Sciencemadness Discussion Board - thionyl chloride synthesis

thionyl chloride synthesis

Jor - 31-1-2009 at 12:01

I really want some SOCl2, for making anhydrous metal salts (like CrCl3) from hydrated metal salts.

I have contacted Sauron and he gave me some inspiring ideas.
I want to avoid the SO3/SCl2 method. SCl2 stinks. SO3 destroy skin on contact, rendering it only useful in maybe a black powder formula

.
PCl5/SO2 , I also don't like that method. Takes a lot of time, and doesn't have good yeilds (50%). Besides I cannot give a good seperation of the POCl3 from the SOCl2, as I do not have a vigreux.

A very promising method Sauron gave me is reacting SO2 with phthaloyl chloride. This is very expensive, but I can make it from relatively cheap benzotrichloride and phthalic anhydride. However, i would need to buy a whole liter, for wich i have no other uses, so I want to look at the other possibilities first.

I can make PCl5, and I can buy chlorosulfonic acid.
So:
-I would like to ask if anyone has information if SOCl2 can be made from chlorosulfonic acid. Sauron said he remembered there was a reaction with mercuric nitrate, but he was not sure. Anyways, this is a no-no. That is too toxic. But are there more methods?
-Sauron also said he vaguely remembered anhydrous sodium sulphite could be reacted with PCl5. Is this true? Does this also give POCl3 as byproduct, or rather NaCl and P2O5? This would be great if it works, as i have anhydrous sodium sulphite, and it would not involve generation of massive volumes of SO2, and the POCl3 contamination may be less than the SO2 method.

Also other ideas are welcome.

Thanks in advance

Sauron - 31-1-2009 at 12:19

I did not vaguely remember that sodium sulfite reacts with PCl5 to produce SOCl2. I said that I found this reaction in the Encyclopedia Britannica 1911 edition online in the Sulfur article. I sent the quotation to you verbatim.

And I just sent you the balanced equation that I believe applies, although that is not in the Brittanica,

Na2SO3 + 2 PCl5 -> SOCl2 + 2 POCl3 + 2NaCl

So kindly do not misrepresent what I told you.

It is true that I remember a reaction between mercuric nitrate and chlorosulfonic acid, but I have not found the source and do not recall details. I do not remember whether this produces SOCl2 or SO2Cl2. Anyway you have better choices to make SOCl2. You can use the Kyrides method, phthaloyl chloride and you can make the reagent yourself using benzotrichloride and phthalic anhydride.

Len1 demonstrated making benzotrichloride on this forum, starting with toluene.

[Edited on 1-2-2009 by Sauron]

Jor - 31-1-2009 at 12:32

Sorry.
I did not have PMs at hand when typing this message. I was not sure if you said that you remembered the sulphite method or actually read it in 1911 britannica. Should have read that PM again, Im sorry my fault.

That equation indeed looks right. I was thinking all the time the sulphite would react 1:1 with the PCl5, and didn't think beyond that!
I'm making a lot of stupid mistakes today, as you can see. :mad:

If anyone has papers on the sulphite reaction you would do me a great favour. I hate it that i can't access many papers, because you will have to pay a lot of money for a membership.
Therefore my best resources are the SMDB Library

Chlorosulfonic would also be a prefreed reagent to start with. I can buy it relatively cheaply, 500mL for 25 euro. And I find this a very interestign chemical, wich i can use for many microscale test-tube experiments as well.

Sauron - 31-1-2009 at 12:40

Just go to Google, search for 1911 encyclopedia, and the Britannica free edition comes right up

Search on that page for thionyl chloride and the Sulfurmonograph comes up. Find the section on halogen derivatives of sulfurous acid. It will start with SOF2, then SOCl2, then SOBr2.

It's there for anyone to read.

woelen - 31-1-2009 at 12:45

Can you really buy chlorosulphonic acid (labstuff?)? I have strong doubts about that, and if you ask for that, that there will be some serious questions.

I also have strong doubts that this chemical can be used for making SOCl2. Chlorosulphonic acid contains sulphur in oxidation state +6 and with mercuric nitrate I do not see how this could be reduced to oxidation state +4. I can imagine though that chlorosulphonic acid can be converted to SO2Cl2 in some way, but that is not interesting for you (SO2Cl2 is much less reactive than SO2(OH)Cl).

Jor - 31-1-2009 at 12:50

Well, Wilco, I have not asked Labstuff yet, but he gave me a lot of restricted chemicals as you have seen, and chlorosulfonic acid was not included.
Why would it be restricted, do you know of illicit uses in the Netherlands?

Sauron - 31-1-2009 at 13:12

Here is the entry I am talking aout from Britannica 1911:

"There are various haloid derivatives of sulphurous acid. Thionyl fluoride, SOF 21 has been obtained as a fuming, gas by decomposing arsenic fluoride with thionyl chloride (Moissan and Lebeau, Corn pt. rend., 1900, 130, p. 1436). It is decomposed by water into hydrofluoric and sulphurous acids. Thionyl chloride, SOCl2 may be obtained by the action of phosphorus pentachloride on sodium sulphite; by the action of sulphur trioxide on sulphur dichloride at 75 -80° C. (Journ. Chem. Soc., 1903, p. 420); and by the action of chlorine monoxide on sulphur at low temperature. It is a colourless, highly refracting liquid, boiling at 78°; it fumes on exposure to moist air. Water decomposes it into hydrochloric and sulphurous acids. On treatment with potassium bromide it yields thionyl bromide, SOBr2, an orange-yellow liquid which boils at 68° C. (40 mm.) (Hartoz and Sims, Chem. News, 1893, 67, p. 82). "

I could not find the J Chem Soc reference 1903 p 420 but it may be a typo as there are many in that site.

The references for this reaction probably can be turned up in Mellor's volume on sulfur or in Gmelin.

The reaction between PCl5 and SO2 which is very similar is in Brauer on page 382.

Solid-solid reactions with moisture sensitive reactants and equally moisture sensitive products are always fun in the Chinese curse sense of fun. Distilling SOCl2 off POCl3 requires a good column and several fractionations, so is tedious. I still recommend the Kyrides method which gives a produce devoid of phosphorus-compound contamination.

[Edited on 1-2-2009 by Sauron]

Sauron - 31-1-2009 at 14:21

Besides the "new" sulfite method, which is only a variation on SO2 and PCl5, and thus only available to those who can get or make PCl5, and the Kyrides method discussed above and in various threads by me, the other methods are:

SCl2/S2Cl2 and SO3 either neat or in oleum

Trichloroarenes sich as hexachloro-m-xylene, or the simplest case benzotrichloride, reacting with SO2 and a catalyst, in several patents and articles posted before by me;

The disproportionation reaction over GAC between PCl3 and SO2Cl2, giving POCl2 and SOCl2 (only practical is you have PCl3, so rots of ruck)

The low temperature reaction of chlorine monoxide with sulfur, another one unlikely to be performed in a home lab;

Did I forget anything?

