ShadowWarrior4444
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Sodium Thiosulfate Synthesis
I have searched for this both on the forum and Google, but I did not seem to find a synthesis procedure for Sodium Thiosulfate.
I seem to have a vague memory of a process that involves boiling elemental sulfur in concentrated NaOH--is this the correct route?
[Edited on 5-1-2008 by ShadowWarrior4444]
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12AX7
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No, that makes hydropolysulfides (SH-, S2H-, etc.).
I seem to recall it involves fusion of sodium sulfate or sulfite with sulfur.
Tim
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MagicJigPipe
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I believe it is sulfite with sulfur in a solvent. Water? Would the sulfur have to dissolve? Would it dissolve in the prescence of the sulfite
anion?
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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ShadowWarrior4444
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| Quote: | Originally posted by 12AX7
No, that makes hydropolysulfides (SH-, S2H-, etc.).
I seem to recall it involves fusion of sodium sulfate or sulfite with sulfur.
Tim |
Ahhh! Now I remember, it was boiling aq sodium sulfite with sulfur. Thank you.
Would anyone happen to know a good synthesis of sodium sulfite from elemental sulfur?
This also reminds me of an experiment I wanted to do involving the formation of polysulfide polymers (which exhibit very good chemical resistance.)
And also that sodium sulfur battery experiment... so much brimstone, so little time.
[Edited on 5-1-2008 by ShadowWarrior4444]
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ShadowWarrior4444
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Upon a bit of research, I found that thiosulfate does indeed form in appreciable amounts from boiling sulfur with alkali hydroxide: http://www.sciencemadness.org/talk/viewthread.php?action=att...
In this case, would it be possible to oxidize the other polysulfides to thiosulfate with H2O2 or another suitable oxidizer? (Perhaps bubbling air
through the heated solution?)
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Klute
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I know it's counter-productive to say this, but you could just buy it. Thiosulfate is the kind of chemical that is so available and cheap that it's
preparation from sulfur would a tedious waste of time, if it's not for historical purposes.
It's used in large amounts in photo developing, and should be available at any outlet selling photo chemicals, even in america or elsewhere. Very
cheap (1 kilo 4E where i buy it).
It is commonly sold as the pentahydrate. It is very usefull to quench oxidizers (a thiosulfate wash or direct addition after brominations or
oxydations, etc), and is used as a standard for titrating oxidizers such as I2, that can be generated in indirect titrations (like for dosing Cu2+).
EDIT: no, that would oxidize the thiosulfate to tetraithionate immediatly. (posted as the same time as you did apparently  )
[Edited on 1-5-2008 by Klute]
\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"
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ShadowWarrior4444
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| Quote: | Originally posted by Klute
I know it's counter-productive to say this, but you could just buy it. Thiosulfate is the kind of chemical that is so available and cheap that it's
preparation from sulfur would a tedious waste of time, if it's not for historical purposes.
It's used in large amounts in photo developing, and should be available at any outlet selling photo chemicals, even in america or elsewhere. Very
cheap (1 kilo 4E where i buy it). |
Indeed, I am aware that it can easily be purchased as 'Hypo' from photographic suppliers. I'm more interested in the lab synthesis from elemental
components at the moment.
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Klute
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Ok, pardon then. Good luck with that one!
Off topic: your photos are absolutely beautifull! Very nice work!
[Edited on 1-5-2008 by Klute]
\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"
-Alice Parr
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ShadowWarrior4444
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| Quote: | Originally posted by Klute
Ok, pardon then. Good luck with that one!
Off topic: your photos are absolutely beautifull! Very nice work!
[Edited on 1-5-2008 by Klute] |
Furthur off-topic:
*huggles Klute*
(Huggles are by far the most manly expression of affection.)
[Edited on 5-1-2008 by ShadowWarrior4444]
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MagicJigPipe
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You could burn the sulfur and bubble the SO2 through NaOH solution to get sodium sulfite. Right?
That's about as basic as you're going to get.
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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ShadowWarrior4444
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| Quote: | Originally posted by MagicJigPipe
You could burn the sulfur and bubble the SO2 through NaOH solution to get sodium sulfite. Right?
That's about as basic as you're going to get. |
Hmm, yes, I was thinking of that but then I would rather avoid the gaseous phase, especially with sulfur compounds. I would also need to construct a
clever apparatus to burn the sulfur and channel the SO2, and while a tin can and some high temp epoxy would work...
Is there any way that involves starting from elemental sulfur dissolved in NaOH (polysulfides.) The traditional method for forming polysulfides is
usually dissolving elemental sulfur in Sodium Sulfite, and as thiosulfate has been seen to form in the NaOH/S reaction, it leads me to believe that a
little oxidative push might allow the formation of Thiosulfate in one aqueous batch. Provided the oxidizer doesnt break down the thiosulfate (hence
why bubbling air through the mixture may be best.)
[Edited on 5-1-2008 by ShadowWarrior4444]
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woelen
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This method is not really suitable. The SO2 you get is very dilute (mixed with a lot of remaining air) and any sulfite formed is oxidized to sulfate
before it can be isolated.
Sulfite, bisulfite and thiosulfate all are so basic that it really is hard to make them economically at a small lab-scale.
I think that the way to proceed making thiosulfate is dissolving sulphur in boiling NaOH, producing sulfide and thiosulfate (disproportionation). The
sulfide can be oxidized, using oxygen from air (just bubbling through the solution for a long time. An important oxidation product is thiosulfate, but
also sulfite and sulfate.
Separation of the thiosulfate is not easy. I wonder how sulfites are made industrially, probably from sulphur burning, but I can imagine with a
process which allows the SO2 to be concentrated (cooling? SO2 liquefies at -6 C) and then the concentrated SO2 is reacted with Na2CO3 or NaOH.
Thiosulfate indeed is made from sulfite and sulphur.
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MagicJigPipe
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Ah yes. I forgot about how easily sulfite is oxidized in the presence of moisture. Perhaps if you did it in zero O2 conditions. What a convoluted
way to such a readily available and cheap substance, though.
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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ShadowWarrior4444
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| Quote: | Originally posted by MagicJigPipe
Ah yes. I forgot about how easily sulfite is oxidized in the presence of moisture. Perhaps if you did it in zero O2 conditions. What a convoluted
way to such a readily available and cheap substance, though. |
*leaps up and down!* No no, the synthesis is for Sodium Thiosulfate--we want the sulfite to be oxidized.
I suppose the main question is: Can the polysulfides produced via NaOH/S be oxidized by Air to Sodium Thiosulfate. (Preferably without any horribly
meddlesome or toxic byproducts.)
On a side note, what *would* happen if one were to bubble NO or NO2...or perhaps N2O though a solution of sulfite or polysulfide?
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woelen
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With N2O I do not expect much to happen, with NO I also doubt that something interesting is going to happen. With NO2 I'm quite sure the sulfite is
oxidized to sulfate, the NO2 being reduced to NO, N2 or N2O. There also may form more complicated salts. Sulfite and nitrite can form all kinds of
mixed sulphur/nitrogen anions, but I don't know all the details of that. It is quite an interesting piece of chemistry, but time does not allow me to
jump into that (not yet!).
The oxidation of the (poly)sulfide solution most likely results in formation of a mix of all kinds of things, sulfite and thiosulfate being some of
them. But expect formation of sulfate, dithionate, trithionate, etc. as well. As I wrote before, isolation of all these chemicals will be a real pain.
Industrial production of sulfite (and subsequent thiosulfate) most likely will go through condensation/concentration of SO2 and then leading this
through Na2CO3 or NaOH.
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