Picric-A
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Ammonium thiocyanate
Ammonium thiocyanate is a usefull compound. It can be decomposed to Carbon disulphide and guanidine thiocyanate upon heating and it forms a nice deep
red 'blood' colour with Fe (III) ions;
6 SCN- + Fe3+ → [Fe(SCN)6]3-
Start by fusing sodium carbonate with urea to produce Sodium cyanaide and CO2 and NH3.
The sodium cyanide is extrcted and purified by recrystalisation and then reacted with sulphur (or thiosulphate) to form sodium thiocyanate;
8 CN− + S8 → 8 SCN−
Now here is where i am stuck. How can you make ammonium thiocyanate from this?
Can thiocyanic acid be made by adding H2SO4 followed by reacting this with NH3(aq)?
Any other better ways of doing this?
thanks,
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kclo4
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Urea + Sodium Carbonate = Sodium Cyanate, not cyanide. NaOCN vs NaCN.
You will need to reduce the cyanate to cyanide using something like carbon, etc.
Doesn't cyanide oxidize easily into cyanate in the presence of O2 when heated? I would try just mixing sodium cyanide with sulfur and heating in an
inert atmosphere to get sodium thiocyanate. The sodium thiocyanate can then react with ammonium sulfate to form sodium sulfate and ammonium
thiocyanate, which will probably turn into thiourea.
Na2CO3 + 2 NH4OCN = 2 NaOCN + (NH4)2CO3
NaOCN + C = NaCN + CO
*Note how two harmless reactants turn into two very harmful products*
NaCN + S = NaSCN
2 NaSCN + (NH4)2SO4 = 2 NH4SCN + Na2SO4
[Edited on 1-8-2009 by kclo4]
If it is carbon disulphide you want, might it be better to ball mill activated carbon and sulfur together, and then rapidly heat it. It has been done
by bromic acid IIRC, but I don't think he ball milled it, and I don't know if he used activated carbon. That could make a big difference. The C + S
reaction gives very low yield however, but I'm sure once everything is said and done, that would be better then starting from urea, using cyanide,
etc.
[Edited on 1-8-2009 by kclo4]
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Picric-A
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Bloody hell! i jsut wrote a huge response then when i clicked reply i got forwarded to SM homepage!!!!!! urgh!
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Picric-A
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in short no u do et CN by heating cyanate and yes you need to keep it form air.
how do i seperate the aqeous thiocyanate from sodium sulphate?
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kclo4
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| Quote: | | in short no u do et CN by heating cyanate and yes you need to keep it form air. |
What?
Separation of ammonium thiocyanate from sodium sulfate is probably possible by fractional crystallization. Alternatively you could possibly use a
calcium salt to begin with so when the sulfate is added calcium sulfate precipitates.
I personally would not use calcium salts since they form powdery hard to separate mud, while sodium sulfate will form nice large crystals.
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not_important
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Yeah, I'd use ammonium sulfate to add to the sodium salt, then cool to crystallise out sodium sulfate as the decahydrate - which also concentrates the
solution.
ammonium thiocyanate 128 g/100 mL (0 °C)
sodium thiocyanate 139 g/100 mL (21 °C)
ammonium sulfate 70.6 g/100 mL (0 °C)
sodium sulfate 4.76 g/100 ml (0 °C)
Quote: Originally posted by Picric-A  | Bloody hell! i jsut wrote a huge response then when i clicked reply i got forwarded to SM homepage!!!!!! urgh!
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I'll bet it's the bug related to the use of < and/or > in a post.
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kclo4
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I think that also, I really wish that could be fixed! 
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S.C. Wack
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There is quite a bit in the Hauptwerk of Beilstein (volume 3) on the acid and its salts. Vanino and Brauer cover them as well. I'd think that one way
to get the free acid would be to precipitate the lead salt from a solution of the potassium salt which is made in Vanino or Vulte, add H2S to a
solution or suspension of this to get the free acid, and neutralize with ammonia.
[Edited on 2-8-2009 by S.C. Wack]
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Alchemist
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NH4SCN
Hello all,
Ammonium Thiocyanate, is formed on heating hydrocyanic acid with yellow ammonium sulfide, or a solution of ammonium cyanide with sulfur. The common
way is by heating carbon disulfide with alcoholic ammonia.
So why not just bubble HCN via Sodium Ferrocyanide and conc. Sulfuric acid through hot yellow Ammonium Sulfide. Yellow Ammonium Sulfide (Ammonium
Polysulfide) is made by adding Sulfur to normal Ammonium Sulfide (via H2S and conc. Ammonia solution).
Later, the Alchemist.....
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JohnWW
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Ammonium thiocyanate is used as a weedkiller, usually mixed with the major constituent 3-amino-1,2,4-triazole, called "amitrole", in the commercial
herbicide also called "Amitrole", which however has been recently banned in the EU. Although non-selective, Amitrole seems to affect broadleaf weeds
more than grasses, unlike Roundup, and can be used around trees in orchards. (I have used the stuff myself). See:
http://fr.wikipedia.org/wiki/Thiocyanate_d%27ammonium
(seems to be available only in French),
http://www.keyindustries.co.nz/site/keyindustries/files/Amit... ,
and (regarding the major constituent)
http://en.wikipedia.org/wiki/3-Amino-1,2,4-triazole
Because it forms complexes with Fe(III) at least as readily as cyanide does, it is similarly at least as toxic.
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