Sciencemadness Discussion Board

Chlorosulfonic acid

Sauron - 7-4-2009 at 21:46

This substance pops up in threads from time to time.

ClSO2OH It is the half acid chloride of sulfuric acid, or may also be regarded as the mixed anhydride of sulfuric and hydrochloric acids.

The usual preparation is done by passing a SLOW stream of DRY HCl gas into 65% oleum, until no more HCl is absorbed. The resulting mix of 100% H2SO4 and chlorosulfonic acid can then be fractionated. Obviously this must be done with exclusion of all moisture.

The hassle is 65% oleum is expensive while commercial chlorosulfonic acid is cheap.

The other hassle is that the reaction is highly exothermic, which is why the passage of HCl needs to be quite slow. The pot should be kept close to room temperature. Any overheating and SO3 can distill out of the mix. Until addition is complete, the condenser should be set for reflux.

I found an alternative prep that I like better:

"Chlorsulphonic acid, SO 2 CI. OH, first prepared by A. Williamson (Proc. Roy. Soc., 1856, 7, p. 11) by the direct union of sulphur trioxide with hydrochloric acid gas, may also be obtained by distilling concentrated sulphuric acid with phosphorus oxychloride:

2 H 2 SO 4 +POCl 3 =2 SO 2 ClOH+HCl+HP0 3

(1911 Britannica, monograph on sulphur)

Since POCl3 can be prepared at high temp. from P2O5 and NaCl, this is practical and cheap.

[Edited on 8-4-2009 by Sauron]

not_important - 7-4-2009 at 23:04

It's also formed in the hydrolysis of sulfuryl chloride SO2Cl2, but I suspect that controlling the reaction is difficult to impractical as I've found few references to that process.

Sauron - 7-4-2009 at 23:40

I was wondering about that, because SO2Cl2 is of course the the acid dichloride of H2SO4, or to rwrite more appropriately SO2(OH)2.

So chlorosulphonic acid is the half chloride, and we couldf call sulfuryl chloride "chlorosulfonyl chloride" if we wished.

My recollection is that SO2Cl2 is not hydrolyzed by cold water but forms a hydrate. So, you would sure haave to expect that one mol well stirred SO2Cl2 treated with one mol cold water must eventually as it rises to ambient and the exotherm kicks in, hydrolyze one and only one Cl to produce chlorosulfonic acid one mol and a mol of HCl.

I am inclined to try this as SO2Cl2 is easier to make than POCl3.

My source re the hydrate is Merck, let me have another look.

"Slowly dec by water, forming H 2 SO 4 and HCl. With ice-cold water it forms a hydrate, SO 2 Cl 2 .15H 2 O, resembling camphor in appearance."

So not ice-water. Cool or room temp. water.

[Edited on 8-4-2009 by Sauron]

DJF90 - 8-4-2009 at 00:05

"With ice-cold water it forms a hydrate, SO2Cl2.15H2O, resembling camphor in appearance." I beleive this is an extract from the Merck Index from google. It would have been better if the stoichiometry was 1:1, as then the hydrate could be formed and then heated to possibly leave chlorosulfonic acid. Perhaps adding 1 mole of hot water to 1 mole of warmed sulfuryl chloride can lead to chlorosulfonic acid (assuming it doesnt form the hydrate... shouldnt be a problem at elevated temperatures). Is there anything to suggest that the half hydrolysed sulfuryl chloride (chlorosulfonic acid) will hydrolyse faster than the unreacted sulfonyl chloride?

not_important - 8-4-2009 at 00:20

That's what I was wondering, too. An alternative might be a 1:1 mix of SO2Cl2 and H2SO4, which if it reacts could give 2 moles of SO2ClOH, or HCl and SO3 which would seem to turn around and react to form SO2ClOH.

Sauron - 8-4-2009 at 03:20

That's a pregnant idea as well. The disproportionation makes good sense, only thing is that the conc H2SO4 better be 100% or a low % oleum (<5%) or you will lose some product to H2O.

With a low % oleum you can add dry HCl to the product to convert aby remaining SO3 to chlorosulfonic.

DJF90, I think chlorosulfonic acid reacts, uh, vigorously with water and I thought sulfuryl chloride did too. Merck Index says not. I got that off the Merck Index 12th Ed. CD and I also have the hardcopy book. Google? Who needs it?

