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Author: Subject: Chlorination of Sulphur
aga
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[*] posted on 24-3-2015 at 10:06
Chlorination of Sulphur


deltaH's thread in Energetics mentioned 'Factice', which led me to attempt to make Brown Factice.

To make White factice, the papers say that Sulphur Chloride SCl2 is used instead of elemental Sulphur, so here is my second effort at SCl2 synthesis.

From http://en.wikipedia.org/wiki/Sulfur_dichloride it appears that the reaction is multi-step and complicated, however the process is simply a matter of passing enough Chlorine gas over powdered elemental Sulphur.

Here's what i came up with :-
rig2.JPG - 190kB

In the vacuum flask on the left is 25g KMnO4 with an addition funnel on top, containing 100ml of 20% HCl, acting as the Cl2 generator.

2 KMnO4 + 16 HCl => 2 KCl + 2 MnCl2 + 5 Cl2 + 8 H2O

The gas is led to one side of the U-tube, at the bottom of which is 5g powdered Sulphur and tiny magnetic stir-bar.

To dispose of excess Chlorine gas the right hand outlet is led into a 'scrubber' filled with NaOH solution.

2 Cl2 + 2 NaOH => NaCl + NaClO + H2O.

The HCl flow was begun at ~1 drip per second, and remained there for the entire run.

At the start, the Sulphur looked like this :-

powder.JPG - 153kB

After 5 mins :-

starts2.JPG - 159kB

At 8 mins 18 seconds it was all a liquid. Note the distinct surface layer :-

nowliquid1.JPG - 152kB

At 30 minutes the liquid was very much Red. Notice the volume increase :-

redliquid.JPG - 141kB

Amazingly the bubbling of the scrubber pot could be affected by agitating the liquid at this stage.

So much so that sufficient agitation caused a slow suck-back effect.

Wagging a magnet under the stir-bar was so effective that i got carried away, causing a lot of suck-back and destruction of the product.

suckback.JPG - 153kB

In the future i must either grow up and take things seriously (unlikely) or make an anti-suck-back jar (much more likely).

Edit: typos, equations and balancing errors corrected (cheers blogfast25)

[Edited on 24-3-2015 by aga]




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[*] posted on 24-3-2015 at 10:27


Quote: Originally posted by aga  

The gas is led to one side of the U-tube, at the bottom of which is 5g powdered Sulphur and tiny magnetic stir-bar.


Ingenious.

I have made S2Br2 several times. This is easy, but never SCl2. IIRC Len1 has a procedure for making it in Prepublication. You have probably seen it I imagine.




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[*] posted on 24-3-2015 at 10:29


I also really like that setup.
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[*] posted on 24-3-2015 at 10:31


Nice job man!
Keep in mind that this stuff is rather unstable, and exists in equilibrium with both disulfur dichloride and sulfur tetrachloride (somehow both, which is weird).
At first when chlorination begins this reaction predominates:
2 S + Cl2 → S2Cl2, once all or most of the sulfur is in the first oxidation state, it oxidizes again to form sulfur dichloride, which at low temperatures can be further oxidized to the tetrachloride, which is quite unstable and only a small fraction will form regardless of excess chlorine being added. Sulfur dichloride slowly releases chlorine forming disulfur dichloride again, so it's best to store it in a freezer.
I'm going to use your setup next time I try the reaction. In the past I've used a pressure equalized addition funnel a two neck flask and a Liebig condenser to distill it as it's produced. What happens is rather than boiling it decomposes to disulfur dichloride which boils at 137.1 °C, I used a big excess of chlorine, which reacts again as shown above to form the pure sulfur dichloride. I have one ampule of the stuff left, and every time I break one to use it, pressure is released and chlorine can be detected via my usual (smell, cough, run, throw up, repete).
I like your setup cause it doesn't require distillation (and I broke my damned Liebigs, both!). However the sulfur I have is only 90% pure, the rest being bentonite clay, so that won't work...
Anyway great job!




