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Magpie
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[*] posted on 4-11-2017 at 12:11
Preparation of S2Cl2


Note: The reagents used are as shown. I have since learned that the proportions are inappropriate. Please do not duplicate. I will post appropriate ratios in this thread soon.

A. Introduction
This procedure will follow that in Len1’s book (ref 1) except for use of Ning’s method of chlorine generation. Len1 achieved a 99% yield on sulfur, or 82.5g of S2Cl2. See Discussion below.

TCCA + 3NaCl + 3H2SO4 --→ 3NaHSO4 + cyanuric acid + 3Cl2

2S + Cl2 -----→ S2Cl2 (-60KJ/mole)

B. Reagents
98.5g of 99% flowers of sulfur (2.7moles)
121.04g TCCA (C3Cl3N3O3) (0.516 moles)
84.3g 98% H2SO4 (82mL) (1.54 moles)
93.1g of NaCl (1.59 moles)
inert gas (N2, Ar, etc)
perfluoropolyether grease (DuPont Krytox)

C. Apparatus
a. Reaction Vessel
Set up a 3-neck 500mL RBF in a ring-stand on a heating mantle. The central neck is connected to a distillation head. Attach to this a water cooled condenser leading to a receiver RBF via a vacuum adapter. The vacuum adapter tublature is connected to a P2O5 trap to protect the system from airborne moisture.

A chlorine sparge tube is installed in a side neck of the RBF extending to within a few mm of the bottom. A thermometer is installed in a side neck.

Grease all ground glass connections.

b. Chlorine Generator
The chlorine generator is to consist of a 2 or 3-neck 500mL RBF. The angled neck is to connect to the chlorine sparge tube of the reaction vessel.

The central neck is fitted with a ≥65 mL p-e addition funnel. The generated chlorine is dried by means of the con H2SO4 in the generator.

It is recommended that all ground glass joints in contact with Cl2 be sealed with a perfluoropolyether grease.

D. Procedure
1. Charge the reaction vessel with the sulfur.
2. Set the heating mantle at about a 40% duty cycle to remove moisture from the apparatus by using a slow inert gas flux added through the chlorine generator head.

3. Once the sulfur is melted, the inert gas is replaced by a fairly rapid Cl2 flow of about 240 mL/min, or 1 drop/s of con H2SO4 onto 121.04g TCCA in the chlorine generator. This takes about 1.2 hr.

E. Results
After an initial lag, while the S2Cl2 product dissolves in the sulfur, drops of a yellow-orange fluid start to gather in the receiver at about 1 drop/s. The flask temperature continues to rise to about 200°C due to the heat of reaction.

From Len1: “Beyond 160°C there is no longer any chlorine color at the reactor outlet. Testing with saturated NaCl solution confirms that no Cl2 passes the reactor oulet unreacted. After xxx minutes the reaction vessel is completely empty save for a few particles of soot. The product in the receiver changes color from yellow to orange in the last stages of the reaction, as free chlorine passing the flask reacts with the S2Cl2 to form a small amount of SCl2, whose red streaks slowly diffuse from the surface. This has the benefit of removing all traces of sulfur from the apparatus.”

F. Yield
My yield of sulfur chloride is 40.7g, or 48.8% S2Cl2 on sulfur.

G. Discussion
The Cl2 generation method I have generally used is that posted in Prepublication by Len1. However, I did stumble upon a method posted by Ning in 2004 on a chemistry forum. Ning’s method replaces 15% HCl and the Cl2 scrubber with con H2SO4. Ning had not proved the viability of this alternate procedure

Len1 achieved a yield of 82.5g of S2Cl2, or 99% on sulfur. During cleanup of the chlorinator vessel I discovered the reason for my poor yield: incomplete Cl2 generation. The vessel contained large amounts of unreacted TCCA. If I use this method again I will provide an agitator in this vessel.

H. Reference
1. Small Scale Syntheses of Laboratory Reagents with Reaction Modeling , p.192, by Leonid Lerner, CRC Press, 2011.

IMG_2115.JPG - 153kB

IMG_2117.JPG - 164kB

IMG_2118.JPG - 107kB

(Edit: Added note to beginning at Magpie's request)

[Edited on 11-16-2017 by zts16]




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[*] posted on 4-11-2017 at 12:23


Good stuff Magpie !

Do you intend to use the S2Cl2 for anything soon ?

If not, store it well ! Mine leaked and jammed the ground glass stopper pretty quickly.




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[*] posted on 4-11-2017 at 13:36


Thanks, aga. Yes, I will be making SCl2 then SOCl2 in the near future.

I have my S2Cl2 stored in a 100mL amber bottle with thermoplastic lid, ptfe lined. Do you think that will survive? If, not what do you recommend?