Sometime before 1980 I did a chore disposing of aggressive reagents down the drain in a hood at the SURD labs in New Orleans (USDA, FDA) and these included chlorosulfonic acid, oleum, sulfuryl chloride as I recall, maybe some fuming nitric as well. (They would not let me haul them away damn it!). But at this late date three decades on I do not remember which reagents made the most fuss when flushed.


[Edited on 8-4-2009 by Sauron]

woelen - 8-4-2009 at 04:09

SO2Cl2 does not react with water at room temperature. I have some of this liquid and it actually is fairly tame stuff, not nearly as reactive and energetic at SOCl2 with water. It only very slowly dissolves in cold water (takes hours for dissolving a big drop of this liquid).

When SO2Cl2 is added to hot water, then it dissolves, giving HCl and H2SO4 and this reaction takes minutes. I have a book from Vilano (old German pre-WWII book about preparative chemistry) which even suggests cleaning SO2Cl2 by shaking it with cold water and then separating the layers which are formed and carefully distilling off the lower-boiling SO2Cl2. According to this book, SO2Cl2 is not capable of forming SO2Cl(OH). It either reacts to complete hydrolysis giving H2SO4 or it does not react at all. Chlorosulphonic acid is MUCH more reactive than SO2Cl2.

Sauron - 8-4-2009 at 04:42

Ism't that Vanino's book?

It makes no obvious sense for SO2Cl2 not to be halfway hydrolyzable.

Here's a reaction of chlorosulfonic acid to give sulfuryl chloride, catalyzed by mercuric sulfate, obviously a disproportionation. The only possible chlorine source is the starting material itself.

2 ClSO2OH -> SO2Cl2 + H2SO4

or more clearly

2 Cl-SO2-OH -> Cl-SO2-Cl + HO-SO2-OH

Logically, H2SO4 ought to chlorinate to either chlorosulfonic acid or sulfuryl chloride, but I have never heard of such a reaction.

We know SO2Cl2 will hydrolyze to H2SO4 and HCl (albeit slowly)

The less than obvious explanation is likely kinetics, ClSO2OH is hydrolyzed so much faster than SO2Cl2 that no chlorosulphonic acid remains when all water is consumed.

a mol of sulfuryl chloride is 134 g.

A mol of water is only 18 g

If SO2Cl2 cannot be hydrolyzed to the half chloride, but only to the acid, then mixing one mol H2O with one mol sulfuryl chloride and waiting till reaction is complete will produce a 1:1 mixture of H2SO4 and unreacted SO2Cl2 with one mol HCl either dissolved or evolved. A simple enough experiment to design and perform, isn't it?

I think a look in Mellor is apropos.

In hindsight I ought to have resorted to ACTOITC from the start

Here is the section on halosulfonic acids, with references.

[Edited on 8-4-2009 by Sauron]

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Sauron - 8-4-2009 at 05:57

And here, sulfuryl halides. Again with references.

Attachment: sulfuryl halides.pdf (401kB)
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Jor - 8-4-2009 at 06:26

I find it strange that sulfuryl chloride reacts so slowly with water, while it reacts violently with alcohols like methanol.

Sauron - 8-4-2009 at 07:51

According to Mellor, Michaelis reports that chlorosulfonic acid is the first hydrolysis product of SO2Cl2. This suggests that the stoichiometric reaction of equimolar H2O and SO2Cl2 at ordinary temperatures (e.g. above ice cold!) ought to be ClSO2OH.

Mellor also reports that equimolar H2SO4 and SO2Cl2 do give 2 mols ClSO2OH so it is really unnecessary to suss out the hydrolysis.

According to O.Ruff, refluxing chlorosulfonic acid over catalytic mercuric sulfate quantitatively decomposes iy into H2SO4 and SO2Cl2, this is the reverse of the reaction immediately above.

[Edited on 8-4-2009 by Sauron]

not_important - 8-4-2009 at 08:24

Plus in the pdf you uploaded there is a reference of McKee & Salls that implies using this route on a commercial scale.

But still there seems to be a number of contradictions in these notes.

Fleaker - 8-4-2009 at 17:05

Someone should put it to the test.

It would be very convenient if SO2Cl2 can be made into ClSO2OH. I'm inclined to trust Mellor's, but this should be confirmed. SO2Cl2 is so easily made that it would be a great source of chlorosulfonic acid, if indeed this works.

