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Author: Subject: CCl4 and CHCl3 from CH2Cl2
Sauron
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[*] posted on 23-2-2009 at 09:58
CCl4 and CHCl3 from CH2Cl2


The pseudonymous "Hpffman" writing in Annalen in a paper elsewhere on this forum, stated that the usual procedure for lab prep of CCl4 was to distill chloroform in a stream of dry Cl2 while illuminating with direct sunlight.

This is recognizable as vapor phase free radical chlorination with the radical source bing UV photolysis.

In the same paper Hoffman commends the utility of SbCl5 as a chlorinating agent, including for vapor phase chlorinations with Cl2 where the SbCl5 is employed catalytically.

Therefore, why not distill dichloromethane and dry chlorine through SvCl5 heated to a temperature at or above the bp of CHCl3. The product should consist of ChCl3, a little CCl4 and some unreacted CH2Cl2.

Run these through again (at least the DCM and the chloroform) until all converted to CCl4.

UV not rquired.

There are roughly 20 C differences between the bps of DCM, chloroform and CCl4. SbCl4 boils higher at well over 90 C..

Ought this not to work?

DCM is after all a lot cheaper than CS2, the other feedstock for CCl4. We might lose a little CCl4 to hexachloroethane but less than with UV photolysis. No sulfur compounds to deal with. Industrially this process (starting with methane and using UV) has largely displaced the chlorination of CS2.

Anyone have ideas?

I cannot buy CHCl3 or CCl4. I can buy DCM.

Having already established that SbCl5 is the answer to making CCl4 from BrCCl3, and the same reagent use useful to chlorinate CS2, this is about the only world left to conquer when it comes to CCl4.



[Edited on 24-2-2009 by Sauron]




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[*] posted on 23-2-2009 at 13:53


Sounds nasty... I really don't care to work with fuming inorganic substances. Not to mention the available chlorine may be fairly low from antimony pentachloride, since I presume after losing one chlorine you end up with an antimony in a lower oxidation state that is perhaps unreactive. The atom economy of the radical chlorination is probably substantially better.

I'm sorry, I have to laugh a little since you're always concerned about tox issues... but antimony pentachloride is going to be highly toxic (and volatile), carbon tet is a carcinogen, and chloroform is... well probably not that bad. :D How much do you need?
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[*] posted on 23-2-2009 at 14:13


Quote:

In the same paper Hoffman commends the utility of SbCl5 as a chlorinating agent, including for vapor phase chlorinations with Cl2 where the SbCl5 is employed catalytically.

Therefore, why not distill dichloromethane and dry chlorine through SbCl5 heated to a temperature at or above the bp of CHCl3. The product should consist of CHCl3, a little CCl4 and some unreacted CH2Cl2.


Sauron has said that SbCl5 may only need to be used in catalytic amounts and the use of dry chlorine should regenerate the SbCl5 as the reaction consumes it. SbCl5 boils at 140C, which is quite a fair bit above the chloromethanes (CCl4 = 77C, CHCl3 = 61C, CH2Cl2 = 40C)

[Edited on 23-2-2009 by DJF90]
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[*] posted on 23-2-2009 at 14:42


Anyone have ideas?

I cannot buy CHCl3 or CCl4. I can buy DCM.


I cannot at present put my hand on the file, but I did notice an interesting prep for CHCl3 with 2 phase electrolysis, with reaonable yields - utilizing NaCl in the aquarius phase and dichlormethane in the more non-polar phase. It basicaly consisted, if memory serves me correctly, of an undivided cell with the 2 phases maintained, and the aquarius phase having electrodes placed to that depth only, and not touching the lower phase. A stir bar was placed in order for the lower, dichloromethane to be stirred. Perhaps with longer reaction times, then CCl4 could also be produced. I will try to find the article. Hopefuly my description hasn't deviated to much from the said article.
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Sauron
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[*] posted on 23-2-2009 at 20:18


DJF90 yes, I actually did read the Hoffman paper, in German as well as in translation.

And I stated above that DCM, chloroform and CCl4 are approx. 20 C apart in bp and indeed, they are 21C and 16 C apart, the point being that no one is going to say they are too close to fractionate.

I looked up SbCl5 in Acros catalog. Twice actually. bp 92 C. Now I suppose the Belgians could be wrong, and I have no ego invested in this datum. I will not complain if it boils at 140 C.

My suggestion of passing the vapor of CH2Cl2 admixed w/Cl2 through SbCl5 at a temp above the bp of the product(s) was to drive them off to condenser. I am not talking about a stoichiometric use of the antimony pentachloride. If I was the injection of Cl2 would not be required. I was merely trying to design a simple procedure.

Anyway thanks for the comment. I will peek at Brauer to see whether the Belgians are in error.

Indeed Brauer says bp 140 C/760 mm w/decomposition so the Belgians need to sit in the corner and face the wall while wearing a pointy hat.

Sigma-Aldrich says 92 C/30mm so obviously Acros just forgot to mention the diminished pressure.

