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woelen
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SnI4: A nice covalent compound of tin
Some time ago, another member from this forum (Jor, credits go to him as well) came up with a nice idea of making SnI4, which is an interesting
covalent and volatile compound of tin.
It can be made using only mundane chemicals and for many members its preparation may be feasible. It has a nicely colored vapor and in the liquid
state it is blood red. I decided to make a webpage about this interesting compound:
http://woelen.homescience.net/science/chem/exps/SnI4/index.h...
[Edited on 17-9-09 by woelen]
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JohnWW
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That would be a possible route to making organotin(IV) compounds. Possible reaction schemes would be to react SnI4 with alkyl- and aryl-lithium or
-sodium compounds, in an inert solvent, with LiI or NaI as insoluble (in that solvent) byproduct. It would also be hydrolyzed by alcohols and phenols
to alkoxy and phenoxy-compounds.
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Picric-A
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Nice work Woelen!
what possible uses does organotin compounds have? maybe a possible less toxic substitute for tetraethyl lead in petrol?
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UnintentionalChaos
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If I'm not mistaken, you can transmetallate a grignard with SnX4, forming the SnR4. I wonder how one goes about making SnR3X though, which can be
converted to SnR3H in-situ with a hydride source.
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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Jor
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Thank you very much. I really like these pictures, much more so then the ones I make  :
http://amateurchemie.nl/viewtopic.php?f=20&t=286&sta...
I'm not sure but if using such a large excess of tin, are you sure your product is not contaminated with SnI2 ? Possibly that's the yellow compound on
the test-tube walls?
Using CS2 indeed seems like a better alternative, although I think it may be more feasible to use DCM when doing this on a larger scale, due to the
toxicity and extreme flammability of CS2.
Very nice woelen 
Does anyone know how to clean my 'dirty' SnI4 from iodine. I decanted the small amount of solvent left (see link above) from from the crystals, and
washed once with a small amount of DCM to remove the iodine. The red crystals from wich the liquid was decanted are almost free of iodine, but the
dark crystals obtained by evaporating the decanted liquid, contain quite some iodine. What would be the best way to remove the iodine without losing
too much SnI4?
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woelen
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Dissolve the material in DCM and add a little bit more tin. The iodine then will react with the tin, while the SnI4 does not react.
Tin(IV) iodide does not react with excess tin. I have my preparation from a book from Vanino, which has a section on the preparation of SnI4. The
yellow color of the material is due to the fine division. You can see this effect with e.g. red prussiate of potash, which is red in the crystalline
state and yellow when crunched to a very fine powder.
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12AX7
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Ahh, your pictures are quite good except one thing: lighting! Bring a few halogen lights next time, place them around to spread out the shadows. You
might also consider using a flash, but only a little, not so much that it drowns out the scene.
Tim
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woelen
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Jor, indeed is the use of CH2Cl2 a better alternative when the reaction is scaled up. I also tried the experiment with CH2Cl2 and it works almost as
well as with CS2. Just use a little bit more of solvent, because iodine dissolves a little bit harder in CH2Cl2 than in CS2. The reaction between the
iodine and tin is fast, also when CH2Cl2 is used. Refluxing is not necessary when powdered tin is used, but probably is necessary when globules or
molten droplets are used.
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UnintentionalChaos
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I would like to report the success of this synthesis using perchloroethylene as a solvent. Due to it's (relatively) high boiling point, it is not as
easy to separate from the SnI4. I achieved this by heating a thin layer of the solution in the bottom of a beaker strongly until the whitish vapor of
condensing perc was replaced by the yellow "smoke" of SnI4 and promptly removing from the heat source. I did lose quite some product stuck to the
bottom of the beaker though. However, perchloroethylene may be more readily available to some experimenters than DCM or CS2. I think I will make some
chloroform for the next time, however.
1.60g I2
Excess (about 1g) mossy tin
About 10ml of Perchloroethylene
Mixture readily reacted. Heating in a hot water bath sped up the reaction threatening violent boiling of the perc due to the exotherm. After several
hours at room temperature, the solution was a transparent, dark orange with no tinge of iodine color remaining. Some small crystals of SnI4 had
formed, which were dissolved by heating and the solution was filtered through a very small plug of cotton before evaporation.
Isolated compound weighed 1.51g.
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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blogfast25
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Interesting...
Next: SnBr4?
