morsagh
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copper thiocyanate
I want to make som CuSCN so please help me.
I have mixed KSCN and CuSO4 but it became green solution.
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blogfast25
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CuSCN implies copper in oxidation state +1. CuSO4 is copper in oxidation state +2, without reduction you cannot obtain a Cu (I) salt.
Try boiling CuSO4 with elemental copper in the presence of KSCN. It works for CuCl.
Cu<sup>2+</sup> + Cu === > 2 Cu<sup>+</sup>
[Edited on 20-2-2014 by blogfast25]
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morsagh
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Cu2+
i have read that the Cu(SCN)2 decompose to CuSCN and (SCN)2
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violet sin
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http://pubs.acs.org/doi/abs/10.1021/ed070p174.3
view PDF,
...However, one of the reactions described, namely the reaction of
Cu2+(aq) with SCN-(aq), deserves a further comment.
Tykodi states that Cu(NCS)~is unstable and decomposes
quickly to CuSCN according to reaction 1
Cu+2(aq) + 2SCN-(aq) --> [Cu(NCS)2(s)] --> CuSCN + 1/2(SCN)2(g)...
...In order to select the proper conditions for a
demonstration, I have mixed 1 M solutions of CuS04 and
KSCN. At room temperature, a black precipitate of
CU(NCS)appeared immediately, and reduction to CuSCN
was so slow that most of the solid remained unchanged
aRer standing at room temperature for 24 h...
and this.
Synthesis, characterization, and structures of copper(II)-thiosulfate complexes incorporating tripodal tetraamine
http://www.ncbi.nlm.nih.gov/pubmed/15476353
ligands.
....The reaction of [Cu(L)(H(2)O)](2+) with an excess of thiosulfate in aqueous solution produces a blue to green color change indicative of
thiosulfate coordination...
[Edited on 20-2-2014 by violet sin]
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Justin Blaise
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I have recently made CuSCN by mixing a CuSO4 solution with a sodium metabisulfite solution, to reduce Cu2+ to Cu+,
then aqueous NH4SCN was added. When the sulfite and copper solutions are mixed, the color changes from blue to green, then when excess
thiocyanate is added, a white precipitate forms. This was filtered and washed with water. It darkened slightly upon drying in air.
Apparently, this method is known, and precipitation of CuSCN is fairly selective as described in this paper, which I do not have access to.
Additionally, I would be wary of mixing thiocyanate and Cu2+ solutions without an additional reducing agent. As described in the first
link violet sin posted, the reaction produces thiocyanogen which can be hydrolyzed to HCN, among other things.
[Edited on 21-2-2014 by Justin Blaise]
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woelen
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If you mix copper(II) ions with thiocyanate at low concentration then you get a green complex, at higher concentration you get a black precipitate.
This black precipitate partially turns white after some time, due to an internal redox reaction between copper(II) ions and thiocyanate ions.
If you add some sodium (bi)sulfite as well, then you get a purely white precipitate. You can add the bisulfite afterwards, when you have the black
precipitate.
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bfesser
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Thread Moved
24-2-2014 at 11:34 |
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