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panziandi
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However couldn't the solution of thionyl chloride in carbon tetrachloride be used as is? For example Jor could dehydrate his chromium chloride
hexahydrate in such a solution? Or could you not use a solution of it to prepare acid chlorides so long as the acid chloride boils above the carbon
tetrachloride?
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Sauron
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Yes, but the chief virtue of thionyl chloride as a reagent for acyl chlorides is that it only has gaseous byproducts (SO2, HCl) and thus, only
requires that the acyl chloride be separated from the excess SOCl2 always used.
Now however the SOCl2 would be in rater dilute solution in CCl4 (1 M, just as the Cl2O was) and your job becomes to get a little acyl chloride out of
a lot of CCl4 and a little excess SOCl2.
Far from idea. SOCl2 is usually used neat.
It might be alright for Jor's application, which is not exactly mainstream.
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panziandi
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True the concentration in CCl4 would be rather low, but if Cl2O was passed into the CCl4 from the catalyst bed then you could generate a higher
concentration of SOCl2 in the CCl4. Yes the use of SOCl2 is usually the virtue of the fact the by-products are gasses, but removing CCl4 from say a
solution of o-chlorobenzoyl chloride or something for example would be quite easy so perhaps generally this reagent could be used for making more
exotic high m.w. acyl chlorides?
Well I think 1M SOCl2 in CCl4 would be fine for dehydrating some CrCl3.6H2O too.
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Sauron
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Ah. You are suggesting to reverse the order of addition. The preparation of Cl2O in CCl4 usually passes in Cl2 first then adds HgO, stirs then filters
and the concentration can build up to 1 M only.
You are suggesting instead to run the generator tube and let the SOCl2 build up. I suspect that since Cl2O is a atrong oxidizer, you will then start
to convert SOCl2 to SO2Cl2.
See the review re solubility in CCl4, I will look again too.
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panziandi
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Well I'm not sure. Is the maximum solubility of Cl2O in CCl4 only 1M, or is it that this method affords only a 1M solution? Because I was suggesting
saturating CCl4 with Cl2O then adding the sulphur. But if 1M is the maximal concentration and Cl2O does oxidize SOCl2 to SO2Cl2 then ignore my posts
as the idea wont work!
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Sauron
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The vapor pressure of Cl2O over CCl4 solutions, at least dilute ones, obeys Henry's Law.
1800-something mmHg/mol% 25 C
600-something mmHg/mol% 0 C.
So at 1 M Cl2O has a pressure of about 270 mm and at 0 C < 100 mm and so you can see why the solution is kept in freezer. Also why you would not
want much more than 1 M. (Because a vapor pressure of 760 means the stuff is boiling out of solution. That would occur at 25 C for a 2.5 M solution.)
Indeed if you read the preps carefully you will notw that there were significant losses during a conventional filtration. Hence my suggestion of
pressure filtration through a frit, and handling the soln in the cold by syringle techniques and other closed system approaches to conserve the Cl2O
as well as avoiding its release.
Chlorine is soluble in CCl4 way over 1 M so that is not the barrier.
I saw a rxn of Cl2O in Cl3CF but thanks to Montreal that is a nonstarter. (R-11 refrigerant.) Unless you want to make your own, then the separation
problem with SOCl2 goes away. R-11 boils at about room temp.
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panziandi
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Ah yes indeed! I must say I did like your suggestion of pressure filtration. Well I am not interested in using Cl2O to make SOCl2 (I have my own) but
I am interested in the Cl2O for chlorinations of aromatics etc.
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Sauron
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It does appear to be faster and easier than direct chlorination of m-xylene. The third chlorine on each methyl group is hard to put on which
translates to wasting a lot of Cl2 and time.
This is also my main interest as frankly there is not much I need SOCl2 for. I have spent several years figuring out better alternatives to it.
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Formatik
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Here is the Gmelin on Cl2O.