[Edited on 24-2-2009 by Sauron]




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[*] posted on 23-2-2009 at 21:56


What is the best way of producing antimony pentachloride as it is a very useful reagent for chlorinations of this type? I have powdered antimony metal and about 50 grams of antimony trichloride produced from antimony sulfide (stibnite) by heating with hydrochloric acid ouside and then distilling the residue producing the trichloride. I have a good chlorine generator set up and a fume hood, so the handling of the chlorine would not be a problem.

[Edited on 23-2-2009 by benzylchloride1]




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[*] posted on 24-2-2009 at 01:12


You are all set.

SbCl5 as anyone who has workedmwith it will tell you is a paon in the ass to store. I would therefore store it as SbCl3 and make it in situ as needed.

SbCl3 + Cl2 -> SbCl5

See Brauer, Handbook of Preparative Inorganic Chemistry for details, but it is simple.

The chlorine as usual needs to be dry.

As you know the trichloride is solid and the pentachloride liquid.

One mol SbCl3 will liquify in chlorine and gain 70 g mass so stop when the tared receiver is at the correct weight.

Distill in vacuum, bp 92/30mm but protect your pump, and if you use an aspirator, place a drying tube inline between the receiver and the vacuum connection.

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

Sooner or later someone will say "But what about the haloform reaction?" to get chloroform.

The haloform is fine on a small scale but unweildy on a larger scale, and as lots of us have discovered, unforgiving if you do not adequately control the exotherm. If that happens the reaction runs away and you lose the mixture out of the flask. Bad bad bad. It is a good way to make 25-50 ml CHCl3 but a bad way to make 250-500 ml, just work out the volumes involved,

If you want liters of CHCl3 and CCl4 then these other methods are the ways to select from.

Halogen exchange with BrCCl3

Chlorination of CS2

Chlorination of DCM and then of CHCl3.



[Edited on 24-2-2009 by Sauron]




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[*] posted on 24-2-2009 at 07:35


Sauron... Another genius method! I myself had looked at dichloromethane to chloroform and carbon tetrachloride. UV chlorination is costly in energy and a mixture of products.

Catalytic chlorination does sound feasible. And once again it is our lovely friend Antimony doing the dirty work ;)

It would save on CS2 which is incredibly flammable and toxic, and not to say not exactly dirt cheap. DCM is much more readily obtained than CS2 and is also fairly cheap for a LR and Technical grade which I would imagine would be well suited here as a feed stock.

Giving this a go Sauron? :p




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[*] posted on 24-2-2009 at 08:11


What about catalytic chlorination of tetrachloroethylene?
Cheaper and more available starting material?
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[*] posted on 24-2-2009 at 08:20


Tetrachloroethylene is not importable into this country. Neither is ethylene dichloride, nor ethylene dibromide.

I am not sure about 1,1,3 trichloroethylene, which can be converted to CCl4. Nicodem posted some references and patents on this a while back. IIRC it is a pressure reaction with O2 and a catalyst.




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[*] posted on 25-2-2009 at 00:21


Quote:
Originally posted by Sauron
I am not sure about 1,1,3 trichloroethylene, which can be converted to CCl4.

-I think you need some sleep ;)
Trichlorethene (trichlorethylene) is by definition 1,1,2 trichlorethene and because there is no other possibility for a trichloro compound of ethene often the front numbers are excluded...
Maybe you meant a trichloropropene compound?




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[*] posted on 25-2-2009 at 00:43


That is a typographical error not a chemical one.

The Cl2C=CH-Cl is oxidized to trichloroacetyl chloride in a chlorooxidation.

The trichloroacetyl chloride falls apart under chlorination with UV photolysis to give CCl4 and gaseous side products CO, HCl, and a little phosgene from reaction of Cl2 and CO.

This happens anytime trichloroacetic acid or dichloroacetyl chloride is photolyzed and chlorinated - this is quantitative. . It also happens when trichloroacetic acid is chlorinated by non-photolytic means, such as with benzoyl chloride, but to a smaller extent. (c.25%) See attached H.C.Brown article from JACS and references therein. Also see the chloral thread and chloral chemistry review from Chem.Rev. posted there.

http://www.sciencemadness.org/talk/viewthread.php?action=att...

I recommend you right-click and use Save Target As...

Left click usually gets a corrupted pdf due to forum software.

[Edited on 25-2-2009 by Sauron]




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[*] posted on 25-2-2009 at 02:26


By the way Sauron,

Because of your interest in halogenated and toxic compounds...

1°)If you warm at reflux trichlorethene with HNO3 69% you get easily a single compound related to chloropicrin (Cl3C-NO2) that is Cl2C=CCl(NO2) (1,1,2-trichloro-2 nitroethene).

It displays the sharp smel of chloropicrin and is realtively toxic...it reacts with diamines to give FOX related compounds.

2°)Upon H2SO4 boiling of Trichlorethene, one can get as final compound chloracetic acid itself a good source for the synthesis of 1.3 dichloroacetone (dichloropropanone)...