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[*] posted on 24-3-2015 at 10:32


Keep it away from ethylene!
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[*] posted on 24-3-2015 at 10:42


Sulfur dichloride reacts with ethyene? I know disulfur dichloride combines to produced bis(2-chloroethyl) sulfide (mustard gas) but does sulfur dichloride work as well?
The reaction for the former is: S2Cl2 + 2 C2H4 → (ClC2H4)2S + S, so this could be applied to sulfur dichloride like this: SCl2 + 2 C2H4 → (ClC2H4)2S. But just because I can balance a reaction doesn't mean it works, do you have a reference?




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[*] posted on 24-3-2015 at 10:53


Wow aga, that is extremely beautiful! Well done :cool:



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[*] posted on 24-3-2015 at 11:09


Very nice experiment. I like direct union of elements reactions.

Shame about the suck back, though. A suck back vessel would have saved it :( .

Also, you used KMnO<sub>4</sub>(permanganate +7), not KMnO<sub>3</sub> (manganate +5).

And, NaOH + plus chlorine leads to NaClO, not NaClO<sub>3</sub>...




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[*] posted on 24-3-2015 at 11:29


Thanks for the comments !

It's a breeze to do, and i shall do it again (properly) in a day or two to get some SCl2 for the White Factice experiment.

Quote: Originally posted by blogfast25  
Also, you used KMnO<sub>4</sub>(permanganate +7), not KMnO<sub>3</sub> (manganate +5).

And, NaOH + plus chlorine leads to NaClO, not NaClO<sub>3</sub>...

Doh ! KMnO3 was a typo.

NaClO3 was my own lazy self not checking the reaction at all, and copying it wholesale off the 'web.

Thanks for noticing and for the corrections.

I should mention that the overall reaction is slightly exothermic, yet starting with 5g of S never made the glass too hot to touch.

[Edited on 24-3-2015 by aga]

[Edited on 24-3-2015 by aga]




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[*] posted on 24-3-2015 at 11:34


I melt the sulfur first and then add chlorine, either works, but I think yields will be better if it starts out molten in your' setup, but with mine it shouldn't make any difference (because the apparatus is closed off).
Depending on the temperature of the hydroxide solution, chlorate can form, I believe hypochlorite decomposes at around 70°C.




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[*] posted on 24-3-2015 at 11:42


Quote: Originally posted by Molecular Manipulations  
Sulfur dichloride reacts with ethyene? I know disulfur dichloride combines to produced bis(2-chloroethyl) sulfide (mustard gas) but does sulfur dichloride work as well?
The reaction for the former is: S2Cl2 + 2 C2H4 → (ClC2H4)2S + S, so this could be applied to sulfur dichloride like this: SCl2 + 2 C2H4 → (ClC2H4)2S. But just because I can balance a reaction doesn't mean it works, do you have a reference?


I believe the SCl2 will be contaminated with S2Cl2.
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[*] posted on 24-3-2015 at 12:05


Quote: Originally posted by careysub  
I believe the SCl2 will be contaminated with S2Cl2.

It will, however an over-dose of Chlorine will make the product predominantly SCl2 initially, decomposing over time to S2Cl2.

It seems that sealing the container ends up causing a slight positive pressure of chlorine gas, halting the decomposition effect.




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[*] posted on 24-3-2015 at 12:08


MM, don't you have a hell of a time cleaning the flask?
Do you distill the S2Cl2 off immediately?




all above information is intellectual property of Pyro. :D
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[*] posted on 24-3-2015 at 12:17


Quote: Originally posted by Pyro  
MM, don't you have a hell of a time cleaning the flask?
Do you distill the S2Cl2 off immediately?

As you can see, the suck-back destroyed the product, and i've left it all in the fume hood overnight for the Cl2 to disappear.

Everyone thinks we're about to re-open our pool 3 months early ...

The previous run ended up with clag-free SCl2 after filtering, and there was no real meass to speak of.

I stored it in a handy plastic container overnight, which the SCl2 ate through, and ran away to freedom (hence this second effort).