Jor does not wish to work with oleum so that oxidation of sulfur chlorides is out (he also regards sulfur chlorides as stinky and toxic.)

I think Jor is well advised to carefully consider the Kyrides methos (phthaloyl chloride and SO2).

garage chemist - 31-1-2009 at 14:53

SO2 + PCl5 reacts smoothly to POCl3 and SOCl2. The real problem is separation of the products. Fractionating this mixture SUCKS, even if you have a good column. There's something with those substances that lets them cling onto one another and resist efficient separation.
I had to do this myself as a practical assignment. The yields and purity were horrible.

Please consider making and using SO3, Jor.
All you need to do is make a tube furnace, and proceed as I have done. Here's your second reason to make a tube furnace!
NaHSO4, when hit with enough heat, releases SO3 in good yield.
SO3 is a highly reactive and exceptionally useful chemical.
Len1 has demonstrated making SOCl2 from SO3 and SCl2 in detail. Follow his work.

Jor, do you have a glassblower that can make things out of fused quartz for you? You should find one.
My synthetic abilities were vastly extended once I started making use of the services of the glassblower at the nearest big university. I can have EVERYTHING IMAGINABLE made out of every glass sort as long as I have the money for it. This is invaluable for a chemist! My tube furnace experiments would have been impossible without this glassblower.

panziandi - 31-1-2009 at 15:06

That is what I don't understand with Jor... You say you don't want to work with SO3 or Oleum and you don't want to work with S2Cl2 because they are corrosive and toxic and smelly, yet you will work with SO2 (also toxic and smell and corrosive) and you want to make SOCl2 which is water reactive, toxic, corrosive and releases HCl and SO2. Anything to make SOCl2 will be nasty to work with, as will separating, purifying and working with the desired product.

HCMX is something I was looking at. I have plenty of xylene and I never use it for anything really! I sometimes melt alkali metals under it but that is about it and I rarely use it as a solvent. I thought about chlorinating it and using it as a nicer chlorinating agent than the usual candidates.

Sauron: Does HCMX or Benzotrichloride react with anhydrous sodium sulphite perhaps?

Sauron - 31-1-2009 at 15:10

Jor apparently has no fume hood.

I just looked up Cl2O in Brauer and this is not so bad. Cl2 dried with H2SO4 as usual us passed into a large U-tube packed loosely with shallow HgO and glass wool plug alternating, the U tube is placed in a water bath regulated to 18-20 C. The best yields are when the Cl2 is admixed with 2 to 3 volumes of dry air. The exit gas is dried over P2O5. I do not yet have the details of the reaction with sulfur in the cold, but I would use the Cl2O directly. It is a yellow-brown gas and EXPLODES ON CONTACT WITH ORGANIC MATTER so don't let it near any. It is also possible to prepare Cl2O in CCl4, but whether that solution is suitable for the rxn with S is an open question. See the pages from Brauer 299-300 attached.

Now I launch myself into Melloe Ch 57.

[Edited on 1-2-2009 by Sauron]

Attachment: Pages from brauer_ocr.pdf (76kB)
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Jor - 31-1-2009 at 15:10

I do not wish to work with SO3. It is extraordinary hazardous ,if I was told right.
First my fume hood motor will be destroyed by it. Second when you work with it a constant stream of smoke will exit the roof. The neighbours will be thinking, what is happening

.
Thirdly and most importantly, I am too afraid to work with it to be honest.
Don't get me wrong, I think it is an extremely useful chemical!
If really want SO3, I think I will one day make a large investment in 1 liter 65% oleum (110 euro Merck). .

I simply do not want to invest the time/money/room in a tube furnace. Realise 90% of my experiments are test-tube scale, making inorganic complexes. I only sometimes do synthesis on a large scale. Thionyl chloride is one of those chems I want to make. But then I rather go via Kyrid.
I simply do not have much experiments that require a tube furnace. But in the future, when I will advance to more complex inorganics, I will make one, as you need one quite often (for example Brauer).

How do you guys handle SO3? Fumehood or outside ofcourse. But what kind of gloves? Because skin will be destroyed instantly, to black tar.

Sauron - 31-1-2009 at 15:18

Consider adding a scrubber system.

You and your neighbors will be happier.

Your blower's motor should be totally isolated from hood exhaust. If it is not you will have a lot of grief.

WOW. I thought I knew my way round SOCl2 but I really ought to have had recourse to Mellor Ch. 57 pp 556-565 sooner. Here they are by attachment.

What I went fishing for, the Cl2O rxn with S, is there with refs, and details, and in addition there are a number of startling preparations which will be of great interest.

The reaction of Cl2O with sulfur is normally very violent, so it is expedient to carry it out in S2Cl2 (sulfur monochloride) as solvent at -12 C.

I will not spoil the surprises for you all. Read the extracted pages.

[Edited on 1-2-2009 by Sauron]

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S.C. Wack - 31-1-2009 at 16:14

Well as you look in Mellor, or anywhere else, you may find it difficult to pin down the sulfite reference on any particular one of Carius' papers. His name always comes up, but always in connection with two or more refs to different things, or none at all. Or calcium sulfite is mentioned instead. It is not mentioned in Gmelin's SOX2 volume at all. In any case the ref is quite old and quite possibly without much detail, and it's a matter of just doing it or not.

Suspects are:
http://dx.doi.org/10.1002/jlac.18581060309
http://dx.doi.org/10.1002/jlac.18591110111

I posted a link to Wurtz's paper on Cl2O and S in the relevant thread almost 4 years ago now - would you believe that SOCl2 has come up before, and more than once. The link still works.

[Edited on 31-1-2009 by S.C. Wack]

Sauron - 31-1-2009 at 16:30

Thanks, S.C. Jor may want to look into that muddle but I am more interested in some of the other stuff in there. Sadly I do not have Gmelin.

mellor is a pain about references because of the manner in which he presents them. They are unnumbered, in order of their appearance in the text, and run together. So while they are not random, they are still needles and it is still a haystack. Oh joy!

[Edited on 1-2-2009 by Sauron]

solo - 31-1-2009 at 16:37

................had you used the search engine ...you might have not started another thread on a subject that's been discussed at excess......solo

https://sciencemadness.org/talk/viewthread.php?tid=1439&...

Note - here is one method mentioned there....

The catalytic oxidation of sulphur dichloride by oxygen
Alwyn G. Evans and G. W. Meadows
Trans. Faraday Soc. 1947, 43, 667 - 674,

[Edited on 1-2-2009 by solo]

Attachment: synthesis of thionyl chloride-The catalytic oxidation of sulphur dichloride by oxygen .djvu (170kB)
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Sauron - 31-1-2009 at 22:47

I like this Cl2O reaction more and more. You need some S2Cl2 as solvent, which is reusable. You need some HgO catalyst, which is partially converted to HgCl2, and that is useful. Otherwise the materials are simply Cl2 and dry air on one hand and sulfur on the other and you can and should make your own S2Cl2 from same two elements anyway

Make and use the Cl2O in situ.