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[*] posted on 4-11-2017 at 13:53


No idea - apart from using it ASAP.

I tried a simax bottle with the blue lid and it discoloured the cap so badly i threw it away.

A ground glass RBF and greased glass stopper seemed like the best idea, yet it escaped from that in a period of about two weeks to a month (i do not recall).

Any contact with water (even traces) and Sulphur crystals appear, in my case, inbetween the ground glass joints, effectively welding the two together, requiring the destruction of both glass items to get the S2Cl2 out.

If you were to cool it to near zero and add about 20% by volume to some similarly chilled corn oil, you might succeed at making white Factice with it, which i did not (mine got burnt as the reaction is very exothermic).

Dumping it in a bucket of water smells bad, also destroys it immediately, which is what i did in the end.




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[*] posted on 4-11-2017 at 14:39


Thank you. I plan to make another batch tomorrow then I will quickly use it to make SCl2.

A good hood is essential for working with these chemicals, it seems.




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[*] posted on 4-11-2017 at 14:54


S2Cl2 or SCl2.

All same-same and will cross-link your skin cell proteins if you get a splash.

Very Very Highly reactive, so take care my friend.




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[*] posted on 4-11-2017 at 15:25


Nice work Magpie. Good to see you're still busy in the lab
What was the rational for using conc sulfuric acid in the chlorine generator (I'm not sure who "Ning" is or what work has been done by them).

Also you say you tested the outlet with NaCl solution. Is this an error? I'd expect NaI to be used due to visible liberation of iodine.

Looking forward to the next reaxtions you have planned.
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[*] posted on 4-11-2017 at 15:39


Just guessing (too drunk to look up/read the paper):

Ning had the idea to add conc sulphuric directly into the TCCA/HCl reaction vessel in an attempt to get Dry Cl2 rather than just do Len's thing of generating Cl2 then drying it later.

In my experience it makes no odds, as any water just precipitates as elemental sulphur in the product, presumably with H and O ending up somewhere else.

Vitally important to know exactly where/how much in industrial scale processes i guess.

[Edited on 4-11-2017 by aga]




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[*] posted on 4-11-2017 at 17:01


Quote: Originally posted by DJF90  

What was the rational for using conc sulfuric acid in the chlorine generator (I'm not sure who "Ning" is or what work has been done by them).


Using con H2SO4 vs dilute HCl followed by an H2SO4 absorber saves messing with 1) more volume, 2) handling an absorber. I think it is a great idea and will work if the chlorine generator is kept well mixed.

Quote: Originally posted by DJF90  

Also you say you tested the outlet with NaCl solution. Is this an error? I'd expect NaI to be used due to visible liberation of iodine.


I did not test this. This is a direct quote from Len's book.




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[*] posted on 4-11-2017 at 17:03


Quote: Originally posted by aga  

Ning had the idea to add conc sulphuric directly into the TCCA/HCl reaction vessel in an attempt to get Dry Cl2 rather than just do Len's thing of generating Cl2 then drying it later.


Ning did not add H2SO4 to TCCA/HCl. No HCl is used. Instead NaCl is used. See the equations in my procedure.

I am going to try Ning's method again tomorrow if I can get an overhead stirrer operating. I don't think a magnetic stirrer will be strong enough.

There was a gross quantity of unreacted TCCA in the generator. Cleanup was a bitch and would not be possible if not for my strong hood flow.

[Edited on 5-11-2017 by Magpie]




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[*] posted on 5-11-2017 at 10:06


Nice work Magpie. Keep it up!
BTW, are those PTFE joints clips you used?




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[*] posted on 5-11-2017 at 10:27


Thanks! Yes, and I've never melted one yet - I love them. Bought them from VWR, IIRC.

BTW, Doug's Lab YouTube has a very nice presentation on making S2Cl2.

Right now I'm struggling to get one of my three overhead stirrers back in operation. The stepper motor types (2 ea, my favorites) have electronic driver problems, and the other I seem to have lost the shaft coupler.




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[*] posted on 16-11-2017 at 05:05


What I have learned from a second attempt at this synthesis is that the Ning Cl2 generation method is very inefficient; so I will not post any reagent quantities for that method.



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[*] posted on 16-11-2017 at 11:27


I had heard from a friend that the most convenient way to make larger quantities of S2Cl2 is to make SCl2 from S2Cl2, which is less exothermic and does not require heating (because S2Cl2 is liquid) and then react this with sulfur to return to S2Cl2, allowing for a cyclic process.

What are your thoughts on this method? I understand if you don't intend to make any more but it's aroused my curiosity a bit.




