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Sauron
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Sometimes an annoying trait in Mellor, and Gmelin, and ATBOIC, is that a promising one line will be revealed, after tracking down the reference where
possible, to lead to a minor product, a crap yield, etc. God knows this may be one such where SO2Cl2 is the major product but a little chlorosulfonic
acid also formed. Preparatively useless. We will not know till we get the refs.
Reference 1, 1854 Proceedings Royal Soc. Chem., is not available from RSC.
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Nicodem
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Quote: Originally posted by Sauron | Nicodem, in the very passage you quote, a variety of chlorinating agents are stated to work on H2SO4 and also Cl2. Also SO2Cl2.
Those are chlorinations. So now you merely scoff at Cl2 doing the job? But are too disinterested to bother checking the references.
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There is no mention of SO2Cl2 there.
Chlorine is indeed mentioned in that citation, but I would have never concluded that the reaction of Cl2 and H2SO4 would give ClSO3H. I would have
just tough the author simplified/miscited/misunderstood a method where chlorine is used in the presence of a suitable reducing reagent like P, PCl3 or
similar. That is all I wanted to point at. Just that your interpretation was wrong. I mean, think about it, using Cl2 you would have to have a redox
reaction which means Cl2O or other chlorine oxides would have to form besides ClSO3H. This would mean the reaction would lead toward products on a
higher thermodynamic energy level, which is simply unlikely in this case. Reactions of H2SO4 with SOCl2, PCl5, and similar, are not redox reactions,
just normal polar reactions without any change in the oxidation states. They are therefore not comparable and you can't use these as examples to
support your claims regarding H2SO4+Cl2.
It is a simple matter of adhering to the chemical theory. If something is against theory it wiser not to claim it to be as simple as it looks before
you have all the data about conditions and reagents used. I intervened due to the same reason as with your remarks about catalysis - I do not want the
younger members to understand basic things in the wrong way.
Quote: | Pf ypu regard this as insufficient obeisance to the gods of thermodynamics, then, burn me for a blasphemer. |
Everybody makes mistakes. I make incredibly stupid mistakes all the time and I still have not burned myself on the stake - on the contrary, I'm always
glad to see there are still people willing to correct my fuck ups. But this is not about you, it is about how your words could be misunderstood.
Catalysis, reaction equilibrium and redox reactions are very important concepts for those who are learning chemistry, so I apologize if it appeared as
if I was somehow picking on you.
…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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Sauron
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Here is Reference 2, Williamson's paper decribing chlorination of H2SO4 with chlorides of P, in two stages, first, giving ClSO2OH and then,
chlorinating ClCO2-OH to SO2Cl2. The paper goes on to describe the reaction between oleum or SO3 with dry HCl.
Nicpdem, no need to apologize, this is all among friends isn't it? I have learned a lot from you over the years so keep it up. And I appreciate the
three citations as that is three less to tease out of Mellow.
Pax vobiscum.
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[Edited on 10-4-2009 by Sauron]
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Sauron
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Here is Reference 3 by Kirby Jackson from Chemical Review, the relevant pages are 81-83.
There's a patent in there for the disproportionation of SO2Cl2 and conc H2SO4 catalyzed by salts of Hg, Sb, Sn or Bi. (See the Mckee/Salls patent
posted downthread.)
The following references state that chlorine alone acts on H2SO4 to give ClSO2OH:
(13) Beckert and Otto, Ber., 11, 2058-2061 (1878)
(16) Behrend, Ber., 8, 1004-1005 (1875)
(227) Muller. Ber., 6, 227-231 (1873)
(358) Williams, J.Chem. Soc. 22, 304-307 (1869)
All of these are readily accessible, I will go fetch the one from RSC then the other three from BnF's Berichte archive.