Cl2O has a great affinity for water and forms HClO, so can be regarded as hypochlorous acid anhydride. Its incompatibility with organic material is therefore underscored. The Cl2 and air need to be dry.

Cl2O converts CS2 to SOCl2 and phosgene. That one will be unpopular on both sides of the equation.

woelen - 1-2-2009 at 00:45

Jor, the CS2/Cl2O route might be an option for you. CS2 can be obtained easily for us, HgO can also be purchased and the others are not a problem at all. Lead the phosgene into toluene, giving you a useful by-product.

The only thing is that I expect that the CS2 must be really cold, and the Cl2O must be diluted with air, otherwise I think you will get fireworks instead of SOCl2

. Having the CS2 very cold has the added advantage that less vapor is drawn into the phosgene stream, allowing for purer phosgene.

Sauron - 1-2-2009 at 01:18

CS2 is expensive and a fire hazard, combining something that flammable with a gas that is known to be a wee bit touchy strikes me as less than ideal. To put the final nail in the coffin, unlike the rxn with sulfur in S2Cl2 at -12, the rxn between Cl2O and CS2 produces a mol phosgene for every mol SOCl2.

So I think thumbs down on this one.

I recognize that Jor has certain qualms about sulfur chlorides, but he is going to have to deal with some of his phobias or else give up on making thionyl chloride, which as chemoleo says is not exactly eau de cologne itself.

woelen - 1-2-2009 at 01:39

Remarkably, CS2 is not that expensive for us and we can buy it in 1 liter quantities, more than we ever need. But of course, I agree on the flamability of this liquid and that's why I made the remark about the fireworks.

Whatever route one chooses for making SOCl2, one always has to be prepared to deal with nasty chemicals, this is not something for the average home chemist.

Sauron - 1-2-2009 at 02:05

That's for sure.

Jor told me he already has HgO.

He was going to make his own PCl5 from red P so he was not averse to generating and drying Cl2. A cylinder of air or a compressor is a piece of cake. S2Cl2 is a great solvent for S. Anyone who has ever made it will tell you that.

I don't want to imprimatur this method till I read the original Wurtz papers. I am still struggling with Melloe.

panziandi - 1-2-2009 at 11:32

Well indeed I thought it's a bit silly to say you want to avoid certain nasty chemicals for smelly, toxic, corrosive reasons yet you are making a vicious toxic, smelly, reactive, and corrosive chemical anyway!

The Cl2O method sounds promising Sauron so long as the glassware is all spotlessly clean! I think anyone performing the Cl2O + S reaction should probably operate from behind a perspex shield or take a similar precaution incase of an explosion in the set up. Other than that it does sound quite simple. The first bit of chlorine produced could be lead into a flask containing excess sulphur, forming in situ sulphur chloride which would dissolve the rest of the sulphur, then switch the chlorine path so that it is lead through the catalyst bed and over into the mix.

Jor - 1-2-2009 at 11:59

Panziandi, as a answer to your first post in this topic:
-sulfur chlorides just stink very bad, much worse than SO2 or SOCl2. I don't want to stink up the neighbourhood. For this reason I also never generate any H2S.
-SOCl2 is also corrosive, just like SO3. But you know SO3 is extremely corrosive, and SOCl2 is 'just' very corrosive. I have had a drop of SOCl2 on me. It hurts but I'm fine. SO3 would have left me with a black hole.

It's just that I don't like to work with chemicals wich can really harm you, even if you work very carefully. SOCl2 is not like that. it is corrosive, can make you cough, but won't cause permanent injury or kill you if you work with care. Oleum can.

SOCl2, HCl, SO2, etc are toxic and corrosive, but not too bad. Not very stinky, not dangerously corrosive, not extremely toxic.

I think the Cl2O method is definately interesting. S2Cl2, ok I will generate a bit for use as solvent, to overcome my phobia.
I have HgO. Produced HgCl2 can be converted back to HgO.
i see one problem. Cl2O. We know how reactive a 5% acidified hypochlorite solution is. Cl2O, the ahydride... Sounds extremely dangerous. If I attempt this, I will clean all glassware with boiling HNO3 or chromic acid.

The catalytic oxidation solo mentions also is interesting, but you need a lot of glassware for it. I will look into that later.

After all, I think Kyrid method is the less dangerous, easiest one. No use of very toxic chemicals, no smells, and risk of explosion. This is my preferred method. By product is benzoyl chloride.

Formatik - 1-2-2009 at 12:42

Whereas CS2 causes a lively explosion with Cl2O forming SO2, CO2, Cl2 and S2Cl2. CCl4 can also be used to milden the reaction between CS2 and Cl2O (see Schützenberger, Ber. 2 [1869] 219) to form SOCl2, COCl2.

Gmelin gives the reactivity of Cl2O. Concerning reaction with sulfur in a solvent or not, it is not much different than what is found in Mellor since they both draw on some of the same references. Generating Cl2O, you would need to know more hazards about it. E.g. Cl2O explodes occasionally just at room temperature. Valuable preparation and saftey also covered in Gmelin. I could scan all of the pages of Cl2O, but I haven't been able to find a decent pdf compiling program of sufficient quality.

panziandi - 1-2-2009 at 12:52

Sorry I just found it a little amuzing that's all! Not calling you a twit or anything, I know HOW smelly sulphur chlorides are a flask broke once whilst I was making some before...really not nice!

I would highly suggest you submerge all glassware in sulphuric/peroxide or chromic acid, trouble with boiling nitric is I could imagine U tubes etc being hard to clean with refluxing nitric, and you really want to ensure NO organics on ANY part. But then again the reaction does seem nice! And the sulphur chloride solvent could easily be made in situ and you wouldn't be exposed to it.

Sauron - 1-2-2009 at 13:17

Why not use CCl4 with sulfur instead of S2Cl2 to moderate the rxn w/ Cl2O?

The Cl2O producing reaction over HgO is rather slow. Brauer says c.5 hours a acculate 15 g Cl2O in trap. Sounds like 3 g an hour. So this is a method for making maybe 50 g a day SOCl2. If is a much better way of making HgCl2. Look at the stoichiometry in Brauer.

If this is too slow you had best consider another method. I have three suggestions.

Kyrides

Kyrides

Kyrides.

[Edited on 2-2-2009 by Sauron]

Jor - 1-2-2009 at 14:04

Yes Kyrides.

You need phthaloyl chloride, wich is expensive, but can be made from phthalic anhydride quite easily, using benzotrichloride.

