Per
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Preparing Na2S2O8
Because Na2S2O8 is an very usefull salt I want try to prepare it.
My suggestions:
Maybe an electrolysis of Na2SO4 would work but I´ve my doubts.
Or an elektrolysis of H2SO4 would work, I think of a 38% to 50% acid, it would prepare H2O2 and H2S2O8 but I don´t know it in the end all the H2SO4
is convert into H2S2O8, does anybody knows more on this electrolysis?
Or does anybody know how the technical process goes?
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Nicodem
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Rather buy Oxone. I can't imagine a reaction where Na2S2O8 can not be replaced by it.
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garage chemist
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Persulfates are always prepared electrolytically.
Sodium persulfate is prepared from ammonium persulfate and NaOH, because only ammonium persulfate can be prepared in a pure form by electrolysis (it
is sparingly soluble in the cold and therefore can be crystallized out of the cell liquor).
It is manufactured by electrolysis of an acidic (H2SO4) ammonium sulfate solution with Pt anode and cathode of e.g. lead, with division of the anodic
and cathodic cell compartments by a diaphragma. There is a method in Brauer.
Potassium persulfate is even less soluble than ammonium and therefore can be prepared even easier and in higher yields. .
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Per
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| Quote: | | I can't imagine a reaction where Na2S2O8 can not be replaced by it. |
I need it to prepare Na2S2O7 and then Ac2O.
Hmm, I don´t understand why a diaphragma is needed for this electrolysis because I think the persulfate is getting by nutralising the
ammoniumhydroxide and sulfuric acid.
Potassium salts are much more expensive than ammonium salts so I would prefer ammonium sulfate.
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Klute
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| Quote: | Originally posted by Nicodem
Rather buy Oxone. I can't imagine a reaction where Na2S2O8 can not be replaced by it. |
I had bad results when trying to oxidize benzyl alcohol with oxone, using Cu(OAc)2 and FeSO4 catalysts, but excellent results whe using (NH4)2S2O8...
using molar equivalents of course...
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woelen
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Is Oxone easy to find? I can easily obtain ammonium persulfate or sodium persulfate and I also found a source for potassium persulfate, but I've never
seen a source of oxone. That chemical sounds interesting to me, I wish I had a source for that.
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Nicodem
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Where I live it can be found in just about any pool section of large stores.
Due to Klute, I have reconsidered about its interchangeability with other persulfates. The solubility, acidity and other issues are also important for
the reaction outcome.
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garage chemist
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When reading the labels on the pool chemicals in the home store, I noticed one that said "preparation with potassium monopersulfate" on the label. I
think this has to be oxone, since I read that salts of monoperoxysulfuric acid are not stable.
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Per
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Firts time I thought that oxone has to be O3, but now I know that that can´t be, can anybody give me the structure (Summenformel) of oxone, please?
Is it easy available in Germany?
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woelen
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As I understand it, oxone is a peroxymonosulfate. This contains the ions SO5(2-). The structure of this ion is
[-O-O-S(=O)2-O-](2-)
It contains a peroxo group, and that makes it a strong oxidizer. The real structure most likely is somewhat more complex, what I have given here most
likely is just one of the extremes of the resonance structure of the ion. With (=O) I mean an oxygen atom, directly attached to the sulphur atom.
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Per
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Thank you,
I ment just a structure as Na2S2O8 or K2SO4 but I don´t know the word for this simple structure in english.
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12AX7
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Crystal structure, or what??
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Per
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Not a crystal structure, just a simple structure (in german "Summenformel") as C6H5Cl or NaCl...
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Nicodem
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It is called empirical formula since it says nothing about the molecular structure, but only sums the elemental analysis in relative atom ratios. It
is mostly useful for ionic and crystalline compounds where there is little or no molecular structure but pretty much useless to describe organic
compounds which all have molecular structure (hence rational formulas are used in organic chemistry).
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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Per
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Thank you very much, that´s the word I missed.
When I´ve the empirical formula I can think of a chemical also when it´s an simple organic compound, but with a name as oxone which I don´t know I
can´t do anything.
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Nicodem
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| Quote: | Originally posted by Per
When I´ve the empirical formula I can think of a chemical also when it´s an simple organic compound |
Really? I don't think so. An empirical formula for an organic compound can fit thousands of different compounds. Only the simplest possible empirical
formulas have a limited number of compounds that fits them. That is why it is considered extremely irritating to use empirical formulas in organic
chemistry. I can tell you from experience that any organic chemist would get very upset if he saw using empirical formulas instead of rational
formulas.
Edit: Oxone does not have an empirical formula anyway. It is a registered tradename for a triple salt composition. That's why you will always see it
refered as Oxone in chemical papers. See http://www.dupont.com/oxone/techinfo/index.html for the information on composition and other properties.
[Edited on by Nicodem]
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Per
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Yes, when you speak about complex organic compounds a rational formula should be prefered but when you speak about such simple compounds as CHCl3 or
SOCl2 a empirical formula should be enough.
And thanks for the oxone link.
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