More Take from Mellor

Sauron - 8-4-2009 at 18:34

A more careful look at Mellor reveals a larger number of preps of chlorosulfonic acid.I group these into three categories:

Disproportionation of SO2Cl2 and H2SO4

Chlorination of conc (pref 100%)H2SO4

This is by Cl2 itself, or PCl3, PCl5, POCl3, by S2Cl2 or SCl2, by SOCl2, and by P2O5 and 100% H2SO4 with passage of HCl gas. The latter is clearly the in situ formation of POCl3.

Stoichiometric Hydolysis

Hydrolysis of Pyrosulfuryl Chloride

I mention this merely for sale of thoroughness,

Controlled hydrolysis of sulfuryl chloride.

It remains now to look at the references and see what is what. But so far it does appear that chlorosulfonic acid behaves consistent with its position as halfway between H2SO4 and SO2Cl2.

Chlorosulfonic acid is assymmetrically substituted, with an electronegative halogen on one side and an electron rich hydroxyl on the other and an electron rich S(=O)2 center. In this light the disproportionation reactions are not at all surprisong since symmetrical products are obtained

2 ClSO2OH <-> H2SO4 + SO2Cl2 (catalyzed to right by HgSO4)

I also see a unity between the half hydrolysis of SO2Cl2 by the addition of a single mol H2O (avoiding formation of the hydrate by not using very cold water) and the disproportionation.

This can only proceed in one of two ways:

a) by formation of one mol ClSO2OH and one mol HCl gas

b) by the formation of 0.5 mol H2SO4 1 mol HCl gas leaving 0.5 mol SO2Cl2 unreacted. The equimolar sulfuric acid and SO2Cl2 then disproportionate to 1 mol ClSO2OH

In both cases the final product is the same.

Explanation (a) is simpler and so favored by Occam's Razor.

Carefully designed p-chem experiments can tell which is really happening.


[Edited on 9-4-2009 by Sauron]

woelen - 9-4-2009 at 22:53

I have done a simple experiment, and it really seems that no SO2Cl(OH) is formed. I took appr. 1 ml of 96% H2SO4 and appr. 1 ml of SO2Cl2. The liquids do not mix, the SO2Cl2 forms a layer on top of the sulphuric acid. When the liquids are shaken vigorously, then a turbid suspension is formed, which in a few minutes separates into two layers again. I allowed the liquids to stand for many hours and in the meantime I vigorously shaked the liquids but the result is the same all over again. I did not yet try heating the mix, I still have the liquids standing in the test tube, forming two layers.

Another interesting experiment would be doing the reverse, taking SO2Cl(OH) and heating this somewhat. Does it form a two-layer system, giving H2SO4 and SO2Cl2? I do not have SO2Cl(OH) though, so I cannot perform the experiment.

@Sauron: You were right about the name of the author of the book. I misspelled his name. This book indeed tells that a good way to clean SO2Cl2 is shaking it with cold water and then carefully distilling it. Preparation of SO2Cl2 is from equimolar streams of SO2 and Cl2 over camphor.

Sauron - 9-4-2009 at 23:35

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.

Nicodem - 10-4-2009 at 00:02

Quote: Originally posted by Sauron  

2 ClSO2OH <-> H2SO4 + SO2Cl2 (catalyzed to right by HgSO4)

....

Heating is necessary for the disproportionation reaction in either direction, stirring ought to speed things up somewhat but at RT this will take forever.

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?

Unfortunately I also did not read the original papers.
I just wanted to clarify a little detail. Catalysts do not dictate the equilibrium constant as one might conclude from your remarks above. I would dare to guess that in the example of SO2Cl2 preparation from ClSO3H the reaction is driven toward the product by distilling it off while HgSO4 only serves to speed up the equilibration (and not to change the direction). In other words, the same catalyst should speed up the formation of ClSO3H from a mixture of SO2Cl2 and H2SO4 (Woelen, if you have some HgSO4 or HgCl2, could you please add it to that test tube?).

PS: The reaction of SO2Cl2 with nucleophilies like H2O, H2SO4 and so on is slow because S-Cl bonds are not polarized in the same direction as in SOCl2 (ClSO2- and -Cl groups have inductive effects of similar strength; I think the bond polarization is even slightly the reverse of that in SOCl2). For the same reason SO2Cl2 is so good in radical chlorinations (the S-Cl bond easily breaks homolyticaly while in SOCl2 it can not).

garage chemist - 10-4-2009 at 00:25

Quote: Originally posted by Nicodem  
I would dare to guess that in the example of SO2Cl2 preparation from ClSO3H the reaction is driven toward the product by distilling it off while HgSO4 only serves to speed up the equilibration (and not to change the direction). In other words, the same catalyst should speed up the formation of ClSO3H from a mixture of SO2Cl2 and H2SO4 (Woelen, if you have some HgSO4 or HgCl2, could you please add it to that test tube?).