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[Edited on 10-4-2009 by Sauron]
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Sauron
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Here's reference 358, the only one in English. I saw nothing about elemental chlorination of H2SO4, only with PCl5.
some archaic terms
hydric sulfate H2SO4 = conc or 100% sulfuric acid
sulfuric acid SO3 = sulfur trioxide
chlorohydrated sulfuric acid ClSO2OH = chlorosulfonic acid
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[Edited on 10-4-2009 by Sauron]
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Sauron
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And Reference 13 from Ber. 11 (1878)
Also no obvious mention of Cl2 as such, although since it is in German it's a little harder to tell.
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woelen
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Quote: Originally posted by Sauron | Heating is necessary for the disproportionation reaction in either direction, stirring ought to speed things up somewhat but at RT this will take
forever.
I would expect the reaction to be slow but eventually the two layers will merge and remain merged and you will have chlorosulfonic acid
The reverse reaction requires Hg or HgSO4 catalyst. Reflux chlorosulfonic acid over a little HgSO4 and you will thwn bw able to fractionate off SO2Cl2
and H2SO4 will remain in the pot.
Why not read the original papers? One line in Mellor, much less my recitation, tells little.
If you say nay you are going against some giants like Ruff and Michaelis. Bad idea!
All your experiment did was show that the reaction is not rapid at ambient and I could have told you that without dirtying a test tube.
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Sometimes just trying things may tell more than reading 1000 pages
Of course I did not prove anything, I just tried to help a little bit by doing this experiment and give some practical results. I now did heat the mix
and let the low-boiling SO2Cl2 reflux for some time, but still there is no visible change. I still have two layers of liquid, sitting in the test
tube.
I do have HgSO4 and I'll add that to the test tube, but I'll first leave it like it is now for some longer time, just to see what happens. I cannot
easily open up the system. I sealed it very well with teflon tape, to keep the nasty vapor of SO2Cl2 from escaping the test tube, and if I add the
HgSO4, then I'll have to destroy my "nice" seal of teflon tape. So, first let's see what happens in the longer run with this system.
I have to agree with Nicodem that addition of HgSO4 should not change the long-term ratio of SO2Cl2, SO2Cl(OH) and H2SO4, it only affects the speed at
which equilibrium is reached. So, I expect that addition of this chemical will not result in formation of decent amounts of SO2Cl(OH), but I'll try
anyway this weekend.
[Edited on 10-4-09 by woelen]
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Sauron
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@woelen:
Well, here is a US patent to McKee and Salls that teaches that sulfuryl chloride and 100% H2SO4 or conc H2SO4 and catalytic amount of Hg or HgSO4 or
HgCl2, or less preferably salts of Db, Sn, or Bi, in an autoclave at 160 C for 8 hours become homogenous and the SO2Cl2 is quantitatively converted to
ClSO2OH.
So reading 1000 pages may not be necessary, but it seems like reading the right two pages in this case is certainly bettre than a little cut and try
without heating, without waiting and without catalyst. All that speculation about the equilibrium lying far to the other side just took a torpedo
well below the water line.
100 parts by weight SO2Cl2
14 parts H2SO4 10%
24 parts Hg
are heated in a closed vessel at 160 C for 8 hours then distilled.
Product
160 parts ClSO2OH
75 parts H2SO4 containing Hg mostly as HgSO4
trace SO2Cl2
The acid and catalyst may be used in another run.
The patent also teaches that SO2Cl2 vapor can be bubbled through H2SO4 at 200-300 C, preferably 259 C, and the distillate condensed sd crude ClSO2OH,
off gases SO2 and Cl2 passed through GAC and SO2Cl2 recovered and recycled. This can be done in glass as it is not a pressure reaction. SO2Cl2 boils
at <70 C.
This means that chlorosulfonic acid is readily obtainable from sulfuryl chloride and ordinary H2SO4 (not oleum) and therefore, from Cl2, SO2 and
H2SO4. Or to put it another way from TCCA and conc HCl, sodium metabisulfite etc. and H2SO4. Plus a little GAC or camphor catalyst for the SO2Cl2. It
means that chlorosulfonic acid is DIY for cheap.
This is good news. Don't you agree? Or would you rather bubble HCl into 65% oleum?
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[Edited on 10-4-2009 by Sauron]
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Sauron
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Here is reference 227 (from the Jackson review) from Ber 6 (1873) by Max Muller.