So all materials you need are benzotrichloride, phthalic anhydride, a little ZnCl2 and SO2. The benzotrichloride is made by chlorination of toluene as len1 has showed in republication. This seems this requires no hard to get chems.
However, I'd rather skip the chlorination of toluene and buy benzotrichloride.

But before buying the benzotrichloride in a month or two, does anyone know if I can prepare phthaloyl chloride from PCl5? I know it can be produced from benzotrichloride and phosgene, so I'm pretty sure PCl5 should work as well, but confirmation would be great.

[Edited on 1-2-2009 by Jor]

[Edited on 1-2-2009 by Jor]

panziandi - 1-2-2009 at 14:47

Yes, PCl5 will chlorinate phthalic acid and you would distill off the POCl3 product which is easily doen since phthaloyl chloride boils much higher than POCl3.

DJF90 - 1-2-2009 at 14:57

Or use the PCl5 to make TCT, which can then be used to chlorinate phthalic acid with even less separation problems

Jor - 1-2-2009 at 14:57

Quote:

Originally posted by panziandi
Yes, PCl5 will chlorinate phthalic acid and you would distill off the POCl3 product which is easily doen since phthaloyl chloride boils much higher than POCl3.

Do you maybe have a reference for me? Does the reaction need a solvent or can I just mix the dry powders, and heat it, distilling of POCl3?

If I can go via PCl5, I will have my SOCl2 really soon!

Within 2 weeks, the required glasware for PCl5 synth. from red P arrives. I have phthalic anhydride at hand. So then I would be ready to set off.

I will make pictures when I have completed it.

If TCT would work, I would probably buy it, but TCT does not work, according to Sauron, be he's not sure.

[Edited on 1-2-2009 by Jor]

panziandi - 1-2-2009 at 15:09

Yes do take pictures it would be interesting to see this.

Well I don't have a ref at hand. If you look in Vogel in the forum library you will probably find some typical preparations of acid chlorides form PCl5 follow one of those, there may even be one for phthaloyl chloride, I do not know since I can't download Vogel atm.

BAsically you would just mix phthalic acid and the PCl5 in a flask, the PCl5 will chlorinate the acid, forming the liquid products which will dissolve the reactants and make the reaction go quicker! The reactions are usually quite exothermic (I once had a pyrex flask crack from reaction of PCl5 and and acid within minutes of mixing!)

Jor - 1-2-2009 at 15:22

I don't think phthalic acid should be used! Phthalic anhydride!

First I think it is less reactive, second, if the method works, it will consume more PCl5!

panziandi - 1-2-2009 at 15:42

I'm not aware of phthalic anhydride going to phthaloyl chloride.

The acid would react like this:

C6H4-(COOH)2 + 2PCl5 → C6H4-(COCl)2 + 2POCl3 + 2HCl

I can't see the anhydride breaking open. You can get acid anhydrides to react with HCl to give acid chlorides...

Sauron - 1-2-2009 at 20:24

Read Kyrides. You do not need PCl5 to make phthaloyl chloride. You make it from phthalic anhydride and benzotrichloride at 200 C for 20 hrs. The anhydride does open up and the byproduct is benzoyl chloride. See my thread A Twofur Reaction. Benzoyl chloride is very useful in its own right for among other things, making acyl chlorides of more volatile carboxylic acid (See H.C.Brown. in JACS) They are formed almost quantitatively and are seperated by fractionation. Hence thread name Twofur One. Two for One.

Phthaloyl chloride has some special properties and is good for making acid chlorides from 5 and 6 membered cyclic anhydrides. For monocarboxylic acids other reagents (TCT, benzoyl chloride) are cheaper. For special cases see my thread on mild chlorinating agents.

SOCl2 is not my fave for most acyl chlorides, it however is the only one that works to make the dichloride of malonic acid. TCT fails at this. TCT works for oxalic and succinic acids - go figure.

Here is Kyrides paper from JACS. There is also a petent he took out for Monsanto his employer.

[Edited on 2-2-2009 by Sauron]

Attachment: Kyrides_phthaloyl.pdf (318kB)
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Sauron - 1-2-2009 at 20:38

And the matching US patents

I had a go round with Len1 about this. He was pushing the oxidation of sulfur chlorides with SO3, and criticized Kyrides procedure for allegedly low yield. The yield was 60-something % which I regard as not bad, especially when one considers the following:

Kyrides was dripping liquid SO2 onto a melt at 200 C therefore residence time is very low.

Kyrides made no sttempt to cold trrap the off vapors and states that considerably SOCl2 may have been carried out that way.

So IMO simply adding a dry ice-acetone trap ought to improve the yield and injecting SO2 under pressure deeper into the melt ought to increase residence time with same effect.

Did I forget to mention ZnCl2 is required catalyst? In small amount.

Len1 was justly pleased and proud of his SOCl2 prep but I thought and still think he gave Kyrides short shrift.

Jor, put your red P away for something where it is needed. This is not it. Making TCT from CA with PCl5 is possible, but buying it is also possible. Using TCT to make phthaloyl chloride is possible but not supported in the lit. to best of my knowledge. And in light of Kyrides, unnecessary.Jor, put your TCT away as well.

[Edited on 2-2-2009 by Sauron]

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garage chemist - 3-2-2009 at 05:17

Jor, look at what Len1 has done regarding SOCl2 synthesis.
With benzotrichloride, there was no reaction at all:
http://www.sciencemadness.org/talk/viewthread.php?tid=10490
If you want to make phthaloyl chloride from PCl5, remember to cleanly separate the POCl3 before reacting it with SO2- the separation of POCl3 and SOCl2 is surprisingly difficult, as I have already stated.
Phthalic anhydride would of course be the better choice, since only 1 mol PCl5 is needed for 1 mol of phthaloyl chloride, and no HCl is produced:
Ph(CO)2O + PCl5 ---> Ph(COCl)2 + POCl3

Using Cl2O would be beyond insane.
This substance is highly explosive and can detonate without apparent cause. This would be far, far more dangerous than working with SO3 could ever be!

I repeat my recommendation to use the SO3 + SCl2 method instead of the Kyrides method.
SO3 is dangerous, but completely manageable in a home lab.
In my many experiments involving it, I have never even worn gloves, to be honest.
I once got a drop on my finger- it immediately becomes black and hot, but the black color completely washes away with water, leaving no visible injury!
If there is immediate washing upon skin contact, no visible harm is done.

Sauron - 3-2-2009 at 08:23

Len1's experiment with benzotrichloride was not supported by the literature. He did not employ any catalyst as required by the literature, and his negative result is therefore unsurprising. The catalysts are not exotic nor are they expensive. FeCl3 (anhydrous)) is one of them.

PCl5 is a wasteful way to make phthaloyl chloride. The ZnCl2 catalyzed reaction of phthaloyl chloride with SO2 is fast and efficient and the huge difference in bp's meakes purification easy. :en1 did not try this method and was unduly critical of it simply because it represented a viable alternative to his pet method.