That is the definition of a catalyst. A catalyst can never catalyse a reaction "in one direction". A catalyst always speeds up the formation of a thermodynamic equilibrium, but does not influence its equilibrium constant. Only the circumstances of the reaction, such as temperature and especially relative concentrations of the reactants, dictate whether a reaction goes into one or the other direction.

For the case of the sulfuryl chloride-sulfuric acid-chlorosulfonic acid system, I remember reading in Sartori's "The War gases" in the chapter about sulfuryl chloride preparation that simply heating chlorosulfonic acid under pressure in an autoclave causes it to disproportionate quantitatively into H2SO4 and SO2Cl2 (which separate into two phases)- and this is WITHOUT distilling off the SO2Cl2. It is also stated that HgSO4 causes this disproportionation to happen during atmospheric pressure reflux. No mention is made about having to continuously remove the SO2Cl2.

So I dare to guess that the thermodynamic equilibrium of the
2 ClSO3H <----> SO2Cl2 + H2SO4 reaction lies far at the right side, and that it is not possible to prepare ClSO3H from SO2Cl2 without very special measures to remove ClSO3H or H2SO4 from the equilibrium as fast as they are formed.

Sauron - 10-4-2009 at 01:21

I said nothing about having to strip the SO2Cl2 off as formed, because Mellor and AFAIK his citations say nothing of the sort. I also recently reread Sartori on these compounds, and posted about it and yes, I saw the pressure disproportionation, but as so few of us own autoclaves I did not mention it.

People think ill of me if I keep badhing them in the face with my Patt 1 L.

Since the point of the thread is prep of chlorosulfonic acid, and it is fairly ridiculous to make readily preparable SO2Cl2 from more difficult to prepare ClSO2OH (unless one can buy it, or has ready access to a cheap supply of 65% oleum) I was focusing on the most facile routes to ClSO2OH that do not rely on SO3, oleum etc. I have 4 Kg 65% oleum but I will not give any of it up to make chlorosulfonic acid!

The most facile rotes appear to be

Hydrolysis of SO2Cl2 with a very limited amount of water and NOT ice cold water

chlorination of conc H2SO4 by Cl2 or any of the usual chlorination agents

Disproportionatin of SO2Cl2 and H2SO4

The lit so far as I have looked to this point in time does not mention Hg or HgSO4 catalysis of this. However the catalysis of the reverse reaction is documented and certainly implies it, in fact requires it.

ClSO2OH refluxes at 153 C so the reflux condeenser recommended is an air condenser. As So2Cl2 has a bp of 69-70 C so it WILL flash off and will pass the air condenser so provision had better be made to condenser and collect it.

You could of course use a coolant at > 50 C and thus reflux both of these, but recirculating heaters are relatively rare and costly compared to recirculating chillers. I would say, 60 C would be about right.

H2SO4 is just goint to stay in the pot.

The reflux temp ought to drop as the chlorosulfonic acid diminishes and sulfuryl chloride increases. So the heating can be reduced and normal cooling commenced. Caution, though as you do not want to crack a condenser at the jacket when reluxing these nasties.



[Edited on 10-4-2009 by Sauron]

Nicodem - 10-4-2009 at 02:16

Quote: Originally posted by Sauron  

The most facile rotes appear to be

Hydrolysis of SO2Cl2 with a very limited amount of water and NOT ice cold water

I don't think this is possible due to the reasons I explained in my previous post. You would only obtain a mixture of H2SO4 and SO2Cl2, but no ClSO3H.
Quote:
chlorination of conc H2SO4 by Cl2 or any of the usual chlorination agents

You can not oxidise H2SO4 any further with Cl2. The sulfur is already at its highest oxidation state.
Quote:
Disproportionatin of SOCl2 and H2SO4

Assuming you meant SO2Cl2 when you wrote SOCl2 (in the sense of previously discussed disproportionation reaction)... Unfortunately the information that Garage chemist just provided indicate that at least at a higher temperature the equilibrium lies toward SO2Cl2+H2SO4 rather than toward ClSO3H. It might be the opposite at room temperature, but unless someone provides a reference, or Woelen demonstrates it experimentally, we can only guess. I also thought it would be toward ClSO3H, that is why I said that the procedure most likely involved distilling off SO2Cl2 as it formed, but it seems this is not the case.
Quote:
The lit so far as I have looked to this point in time does not mention Hg or HgSO4 catalysis of this. However the catalysis of the reverse reaction is documented and certainly implies it, in fact requires it.