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Sauron
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And reference 16 the last of the four references that Jackson says teach that Cl2 directly chlorinates H2SO4. Well, if so we can't prove it by these
four papers because as far as I can see none of them contain ANY such statement at all.
Fortunately this was something that popped out of Nicodem's book and not from Mellow so I do not feel too bad, I will continue with Mellow and see
what I can see.
______________
I set out at start of this thread to try to find a cheaper easier way to prepare chlorosulfonic acid from more accesible materials.
The literature suggests three such methods: controlled hydrolysis, chlorination and disproportionation. In all three cases the reagents are sulfuryl
chloride, sulfuric acid, or both.
Now I really only need one viable method so I really don't care if one or two of the three do not pan out as long as at least one does.
I don't care which.
My ego is not invested in any of them.
It would be neat if all three work, it would be a vindication for the old literature. A slap in the face for conventional wisdom.
But that's not the major consideration.
[Edited on 10-4-2009 by Sauron]
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Fleaker
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I'm curious about how the SO2 and Cl2 over finely divided platinum black at red heat works? I have a strong feeling that it doesn't work because your
platinum will react with the chlorine. I base that feeling on the fact that I have done something similar in removing Pt off of Al2O3 using a mixture
of those two gases. The only thing I can think of is the fact that the wetness of the gases may have something to do with it.
Just a little quip!
Neither flask nor beaker.
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--The Dark Lord Sauron
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Sauron
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There's another claim that Cl2 and SO2 gives chlorosulfonic acid when passed through activated charcoal. I have not looked it up, but this ought to
make only sulfuryk chloride.
The one about CCl4 and oleum is easy to understand, that makes two products, pyrosulfuryl chloride, and LOTS of phosgene. Hydrolysis of the former
gives chlorosulfonic acid. So at least it is logical though insane.
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Sauron
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Quote: | Quote: Originally posted by Sauron | Here is Reference 2, Williamson's paper decribing chlorination of H2SO4 with chlorides of P, in two stages, first, giving ClSO2OH and then,
chlorinating ClCO2-OH to SO2Cl2. The paper goes on to describe the reaction between oleum or SO3 with dry HCl. |
Kirby Jackson cites same paper as supporting the direct chlorination of H2S)4 by the element,
The authir is not A,W,Williamson who was the first to prepare chlorosulfonic acid, He is R.Williamson. He does state that chlorine reacts with H2SO4,
but offers no details at all.
In general the archaic terminology used is confusing.
SO3 is described as anhydrous sulfuric acid or simply sulfuric acid.
H2SO4 as hydrated sulfuric acid or hydric sulfate
ClSO3H as chlorohydrated sulfuric acid
The same term in some instances is used for SO2Cl2.
I suspect that inadequate attention has led to false conclusions by later reviewers. It is apparent that Jackson mischaracterized a number of his
citations and based on the verbatim descriptions and the publication dates, Mellow drew heavily on Jackson and propagated his errors.
I now agree with Nicodem that elemental chlorination of H2SO4 in absence of a catalyst is unlikely to work, and in many instances substances like S
and P are not really catalysts but merely are forming chlorides in situ which can react with H2SO4, The Cl2 reacts only with the S or P. That is not
catalysis.
So far the references for controlled hydrolysis have all been inaccesible save one, and I await translation of hat lone paper.
Therefore barring sone new revelation, disproportionation looks like the clear choice.
[Edited on 11-4-2009 by Sauron] |
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Sauron
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There are three main methods of preparing CSA.
SO3 + HCl(g) has disadvantage of using costly 65% oleum.
Reacting SO2Cl2 + H2SO4 (pref.100%) and Hg catalyst 8 hrs at 160-200 C is a pressure reaction, and my 316 SS Parr is perhaps not resistant enough.
But the variant reaction is not a pressure one and can be dome om glass. US1554870; modifications are my own.
