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Author: Subject: oleum & SO3
Picric-A
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[*] posted on 7-1-2010 at 11:35


If you dont have the equiptment to make SO3/Oleum then you certainly dont have the equiptment to use/store it safely SO DONT!
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[*] posted on 7-1-2010 at 11:40


I simply do not have equipment suitable to very high temperatures or pressurise the reaction vessel, Picric-A. The oleum shall be stored only for a day. The stumbling block for me is just related to elevated temperatures like 600 ºC.

Best regards, Dúlio.




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Picric-A
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[*] posted on 7-1-2010 at 11:42


600 can easily be reached by a bunsen burner... or any gas burner for that matter.

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[*] posted on 7-1-2010 at 11:45


Even a candle goes above 1.000 ºC, Picric-A. The matter for me is how to build a reaction vessel able to resist such temperatures.

If it not bothers you, add me on MSN.

Best regards, Dúlio.

[Edited on 7-1-2010 by D S2 A]




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[*] posted on 7-1-2010 at 11:49


Quote: Originally posted by D S2 A  
Even a candle goes above 1.000 ºC, Picric-A.

Best regards, Dúlio.

[Edited on 7-1-2010 by D S2 A]


True.. but i would like to see you try heating half a gram of (say...) sand to 1000 degC with a candle...

Ps. I cannot go on MSN here (it is blocked by the school grr.) so if you want to contact me use U2U)

[Edited on 7-1-2010 by Picric-A]
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[*] posted on 7-1-2010 at 11:51


It is just an example, Picric-A. :)

Best regards, Dúlio.




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[*] posted on 7-1-2010 at 13:01


This may be of interest.
http://www.google.com/patents?hl=en&lr=&vid=USPAT3917521&id=...
In section 4 the patentee states that, by electrolysis, the concentration of dilute H2SO4 can be brought to 100% and above.
It is presumed that above 100% means oleum. . .
The downside is that platinum electrodes work best.
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[*] posted on 8-1-2010 at 06:25


Unfortunately I do not have either equipment nor knowledge do deal with electrolysis. Any other idea?

Best regards, Dúlio.




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[*] posted on 15-12-2011 at 05:23
Stoichiometric Magnesium Sulfate and Sodium Pyrosulfate


Hi, this is my first post on this site. The process was carried out some 6 months ago, and I've since lost the photos and product.

1 mole (or proportion) of anhydrous Sodium Pyrosulfate (Na2S2O7) {prepared by thermal decomposition of Sodium Persulfate (Na2S2O8)} and 1 mole (or proportion) of anhydrous Magnesium Sulfate (MgSO4) {prepared by heating Epsom Salts (MgSO4.7H2O) at c. 250'C for several hours} were finely ground and mixed using mortar and pestle and the resulting white powder placed in a small retort. Heating over LPG burner flame resulted in a gradual rising, swelling and a change in colour to a metallic grey (similar to lead (a little whiter) or many amalgamated metals). Up to this point no fumes or condensation were observed. After effectively total conversion to this spongy-appearing, grey form, a clear liquid began to distill off and was collected in concentrated Sulfuric Acid (H2SO4). A weight gain corresponding to 0.8 mole (or proportion) of sulfur trioxide (SO3) was measured at the completion of the distillation run. When the receiver was removed from the end of the condenser, white fumes with an acrid smell developed from the clear liquid present at the end of both joints.

(The amounts involved in the run I describe correspond to an actual yield of 16g SO3 out of a theoretical 20g, I wont specify the weights of starting materials as I would be extrapolating, however I remember the yield values very clearly. The vessel was a 125ml retort [just like a retort is meant to look] with the condenser mounted in a 2 liter plastic bottle full of ice water [refreshed at about room temperature] and the burner was an LPG hotplate burner such as sold in camping stores for connection to a 9kg LPG or propane bottle.)

