichte
hxxp://yyy.4shared.com/file/90120350/80185387/ocn.html
[Edited on 1-3-2009 by kmno4]
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McLovin382
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Excuse me for maybe being a cyanide chem noob, but I'm wondering about reacting an alkyl cyanide (particularly acetonitrile) with anhydrous NaOH to
yield NaCN and an alcohol, according to the formula:
CH3CN + NaOH -> NaCN + CH3OH
Would this work? Or is there a reason that it wouldn't, and what would happen? It looks like a winner to me but I can't find it mentioned anywhere, so
I'm assuming that I might be wrong about it somehow.
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kmno4
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| Quote: | Originally posted by McLovin382
CH3CN + NaOH -> NaCN + CH3OH
Would this work? |
ΔG of this reaction is +44kJ/mol, so thermodynamic says that it goes but from right to left (apart from possible chemical reasons/reactions).
This is too high positive value to be shifted to negative values somehow. At least I think so 
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garage chemist
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No, it won't work. Alkyl cyanides are hydrolysed to carboxylic acids (acetic acid in the case of acetonitrile) and ammonia when heated with aqueous
alkali. They will not release cyanide ions.
Only alpha-hydroxynitriles, called cyanohydrines, will give cyanide upon treatment with a strong base. For example acetone cyanohydrin
(2-cyano-2-propanol), when added to an alcoholic solution of KOH, gives a KCN precipitate (very pure KCN at that).
But those cyanohydrins are previously made from the carbonyl compound and HCN, so this is only useful to prepare clean KCN from a crude material
(impure cyanide can be used to prepare acetone cyanohydrin by mixing with acetone and acid, then the cyanohydrin is isolated and purified).
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Nicodem
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Acylcyanides (R-CO-CN) also very easily hydrolyse to carboxylic acids (carboxylates in basic) and hydrogen cyanide (cyanides in basic).
Nitriles, or less commonly called alkyl cyanides (R-CN), can not hydrolyse to cyanide unless there is a viable mechanism that makes this route
possible rather than the hydrolysis of nitrile group (-CN) itself to the amide (-CONH2) or finally to the carboxylic acid (-COOH). One such is the
elimination mechanism, like in cyanohydrins, as described above by garage chemist. This was also discussed a few pages behind.
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kmno4
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McLovin382 says about anhydrous conditions.
In this case MeCN will not hydrolyse ( it can be deduced also from Nicodem's post). Let's stay more "cyanide" than "nitrile" in this topic.
ps. there is an aldol-like condesation benzaldehyde with MeCN and KOH described in OS. MeCN itself is quite resistant to anhydrous hydroxides.
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DJF90
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Its called the benzoin condensation. I'm sure details can be found in a textbook.
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kmno4
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| Quote: | Originally posted by DJF90
Its called the benzoin condensation. I'm sure details can be found in a textbook. |
"benzoin condensation" it is benzaldehyde + CN(-)
Benzaldehyde+MeCN+KOH is not benzoin cond.
[Edited on 4-3-2009 by kmno4]
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DJF90
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Sorry read NaCN... not sure what happens with MeCN... Heres the benzoin condensation for those who are interested:
http://www.organic-chemistry.org/namedreactions/benzoin-cond...
http://www.chempensoftware.com/reactions/RXN115.htm
https://themerckindex.cambridgesoft.com/TheMerckIndex/NameRe...
[Edited on 4-3-2009 by DJF90]
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octogen
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One of the important use of HCN was during WW2,By secret agencies of Germany,for “self destroying”.they called it RED ARROW, and it was small
glass capsule coated with red rubber.the capsule contained pure HCN ,and it had to be crushed between teeth, which caused coma after 20 seconds and
death approximately resulted after 5 minutes.
can anybody help me to get account for FTP ? i asked madhatter but he didnt reply me yet.should i wait?
[Edited on 8-3-2009 by octogen]
[Edited on 8-3-2009 by octogen]
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Jor
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Are you sure about the HCN in ampoules for suicide?
I recall all officers carried an ampoule with KCN crystals, wich they called cyankali, and they would crush it between their teeth when captured by
the enemy.
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octogen
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Yes i am sure, and actually this design was very fast acting (better than KCN),and sometimes they conceal it inside butt of cigarette.