As to Cl2O I agree that the rxn with CS2 is hazardous, and I do not recommend it.

The generation of this gas as described in Brauer however, is quite slow, so that if the Cl2O is reacted with S in S2Cl2 in the cold and the generator U-tube is also cooled as stated, the Cl2O does not accumulate but reacts in situ. If it were to accumulate the rate is c. 3 g/hour. Therefore the amount of Cl2O present in the system at any time, when it is being consumed as fast as it is being made, is trivial. 3 grams per hour means 50 mg/min being formed. What is the explosion hazard from say 1oo mg of this gas?

That does not sound like Krakatoa to me.

On the inlet side we have a cyl of dry air and a Cl2 generator and a drying train. These go to a U tuve submerged in an ice-brine bath at -12 C. The U-tube contains HgO. The U-tube is connected to the reactor containing S in S2Cl2 also chilled to -12. The Cl2 forms in the U-tube and is reacted in the solution of S. Both the U-tube and the reactor are under water and well chilled. So on this scale just what exactly is the explosion hazard?

The valid criticism of this method is that is slow.

If it were possible to scale it up your point would be well taken, but on the Brauer scale it looks safe enough to me.

Jor has never said how much SOCl2 he wants to make.

[Edited on 4-2-2009 by Sauron]

panziandi - 3-2-2009 at 10:49

I have to agree with Sauron, I see no real danger in the Cl2O method so long as the reaction is performed at a low temperature since the levels of Cl2O generated at any one time is very low and immediately would be carried over in a current of air to react (I would imagine very rapidly) with the sulphur.

Sauron - 3-2-2009 at 12:32

Also for those who prefer not to work with S2Cl2, CCl4 is a suitable replacement. I wonder whether other perchlorinated hydrocarbons are also inert to Cl2O? Hexachloroethane?

If a larger quantity of SOCl2 is needed than 50 g a day I suggest the Kyrides method, or the SO3 oxidation of SCl2, or the HCMX/catalyst method.

I just ran a quick cost analysis for the SO3 method vs the Kyrides method, and also between buying phthaloyl chloride for the latter vs making it from benzotrichloride. Surprisingly, all three methods come out roughly the same, hovering about 60 cents a gram for SOCl2 product.

The Cl2O method is a lot cheaper, since the air and chlorine cost about nothing, and the Hgo catalyst is regenerable, and S costs about nothing. Once again its main drawback is that it is tediously slow.

[Edited on 4-2-2009 by Sauron]

S.C. Wack - 3-2-2009 at 15:53

I can't see how the method in Brauer can give a specific yield when the experimental is so vague; maybe it's easy to add the chlorine too fast or slow. The related version in Inorg. Syn. gives some better guidance.

[Edited on 3-2-2009 by S.C. Wack]

Jor - 3-2-2009 at 16:16

I have decided that I am going to make one large batch of thionyl via Kyrides, when I have the money to buy the chemicals.

Phthalic anhydride is one of the cheapest chems I know. I already have 200g. Benzotrichloride is also very cheap, a liter from Acros at 25 EURO.
Even without a good collumn, seperation seems rather easy. Maybe I lose some phthaloyl chloride when I collect the benzoyl chloride fraction, but that's not a real concern.
My largest flask is a 250mL 3-neck, so I can't do everything in one go. Well no problem, that I can trial and error the first time.
Zink chloride, I sealed old Merck bottle, so that's not a problem as well. And SO2, i will buy some more potassium metabisulphite (home brewers use it, it is dead cheap). So basically, this is a very cheap synthesis of thionyl chloride, but the only problem is that you need quite some time to perform the reaction, and I don't want to leave a reaction unattended.

I think the method of Cl2O is a very nice one, but indeed, you spend a lot of time, only getting 3g of Cl2O. I'd rather first hear other people's experiences.

By the way, thanks Sauron for your last 2 PDFs. I will use that procedure.

And as a back-up method, I can go via PCl5, like garage chemist noted. This is precious, but I can buy red P, so I can make it via GC method, substituting chloroform for DCM. Would distilling the phthaloyl chloride a second time without vigreux seperate it from most POCl3? I do not mind a 1-2% POCl3 contamination in SOCl2.

[Edited on 3-2-2009 by Jor]

len1 - 3-2-2009 at 18:50

Quote:

Len1's experiment with benzotrichloride was not supported by the literature. He did not employ any catalyst as required by the literature, and his negative result is therefore unsurprising. The catalysts are not exotic nor are they expensive. FeCl3 (anhydrous)) is one of them.

My guide details the use of ZnCl2 catalyst.

It also details how phthaloyl chloride is obtained from PhCCl3 in good yield. I still have 120ml of it, but using this to get SOCl2 in low yield does not excite me. I actually agree with GC, which I guess is not surprising because he does what he says.

This forum is an ancient hostory of posts of people promissing Ill do this, Ill do that, and then nothing. Its all on archive. Check. Wish you better luck.

Sauron - 3-2-2009 at 21:19

You continue to obfuscate, Len1, ZnCl2 is not the succesful catalyst in the benzotrichloride or HCMX chlorination of SO2, and so it remains unsurprising that your attempt with it failed. You continue to characterize a 66% yield as low, when in fact you are well aware, because I pointed out to you months ago, that Kyrides himself stated that he made no attempt to analyze the contents of his cold trap and that a substantial amount of SOCl2 was probably admixed with SO2 there. So a simple steo would have increased the already good 66% yield to yield perfectly comparable to those in "your" SO3 method - a method that actually predates the Kyrides one by decades, dating from 19th century.

As to your continued little ad hominem tirades, my reply is NUTS. Since you rarely bother to put in any appearance here, no further rebuttal is required. Go dream your dreamjs of making money publishing your handbook. It will be amusing to see how many copies get ripped off on the internet.

Jor, good decision. Acros price for phthaloyl chloride is $95 US/500 ml ehich is 750 g and 90%. Making it from benzotrichloride you get same weight phthaloyl chloride as you put in, and you get benzoyl chloride as well so the effective cost plummets. The bp of phthaloyl chloride is almost 300 C so you will have little trouble distilling off the benzoyl chloride. The phthaloyl chloride will stay in the pot. Kyrides says 94% pure, remainder is phthalic anhydride. Same impurity in the commercial product.

S.C.Wack, the Brauer writeup clearly states that 15 g Cl2O collected as solid in the LN trap over 4-6 hours. If we take that to be 5 hours then 3 g/hr is the mean. No the author did not detail exact rate of flow of Cl2 and air. Rather hard to do so reproducibly without a flowmeter or a mass flow controller isn't it? However, I do not see how it matters. The amount of Cl2O in system, when it is being consumed in situ, will remain very low at any given time with any reasonable rate of flow.