Like I said before and like Garage chemist explained even more in depth, there is no such thing as changing direction of the same reaction by different catalysts. The catalyst has absolutely no influence whatsoever on the equilibrium constant. You can not catalyse a "reverse reaction", you can only catalyse the reaction, because it is exactly the same reaction. All a catalyst can do is increase the reaction rate (that's what it is used for). For example, see http://en.wikipedia.org/wiki/Catalysis . You can not fight with thermodinamics without energy.

[Edited on 10/4/2009 by Nicodem]

Sauron - 10-4-2009 at 02:56

Nicodem I posted an entire subchapter from Mellor with references and these claim that controlled hydrolysis of SO2Cl2 to chlorosulfonic acid DOES work, that chlorination of conc H2SO4 DOES work, with Cl2, PCl3, PCl5, POCl3, SOCl2 (yes thionyl chloride) anyway which are I what I called the usual suspects. Clealrly these are not disproportionation reactions, but chlorinations.

The same text and refs also state that SO2Cl2 + conc H2SO4 -> 2 ClSO2OH.

You are taking an offhand experiment by woelen without any serious effort to learn what conditions are required, and a comment from gara chemist, and then demanding references when I have already provided a raft of them. Why don;t you bother reading Melloe on chlorosulfonic acid and Mellor on sulfuryl chloride. There they are attached upthread.

You say H2SO4 cannot be chlorinated but asmall army of eminent chemists teach otherwise. You may want to reexamine your premise.

I have 7 volumes of Mellor sitting on my desk awaiting dissection and scanning. The exerpts above are not from these or the other 7 volumes I have purchased and not yet received, they are from Mellow's Sulfur chapter out of Volume X which has long been in the forum library. I can't help wondering why I am scanning 17,000 pages if no one wants to read even the ones we already have? Very disappointing!

Sauron - 10-4-2009 at 03:06

Further. re hydrolsis of SO2Cl2:

Take ONE mol SO2Cl2 and add ONE mol water at ambient with stirring.

TWO mols water would be required to completely hydrolyze SO2Cl2 to H2SO4 + Hcl (g)

Therefore, there are two and only two possibilities

I am repeating myself but you seem to have missed this

A. ONE mol of the half hydrolysis product form ClSO2OH

B. HALF a mol H2SO4 and HALF a mol HCl gas form and the other half of the SO2Cl2 is untouched.

So, we have the conditions for the disproportionation to same product as (A).

A deeper look at Mellor's sources will establish time and temp (hopefully)

It is necessary to avoid use of water cold enough to form the monohydrate or the 15H1O hydrate which are stable camphorlike solids.

Nicodem - 10-4-2009 at 03:18

Quote: Originally posted by Sauron  
Nicodem I posted an entire subchapter from Mellor with references and these claim that controlled hydrolysis of SO2Cl2 to chlorosulfonic acid DOES work, that chlorination of conc H2SO4 DOES work, with Cl2, PCl3, PCl5, POCl3, SOCl2 (yes thionyl chloride) anyway which are I what I called the usual suspects. Clealrly these are not disproportionation reactions, but chlorinations.

Maybe I should have said that I'm not interested in the topic. The only reason I posted in this thread was to comment on your way of treating thermodinamic rules. Just to clarify a certain thing, rather than contribute to the topic.
Anyway, while I'm here I will also add that there is absolutely no way you can get ClSO3H from only Cl2+H2SO4 unless you reduce Cl2 in situ with something like phosphorous. And I'm not even going to check the reference you mention (what for?). The other reagents you mention (PCl3, PCl5, POCl3, SOCl2) are something completely different and it is expected they would give ClSO3H from H2SO4. But with Cl2+H2SO4 where are the Cl atoms going to take the electrons from?
About the H2SO4/SO2Cl2/ClSO3H equilibrium. I thought, we already concluded that the reaction is indeed working and several sources conclude so. I was not disputing that, I only wanted to say that I have yet to see a reference claiming the equilibrium is toward ClSO3H.
For example, in the book Chlorosulfonic Acid there is no mention of this reaction being a preparative method. It does list only the methods already mentioned in this and other threads of the forum (page 1):
Quote:
Chlorosulfonic acid was first prepared by Williamson[1] in 1854 by the action of phosphorus pentachloride on concentrated sulfuric acid and later[2] by the direct action of hydrochloric acid on sulfuric trioxide. Other methods of preparation include: distillation of fuming sulfuric acid (oleum) with phosphorous pentoxide in a stream of gaseous hydrogen chloride; the action of phosphorus trichloride or oxychloride, chlorine, thionyl chloride, or sulfur monochloride on concentrated or fuming sulfuric acid; passing a mixture of sulfur dioxide and chlorine into glacial acetic acid; or reaction of carbon tetrachloride with fuming sulfuric acid.[2]