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benzylchloride1
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Quote: Originally posted by UnintentionalChaos  | | If I'm not mistaken, you can transmetallate a grignard with SnX4, forming the SnR4. I wonder how one goes about making SnR3X though, which can be
converted to SnR3H in-situ with a hydride source. |
. The Trialkyl tin halide can be prepared by a metathesis
reaction between a tin(IV) halide and a tetraalkyl tin complex. An example would be the synthesis of diethyltin dichloride. The procedure for this can
should be able to be adapteed to the synthesis of the trialkyl tin halide.
Procedure:
10g of tetraethyl tin and 11.1g of tin(IV) chloride, equimolar amounts were placed a a 100ml RBF. A condenser with a calcium chloride tube was
attached to the flask. The mixture is then heated at 210 to 220 Celsius in a silicone oil bath for 15 minutes. The mixture was air cooled and then
cooled in a cold water bath until the product crystallized. The product was then recrystallized from a boiling hydrocarbon solvent with a boiling
point range of 110 to 140 Celsius, xylene probably could be used. The mixture was suction filtered hot and cooled to room temperature. The white
needles of diethyltin dichloride were filtered off and dried. Reference; Angelici, Synthesis and Technique in Inorganic Chemistry, 2nd edition.
Can sodium borohydride be used for forming the trialkyltin hydride? I have 250g of tributyltin chloride and at least 30g of sodium borohydride. This
reagent has many uses in synthesis. All of the procedures I have seen have used lithium aluminum hydride as the hydride source.
I have prepared tin(IV) iodide and its triphenylphosphine complex which is very dark red in color. Tin (IV) bromide can be prepared by slowly dropping
dry bromine on to a slight excess of mossy tin, briefly refluxing and then distilling the tin halide at atmospheric pressure using a propane torch.
The tin (IV) bromide soon crystallized in the receiving flask. The tin (IV) bromide was then used for the synthesis of tetraethyl tin.
[Edited on 20-9-2009 by benzylchloride1]
[Edited on 20-9-2009 by benzylchloride1]
Amateur NMR spectroscopist
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Jor
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Do you handle these alkyl-tin compounds at home? These are very toxic and are of very high environmental toxicity.
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JohnWW
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Yes, I have heard of some organotin(IV) compounds, especially tributyltin derivatives, being used in marine anti-fouling paints on the hulls of boats,
to prevent the growth of seaweed, barnacles, teredos, mussels, rock-oysters, etc. on the hulls; but that it has fallen into disfavor as the result of
causing deformities in non-target fish species.
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itchyfruit
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Would indium powder be ok?I know their not in the same group, but they are next to each other so must have some similar properties.
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woelen
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I can imagine that it also works for indium, making InI3. InI3, however, probably will not be such an interesting compound. I expect it to be a white,
somewhat volatile and easily hydrolized compound. I could give it a try, I have (a small quantity of) 200 mesh indium powder.
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itchyfruit
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I was going to try it as i don't seem to have tin powder. don't waste what you have on my dumb theory i shall report back imminently 
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blogfast25
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Woelen:
What surprised me was that the reaction proceeded at room temperature.
You could also try and reduce the SnI4 back to metallic Sn, e.g. with Mg. That could be a very exothermic reaction.
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densest
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@woelen - beautiful pictures! I wonder if there's any way to make I in situ to avoid the US restrictions? Gotta think about that one....
@itchyfruit - the ancient Chem Rubber handbook says InI3 is higher-melting (210) and orange-red. Still would be interesting to see it! I don't know
which oxidation/coordination state you'd get: InI, InI2, and InI3 are listed.
[Edited on 21-9-2009 by densest]
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itchyfruit
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I tried with hexane and Xylene and i'm not having much joy.
I'll give it another go tomorrow with the di isopropyl ether(i don't really want to open it indoors)
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not_important
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Preparation of InI3 and InI http://www.orgsyn.org/orgsyn/prep.asp?prep=v79p0059
As they mention indium, as well as gallium, wet glass and stick to it rather well.
While In(I) is well defined, the 'inert pair effect' being reasonably active, In(II) is not stable as such in simple compounds. Many of the In(II)
compounds listed in the older literature are really mixed valence compounds In(I)In(III)X4 .
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Panache
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tetra alkyl tin catalysts are commonly available as initiators for silicon rubbers. I know i can go not 3 kilometers from where i live and buy both
the tin (FOR GENERAL USE SILICON CASTING RESINS, sry caps) and platinum (for food grade silicon rubber applications applications) readily and easily.
However if you don't live in Australia this is irrelevant except for the fact that one may be able to feel safer in relation to their use because the
Australian government surely wouldn't allow their general purchase if they were not safe.