I will take your hint and have a look at Inorg.Syn. on this. It really is not a fast enough method for my purposes, but, it's good to have details. Here is the citation you did not provide: Cody in vol 5 p 156. I have this and will post it shortly.

The attached file includes generation of neat Cl2O, and its solution in CCl4; its dissolution in water to produce HOCl, and the preparation of calcium hypochlorite from that hypochlorous acid solution.

[Edited on 4-2-2009 by Sauron]

Attachment: Pages from IS-5.pdf (307kB)
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Sauron - 3-2-2009 at 23:39

It should be obvious to anyone reading the Inorg.Syn. article that the preparation of Cl2O in situ in CCl4 is easier and safer and faster than the methods for making the neat gas or condensed Cl2O.

To briefly summarize, a solution of Cl2 in CCl4 is prepared of known Cl2 content, and dry yellow HgO is added 3.36 g per g Cl2, the mixture is stirred, and the precipitate is removed by filtration. It is stated that initial yield 97% is reduced by losses in filtration. I would therefore suggest a pressure filtration through a fritted glass filter. (Not vacuum filtration).

The regeneration of the HgO catalyst which is facile is also described.

The resulting solution of known amount of Cl2O in inert CCl4 can then be used to prepare SOCl2 by the slow addition of slifgt excess dry S at -12 C. The SOCl2 can then be distilled from CCl4 and unreacted S.

UNFORTUNATELY SOCl2 and CCl4 have exactly the same boiling point 76 C.

Workaround: find an alternative inert solvent. Trichlorobromomethane would work. Hexachloroethane would work.

This makes one wonder about all those articles cited in Mellor about the use of CCl4 to moderate the rxn of CS2 and Cl2O. The SO2 will be impossible to separate from the CCl4 at least by fractionation.

------------------

The attached JACS article from 1982 described the use of Cl2O as a powerful selective chlorinating reagent for organic substrates. If this is "beyond insane" the please take it up with the ACS and the authors. Personally I find it very interesting that the alleged demon Cl2O has been tamed and put to practical use on organic substrates without explosions.

The authors employed Cl2O c.1 M in CCl4 which they state can be safely handled and stoted < 0 C. The reagent gives 99% yields of benzotrichlorides even with deactivated arenes such as p-nitrotoluene - these benzotrichlorides are otherwise very difficult to prepare and are useful in the synthesis of the corresponding trifluoromethylbenzenes.

They went on to demonstrate the use of Cl2O in TFA to effect primary ortho ring chlorination of deactivated arenes.

All very interesti

[Edited on 4-2-2009 by Sauron]

Attachment: ja00381a032.pdf (385kB)
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panziandi - 4-2-2009 at 04:47

VERY interesting Sauron! I agree with you about the limited danger of Cl2O, sure if you generated bucket fulls in one go the explosion risk would be real, but when you realise the catalyst bed is turning out 3g/hr diluted in a carrier gas, the danger isn't that real especially if the Cl2O is being reacted in situ and not collected. And by operating at <0*C too...

If I have time when I next go home, perhaps I shall try a Cl2O chlorination of something...

Sauron - 4-2-2009 at 06:57

This ties in very nicely with the chlorination of CS2 to make CCl4.

Because that reaction produces first a mixture of Cl3CSCl and S2Cl2, then after distillation and refuction of the trichloromethyl sulfenyl chloride to CCl4, the sulfur chloride is left over as a side product.

Now we have a USE for the side product, as solvent for the production of SOCl2 from S w/Cl2).

And yet another use for the CCl4, as solvent for in situ generation of Cl2O, for the preparation of benzotrichloride and HCMX. In both cases the solvents are recoverable.

It is unfortunate that the S can't be reacted in CCl4 since the SOCl2 can't be separated from the carbon tetrachloride. I really want to find a higher boiling alternative inert solvent compatible with Cl2O. Where I am I cannot buy CCl4. That's why I have to make it.

Upthread when I mentioned hexachloroethane I overlooked the fact that it is a solid.

The main two candidates therefore are Cl3CBr and tetrachloroethylene. But I am not sure the former will not halogen exchange with Cl2O, and I am equally uncertain that the pi bond in the latter is inert to Cl2O. I know I can buy the bromotrichloromethane because I have a liter of it here. I have not tried to buy the tetrachloroethylene ("perc") yet.

------------

Cl2O reacts with Cl2C=CCl2 to form a mixture of chlorinated and oxidation products. So this solvent is not inert. Lit. shortly.

[Edited on 4-2-2009 by Sauron]

panziandi - 4-2-2009 at 09:15

You could always attempt to make a solution of Cl2O in the Cl3CBr and then perhaps remove the Cl2O by addition of a reducing agent, then analyse the Cl3CBr to see if there is any CCl4 present in it? If there is a halogen exchange then the Cl3CBr can not be used as a solvent, on the other hand if there is an exchange you have another method of preparing CCl4! Just a note of reminder, HgF2 can replace halogens in trihalomethanes with F's, just a proposal that HgCl2 may perform a similar reaction (and it is a by-product of the conversion of Cl2 > Cl2O)...

Sauron - 4-2-2009 at 09:48

Here's Chemical Review monograph on the chemistry of Cl2O from the 1970s. Cl2O is of industrial and technological importance, particularly in the bleaching of wood pulp.

[Edited on 5-2-2009 by Sauron]

Attachment: cr60302a004.pdf (532kB)
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S.C. Wack - 4-2-2009 at 16:11

Quote:

Originally posted by Sauron
S.C.Wack, the Brauer writeup clearly states that 15 g Cl2O collected as solid in the LN trap over 4-6 hours. If we take that to be 5 hours then 3 g/hr is the mean. No the author did not detail exact rate of flow of Cl2 and air. Rather hard to do so reproducibly without a flowmeter or a mass flow controller isn't it? However, I do not see how it matters.

So what? How are we supposed to figure out the amount of reactants based on yields, when we don't even know conversion %'s? How could a lack of detail such as amount of reactants to obtain a specific yield, or at least the yield based on reactants, not matter? I'm supposed to build a flow rate based on that, when I don't even know how much chlorine is converted with an amount of HgO that is not given other than "shallow layers"? I'm all for experimentation, but vague, unreproducible experimentals are not quite so great as explicit ones, as I innocently, I thought, pointed out.

Sauron - 4-2-2009 at 21:50

S.C., don't get your knickers in a twist. You'll do yourself an injury.

Forget the prep of neat Cl2O,

These problems do not exist in the prepn of Cl2O soln in CCl4 where the Cl2 content of the CCl4 is quantifiable by iodimetry and for that matter by weight. Knowing how many g Cl2, one adds dry yellow Hgo prerpared as advised, in the specified amount per g Cl2 (3.36 g if I remember) and stir. The conversion is c.97%. Did you read the review from CR? Or the JACS article? Or for that matter the very Inorg Syn writeup you recommended? (Thanks.) If so then your criticisma are all answered.