And energywise, Cl2O has a heat of explosion of 210 cal/g compared to 348 cal/g for ClO2 and 357 cal/g for mercury fulminate compared to HN3 is about
1550-1600 cal/g, NG is 1455 cal/g, RDX is 1324 cal/g. Based on this and lead block tests of liquid ClO2, condensed Cl2O would represent a similar
hazard to handling primaries, but it is less stable.
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Sauron
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Very odd. According to Gmelin, the reaction between CS2 and Cl2O is violent/explosive. But it is also said that CS2 can be used as solvent for sulfur
to moderate the reaction with Cl2O (instead of CCl4, or S2Cl2)
Do we take it then that the reaction of Cl2O with S (to produce SOCl2 exclusively) is so much faster than the reaction between CS2 and Cl2O (producing
SOCl2 and Cl2C=O) that CS2 cab be employed as solvent/siluent?
Very odd.
"SOCl2 entsteht bei Eine. auf Cl2O-Gas stark gekahlte Schwefelblumen oder auf eine Lsg. von S in CS2, (citation)"
Cold flowers of sulfur, or a soln. of S in CS2. It;s pretty hard to mistranslate that sentence.
What I don't get is: CS2 is not inert to Cl2O, so WTF?
Normally the solvent for reacting CS2 w/Cl2S is CCl4 which is inert. Just as normally S2Cl2 is used to react the gas with S, we are taught at -12 C.
Unfortunately Gallica does not have the 1834 volume of Ann.Chem.Phys. so I can't obtain the Ballard article there.
And I did obtain the page cited in Cmpt.Rend. 1866 p 491 but not a word on there by C.A Wurtz. (Or A.Wurtz).
The above reference is to A.Wurtz in Ann., which I hope to have shortly.
The following attachment is from Ber. 2, p 218-219 (1869) by P.Schutzenberger, concerning CS2 in CCl4 reaction with Cl2O. Due to the phosgene
byproduct this is not so interesting, anyway CS2 is an expensive raw material and SOCl2 is impossible to separate from CCl4 by any method I know. So,
obtaining this paper is only a small victory.
The crus of the matter appears to be in the 1834 Ballard paper in Ann.Chem.Phys. which not even BnF Gallica has. hat is the one where S2Cl2 is
employed as solvent.
And the Wurtz paper is talking about S in CS2, which is very strange since CS2 is not inert. But at least this gets around the separation problem.
[Edited on 9-2-2009 by Sauron]
Attachment: Schutzenberger.pdf (93kB)
This file has been downloaded 657 times
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S.C. Wack
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| Quote: | Originally posted by Sauron
And I did obtain the page cited in Cmpt.Rend. 1866 p 491 but not a word on there by C.A Wurtz. (Or A.Wurtz). |
Had you simply clicked the link that I mentioned in my first post of this thread, my link in the other thread linked to here earlier, and my direction
to start on page 490, you would see "Synthese du chlorure de thionyle; par M. AD. WURTZ.".
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Sauron
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If this is the paper you are talking about, thanks anyway but I have already requested it.
Synthese des Thionylchlorürs
A. Wurtz
Liebig'a Annalen 139 (1866) (p 375-376)
DOI: 10.1002/jlac.18661390314
[Edited on 9-2-2009 by Sauron]
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S.C. Wack
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No that isn't it. You said "Cmpt.Rend. 1866 p 491" and that is what I referred to. A link to that thread in this one has already been posted.
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Sauron
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It's page 460 not 490.
Wurtz article attached.
Contrary to the Gmelin quote above, this paper says nothing about using CS2 as solvent for this reaction, the solvent is clearly S2Cl2. Wurtz said
SCl2 but the bp he gives for the sulfur chloride 138 C is that of S2Cl2 and not that of SCl2 which is anyway too close to SOCl2's bp to be easily
separated.
So unless there is a surprise in the Annalen parallel paper by same author, Gmelin was in error.
This would solve the mystery of the seemingly inert CS2 which makes no sense.