[Edited on 04-20-1969 by clearly_not_atara]
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[*] posted on 16-11-2017 at 11:56


Quote: Originally posted by clearly_not_atara  
I had heard from a friend that the most convenient way to make larger quantities of S2Cl2 is to make SCl2 from S2Cl2, which is less exothermic and does not require heating ...

Huh ?

It's the same method, and neither is very exothermic in my limited amateur experience, nor does the sulphur require melting.

You just react sulphur with chlorine gas to make S2Cl2.

If you keep going with the chlorine, you get SCl2.

I suppose knowing when to stop is the key, which i've never been good at.




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[*] posted on 16-11-2017 at 12:02


Quote: Originally posted by Magpie  
What I have learned from a second attempt at this synthesis is that the Ning Cl2 generation method is very inefficient; so I will not post any reagent quantities for that method.

It is a shame that Ning's method isn't great, but it does show ingenuity when other reagents are not available,

Len1's method is so simple and easy, i really would not bother with any other method.

Here i can only get DCCA, not TCCA, yet it works equally well and predictably, just with less product-per-pound.




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[*] posted on 16-11-2017 at 12:14


Quote: Originally posted by aga  
Quote: Originally posted by clearly_not_atara  
I had heard from a friend that the most convenient way to make larger quantities of S2Cl2 is to make SCl2 from S2Cl2, which is less exothermic and does not require heating ...

Huh ?

It's the same method, and neither is very exothermic in my limited amateur experience, nor does the sulphur require melting.

You just react sulphur with chlorine gas to make S2Cl2.

If you keep going with the chlorine, you get SCl2.

I suppose knowing when to stop is the key, which i've never been good at.


What I think clearly_not_atara is trying to say is that once you have some S2Cl2 it is easier to chlorinate to SCl2 and then comproportionate by adding elemental sulfur. Theoretically and practically this makes sense, as using excess sulfur in the second step and then distilling the product will yield a product free from SCl2 without having to guestimate when to stop passing chlorine. The downside is that you need some S2Cl2 or SCl2 to start with (but after that initial "difficulty" makng more should be relatively simple)

Alternatively, you could use the S2Cl2 as a solvent for further sulfur and proceed to chlorinate as usual. A short reflux over some fresh sulfur prior to distillation is still good practice to eliminate the higher chloride.

[Edited on 16-11-2017 by DJF90]
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[*] posted on 16-11-2017 at 12:24


Quite honestly it was not difficult or time-consuming at all starting from powdered sulphur to arrive at a mix of the two.

Just running the chlorine for longer gets you near 100% SCl2.

As Magpie rightly says, there is a Doug's Lab video on utoob showing/explaining the process very well.

Edit:

https://www.youtube.com/watch?v=oYw89ieffa4&t=116s

[Edited on 16-11-2017 by aga]




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[*] posted on 16-11-2017 at 14:01


Quote: Originally posted by clearly_not_atara  
I had heard from a friend that the most convenient way to make larger quantities of S2Cl2 is to make SCl2 from S2Cl2, which is less exothermic and does not require heating (because S2Cl2 is liquid) and then react this with sulfur to return to S2Cl2, allowing for a cyclic process.

What are your thoughts on this method? I understand if you don't intend to make any more but it's aroused my curiosity a bit.


I found making S2Cl2 to be quite easy once you have all apparatus in place. You also need a good hood for unplanned fugitive releases of Cl2, and S2Cl2 (its smell is awful).

The reason I say Ning's Cl2 method is questionable is that I had added 110% of the stoichiometric reagents for making Cl2 yet I only had a 38% yield on sulfur. I am now trying to get the last bit of black sulfur residue out of the reactor using boiling NaOH/alcohol.

In practice the Ning method was easy to use, but you do need a strong mixer. My Wheaton mixer was a poor choice. Unfortunately, both of my stepper motor mixers are having their electronics repaired. This would be a piece-of-cake for them as they can produce high torque at low speed.

Tomorrow I will be making SCl2 from my 118g of S2Cl2.

[Edited on 17-11-2017 by Magpie]




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[*] posted on 16-11-2017 at 15:41


Very informative and interesting documentation. Have you considered taking a time laps of some of your reactions? As a side not I recently found out that many schools with labs often dispose of their old containers and bottles. I recently saved a number of amber jars for a life in the dump. Perhaps you could inquire and with luck come up with a chemical resistant container for large volumes of S2Cl2 in the future.



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[*] posted on 16-11-2017 at 16:42


The residue in the reactor is a black solid. Most all of it came out (a little black goes a long way). My understanding is that this is soot (carbon) that comes in as an impurity with the sulfur.



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[*] posted on 18-11-2017 at 09:39


Whatever "Ning's method" is, it generates a lot of HCl gas alongside the Cl2. If you just add aqueous HCl to TCCA, that has the advantage of holding onto the HCl until it can react with the TCCA. HCl is VERY soluble in water. Cl2, less so.

