10-16-03 23:30
No 465044
Well after a comment made by Antoncho Post 464917 (Antoncho: "Thanx a lot, Imp!", Chemistry Discourse), SWIM decided to see how effective a reducing agent SnCl2 is, so a quick experiment was performed...
10g tin metal were dissolved in 40ml HCl to generate SnCl2. The water clear solution was filtered of insolubles, then 2ml nitromethane was added with a pipette in one portion. The nitromethane formed a layer on top, but then in a matter of seconds quickly dissolved in the solution with the evolution of much much heat. The solution almost began to boil, but settled down after several minutes. It was clear in colour. Basification caused tin hydroxide to crash out of solution and a fishy ammonia-like smell - the methylamine.
35g tin metal were dissolved in 50ml HCl to generate 0,3 mol SnCl2. Filtered, then added 0,1 mol nitromethane, 6,5g or 5,75ml. Very exothermic reaction insued, and was allowed to relax. Basification caused same result.
SWIM expected something like this happened...
2CH3NO2 + 6SnCl2 + 24HCl ---> (CH2N+H3)2Sn-Cl6 + 5H2SnCl6 + 4H2O
So what do you guys think? SWIM liked how quick and simple it was, although it was a simple aliphatic nitro compound.
(Newbee)
10-17-03 02:47
No 465082
yes, i have read of tin being used to reduce nitrophenyls to phenylamines, i didn't know if it would work for nitroalkanes or not, but i guess i know now.
in the future you might want to add the nitromethane more slowly with a drop funnel, and use an ice bath to avoid a firey death or other wacky hyjinx along those lines.
i wonder if the tin method could be used with ketone/nitromethane for a methyl man style reductive amination?
(Official Hive Translator)
10-17-03 05:54
No 465109
SnCl2 reduces nitropropenes to oximes, so i'd guess that should also bee the case with aliphatic NO2's ... but since you say there was a fishy smell...
Well, i don't know how formaldoxime smells.
(Stranger)
10-17-03 07:45
No 465118
so i'd guess that should also bee the case with aliphatic NO2's ...
Not at all Antoncho. Sn and Fe with HCl will almost always reduce a nitro compound to the amine - they are for complete reduction of aromatic/aliphatic nitro compounds. As a matter of fact, Zn and HCl will usually lead to the hydroxylamine (contrary to what you might believe).
Nitrostyrenes are a much different type of animal compared to aromatic/aliphatic nitro compounds. Yes, they will form oximes with SnCl2/Fe and HCl (of course in the acidic environment the oximes usually hydrolyse to the carbonyl compound), but nitrostyrenes also form oximes with Na2S2O4. Na2S2O4 being another reagent used to reduce nitro to amino groups. And even better, surpizingly Zn/HCl reduces nitroethenes to amines more efficiently than Al/Hg! See what a bizarre way they react? It is very difficult to predict what an effective reducing agent will be.
SWIM always wanted to give SO2(g) a try as a reducing agent. A long time ago, SWIM bubbled a solution of CuSO4/NaCl with SO2 for 15-20 minutes to obtain CuCl. It was interesting because at first, the solution became darker (a sulphur complex?), but then as more SO2 was absorbed it faded to a very light yellow with the CuCl precipitate. As expected, a drop of H2O2 on the crystals caused immediate reduction and the formation of green CuCl2. SO2 and zinc seems to form zinc dithionite as you stated Antoncho - this is promising.
So what other useful things might we due with SnCl2? A big problem with SnCl2 is that you have to bubble H2S into the solution in order to precipitate it out without causing basification (although sometimes it will form an insoluble adduct making isolation a breeze). Throw some ideas in, it will be fun to discuss.
Stratosphere:
SWIM doesn't think it would be practical as a substitute for the Al/Hg. It could probably reduce the formed imine, but it would seem a step backwards instead of forwards in regards to new synthetic pathways. Do you understand what SWIM is trying to convey?
(Newbee)
10-17-03 21:25
No 465245
if it reduced the imine to the N-alkyl-methylamine with good yield, i don't neccasarily understand what would be backwards about it, it would relieve the chemist of having to work with HgCl2 or of having any mercury residues leftover in his/her candy.
(Stranger)
10-17-03 23:06
No 465267
Well, give it a try then! SWIM thinks it will be a much bigger pain trying to workup the reaction mixture compared to the Al/Hg. Basifying will cause a bunch of tin hydroxides to crash out and turn your mix into a gel (that is unless you want to bubble H2S to precipitate the tin?). Also, you'll need A LOT of SnCl2 to reduce both your nitromethane and your imine, making matters worse.