This is it for the moment, an attempt to convert to Thionyl Chloride failed and I lost what I had left. The system I was working with reaches a maximum internal temperature in the high 400'Cs as best i know and the late onset of distillation suggests to me the absence of any unrecognised water of crystallisation. I found this procedure to be accessible and productive to an extent beyond the others I came by in this forum. Owing to the fact that it remains merely an interpretation of the vague procedures outlined in the German patents already referenced in this thread, I felt that this was the right place to share this. I hope this is useful to somebody, even if I have misinterpreted the results.

This is only the beginning of a response to the stimulus I have gained from the pages of ScienceMadness and I will endeavour to share more of the developments which lead on specifically from ideas which arose out of this forum.

Thanks, Matt.

[Edited on 15-12-2011 by matt]
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[*] posted on 19-3-2013 at 15:00


Sulphur trioxide reacts with nitrogen pentoxide in carbon-tetrachloride solution, with the formation of a crystalline precipitate melting at 124° to 128° C., which is probably (SO3)4.N2O5:
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[*] posted on 19-3-2013 at 15:06


Quote: Originally posted by matt  
1 mole (or proportion) of anhydrous Sodium Pyrosulfate (Na2S2O7) {prepared by thermal decomposition of Sodium Persulfate (Na2S2O8)} and 1 mole (or proportion) of anhydrous Magnesium Sulfate (MgSO4) {prepared by heating Epsom Salts (MgSO4.7H2O) at c. 250'C for several hours} were finely ground and mixed using mortar and pestle and the resulting white powder placed in a small retort. Heating over LPG burner flame resulted in a gradual rising, swelling and a change in colour to a metallic grey (similar to lead (a little whiter) or many amalgamated metals).[Edited on 15-12-2011 by matt]


A metal? There's only one metal in that mix as far as I can tell, and I don't think it'd form this easily.




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[*] posted on 26-3-2013 at 16:24


Quote: Originally posted by AndersHoveland  
Sulphur trioxide reacts with nitrogen pentoxide in carbon-tetrachloride solution, with the formation of a crystalline precipitate melting at 124° to 128° C., which is probably (SO3)4.N2O5:


The addition of sulfur trioxide to carbon tetrachloride is one of the early phosgene preparations.




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[*] posted on 8-4-2013 at 21:13


Yes, I recently repeated this procedure, on a larger scale (1 molar), this time only getting a 50% yield although on the upside my glassware didn't crack from the heat. The metallic color, I believe, is carbonisation of impurities in the pool chemical grade reagents I used, the melt returned to white on continued heating although I'm not sure if that contradicts my idea of carbonised impurities. IIRC, the article which listed results for various alkali and alkaline earth metal pyrosulfates nominated lithium as the most easily thermally decomposed. Large amounts of Lithium Sulfate might require some effort to arrange, but hopefully the Lithium itself could be recovered from post-reaction by-products by some sort of metathesis. From my understanding of pyrosulfates, an anhydrous lithium pyrosulfate would probably be more difficult to obtain than the oleum to be produced from the combination of Na2S2O7 and Li2SO4. This is the direction I hope to take it in next as neither 50% yields nor one-time sacrificial glassware seem efficient enough to me to consider oleum as a first choice where other reagents are suitable.
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[*] posted on 9-4-2013 at 15:26


Quote: Originally posted by matt  
IIRC, the article which listed results for various alkali and alkaline earth metal pyrosulfates nominated lithium as the most easily thermally decomposed.


Just last week I looked up the abstract for the lithium pyrosulfate -> SO3 temp. article by Spitsyn IIRC, CA 20435 (1960)...the long abstract gave the impression that Gmelin's may have taken the figure out of context, not surprising considering the quoted temp...there may be measurable losses....




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[*] posted on 28-10-2013 at 11:56


"Bismuth sulfate (Bi2(S04)3) is found in the form of white hygroscopic
crystals, which readily decompose in water to give basic subsulfate and
dissolve without decomposition in aqueous sulfuric acid. Above 465°C, it is
converted to the oxide under the liberation of sulfur trioxide."