S2Cl2 disulfur dichloride "sulfur monochloride" bp 138 C
SCl2 sulfur dichloride bp 79 C unstable, disproportionates to S2Cl2
[Edited on 9-2-2009 by Sauron]
Attachment: Wurtz.pdf (157kB)
This file has been downloaded 747 times
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Formatik
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| Quote: | Originally posted by Sauron
Very odd. According to Gmelin, the reaction between CS2 and Cl2O is violent/explosive. But it is also said that CS2 can be used as solvent for sulfur
to moderate the reaction with Cl2O (instead of CCl4, or S2Cl2)
Do we take it then that the reaction of Cl2O with S (to produce SOCl2 exclusively) is so much faster than the reaction between CS2 and Cl2O (producing
SOCl2 and Cl2C=O) that CS2 cab be employed as solvent/siluent?
Very odd.
"SOCl2 entsteht bei Eine. auf Cl2O-Gas stark gekahlte Schwefelblumen oder auf eine Lsg. von S in CS2, (citation)"
Cold flowers of sulfur, or a soln. of S in CS2. It;s pretty hard to mistranslate that sentence.
What I don't get is: CS2 is not inert to Cl2O, so WTF? |
It doesn't state that CS2 can be used to moderate it per se. The only thing I can think of this sentence right now is that Wurtz in Liebig's Annalen
might have described that SOCl2 forms from S in CS2, regardless of a violent interaction being described here.
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Sauron
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The question is not whether Gmelin explicitly stated that CS2 moderates the reaction. They didn't, and it doesn;t. That the quote implies so is my
interpretation.
No, the question is whether either of the cited Wurtz papers said anything at all about S in CS2, and the answer insofar as the Compt.Rend. paper is
NO. The jury has yes to hear the evidence of the Annalen paper.
Well, as I will have the Ann. paper shortly, we will see, but frankly I expect Wurtz to teach the same thing in that paper that he does in Compt.Rend.
Your faith in the accuracy of Gmelin is laudable, and we will see if it is justified.
There is of course no reason at all to treat S in CS2 when both will react viol;ently with Cl2O - singly.
The moderating reactions are:
S in S2Cl2 per Wurtz
CS2 in CCl4 per Schutzenberger, see above
Wurtz method allows isolation of the thionyl chloride.
Schutzenberger's method does not.
Anyway let's not speculate, we will not have long to wait for the Ann. Wurtz paper.
[Edited on 9-2-2009 by Sauron]
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Klute
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Translation of the Compt. Rendus Wurtz paper:
| Quote: |
INORGANIC CHEMISTRY- Synthesis of thionyl chloride; by M. Ad. Wurtz.
It's is known that M. H. Schiff has obtained thionyl chloride by double decomposition, by treating sulfurous gas (SO2) by phosphorous pentachloride.
In thsi reaction, 1 atmo of oxygen is exchanged for 2 atoms of chlorine:
SO2 + PCl5 = SOCl2 + POCl3
Acoording to my experiments, thionyl chloride is formed by direct combinaison of hypochlorous anhydride and sulfur. A molecule of thionyl chloride is
formed as a molecule of hypochlorous anhydride is fixed onto a atom of sulfur:
Cl2O + S = SOCl2
To undertake this synthesis, I pass vapors of hypochlorous anhydride in sulfur chloride [surely S2Cl2] containing suspended sulfur, and I stop the
operation before the latter has totally disappeared. It is easy to seperate thionyl chloride and sulfur dichloride by fractionnal distillation. The
former boils at 78°C, the second at 139°C. I have thus obtained notable amounts of thionyl chloride. Pure, this compound is an colorless liquid,
highly refringent, with an irritating smell reminding that of sulfurous gas and that of sulfur chloride. AT 0°C, its density is equal to 1,675.