[Edited on 25-2-2009 by PHILOU Zrealone]




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[*] posted on 25-2-2009 at 04:40


It may surprise you but I have no particular interest in chloropicrin, and no particular interest in trichloroethylene. The latter was suggested by Nicodem as a shortcut to trichloroacetyl chloride at a time when more facile routes to CCl4 were not yet at hand. Things have changed.

And my interest in CCl4 and CHCl3 is almost entirely a matter of their utility as solvents and occasionally as reagents.

Stupid regulations born of hidebound bureaucracy make us all jump throiugh hoops like these. I do rather enjoy frustrating all that when I can. To a very great extent I am done with such preliminaries and can now get down to brass tacks.




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[*] posted on 25-2-2009 at 18:10


Snip...

Quote:
Originally posted by PHILOU Zrealone
By the way Sauron,

Because of your interest in halogenated and toxic compounds...



His name is Sauron, not Sarin;)
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[*] posted on 26-2-2009 at 08:34


Just don't call me late for dinner. :)

Now let's get back to chemistry.




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[*] posted on 26-2-2009 at 12:00


LOL!^^^ ;)
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[*] posted on 22-2-2010 at 21:54


Quote: Originally posted by Sauron  
The pseudonymous "Hpffman" writing in Annalen in a paper elsewhere on this forum, stated that the usual procedure for lab prep of CCl4 was to distill chloroform in a stream of dry Cl2 while illuminating with direct sunlight.

This is recognizable as vapor phase free radical chlorination with the radical source bing UV photolysis.

In the same paper Hoffman commends the utility of SbCl5 as a chlorinating agent, including for vapor phase chlorinations with Cl2 where the SbCl5 is employed catalytically.


Does anyone know what this reference is about? I cant find any articles on the subject of SbCl5 by either Hoffmann, or the more famous A W Hofmann in Annalen der Chemie and/or Pharmacie for any year. I dont think this exists.

[Edited on 23-2-2010 by len1]
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[*] posted on 23-2-2010 at 03:18


That is because you are an arrogant ass.

I posted the German original in Wanted References Needed Translations last year and one of the members (maybe formatok) translated it and posted that.

I will be happy to furnish either to any member - but not you. After all you don't need something that "doesn't exist".

"Hoffman" was a frequent PSUEDONYMOUS contributor to Annalen and had no connection with any of the several chemists os same or similar name.

His articlr describes theee exothermic reaction of CS2 and SbCl5 as well as that of CS2 and Cl2 over SbCl3; and more briefly the gas prase chlorination of ethylene to 1,2-dichloroethane, and of acetyene to 1,1,2,2-tetrachloroethene
- in boyj cases by passimg a mixture pf Cl2 and the hydrocarbon over heated SbCl5.

[Edited on 23-2-2010 by Sauron]




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[*] posted on 23-2-2010 at 03:42


It really doesnt matter that you say you wontpost - i have access to the entire annalen and its not there

You can of course write whatever you happen to choose about me, it stands for nought as your 5000+ posts of what you plan to do with no outcome vouch for your credibility. In contrast I stand behind everything I say.

[Edited on 23-2-2010 by len1]
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[*] posted on 23-2-2010 at 03:47


I can't help it that you don't know how to search.

You are just setting yourself up for a fall, because the paper IS real, and as stated, so upi are going to look foolish and I will be delighted to administer the blow.

[Edited on 23-2-2010 by Sauron]




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[*] posted on 23-2-2010 at 04:28


Quote: Originally posted by Sauron  

I posted the German original in Wanted References Needed Translations last year and one of the members (maybe formatok) translated it and posted that.



It was I.
Here is the link:
http://www.sciencemadness.org/talk/viewthread.php?tid=11698&...

and here is the paper:
Attachment: About_the_Reaction_of_CS2_with_SbCl5.pdf (21kB)
This file has been downloaded 733 times
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[*] posted on 23-2-2010 at 04:51


Thanks fractional for the reference - that was interesting.

I wansnt of course stating that there is no article - I couldnt be sure of that - just what I said - that there is no Annalen article whose author comes up as Hoffmann/Hoffman etc. on the subject.
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[*] posted on 23-2-2010 at 04:53


Thanks fractional

Here is the original paper by "Hofmann" p264 Annalen 115 (1860)

READ IT AND WEEP LEN1

And as to your frantic backpedaling:

"Does anyone know what this reference is about? I cant find any articles on the subject of SbCl5 by either Hoffmann, or the more famous A W Hofmann in Annalen der Chemie and/or Pharmacie for any year. I dont think this exists.."

So eat your words along with the crow.

Why not write an Illustrated Practical Guide on How to Open Mouth and Insert Foot.



[Edited on 23-2-2010 by Sauron]

Attachment: Annalen, 1860, 115, pp264.pdf (165kB)
This file has been downloaded 499 times



[Edited on 23-2-2010 by Sauron]




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[*] posted on 23-2-2010 at 05:14


Interesting, when you do a search on Annalen (anyone can do this even without access) for Hofmann, this article doesnt come up. Yet when you go to the contents pages it is there, without attribution to an author, obviously you cant trust Wiley's search engine.

Sauron have you been bitten? Though not recently, its getting worse.
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