Edit:

Sorry, i thought you meant Mmmm instead of Molecular Manipulations.

[Edited on 24-3-2015 by aga]




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[*] posted on 24-3-2015 at 12:17


Ever melted rubber in glassware? It's easier to buy a new flask then clean the shit.
Since I can't afford such things, I cleaned it out yes. I melted it and poured out what was left, let it cool and scraped out some more, added nitric acid, sulfuric acid with hydrogen peroxide and finally toluene to get most of it out. The sulfur I think wasn't the hard part, toluene would taken care of that from the start, it was then damn clay.
Yeah I had distillation going at the time of the reaction. Otherwise it would have just decomposed to disulfur dichloride.




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[*] posted on 24-3-2015 at 12:27


Sounds nasty! should try hot chromic acid as per Vogel's prescription :)

I'm trying this as soon as I get my lab relocated!




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[*] posted on 24-3-2015 at 12:49


Quote: Originally posted by Molecular Manipulations  
Ever melted rubber in glassware? It's easier to buy a new flask then clean the shit.

I tried Making factice artificial rubber in two 250ml beakers, and it didn't work.

The beakers were horribly gooped up with brown tar.

Toulene hardly touched it, nor did acetone.

Pihraña Fluid was a thought, although my H2O2 is just 3%.

A few hours in a charcoal fire removed all of the brown goop, but also removed the graduations, which i liked.




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[*] posted on 24-3-2015 at 14:01


Quote: Originally posted by Magpie  
IIRC Len1 has a procedure for making it in Prepublication. You have probably seen it I imagine.

I hadn't seen it as it happens.

Having now looked at it, all i have done is pass chlorine over sulphur powder and got lucky !

Len1's Work is rather more involved, precise and useful than my random experiment.




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[*] posted on 24-3-2015 at 14:46


Quote: Originally posted by aga  

Len1's Work is rather more involved, precise and useful than my random experiment.


Yes, it is easy to get over awed by Len1's accomplishments. He is after all a professor at a university in Australia. When doing the experiments for his book I believe he had full access to all of his school's labs, library resources, colleagues, etc. This is not to take away from his hard work and brilliant mind.




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[*] posted on 24-3-2015 at 15:05


My 1 hour's tinkering, a few photos and a final failure due to over-excited idiocy really bear no comparison to Len1's paper.

Having said that, it seems to work, and is do-able for an amateur.




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[*] posted on 24-3-2015 at 15:08


Quote: Originally posted by Magpie  

Yes, it is easy to get over awed by Len1's accomplishments. He is after all a professor at a university in Australia. When doing the experiments for his book I believe he had full access to all of his school's labs, library resources, colleagues, etc. This is not to take away from his hard work and brilliant mind.

Do you know which university he is a professor at? I am currently sitting in a lecture hall at a university in Australia :)
Quote: Originally posted by Pyro  
MM, don't you have a hell of a time cleaning the flask?
Do you distill the S2Cl2 off immediately?

Cleaning the flask was actually really easy (much to my surprise). All you need to do is get a hot dilute solution of NaOH and the sulfur comes right off leaving the flask sparkling clean. I have some cool pictures of the reaction of sulfur and chlorine, perhaps I'll post them when I get home.
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[*] posted on 24-3-2015 at 15:50


Quote: Originally posted by Oscilllator  

Do you know which university he is a professor at? I am currently sitting in a lecture hall at a university in Australia :)


Flinders University, Adelaide




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[*] posted on 24-3-2015 at 16:05


Quote: Originally posted by Magpie  

Flinders University, Adelaide

To bad, I'm at the university of new south wales :(
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[*] posted on 25-3-2015 at 13:24
Success !


Tried again with an anti-suck-back device and some brains engaged.

Result is 9.38g, 6ml of stuff, having started as 5.25g of flowers of Sulphur.

Woohoo !



product.JPG - 115kB




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[*] posted on 25-3-2015 at 13:32


Nice, 31% yield ain't bad for such a simple apparatus.



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