Author Topic: SnCl2 as a reducing agent  (Read 5979 times)

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Organikum

  • Guest
You talk of electronics/electro solder here...
« Reply #20 on: May 02, 2004, 11:20:00 PM »
You talk of electronics/electro solder here yes? As solder for copper water pipes doesnt contain lead and is much cheaper.


armageddon

  • Guest
SnCl2 again
« Reply #21 on: May 03, 2004, 09:46:00 PM »
Hi!

The copper idea sounds good, but I think I found a nice solution of my tin problem, too:

tin(0) reduces tin(4) to tin(2) and becomes tin(2) itself... (at least this is my explanation for the following)

My idea was to start a SnCl2 reduction with just a little bit SnCl2 to get it going, lots of HCl and the right amount of elemental tin to generate enough tin(2)chloride for complete reaction. The following happened (I think): SnCl2 gets oxidized to SnCl4 while reducing something, but the elemental tin(0) already present immediately reacts with the tin(4) and, voila: two SnCl2 molecules!! Which again reduce something, get oxidized to two SnCl4 etc.
(you surely can imagine that the reduction done this way - with in situ SnCl2 formation - is WAY faster than first forming tin(2)chloride and THEN using it to reduce something; the speed of rxn almost doubles with every molecule that is being reduced, and the generation of SnCl2 also is a lot faster if the formed tin(2)-chloride is immediately oxidized, giving new tin(0) atoms a good opportunity to react with)

At least, a reduction to a propiophenone with SnCl2 (not enough reducing agent; maybe 1:2 molar ratio tin(2)chloride/----), but with calculated extra amounts of HCl and tin(0) did require not significantly more time for completion than if 2.2x molar excess of reducing agent had been used - ca. 2,5 hours.
At the end of this time, all tin had been dissolved and a distinct color change indicated completion of reduction.
As you can see this is a bigĀ  difference to just heating dil. HCl with tin(0) (many hours; not complete dissolution)...

I don't know if tin(0) really can reduce tin(4) to tin(2), but it would be a good explanation for what happened. What do you think?

Oh, and while on the topic of metal salts: why not regenerating elemental tin from SnCl4 solution by adding zinc dust/HCl? The result would be fine Sn-sponge (best suitable for dissolving in HCl) and aequous acidic ZnCl2 solution - urushibara-usable  ;) !

Greetz A


imp

  • Guest
Sorry for the wait
« Reply #22 on: May 04, 2004, 04:52:00 AM »
Hi armageddon,

SWIM used soldering iron as the tin source. It has some 5% antimony/silver in it, and 95% tin. SWIM didn't mention one thing however... how the tin was prepared.

The soldering wire was held about 1 foot above a frying pan, and with a torch the solder was melted and allowed to splatter into the frying pan. The molten tin quickly solidified and formed thin "plates" of the metal that reacted very quickly/vigourously with 30% HCl. You can evaporate the solution and cool to get the dihydrate crystals for nitrostyrene reductions in EtOAc.


imp's apology to The Hive: Sorry, SWIM has been very busy the past 6 months. SWIM has MANY good articles (subsitituted methcathinones, formylations, useful OTC alkoxy cleavage,...2C-SCN stuff,....pharmacological stuff... and much more) to post, but alas it seems SWIM will be busy for quite some time. SWIM hopes to post the more interesting stuff soon though.
With so much love, imp.

armageddon

  • Guest
thanks, Imp!
« Reply #23 on: May 05, 2004, 02:49:00 AM »
Hi! Thanks, Imp! Your idea of making thin tin plates (nice phrase)  ;D  is pretty cool - maximum surface...

I wonder if the antimony/silver helped dissolving your solder just like copper does? I have both pieces of tin and fine granules, but both with >99% purity - maybe some metal "impurities" would bee helpful?

Greetz A


armageddon

  • Guest
even faster
« Reply #24 on: May 11, 2004, 01:16:00 AM »
If you melt tin with a torch and let it drip down on the floor (linoleum), the molten tin will form very thin plates, because the tin doesn't solidify as quick as if using a frying pan (the steel removes the heat too quick, so the tin solidifies instantly, giving only rather thick plates). The so generated tin plates dissolve very quickly in 31% HCl if some additional copper wire is cut into small pieces and dumped into the acid, too...

To make tin(2)chloride dihydrate crystals, dilute the resulting clear solution to less than 20%, vacuum distill until white precipitate appears, chill in the fridge, vacuum filter the precipitate and wash with toluene or solvent of choice to remove residual HCl (but alcohols/acetone/ethers will dissolve the dihydrate, so don't use them  ;) ), let it dry by pulling air through it and dry over drying agent in dessicator - and there you are: crisp, white needle-shaped crystals.
BTW be careful with the concentrated dihydrate solution. It is not only acidic but also acts a bit like those ink-removers or some kind of strong bleaching agent - it decolorizes every colored piece of clothing it comes in contact with!!

(THX Imp/Orgk!)

Greetz A


armageddon

  • Guest
H2O2
« Reply #25 on: May 31, 2004, 06:01:00 PM »
Hi!

Adding hydrogen peroxide 30% speeds up things alot, but bee careful: strong heat evolution (boiling acid  ;) )...

Peace A


calcium

  • Guest
Stannous Chloride
« Reply #26 on: May 31, 2004, 10:32:00 PM »
Why not just buy it?

I found Stannous Chloride(SnCl2, CAS #7772-99-8) for $30.00 per 100 grams at a photo chem dealer. It certainly isn't watched at all.

armageddon

  • Guest
not watched but still suspicious *lol*
« Reply #27 on: June 01, 2004, 01:20:00 AM »
Well 100g SnCl2 is just enough for reducing 0.2mol nitrostyrene - not much at all. And I would like to know what your photo chem supplier will think if you buy one kilo stannous chloride for 300 bucks (I am not familiar with developing photos, but usually you need very small amounts of chemicals for this purpose, and 1000g SnCl2 should last you well for developing a few thousand films maybe?) - and then imagine his astonished look when you walk in one week later and demand same thing again... ;D

(BTW the only photo chem dealer in my town doesn't even have GAA - I doubt he'll sell SnCl2.. :( )