According to my experiements, it boils at 78°C under a pressure of 0,746 m (of Hg?). Added to water, it falls to thez bottom then quickly decomposes,
similarily to phosphorous pentachloride, into hydrochloric acid and sulfurous gas:
SOCL2 + H2O = 2HCl + SO2
The reaction of hypochlorous anhydride with sulfur is so energetic, that liquid anhydride explodes when put into contact with sulfur. Hence the need
of calming the reaction by diluting the sulphur in an inert liquide such as sulphur monochloride, that is cooled to -12°C for the whole experiment. I
also insured myself that thionyl chloride is formed, in small quantities, when gaseous Cl2O is drawn upon strongly cooled sulphur, or in carbon
disulfide charged with sulphur.
I must add that these experiments are not without danger. I first conducted them by condensing the anhydride to a liquid state, and drawing the vapors
by a rapid stream of dry CO2 directed onto the sulphur. I have renounced using this procedure because of the instability of the hypochlorous anhydride
that cannot be kept for more than a few hours. When liquid and kept at -12°C, it does not spontaneously detonate, but decomposes in a few seconds
with vivid boiling. Its vapors explode with an extreme violence under the slightest of influences, as mentioned by M. Pelouze.
It is thus shown that hypochlorous anhydride Cl2O can be directly fixed on compounds playing the role of radicals, and that many expriments could be
tried on the subject. As a final note, let’s remind that this property of Cl2O is in agreement with the important facts discovered by M. Carius
concerning the fixation of hypochlorous acid on certain carbonated hydrogens.
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Sauron
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Thanks, Klute for the fine translation. Formatik and I should both be satified. Gmelin did not err, but they ignored the main thrust of the article
and focused on the preparatively useless part.
As we will now show, the process of generating Cl2O being natchwise is limited by its stoichiometry tyo modest scales.
2 Cl2 + 2 HgO -> Cl2O + HgO.HgCl2
Two mols Cl2 and two mold HgO are employed to make a single mol Cl2O because half of the reactants are tied up in the HgO.HgCl2.
This is easily regenarated to HgO but, that is damn near a Kg of Hgo and only theoretical 86 g Cl2O. The yield of SOCl2 will be a little over 100 g
(theoretical 118 g). The good news is that making SOCl2 from S and Cl2 is as cheap as dirt, ignoring the reusable HgO. The bad news is that it really
isn't scalable.
Anyway one takes the good with the bad.
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Sauron
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Thanks to vovan78 I have the Wurtz paper from Annalen 139 (1866( and as expected it is a word for word Gernan version of the Comp.Rend. article same
year same author.
Get it from Refs if you want it. Now we have same thing in three languages.
The solvent is of course S2Cl2 and not sulfur dichloride, as made clear by the bp.
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Sauron
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Refer to the Inorg.Syn. procedure for Cl2O prep. and to the Brauer prep (just for the stoichiometry and mass balance). Now consider that we would not
condense the Cl2O but use it in situ as formed to react with S dissolved in S2Cl2 at -12 C.
The Cl2 input is 5 L/hr and dry air at 10 L/hr. This corresponds to 15 g Cl2/hr.
The scale on which I am calculating this is to prepare mol SOCl2. The stoichiometry for Cl2O generation is
2 HgO + 2 Cl2 -> Cl2O + HgO-HgCl2
433.2 141.8 86.9 488.1
On that scale we would be inputing 142 g Cl2 so 15 g/h that will take < 10 hrs
The reaction tube is 3.5 cm ID x 100 cm so unless I messed up the arithmetic, 1000 ml (cc) and contains433 g HgO initially, and an equal weight of
broken glass tubing (I will use Raschig rings) but anyway the Hgo has a density well over 11 g/cc so this is not a problem.
2 mols Cl2O requires 2 mols S and produces theoretically 2 mols SOCl2
Cl2O + S -> SOCl2
86.9 32 118.9
S2Cl2 has a large capacity for dissolving sulfur, even at -12 C. Some excess S should be provided, per Wurtz's admonition to stop the reaction before
all S has been converted. I think it is safer to ensure that the Cl2O supply will run out first.
