dann2
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SnCl4:5H2O to SnCl4
Hello Folks,
Having obtained a quantity of SnCl4:5H2O (lab grade, white solid). I was hopeing that it may be possible to convert some of it to SnCl4 (liquid). I
have asked this before in here and did not get very positive responses (perhaps it simply is not feasible).
Any suggestions.
TIA,
Dann2
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UnintentionalChaos
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The only immediate thought is to run a stream of hot dry HCl over it, but that is effectively impossible with almost any home lab.
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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not_important
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I agree with UnintentionalChaos on this. One alternative method, heating the hydrated salt with a large excess of NH4Cl, does not work with volatile
chlorides. Other alternatives are reacting with one of several reactive acid chlorides, such as SOCl2 or PCl3. Unfortunately many of these form
complexes with SnCl4 and/or have boiling points too close to SnCl4 to be easy to separate; on top of that most are expensive and difficult to obtain.
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Nicodem
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Heating over HCl atmosphere is a bit impossible given the volatility of SnCl4.
I guess the simplest method would be to reduce SnCl4*5H2O to elemental Sn and the prepare SnCl4 from this like it is generally done. 
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Eclectic
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And if you are still working on the Sb doped conductive tin oxide, the hydrated salt is what you should be using anyway. You don't get SnO2 from
SnCl4 unless there is water available in the reactants.
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dann2
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Hello,
Thanks for replys. I think I can condense all answers (considering my particular set up) as.. NO, you cannot easily get rid of the water.
I wanted to try this (for a change). It calls for SnCl4 (no H2O)
http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/...
It will be going on the back boiler for now.
Will get back to the DTO on Ti soon though.
BTW Electic:
I placed a stick of Tin metal in a strong solution of SnCl4:5H2O (in water) and the Tin did dissolve (as you said elsewhere). What reaction is going
on? There are small amounts of black/brownish stuff. The solution has gone from clear to light yellow.
Dann2
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UnintentionalChaos
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Reduction of stannic ion to stannous ion and oxidation of elemental tin to stannous ion. Light yellow color in solution and brown/black crud is
probably contamination in the tin metal, unless your tin was very high purity, at which point I have no idea.
Overall,
Sn(0) + Sn (4+) -> 2Sn (2+)
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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Eclectic
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It may also be a tin oxide polymer forming from a mix of SnCl2 and SnCl4 hydrolysing, as referenced in one of the patents Rosco dug up, that is
responsible for the yellow color. I thought the brown-black precipitate I got was a Sb compound due to reduction of SbCl3, but if your tin was pure,
maybe it's SnO.
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Antwain
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Just a thought here...
I was reading cotton and wilinson just now, and I saw something interesting....
"germanium tetrachloride and GeBr4 are also hydrolised, but in 6-9M acid there is an equilibrium involving such species as [Ge(OH)nCl6-n]2-,and from
concentrated acid solutions the tetrahalide can be distilled and separated out."
It does not say that this method can be used for SnCl4, but it does say that tin is distinctly amphoteric, while germanium is barely so.
now it is worth noting that the bp. of GeCl4 is 83.1*C and the constant boiling mixture of HCl and H20 is ~110*C while the bp of SnCl4 is 114*C.
Now this is painfully close, but if you turned the reflux rate right up and did a proper fractional distillation.... could you use the excess of HCl
in the 40% acid (over the constant boiling mixture) to carry with it the water of hydration of SnCl4? I realise that 3 phase systems are never that
simple and 110 and 114*C are pretty close, but is it theoretically possible?
Alternately... doesn't the constant boiling mixture and temperature of say HCl and H2O vary with pressure. This is probably even more of a theoretical
than a practical solution, but by varying the pressure could you make the constant boiling mixture of HCl+H2O significantly greater then SnCl4, so
that SnCl4 could be fractioned off?
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not_important
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110 and 114*C are more than pretty close, they are real close and will need many plates to obtain good separation.
Many of the acid-water azeotrope ratios don't vary a lot with changing pressure, I found this out when looking into the possibility of getting a more
highly concentrated nitric acid by distillation under non-atmospheric pressure. I don't remember the HCl-water curve, but it should be fairly easy to
find.
I still think that starting with metallic tin and chlorine is the way to go.
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