Jor
National Hazard
Posts: 950
Registered: 21-11-2007
Member Is Offline
Mood: No Mood
|
|
SOCl2 via COCl2
The text below is what I posted in another topic, but maybe it's better to give it it's own topic.
-------------------------------------------
Now that I think of it, I read on wikipedia that phosgene reacts with sulfur dioxide to form thionyl chloride and carbon dioxide. Now this is very
interesting as phosgene is so easily produced. I recently bought a lot of glassware, so I might be able to do this on a small scale.
My idea, generating phosgene from chloroform in a SMALL apparatus (such there is very low space volume except for the liquids, meaning that little
phosgene just hangs around in the apparatus making opening the apparatus after the rxn a hazard), and leading it into ice cold xylene (or toluene, but
seperating the SOCl2 might be hard). There will have to be a tube from this leading into ammonia.
Next take this solution in a 3-neck with a condensor and CaCl2-guard and bubble in dry SO2 dried with H2SO4. Boil the solution briefly to eliminate
all excess COCl2 from the system, during this step I will put a large dish containing hot ammonia in the hood so most COCl2 will leave as urea.
A few question though:
-Does anyone have a reference how fast this reaction with SO2 is? Do they also react in the gas phase? I don't want the bubbling into the xylene cause
COCl2 to leave unreacted, wich would mean dimished yeilds and phosgene release. If they react in the gas phase, the SOCl2 will condense and drip back.
-Besides from CaCl2 in the guard tube in the condensor, is there a solid wich I can also put next to the CaCl2 (with cotton in between) wich will
effectively remove all phosgene from the exit stream? I was thinking some solid alcohol, but I don't have any. Will tartratic acid or malic acid do
fine?
-Does the reaction also work with Na2SO3 anhydrous? This is much more convenient than bubbling SO2 in the liquid, wich will cause excessive
evaporation of SOCl2 and some COCl2.
Ofcourse if I do this I will do it in my hood at full power and sash down. Besides, when I open the apparatus, I will boil a dish of ammonia just
below the duct to destroy all phosgene so hardly any is release in the air outside. And I will wear a wetted (with water or maybe 10% EtOH) powder
mask (how do you call it in English ) around my mouth. Maybe overkill, but this gas is so lethal that I can't take risks.
--------------------------------------------
Now ScienceSquirrel mentioned the following:
You should not consider making and reacting phosgene without a schlenk line, gas scrubbers, an efficient hood, gas testers and all the other gear that
makes really nasty chemistry safe in a professional environment.
Now he could be completely right. But when I work as I have explained above with hood at full power, this reaction could be done safely right, on a
small (say 20g) scale? Now say 10-20% of the gas will leave unreacted? This is thus at most 4g for one run , wich is about 1L of gas in the worst
case, probably spread over a few hours. Most of this will be absorbed with some neutralising agent in the guard tube, the rest will be scrubbed with
an improvised srubber (warm conc. ammonia right below the duct of the hood). Now how does this sound?
[Edited on 24-5-2011 by Jor]
|
|
|
Sedit
International Hazard
Posts: 1939
Registered: 23-11-2008
Member Is Offline
Mood: Manic Expressive
|
|
For the production of Sulfuryl chloride it is synthesized thru a direct reaction of the two gasses SO2 and CL2. These are normally fed into the top of
a tube filled with activated carbon to give it the surface area to react. Liquid SO2Cl2 drips out of the bottom of the reactor.
I believe if would be wise to attempt the same here since it would be much worse having left over phosgene comming out the it would in the SO2Cl2
synthesis.
I will attempt to find the patent I spoke of which used Acetate esters as a catalyst for the Sulfuryl chloride synthesis. That may very well apply
here to but I would have concerns of the SOCl2 chlorinating the ester.
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
|
|
|
ScienceSquirrel
International Hazard
Posts: 1863
Registered: 18-6-2008
Location: Brittany
Member Is Offline
Mood: Dogs are pets but cats are little furry humans with four feet and self determination! 
|
|
To be honest it is not just the toxicity of phosgene that puts me off but the legal implications.
Making small amounts of chlorine, etc to demonstrate reactions or for synthesis could be passed off as chemical curiosity if your activities come to
the attention of the authorities.
Chlorine has uses for shocking swimming pools and is a common laboratory chemical in cylinders, etc.
Phosgene has no uses outside chemical manufacture or fairly specialised labs, most places work around using it by employing diphosgene, triphosgene or
alternative reagents.
You might have an interview with the local police or fire dept for making chlorine but you would be in a fairly strong position. I would not want to
try and defend myself for making phosgene.
|
|
|
entropy51
Gone, but not forgotten
Posts: 1612
Registered: 30-5-2009
Member Is Offline
Mood: Fissile
|
|
Quote: Originally posted by ScienceSquirrel  | | You might have an interview with the local police or fire dept for making chlorine but you would be in a fairly strong position. I would not want to
try and defend myself for making phosgene. |
Do you really believe that the local constabulary can distinguish
the difference? Or that they care?
After they see the flasks and the reagent bottles I don't think you can defend yourself against a charge of witchcraft, sorcery, terrorism, whatever.
|
|
|
ScienceSquirrel
International Hazard
Posts: 1863
Registered: 18-6-2008
Location: Brittany
Member Is Offline
Mood: Dogs are pets but cats are little furry humans with four feet and self determination!
|
|
I have some experience in this area as I run a legal operation known to the police and Customs & Excise.
Admittedly I am not in the first flush of youth and I have dedicated secure premises that are not close to residential premises.
I keep them informed of what I am up to and I do not have any problems at all.
|
|
|
Jor
National Hazard
Posts: 950
Registered: 21-11-2007
Member Is Offline
Mood: No Mood
|
|
Sedit, the formation of SOCl2 is an entirely different kind of reaction than formation of SO2Cl2. They look similar but are completely different kind
of chems. Besides prep. of SO2Cl2 is an oxidation, while that of SOCl2 is not an oxidative chlorination, so I doubt that these reaction have
similarities in kinetics and catalysts.
ScienceSquirrel, I see you point. It might give some troubles. I will decide later if it is worth it or not because of legal issues, but is the way I
described how I would do the reaction safe enough from my point of view and that hardly any phosgene will be released?
And ofcourse I wonder how fast COCl2 reacts with SO2.
Otherwise I will have to try the SO3 + SCl2 process or let it go. Kyrides simply is too much time and I don't have that time.
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