The HgO-HgCl2 is hydrolyzed with NaOH (aq) and dried, and is ready to use again. So a 500 g purchase of yellow HgO will last many reactions. That is
good because it is not cheap.
----------------------
Noting that S2Cl2 is used industrially as a solvent for Cl2, I wonder if it might be possible to prepare Cl2O in situ in S2Cl2 containing Cl2 and S at
-12 C by adding HgO?
This is worth a try, as it parallels the similar procedure in Inorg.Syn. using CCl4 as solvent.
The S and Cl2 should not react or react only slowly with each other at -12 C, likewise Cl2 ought not to react with S2Cl2 at that temp. to form SCl2.
But the Cl2 + HgO reaction will go.
And the Cl2O thus formed will react with the dissolved S.
The resulting SOCl2 would be readily seperable from the S2Cl2, unreacted S and precipitated HgO-HgCl2.
A careful reading of the lit. should find any flaws in this proposition.
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Formatik
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Satified I am, for the most part. Wurtz said he first conducted the reactions using a rapid CO2 stream which mixed with vapors from liq. Cl2O, these
vapors were then led to the sulfur. Since he reports no explosion with CS2 and S, he might have found a way of moderating by diluting with excess CO2.
That's reminiscent of ClO2 as well. ClO2 greatly diminishes in explosibility as it becomes diluted, as it has been done like with CO2 in its
preparation.
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Sauron
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Formatik, if you are going to quote someone do not quote so selectively. Wurtz also said in same article that those experiments with CO2 carried were
on a small scale and that he abandoned working with condensed Cl2O, And that is what I meant when I referred to these as preparatively useless.
In comparison, Wurtz states that he obtained notable amounts of SOCl2 by the use of S2Cl2 as solvent for S, and reacting with Cl2) vapor (not liquid)
at -12 C.
I find it odd that Gmelin, therefore, cites these two publications of the identical article as advancing the abandoned and less productive process,
while ignoring the focus of Wurtz's reports entirely.
The entirety of mention of S in CS2 is confined to less than one sentence:
"I also insured myself that thionyl chloride is formed, in small quantities, when gaseous Cl2O is drawn upon strongly cooled sulphur, or in
carbon disulfide charged with sulphur.
Clearly the priorities of the editors of Gmelin are different than those of their readers.
I can see no justification for any conclusion but that the primary teaching of Wurtz is to use S2Cl2 as solvent for S in this reaction.
I like Gmelin, and I like Mellor, but sometimes they can result in wild goose chases."
[Edited on 10-2-2009 by Sauron]
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Formatik
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I didn't mean to imply confining the statements to liquid Cl2O, especially since that is too hazardous to work with to begin with.
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Sauron
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Well, if you look at the Inorg.Syn. prep you will see that dry air is used as a diluent for Cl1 in the generation of Cl2O, the same dry air (which
does not participate in the reactions per se) sweeps the product out of the reaction tube and into the S2Cl2 soln of S, so it serves as a diluent for
Cl2O, while S2Cl2 serves as a diluent for both.
I appreciate that the compilers of these reviews are looking for novel reactions. The way it is written in Gmelin, it appears as if Ballard not Wurtz
first employed S2Cl2 as solvent for S.
Mellor credits Wurtz with that.
I would reject CS2 on purely cost grounds relative to S.
As for S2Cl2, the cheap way to make it is from the elements. But it's a mess. A neater was is to simply make CCl4, in which case S2Cl2 is
byproduct.The AKSO patents provide facile means for isolating pure SCl2 (for distillation from Cl3CSCl) or pure S2Cl2 (for distilling from CCl4)
simply by employing a column of GAC at optimum temperature. SCl2 will equilibrate to S2Cl2 and Cl2, given a little time, while S2Cl2 is stable.
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Sauron
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I was hoping to propose a process similar to the in situ generation of Cl2O in CCl4, but substituting S2Cl2.
Unfortunately S2Cl2 is not inert to HgO; HgCl2 forms rapidly and exthermically along with SO2 and S.
So this is out the window.
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