Boiler A contaims SO2Cl2 at its boiling point. The vapor is comducted through glass to reactor B and is released near bottom so it reacts with the
charge of 100% H2SO4 and catalsi at 250 C. CSA distills off and is comdensed into receiver C which is maintained above the bp of SO2Cl2.
Thus any unreacted SO2Cl2 and any SO2 and Cl2 gases are led through tube D containing granular activated carcomn so that SO2 and Cl2 recombine and the
SO2Cl2 returns to boiler A.
Receiver C is also attached to a cold trap in line with a bubbler and a drying tube to excluse moisture.
Since SO2Cl2 is easile made from its component gases and catalytic GAC or camphor, and 100% H2SO4 from concentrated acis by addition of calculated
amount os oleum, this is an inpensive process for CSA that is run in all-borosp;pcate glassware at normal pressure.
CSA is purified by fractionation.
[Edited on 1-2-2010 by Sauron]
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Sauron
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All connections need to be glass.
These are all aggressive corrosives and temperatures range from 65-70 C (SO2Cl2 vapor) to 160 C (CSA vapor) and 250 C hot 100% H2SO4. Take all
precautions.
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Maya
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there are also some variants, some which are explosive,,,, yikes!!!
I would distill only from oleum....
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Sauron
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"Explosive"?
News to me.
I have seen no lit. on this.
Have you any references? I' much appreciate seeeing any.
I certainly would hesitate to distill CSA from oleum, a ptocedure likely to produce pyrosulfuryl chloride, (ClSO2)2O, the anhydride of CSA, by
abstraction of a mol of water from two mols of CSA.
Much CSA was made during WWI by treating CCl4 with oleum to obtain phosgenem and pyrosulfuryl chloride as by proct. Careful hydrolysis of the latter
gives CSA. The deadly downside of this is obvious.
[Edited on 4-2-2010 by Sauron]
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Sauron
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For yjr sake of complrtrnrdd I should mention a process exemplified in a 1950 US patrnt (attacged) for preparation of pyrosulfuryl chloride sans
phosgene.
SCl2 + 3 SO3 -> (ClSO2)2O + 2 SO2
SOCl2 + 2 SO3 -> (ClSO2)2O + SO2
The process uses neat SO3 as vapor or liquid, and rather a lot of it, for a relatively modest yield of pyrosulfuryl chloride. Scl2 is IMO a superior
feedstock to SOCl2, as the former is essentially a waste product of CCl4 preparation while SOCl2 is more useful elsewhere. But IMO unless there is
some use for PSA other than making CSA, I'd just give this a miss.
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Maya
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Ooops, I meant the SO3 used in the preparation of CHSA.
there are 3 isoforms, one of which goes boom, therefore
always distill your SO3 from oleum and don't try to distill
totally dry SO3
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Sauron
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You are referring to the misnamed alpha explosion of alpha SO3 which is in noway an explosion.
Which isoform is produced on distillation is determined by the condensation temperature.
See Merck's monograph on SO3
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garage chemist
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SO3 is not explosive at all, no form of it. I have distilled SO3 of various purities and all isomeric forms very often. Have you? Probably not.
The "alpha explosion" of SO3 is simply a vapor pressure explosion. Alpha SO3 is a modification that cannot be melted at atmospheric pressure, it
sublimes instead. If one tries to melt it, the pressure in a sealed vessel can rise very high and rupture it.
The other modifications can be melted at atmospheric pressure without significant pressure rise.
In a distillation setup, it is irrelevant which modification you have- the apha simply sublimes instead of melting first, and upon condensation turns
into the liquid isomer again.
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Sauron
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I agree that "exxplosion" has no proper place in this thread. Maya introduced it not me.
alpha SO3 mp 62 C has vapor pressure 2X that of beta SO3 mp 34.4 C. Gamma SO3 mp 16 C usually liquid at r.t.
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Maya
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well then good if alpha SO3 doesn't explode, it just expands rapidly.
I've distilled it in the past and was very wary of it, I guess I can
take less than extraordinary precautions in the future then.....
It sure forms some of the most beautiful white crystals I've ever seen.
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Sauron
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It was just a triumph of hyperbole over precise description.
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