I am looking for :Explosives and Bomb Disposal Guide by Lenz,or simillar books about circuit and electronics of bombs (like :eod fbi manual , which i
have already), i know there is some in FTP, but i dont have access , can you please help??
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benzal
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Just putting it out there as in most of these synths you end up with a hard to seperate mixture, high cost/hard to find chems maybe it could be made
from formic acid (not to hard to make) and amonia (easy). React the two to get ammonium formate then heat to get formamide keep heating strongly to
decompose the formamide into HCN and Water vapour. Bubble the reaction stream into NaOH/KOH to get a mixture of cyanide salt and amonia, evaporate off
the liquids to get cyanide crystals. Got the idea from wikipedia...
Formamide will begin to partially decompose into carbon monoxide and ammonia at 180°C. When heated strongly, formamide decomposes to hydrogen cyanide
(HCN) and water vapor.
I wouldnet want to try this as there will be alot of toxic gasses floating round and I dont need cyanide but if you realy want a small amount of
cyanide this could possibly be a starter for further research.
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jmneissa
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Okay so I have read around about cyanide's and all there uses in the lab but where ever I look I always see all the warning about how poisonous and
dangerous it is. But the MSDS sheets for everything always over exaggerate the unhealthiness of everything. I wanted to know your guys honest opinion
on how dangerous cyanide is and is it something that a amateur chemist should be messing with even if all the proper safety precautions are taken?
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Ketone
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Quote: Originally posted by jmneissa  | | Okay so I have read around about cyanide's and all there uses in the lab but where ever I look I always see all the warning about how poisonous and
dangerous it is. But the MSDS sheets for everything always over exaggerate the unhealthiness of everything. I wanted to know your guys honest opinion
on how dangerous cyanide is and is it something that a amateur chemist should be messing with even if all the proper safety precautions are taken?
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Depends a bit on if it's hydrogen cyanide or a cyanide salt, like say sodium or potassium cyanide, but both are very toxic.
The MSDS'es aren't bullshitting you when they say it is.
I wouldn't want to handle hydrogen cyanide without air-tight apparatus in a fume hood / outdoors and I'd prefer a gas mask on top of that...
And I'd never use it (Obviously it should always be generated as needed btw, never stored) in or around my home or any place where others would be at
risk.
Cyanide salts are safer of course, but you still should wear good gloves and a dust mask and be sure not to ingest any of it..
And as before - I myself wouldn't want to use it around my home.
It isn't an exaggeration to say that just a little amount WILL kill you. (alteast unless you have antidote)
BTW Just what do you consider "all the proper safety precauations"?
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Jor
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Really, I think salts of cyanide can be handled quite safely. As long as you don't create HCN, and wear gloves and try not to get any CN- solution on
the skin, you will be fine.
I myself have 5g of KCN, and use it for transition metal study (metals form complexes with CN-). I use utmost care in handling it. However it's not my
scariest chemicals. I more afraid of my 2g of white P and mercury salts.
And HCN is not instant death... 50-100mg are fatal, wich is )assuming worst case) 0,05 g / 27 g/mol = 0.00185 mol
0,00185 x 24,5 = 0,0453 = 45,3 mL pure HCN
Assume we get a 1000ppm concentration (wich is very unlikely, you have to release 1000ml of pure HCN per m3), and assuming you inhale 2L per breath
(wich is 2mL HCN), you have to inhale 22 times at 1000ppm to die, round it to 20. Inhaling chlorine at this concentration 20 times would also kill
you. So the real danger is acciddntly hoding your nose close to the container and inhaling a very large concentration (1-2%), wich will kill
instantly. As long as your keep your lose at distance from the container and use good ventilation (outisde , but prefered is fume hood) it seems that
you will be fine...
Ofcourse skin contact with even a single large drop of liquidd HCN may be fatal. It matches dimethylmercury in skin toxicity, as it is absorbed.
Or am i wrong here? I'm just speculating...
One thing is for sure, there are more toxic gasses out there, like COCl2, H2Se, AsH3, etc.
Although 50mg is fatal, it wouldn't surprise me if 10mg can severely injure you...
So I think HCN is a little bit overestimated, but it is still a very dangerous highly toxic gas with poor warning properties for most people.
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