Cl2 is soluble in water in the presence of Cl- ions, but as the HCl reacts with the TCCA, there become fewer and few Cl- ions to hold onto Cl2, and the Cl2 leaves as gas.

The black stuff could be from vapors generated by the reaction of H2SO4 with cyanuric acid. The direct reaction of TCCA and H2SO4 normally produces a sticky residue with a strong smell that's difficult to clean out of glassware, and doesn't dissolve in many common solvents. It tends to coat the TCCA, preventing further reaction, which makes it hazardous to attempt to rinse out this residue with acetone (which seems to be one of the few things that will dissolve it). Obviously, TCCA + acetone will yield chloroacetone, a strong lachrimator.

[Edited on 11/18/17 by Melgar]




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[*] posted on 18-11-2017 at 11:20


Quote: Originally posted by Melgar  
Whatever "Ning's method" is, it generates a lot of HCl gas alongside the Cl2. If you just add aqueous HCl to TCCA, that has the advantage of holding onto the HCl until it can react with the TCCA. HCl is VERY soluble in water. Cl2, less so.

Cl2 is soluble in water in the presence of Cl- ions, but as the HCl reacts with the TCCA, there become fewer and few Cl- ions to hold onto Cl2, and the Cl2 leaves as gas.


Thank you for this insightful analysis. Ning method = no good. Len1 method = excellent. I just made Cl2 from TCCA (see post above) and this method performed flawlessly.





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[*] posted on 18-11-2017 at 14:50


Less efficient, harder to clean up, unknown residues ....

Thanks for trying out the Ning process and telling everyone what the results were.

If nobody ever tried it, nobody would ever know.

As far as i recall, you're the Only one to have tested it out and reported the results.

Superb write-up BTW.

[Edited on 18-11-2017 by aga]




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[*] posted on 2-12-2017 at 19:10


Per Atomistry.com on S2Cl2 (link: http://sulphur.atomistry.com/sulphur_monochloride.html), to quote:

"Sulphur Monochloride or Disuiphur Dichloride, S2Cl2, the initial product of the combination of sulphur and chlorine, was first thoroughly studied in 1810 by Davy and Buchholz, independently.
....
Sulphur and chlorine interact slowly at the ordinary temperature but much more readily on warming. The customary procedure is to pass dried chlorine into fused sulphur or over dry " flowers of sulphur " until most of the sulphur has disappeared. The resulting monochloride contains considerable amounts of higher sulphur chlorides in solution, but if the mixture is heated for some time under a reflux condenser the pure monochloride can subsequently be distilled over. "

As such, a process I think would be interesting to explore, reducing the possible presence of polysulfides, would to fill a transparent elongated vessel (which may be of high volume) with heavy chlorine gas followed by the introduction (and then removal) of a drying agent. Add dried flowers of sulfur (perhaps by blowing to reduce sulfur clumping) to which the dried chlorine is present in slight excess. Warm the sealed vessel with sunlight and UV light.

My expected reactions:

2 S + Cl2 = S2Cl2 (slowly on warming)

Cl2 + hv = .Cl + .Cl (per photolysis)

S + .Cl = .SCl

.SCl + .SCl = S2Cl2

S2Cl2 + hv = .Cl + .S2Cl (See http://www.nrcresearchpress.com/doi/pdf/10.1139/v73-502 )

And, with chlorine in slight excess, the reverse reaction:

.Cl + .S2Cl = S2Cl2

With any local high sulfur concentration and by radical reactions, some possible SnCl2 creation:

S + S2Cl2 = S3Cl2
.S2Cl + .S2Cl = S4Cl2 = S + S3Cl2

Also, a small amount of SCln per the reaction with excess chlorine:

S2Cl2 + Cl2 = 2 SCl2
S2Cl2 + 3 Cl2 = 2 SCl4
-------------------------------------

Another variation involving continuous gas feed would be to burn a H2S flame in an atmosphere of 1.5 parts chlorine. Here is a source to quote:

"If chlorine is in excess sulfur chlorides also could be produced."

Link: https://practicum.melscience.com/experiments/reaction-of-chl...

Reactions:

2 H2S + 2 Cl2 = 4 HCl +2 S
2 S + Cl2 = S2Cl2

Net: 2 H2S + 3 Cl2 = 4 HCl + S2Cl2

Likely also some SCl2 formation.

Mixing the gases in a vessel may also work. Problem is the toxic nature of both gases. Also, any air presence introduces H2O which decomposes sulfur chlorides.

[Edited on 3-12-2017 by AJKOER]

[Edited on 3-12-2017 by AJKOER]
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