You should also remember that Al/Hg is a much more effective reducing agent than SnCl2, so your yields might not be nearly as good. Finally, you're not going to get any Hg in your final product from the Al/Hg, it is a myth. Unless you don't know what you're doing, Hg contamination is a stretch. And anyway, don't you recrystallize your final amine.HCl
?? No, they never do
. So, in SWIM's opinion, it is a step backwards in the sense that you'll need a much larger amount of reducing agent, a more difficult work up, most probably more expense, lower yields, and the stress of treading on unfamiliar grounds.
(Newbee)
10-18-03 01:42
No 465300
i guess i didn't get as far as worrying about the workup part
playing with Hg always makes "my friend" a bit nervous, but i suppose hes being overly paranoid from reading things about methyl mercury etc.
imines can also be reduced with urishibira nickel (i think).
(Hive Bee)
04-21-04 13:58
No 502028
Hi!
Imp: could you please describe how you dissolved tin in HCl? It sounds stupid, I know, but my tin doesn't dissolve. I have some 30 grams tin shot suspended in ~100ml HCl 37%, it has been stirring for now ~2 hours at reflux and nothing has dissolved yet... WTF??
EDIT I just decanted the solution from the remaining tin: 23 grams left - after 3 hours refluxing in conc. HCl!! Wierd../EDIT
(merck says tin dissolves readily in concentrated HCl. I start wondering what the term "readily" means?)
Is there any trick to achieve fast dissolution of tin?
"..ein Trank von unterschiedlicher Farbe, in ihm ist Heilung für die Menschen."
(Hive Bee)
04-21-04 18:12
No 502063
armageddon, how do you reflux 37% HCl? What refluxes cant be more than 20% HCl as every HCl exceeding the azeotrope will leave the flask as gas...... cough, cough....
(Hive Bee)
04-21-04 20:11
No 502100
ragnaroekk: I know the hydrochloric does evaporate. I just thought that heating would help in dissolving my tin granules...
Besides, tin should dissolve slowly in diluted HCl, too - says Merck. Well, 5 hours were enough to dissolve 10.2 grams (of 30 gr.) tin in 20% HCl. And a test tube containing ~1g tin granules and 5ml 37% HCl didn't dissolve anything (maybe 0.1g) until now...
..doesn't sound better to me!
Guess I'll have to go and buy some tin(2)chloride...
"..ein Trank von unterschiedlicher Farbe, in ihm ist Heilung für die Menschen."
(Hive Bee)
04-22-04 02:14
No 502158
same problem with many transition metals. i've been talking to a friend about making nickel salts and there's the same problem - it just doesn't dissolve in it.
the thought that came to me as a solution was to start with oxide. Is that silly? it seems reasonable to me as this would make it more prone to forming the hydroxide and thus the salt. Isn't tin oxide quite easy to get - i think it is a concrete pigment or something like that. What other ways can be used to promote the dissolution of these metals which don't dissolve well in HCl? I was thinking maybe putting a strong oxidiser in there, permanganate, hypochlorite, peroxide... What if one had fine tin metal and mixed it thoroughly with bleaching powder and hydrated it with conc HCl?
...or would that be nasty and make lots of chlorine or something...
(Hive Bee)
04-22-04 06:55
No 502200
it is alleged that bleaching powder and water alone will react with tin, but i would think not to the desired cpd, with or without acid. i've really no idea, though i am playing with tin cpds. at the moment. dropping acid onto bleaching powder is a good way to get people to clear a room. i will skip this experiment.
tin metal definitely dissolves in hot, concentrated HCl. you should see good bubbling of H2. since we're quoting Merck here: "...readily with concd HCl..."of course you need a lot of acid to keep the concentration up. when Merck says slow for some formation, this may mean weeks or several months. only the stannous oxide (SnO) dissolves in HCl, though this is argued about in some refs. stannic oxide doesn't seem to react well with anything. perhaps boiling concd H2SO4 or K/NaOH. certainly white hot charcoal. this is not to say a route to the chloride from stannic oxide is a horribly bad way, but...the best choice is the metal. i'll look in to this some anyways.
...wait for the ricochet.
(Hive Bee)
04-22-04 08:00
No 502218
i forgot about oxychlorides (*d'oh*)
if this route were taken, what about then somehow reducing it? oxidising further?
(Stoni's sexual toy)
04-22-04 08:22
No 502220
> I have some 30 grams tin shot suspended in ~100ml HCl 37%,
> EDIT I just decanted the solution from the remaining tin: 23 grams left
> - after 3 hours refluxing in conc. HCl!!
OMG! So you have to wait a NEARLY A WHOLE DAY for it to dissolve! This is of course totally unacceptable.
BUSH/CHENEY 2004! After all, it ain't my country!