[1] AW. Williamson, Proc. R. Soc. London, 1854, 7, 11.
[2] AW. Williamson, J Chem. Soc., 1857, 10. 97.
[3] KE. Jackson, Chem. Rev., 1939, 25, 83.

(I bolded the method I find most suitable for an amateur lab, especially since it has the added bonus of making an equivalent of AcCl as a side product)

Furthermore on the page 3 it discusses this disproportionation as directed toward SO2Cl2+H2SO4.

Sauron - 10-4-2009 at 03:50

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.

Well, I am not disinterested and I will dig out the references.

SO2 and Cl2 obviously form SO2Cl2 in situ and AcOH is a known catalyst for this reaction - not as popular as GAC or camphor. I saw nothing about ClSO3H from this.

I did see a ref to imperfectly dried Cl2 and wet SO2 over Pt black at red heat forming ClSO3H. What is this but formation of SO2Cl2 and partial hydrolysis by steam

In reciting what Mellor said on the disproportionation reaction I may have expressed myself poorly, but I was accurately stating the text. So when I said that no mention was mae of catalyst in the formation of ClSO2OH from SO2Cl2 and that in the decomposition/disproportionation of ClSO3OH to SO2Cl2 and H2SO4, Hg or HgSO4 is employed, I did not mean to state that the former would not work with selfsame catalyst, nor that the latter would not work without that catalyst. OBVIOUSLY these are the same reaction with a double headed arrow, and equally obviously the catalyst does not dictate the reaction, or the rate constant, merely accelerates it.

But till proven otherwise I assume that since Mellor states that BOTH reactions work, that this is indeed the case.

If ypu regard this as insufficient obeisance to the gods of thermodynamics, then, burn me for a blasphemer.



[Edited on 10-4-2009 by Sauron]

not_important - 10-4-2009 at 04:32

Interesting that the book on chlorosulfonic acids lists passing a mixture of sulfur dioxide and chlorine into glacial acetic acid as a method of preparation, as that is given elsewhere as a means of preparing sulfuryl chloride, with the acetic acid essentially unchanged.

So either some chemical relationships changed when Queen Vicky passed on, or this group of reactions have a more complicated relationship that the references lead one to first believe.

Sauron - 10-4-2009 at 04:44

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.

Nicodem - 10-4-2009 at 04:54

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.

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.

Sauron - 10-4-2009 at 05:02

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]

Sauron - 10-4-2009 at 05:30

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]

Sauron - 10-4-2009 at 08:04

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]

Sauron - 10-4-2009 at 09:19

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 - 10-4-2009 at 09:51

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.

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]

@woelen:

Sauron - 10-4-2009 at 10:47

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]

Sauron - 10-4-2009 at 11:03

Here is reference 227 (from the Jackson review) from Ber 6 (1873) by Max Muller.

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Sauron - 10-4-2009 at 11:50

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]

Fleaker - 10-4-2009 at 16:16

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!

Sauron - 10-4-2009 at 20:04

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.

Sauron - 11-4-2009 at 14:14

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]

Sauron - 1-2-2010 at 08:26

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]

Sauron - 1-2-2010 at 08:48

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.

Maya - 3-2-2010 at 16:26

there are also some variants, some which are explosive,,,, yikes!!!

I would distill only from oleum....

Sauron - 3-2-2010 at 19:27

"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]

Sauron - 4-2-2010 at 09:54

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 - 13-2-2010 at 08:08

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

Sauron - 13-2-2010 at 21:54

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

garage chemist - 13-2-2010 at 23:43

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.

Sauron - 14-2-2010 at 03:45

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.

Maya - 14-2-2010 at 11:47

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.

Sauron - 14-2-2010 at 14:12

It was just a triumph of hyperbole over precise description.