Organic Bismuth Chemistry Hitomi Suzuki

TYPO?
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[*] posted on 2-11-2013 at 11:02


For a preparation of SO3 from P4O10 and H2SO4, see the attached paper by Evans. Notice Evans calls SO3 and P4O10 "anhydrous sulfuric acid" and "anhydrous phosphoric acid". Today we would call them acid anhydrides not anhydrous acids.

Attachment: sulfur_trioxide_evans1848.pdf (358kB)
This file has been downloaded 480 times

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[*] posted on 27-9-2017 at 09:38


Today I made 2-3ml of oleum using the procedure of CD-ROM-LAUFWERK as presented by garage chemist. This is an extremely facile method. Phosphoric acid is first dewatered to metaphosphoric acid (HPO3) under strong heat. This then dewaters the H2SO4 to SO3.

The hot phosphoric acid severely corrodes the 100 mL rbf but garage chemist says NaOH will remove this.

oleum.JPG - 127kB

[Edited on 27-9-2017 by Magpie]

[Edited on 27-9-2017 by Magpie]

[Edited on 27-9-2017 by Magpie]




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[*] posted on 27-9-2017 at 10:08


Quote:
Phosphoric acid is first dewatered to metaphophoric acid (HPO3) under strong heat. This is then dewatered to SO3.

Didn't know (HPO3) was such a strong desiccant, tbh, but NaOH will further corrode your already damaged RBF.


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[*] posted on 27-9-2017 at 11:07


Quote: Originally posted by hissingnoise  
Didn't know (HPO3) was such a strong desiccant, tbh, but NaOH will further corrode your already damaged RBF.

I've been using KOH a lot lately, since I've been able to get it for about the same price as NaOH. Although it's a stronger base, it has significantly less of a corrosive effect on glass compared to NaOH. Potassium salts are also much better than sodium salts for salting out an aqueous layer. There seems to be very little that potassium salts dissolve significantly in besides water.




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[*] posted on 27-9-2017 at 12:37


I don't think anything can actually reverse the damage metaphosphoric acid does to glass... you can remove the phosphate, at least, with alkali. In the future consider preparing your HPO3 in stainless steel.

Pretty cool that metaphosphoric acid can make oleum, though. Chlorosulfonic acid and tosyl chloride become OTC, if only you can find a way to contain the rxn mixture. Come to think of it, it might be possible to go all the way to TsCl in situ by starting with a mixture of H2SO4 and TsOH, adding HPO3, and gassing with HCl. If produced successfully, tosyl chloride (s.g. 1.3) will float on top of the rxn mixture (s.g. ~1.8).

[Edited on 27-9-2017 by clearly_not_atara]
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[*] posted on 27-9-2017 at 17:21


Is tosyl chloride the same thing as para-toluenesulfonyl chloride? Because I'm pretty sure that's available on Amazon if anyone needs any.



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[*] posted on 28-9-2017 at 15:53


the grit left on my flask after dehydrating the phosphoric acid stayed on despite me bombarding it with everything I could to try and clean it. If you want to do the meta phosphoric acid method to oleum, get yourself a 3" copper endcap or a flask you dont mind losing.
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[*] posted on 28-9-2017 at 18:24


I was able to remove the grit by refluxing with concentrated KOH solution for a few hours.

edit: No, this did not work. See pictures below:



IMG_2114.JPG - 155kB

[Edited on 29-9-2017 by Magpie]




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[*] posted on 28-9-2017 at 18:52


Today I made another batch of oleum, this time at 4X scale. I used a 600mL beaker for preparing the HPO3 and a 250mL flask for making the oleum. The yield was excellent at 29.6g vs an estimated 2-3g for the 1X scale.

I should caution that my ground glass joints leaked profusely. Therefore a good fume hood is mandatory.

2 pictures will be posted as soon as I figure out how with my new computer.

making oleum at 4xIMG_2112.JPG - 150kB IMG_2113.JPG - 134kB

[Edited on 29-9-2017 by Magpie]




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[*] posted on 29-9-2017 at 17:07


The NaOH did Not remove the corrosion product from my flasks. See above picture.



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