There is another JACS article on the analysis of mixtures of Cl2) and Cl2.

In the sole instance where in situ prepn in CCl4 is unsuitable, that of SOCl2, the Inorg.Syn. method is followed in preference to the one from Brauer, the amount of ractants are specified, 5 L/hr Cl2 and 5 L/hr air, the amount of catalyst is specified, and the conversion is estimated. I'd simply run it into the solution of excess S in S2Cl2 and based on weight gain, stop the Cl2 flow when done, flush the reaction tube with air only, then stir the S2Cl2 mix some more before distilling off the SOCl2. No similarity in bp there. There's 60 degrees between the thionyl chloride and the solvent.

No Cl2O will remain in the system either in the generation tube or the reactor pot. The S2Cl2 can be reused (just add sulfur) and the HgO regenerated by boiling with NaOH then drying as described in the texts.

panziandi - 5-2-2009 at 02:35

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?

Sauron - 5-2-2009 at 02:44

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.

panziandi - 5-2-2009 at 03:49

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.

Sauron - 5-2-2009 at 08:25

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.

panziandi - 5-2-2009 at 08:48

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!

Sauron - 5-2-2009 at 09:29

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.

panziandi - 5-2-2009 at 09:41

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.

Sauron - 5-2-2009 at 10:17

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.

Formatik - 7-2-2009 at 16:20

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.

Sauron - 8-2-2009 at 04:18

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)
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S.C. Wack - 8-2-2009 at 08:11

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.".

Sauron - 8-2-2009 at 08:42

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]

S.C. Wack - 8-2-2009 at 09:55

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.

Sauron - 8-2-2009 at 10:13

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)
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Formatik - 8-2-2009 at 22:50

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.

Sauron - 8-2-2009 at 23:31

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]

Klute - 9-2-2009 at 03:39

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.

Sauron - 9-2-2009 at 04:10

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.

Sauron - 9-2-2009 at 04:35

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.

Sauron - 9-2-2009 at 10:12

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.

Formatik - 9-2-2009 at 10:46

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.

Sauron - 9-2-2009 at 17:27

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]

Formatik - 9-2-2009 at 18:05

I didn't mean to imply confining the statements to liquid Cl2O, especially since that is too hazardous to work with to begin with.

Sauron - 9-2-2009 at 18:43

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.

Sauron - 10-2-2009 at 06:57

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.

Damitwhy - 30-8-2011 at 21:23

I've found myself with a spoilt Sulphur trioxide Oleum sample of 28.8grams which after all the hard work in making decided to go ahead and try to use in making SOCl2 with SCl2 made previously...

I set up reflux condenser and dropping funnel on two neck adaptor attached to a 250ml flask, weighed and placed 30grams Sulphur Dichloride in flask with magnetic stir bar, weighed and placed cold (suspect) Oleum in dropping funnel, flask was cooled in ice bath ontop of magnetic stirrer hotplate.

Began adding (suspect) Oleum dropwise with stirring at a slow rate, bubbles of gas could be seen flowing into a Sodium Hydroxide solution that was attached to the gas out let from the drying tube on the condenser....

After all (suspect) Oleum was introduced I continued stirring changed ice bath then took a break...

Several hours later I returned to find ice had melted but slow bubbles in hydroxide outlet were still being produced so turned off magnetic stirrer and let settle to find reaction mixture had two liquid phases one light yellow top layer and one dark brown lower layer.

I changed to oil bath and swapped out the dropping funnel for thermometer to measure refluxing temp and I began to reflux with Hotplate Temp at 80ºC and found reflux temp to be 39ºC - 42ºC.... This is when I realized some thing was'nt quite right...

At this point I could only assume that I hadnt quite gotten all the Dichloromethane out from the production of the Sulphur Dichloride and it must be a contaminant either that or something else with a lower Boiling Point had been made...

So I've refluxed for another hour then set up to distill what I can monitoring temp of distillate to be ranging from 25ºC right up to 55ºC before no more distillate comes over...

Dark brown liquid still remained in flask and distillate has slight yellow colouration but still bubbles are visible in Hyroxide solution attached to gas outlet on receiver flask...

I decided to change receiving flask and continue distilling with increased heat I found with each increase up to 130ºC a Yellow Distillate would be seen creeping up the swan neck toward the condenser but this was slow in froming and not enough to collect in the receiver...

So After redistilling the distillate it turns slightly lighter yellow but still fumes in air and 5ml or so evaporating completely with strong acidic sulphur smell within seconds when poored in a beaker in the fume hood... Is this my Thionyl Choride? will test later today...

Re tried all the above with Concentrated Sulphuric Acid inplace of (Suspect)Oleum and found all results nearly completely the same Just less residual darkbrown liquid after distillation..

I found the Residue NOT so much the distillate reacts violently with water producing copious amounts of white gases/steam with lots of heat and the strong acidic smell of Hydrogen Chloride and Sulphuric Acid..

Tell Me What Could be the Residue?

AJKOER - 29-6-2012 at 10:16

Would it be possible to safely perform the following based on the reaction of Sulfur with an organic solution of Cl2O from aqueous TCCA:

1. Add a small amount of water to TCCA to form a concentrated HOCl solution. Actually, due to a limited hydrolysis of TCCA in a neutral solution, this reaction may proceed very slowly until Step 2 is performed to drive the reaction to the right .

2. Add CCl4 to capture Cl2O by shaking. Note, any Chlorine also formed from decomposition of HOCl to HCl reacting with TCCA, will also does dissolve in CCl4, but HOCl itself is not soluble.

3. Keeping a low concentration of Cl2O in CCl4 (under 10%), slowly add small quantities of Sulfur (not finely powdered) to the mixture. This is assuming the absence of an immediate detonation and a not overly vigorous reaction that cannot be controlled by cooling and/or working with a cooled reaction mixture.

[Edited on 29-6-2012 by AJKOER]

Litmus - 26-6-2014 at 22:29

All kinds of ideas come to mind for generating SOCl2. Many of the ideas proposed on this thread I'm not versed enough to give a useful reply. But I get the general impression that making this stuff is tricky business, resulting in the thread's domination by a pitched battle between Len's ambitious synthesis by the more or less industrial route, involving first the generation of S2Cl2/SCl2 and then subsequent oxidation by SO3, a nasty corrosive sewer gas you don't want to get near to as pointed out by Sauron, while Sauron touts the Kyrides method, which involves an equilibrium reaction between the more user-friendly SO2 and the chloric acid of Phthalic acid anhydride, TCL (more or less) pushed to the SOCl2 side and catalyzed by zinc chloride(or the ZnCl2 helps push it to the left). Anyway, both methods have their pros and cons, involving yields, experimental difficulties, number of reagents involved and their hazards, etc. As far as I can see.