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woelen
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Just out of curiosity I tried a few variations on this reaction, all in CH2Cl2:
- In + I2 does not seem to work. The I2 dissolves, but seems not to react. I now have it in a test tube, well stoppered, for more than a hour, but no
reaction. I'll leave it around for a few days and see whether it reacts slowly.
- Sn + Br2 works, but much slower than Sn + I2. This surprises me. But the reaction works. I used excess tin with a small drop of bromine, dissolved
in 0.5 ml of CH2Cl2. I first dissolved the Br2, then added the tin. After 15 minutes, the solution is colorless. When the CH2Cl2 is added to warm
water, then the CH2Cl2 boils away and a clear and colorless liquid remains behind. When some dilute NH3 is added to this, a white gelatinous
precipitate is formed, which must be hydrous SnO2. The solution of SnBr4 in CH2Cl2 fumes somewhat, when it is in contact with air.
- Cu + Br2 does not work in CH2Cl2, but works in water. The Cu becomes covered by a black layer and then the reaction stops, due to insolubility of
the reaction product in DCM. When a few drops of water are added, then the reaction continues, giving a white/blue turbid liquid, and the copper
granules are covered by a white solid. The white/blue liquid contains a mix of solid copper(I)bromide and dissolved copper(II)bromide.
- A funny thing is observed when tin, a really tiny little pinch of tin(IV) iodide and bromine are added to DCM. First, the liquid is red/brown, due
to dissolved bromine. It remains like that for a while, but when the color of bromine becomes weaker, then the liquid becomes purple, due to dissolved
iodine and finally the liquid becomes very pale yellow, due to dissolved SnI4. So, apparently the SnI4 is converted to SnBr4 and iodine is set free,
which can be seen when the amount of bromine is not large enough anymore to mask the color of the small amount of dissolved iodine.
I'll come back on the In + I2 experiment. I'll see how it looks tomorrow.
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Jor
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| Quote: Originally posted by woelen | Just out of curiosity I tried a few variations on this reaction, all in CH2Cl2:
- In + I2 does not seem to work. The I2 dissolves, but seems not to react. I now have it in a test tube, well stoppered, for more than a hour, but no
reaction. I'll leave it around for a few days and see whether it reacts slowly.
- Sn + Br2 works, but much slower than Sn + I2. This surprises me. But the reaction works. I used excess tin with a small drop of bromine, dissolved
in 0.5 ml of CH2Cl2. I first dissolved the Br2, then added the tin. After 15 minutes, the solution is colorless. When the CH2Cl2 is added to warm
water, then the CH2Cl2 boils away and a clear and colorless liquid remains behind. When some dilute NH3 is added to this, a white gelatinous
precipitate is formed, which must be hydrous SnO2. The solution of SnBr4 in CH2Cl2 fumes somewhat, when it is in contact with air.
- Cu + Br2 does not work in CH2Cl2, but works in water. The Cu becomes covered by a black layer and then the reaction stops, due to insolubility of
the reaction product in DCM. When a few drops of water are added, then the reaction continues, giving a white/blue turbid liquid, and the copper
granules are covered by a white solid. The white/blue liquid contains a mix of solid copper(I)bromide and dissolved copper(II)bromide.
- A funny thing is observed when tin, a really tiny little pinch of tin(IV) iodide and bromine are added to DCM. First, the liquid is red/brown, due
to dissolved bromine. It remains like that for a while, but when the color of bromine becomes weaker, then the liquid becomes purple, due to dissolved
iodine and finally the liquid becomes very pale yellow, due to dissolved SnI4. So, apparently the SnI4 is converted to SnBr4 and iodine is set free,
which can be seen when the amount of bromine is not large enough anymore to mask the color of the small amount of dissolved iodine.
I'll come back on the In + I2 experiment. I'll see how it looks tomorrow. |
Cu + Br2 does work! I added some extremely fine copper powder (black, stains everything) to a solution of bromine in DCM. I left to stand for 2 hours,
and decanted the liquid. The result is a black powder, wich quickly dissolves in water giving a blue solution. This is thus a great way of making
anhydrous CuBr2.
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woelen
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Yes, you have very fine copper, I used copper wire (from electricity flexible wires, isolation stripped away). This is a nice synth for anhydrous
copper(II)bromide, but only if you have ultra fine copper powder. With coarser copper, the reaction stops once a black layer is on the copper.
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itchyfruit
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Having left these for a couple of days now the Hexane one has turned a light brown colour and the Xylene one is white/clear.
Woelen you appear to be correct
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