(Hive Bee)
04-22-04 12:15
No 502233
Os: I think the problem here is indeed my impatience, but I don't see why I should wait more than one day for ~50 grams of a transition metal salt if I can just buy it, and I doubt that it is cheaper to use gallons of acid and (rather expensive) lab grade tin powder...
(BTW 10 grams in 50ml 37% at RT didn't fully dissolve until now although hydrogen evolution can still be seen (more than 18 hours have passed), perhaps Merck wants to tell us that 0,1 grams tin dissolve readily in 500ml conc. HCl or something like that - concentration of the acid seems to be lowered too quickly with big amounts of metal)
Greetz A
"..ein Trank von unterschiedlicher Farbe, in ihm ist Heilung für die Menschen."
(Hive Bee)
04-23-04 18:04
No 502479
While we're on the topic of makin tin chlorides, maybe some bee with electrolysis experience can help me:
Could I take a tin electrode, suspend it in HCl and pass current through it to reduce the elemental Sn(4) to Sn(2)-chloride?
What conditions should I use?
(how much current, how long, or more exactly: how much voltage/amperes for how long? Using, let's say, an electrode weighing 20 grams)
Waiting days until my tin dissolves without aid isn't good for my impatience, Os...
Peace A
"..ein Trank von unterschiedlicher Farbe, in ihm ist Heilung für die Menschen."
(Chief Bee)
04-23-04 22:47
No 502530
reduce the elemental Sn(4) to Sn(2)-chloride
You need to study. All free elements are per definition in oxidation state zero. Tin metal is therefore Sn0, and needs to be oxidized to become Sn2+.
The Hive - Clandestine Chemists Without Borders
(Hive Bee)
04-25-04 17:32
No 502868
Hi!
oops! I read that Sn4+ occurs in acid solutions in traces, made me confused.. Of course elemental tin has the oxidation state ZERO...For bees with impatience (like me): reducing nitroalkenes to ketones can be accomplished by just refluxing them with elemental Sn, HCl, toluene and water (like Post 392067 (Aurelius: "P2P from Tin (II) and nitropropene", Methods Discourse) - the needed SnCl2 will be generated in situ. Just calculate the right amount of tin/HCl. The tin will dissolve readily - quicker than suspending it in conc. HCl and waiting several days... (wierd, but works!)
Greetz A
"..ein Trank von unterschiedlicher Farbe, in ihm ist Heilung für die Menschen."
(Wonderful Personality)
05-02-04 18:22
No 504370
Hydrated tin(II)chloride, SnCl2.2H2O, is conveniantly made by dissolving tin in hot HCl in the presence of copper. The copper speeds the process significantly up.
Ref:
Elements of Chemistry, part II, inorganic chemistry, Miller, New York, 1871 page 561.
ADDON: Even better is to add small tin pieces to copper chloride (thy green stuff) in HCl - the copper prcecipitates finely divided and this gets it really going. If one is VERY impatient some hydrogen peroxide will speed things up. But this is to be done very carefully if one doesnt want to do a clean up afterwards which for sure will take longer than the whole procedure would take in anyway......
(acetaminophanatic)
05-02-04 22:36
No 504417
Perhaps lead-free solder would bee a decent source of almost-pure tin on the OTC and cheap.
I've been chased by both cops and robbers. So what does that make me?
(Wonderful Personality)
05-02-04 23:20
No 504426
You talk of electronics/electro solder here yes? As solder for copper water pipes doesnt contain lead and is much cheaper.
(Hive Bee)
05-03-04 21:46
No 504621
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 big 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
"..ein Trank von unterschiedlicher Farbe, in ihm ist Heilung für die Menschen."
(Hive Bee)
05-04-04 04:52
No 504678
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.
(Hive Bee)
05-05-04 02:49
No 504896
Hi! Thanks, Imp! Your idea of making thin tin plates (nice phrase)
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
"..ein Trank von unterschiedlicher Farbe, in ihm ist Heilung für die Menschen."
(Hive Bee)
05-11-04 01:16
No 506314
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
"..ein Trank von unterschiedlicher Farbe, in ihm ist Heilung für die Menschen."
(Hive Bee)
05-31-04 18:01
No 510544
Hi!
Adding hydrogen peroxide 30% speeds up things alot, but bee careful: strong heat evolution (boiling acid
)...Peace A
"..ein Trank von unterschiedlicher Farbe, in ihm ist Heilung für die Menschen."
(Hive Bee)
05-31-04 22:32
No 510589
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.
(Hive Bee)
06-01-04 01:20
No 510612
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...
(BTW the only photo chem dealer in my town doesn't even have GAA - I doubt he'll sell SnCl2..
)
"..ein Trank von unterschiedlicher Farbe, in ihm ist Heilung für die Menschen."