Sulfur dichloride or disulfur dichloride is easy enough to make. A simple experiment is described here: http://lanthanumkchemistry.over-blog.com/160-index.html More or less Len's first step in his synthesis. I guess the question that comes to my mind, is why can't S2Cl2/SCl2 be oxidized more simply, i.e. via hydrogen peroxide or some other easier oxidation route. Seems to me you're more than half-way there with sulfur chlorides, but not.... Hmm.

Anyway, there's another method mentioned on the Wikipedia page on SOCl2 that uses SO2 and doesn't require phosphorus, done with phosgene. Note phosgene is also a decomposition product of chloroform and perhaps methylene dichloride as well when exposed to UV light(why it's stored in brown bottles), and a common byproduct of the haloform reaction( as in the well-known reaction between sodium hypochlorite solution(bleach) and acetone). Okay, phosgene's no fun either, but nonetheless it sounds intriguing. I've been researching this up and down for awhile and found nothing so far. So many on the forum seem much better at this. If someone can point me in the right direction, it would be a great help. The wikipedia page itself gives no references for this particular reaction. Unless it's bogus :mad:

, however the word "phosgene" is given expressly in the article regarding this reaction, which professes to produce thionyl chloride from phosgene and sulfur dioxide.

AJKOER - 4-7-2014 at 05:27

Here is a good Patent that discusses several catalysts for commercial paths to SOCl2. To quote from Patent US 3,419,353 (link to pdf viewer https://docs.google.com/viewer?url=patentimages.storage.goog... ):

"The SC12 is oxidized with oxygen, or an oxygen-containing gas, to thionyl chloride, for example, as taught by Evans et al., Faraday Society Transactions, vol. 43, pp. 667-673 (1947), by passing the two over an activated carbon catalyst at a temperature of about 150 to 250 C. As an exemplary activated carbon catalyst may be mentioned a calcium chloride-treated charcoal which may be prepared by soaking charcoal in an aqueous solution of CaCl2, followed by filtering, washing with alcohol and then with ether and drying at about 100 C."

Also, a good review of the chemistry of employed commercial routes, to quote:

"Commercial processes for the preparation of thionyl chloride, SOCl2, are generally based on the oxidation of sulfur dichloride, SCl2, with sulfur trioxide or oxygen or a combination of sulfur dioxide and chlorine. These reactions may be represented as follows:

(1) SCl2 + SO3 ---) SOCl2 + SO2 (see http://www.sciencemadness.org/talk/viewthread.php?tid=1439
(2) 2 SCl2 + O2 ---) SO2Cl2 + SCl2 = 2 SOCl2
(3) SCl2 + Cl2 + SO2 ---) 2 SOCl2 (200 C with a catalyst of activated carbon, see U.S. Patent 2,431,823)

The synthesis is often carried out in plural steps; for example, sulfur dichloride is usually first formed, or formed in situ, by the reaction of one mole of sulfur monochloride, S2Cl2, with one mole of chlorine, as disclosed by Pechukas in U.S. Patent No. 2,431,823. Then the sulfur dichloride is converted as indicated in the equations. "

This patent's suggested method is:

2 HCl + 1/2 O2 = H2O + Cl2 (Deacon catalyst)
Cl2 + S2Cl2 = 2 SCl2 (catalyst absorbent charcoal or antimony pentachloride, SbCl5)
SCl2 + 1/2 O2 = SOCl2 (catalyst charcoal treated with aqueous CaCl2, dried)
SCl2 + S = S2Cl2

For a net reaction of:

2 HCl + S + O2 ---) SOCl2 + H2O

where the water is removed prior to the formation of the thionyl chloride.
-------------------

If I dare to offer some substitutions for the home chemist, first conventiently prepare and dry Cl2 via another path than the author's requiring a catalyst. Add SO2 to reaction mix (explained below) and lastly, especially if the preparation of a good Carbon catalyst presents an issue, replace O2 with freshly prepared and dried Singlet oxygen. The latter is a more reactive species of O2 albeit with a shorter life span (30 minutes) and more costly (requires the action of dilute H2O2 on chlorine bleach, NaOCl), but I would hope for an improvement in yield.

Interestingly, to quote:

"Plasma-chemical oxidation of SO2 in air by pulsed electron beams ...
iopscience.iop.org/0022-3727/34/8/316
by YN Novoselov - ‎2001 - ‎Cited by 8 - ‎Related articles
The effects of the electron beam parameters, the external electric field and the ... are given as functions of the concentration of SO2, oxygen and water vapour in the ... Analysis of the rates of the processes involving singlet oxygen molecules."

which suggests to me a small possibility that:

2 SO2 + ¹O2 ---) 2 SO3 (with normal air, a catalyst based on V2O5/K2O/SiO2, at over 340 C, see Patent 8,323,610 )

Another source ("One conceivable mechanism of UV-light induced SO2 Oxidation to H2SO4", published in Atmos. Chem. Phys.,10,3141–3145,2010), link https://www.google.com/url?sa=t&source=web&rct=j&... , per page 3144 to quote:

"Nevertheless, the performed analysis shows readily the potential for the enhanced SO2 oxidation in air with O3 under UV irradiation via the chemistry involving electron excited oxygen molecules.The most promising is likely the reaction of SO2 with O2(b1+g,υ). "

So with the possible formation of some SO3, we have per reaction (1) above:

2 SCl2 + 2 SO3 ---) 2 SOCl2 + 2 SO2

regenerating the SO2 for more Singlet oxygen consumption,....implying the net reaction in the presence of SO2:

2 SCl2 + ¹O2 --SO2--) 2 SOCl2

which gives limited support for a small improvement with respect to substituting Singlet oxygen for O2 with a less than perfect constructed activated Carbon catalyst. However, if employing both Singlet oxygen and a heated Carbon catalyst at 200 C in the presence of some Cl2 (from the creation of the SCl2), there is a possible formation of phosgene. This issue may not be successfully addressed by allowing the reaction to proceed with an excess of SO2, enabling yet another route, via COCl2 to SOCl2, as per the previously cited Mellor reference, to quote:

"at temp, above 200° with the formation of thionyl chloride and sulphur tetrachloride according to the equations: SO2+COCl2=SOCl2+CO2 and SO2+2COCl2=SCl4+2CO2. The first reaction predominates at lower temp, and with excess of sulphur dioxide, and by suitable adjustment of conditions one or other of the reactions may be almost entirely excluded. The reactions are carried out by passing the gases over a heated contact substance, such as wood charcoal, and the carbonyl chloride may be partly or entirely replaced by a mixture of carbon monoxide and chloride, or carbon monoxide and sulphuryl chloride may be employed. This mode of preparation gives good results. "
unless the reaction temperature exceeds 200 C in the presence of SO2. Note, Cl2 in the presence of SCl2 and SO2 also forms SOCl2 per reaction (3) above.

[Edited on 4-7-2014 by AJKOER]