Polverone
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surprised by dichloroacetylene
Recently I've been experimenting with the reaction of trichloroethylene with strong bases in alcohol, in order to prepare dichlorovinyl ethyl
ether (which I will then try to hydrolyze to chloroacetic acid). Out of curiousity, I tried reacting a bit of trichloroethylene with KOH (which
I'd been dissolving in ethanol) in DMSO, since chloroform gives interesting reactions in DMSO with NaOH and Na2S.
The KOH solubility in DMSO seemed poor, and it just accumulated an irregular darkness on the KOH flakes and some darkening of the solution. Addition
of trichloroethylene didn't seem to do anything. I decided to add some water to dissolve the KOH and dispose of everything when I was done. The
addition of water of course made the mixture hot as the KOH was dissolved, and it was bubbling pretty vigorously. I thought that these bubbles were
just localized boiling until suddenly there was a little "fwoomp" and a tongue of smoky orange flame shot out of the test tube. I was so
startled I almost dropped it. Some time ago I'd read about dibromoacetylene, the spontaneously flammable and highly toxic product of the reaction
between KOH and tribromoethylene, so I very quickly realized that this was probably dichloroacetylene. I dropped the test tube in the sink and flooded
it with water, but not before one more burst of flame shot out.
This could make a fairly impressive demo of some sort, especially since the materials (a degreasing solvent and a strong base) are so easy to get, but
the toxicity of dichloroacetylene probably recommends against this.
Memo to self: only react trichloroethylene with alcoholic alkali solutions.
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DDTea
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Dichloroacetylene is a truly nasty compound... Not only does it cause lung damage, but also nerve damage. That is, if it doesn't catch fire
first. As you noticed, it is very pyrophoric, and reactions to produce it are usually done under inert atmosphere. Still, because of its easy
production, I'm sure we could find some mad-science use for it...it's actually a very interesting compound.
Maybe if anything, it could be used as a pyrophoric ignition source for vapor cloud experiments...but that's getting into practical use.
I once had a wacky idea of making some Dichloroacetylene in a sealed container, and then calling it "An Angry Genie." 
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BromicAcid
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How about reaction with AgNO3 to try to make dinitroacetylene. Although my 'Nitrocarbons' book says that despite numerous attempts that
compound has never been syntheised.
Some information on dichloroacetylene
That link says dichloroacetylene is a liquid and that when it boils it explodes  But it doesn't list a boiling or decomposition point, I guess it doesn't matter as if you tried to make it you would want to keep it at
as low a temperature as possible whenever possible just because of the volitility of it and the nerological impairments it can cause and of course the
fact that it is spontaneously flamable in the presence of O2.
After reading Samosa's idea for the angry genie I can't help but think of the dichloroacetylene shooting out and taking form questioning of
Polverone "You summoned me?'' And then Polverone promptly freaking out and drowning the mix with water and the 'genie'
giving a death cry 
[Edited on 5/26/2004 by BromicAcid]
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chemoleo
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Interesting.
Anyway, to get the dinitroacetylene, I guess it should be the silvernitrite rather than the nitrate?
Anyway, this seems the most obvious route, hence I doubt it'd work - else they would have isolated that way already! Also, it is possible that
the carbide entitiy during the reaction will directly precipiate with the silver ion, forming silver carbide or some derivatives.
I wonder what one could do with it, the dichloroacetylene.
Any solutions containing some Na-salt (ie. alcoholates, acetates) should react to form some rather unusual substances!
What happens in the presence of water? does it form HCl and ethylene? What with alcohol? Questions over questions.
Anyway, very interesting reaction. Good you mention it because I planned to systematically test all my chlorocarbons with NaOH
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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Polverone
Now celebrating 21 years of madness
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If you react trichloroethylene with an excess of sodium ethoxide, you get the highly reactive alpha-beta dichlorovinyl ether. It gives various
products of interest when reacted with alcohols, phenols, water, and hydrogen chloride. The product of most immediate interest to me is chloroacetic
acid. See the post "chloroacetates and acid chlorides from TCE" in the <A
HREF="http://www.sciencemadness.org/talk/viewthread.php?tid=35">chloroacetic acid thread</A>.
I will have to try this soon since Organikum has recently posted a trivial preparation of sodium ethoxide from alcohol and NaOH.
[Edited on 11-9-2004 by Polverone]
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IrC
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Old thread I never looked at before but interesting. I searched for threads on 'chloroacetates and acid chlorides from TCE' and 'chloroacetic acid',
no result, a few hits but not the correct one (viewthread.php?tid=35").
Polverones link at bottom does not exist AFAIK. Anyone know where the info is?
[Edited on 11-26-2010 by IrC]
"Science is the belief in the ignorance of the experts" Richard Feynman
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Rosco Bodine
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Here is the unmangled link
http://www.sciencemadness.org/talk/viewthread.php?tid=35
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IrC
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Thanks Rosco I must have brain failure. Usually I am one who looks at the URL every time I click a link. Call it learned reflex dealing with phishers,
normally I check to be sure I'm going where the link indicates. If I would have done so here I could have cut out the error in the URL. Failed to see
it again when I copied the end of the URL for my question. I also realized my mistake in search. Seems it searches from where you are at the time.
After highlighting 'All forums and sub-forums' I found the page. What I get for reading into the late hours instead of sleeping I guess.
"Science is the belief in the ignorance of the experts" Richard Feynman
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woelen
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This thread is new to me and looks quite interesting. I tried the following:
- Take half a ml of trichloroethylene
- Add a spatula of NaOH --> No reaction occurs
- Add a few drops of water --> The NaOH liquefies, the liquid becomes hot, no other changes
- After a few minutes, I added appr. 0.5 ml of ethanol. Still no reaction.
So, I am quite surprised by Polverones observation. Right now I cannot use my DMSO, it is a big and hard chunk of ice at the bottom of the bottle 
I'll let the DMSO melt inside in a warmer place, but that takes a loooooong time. I don't want to heat it, because local hot spots may lead to local
decomposition and contamination of the product.
[Edited on 26-11-10 by woelen]
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The WiZard is In
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Quote: Originally posted by Polverone  |
The KOH solubility in DMSO seemed poor, and it just accumulated an irregular darkness on the KOH flakes and some darkening of the solution. Addition
of trichloroethylene didn't seem to do anything. I decided to add some water to dissolve the KOH and dispose of everything when I was done. The
addition of water of course made the mixture hot as the KOH was dissolved, and it was bubbling pretty vigorously. I thought that these bubbles were
just localized boiling until suddenly there was a little "fwoomp" and a tongue of smoky orange flame shot out of the test tube. I was so startled I
almost dropped it. Some time ago I'd read about dibromoacetylene, the spontaneously flammable and highly toxic product of the reaction between KOH and
tribromoethylene, so I very quickly realized that this was probably dichloroacetylene. I dropped the test tube in the sink and flooded it with water,
but not before one more burst of flame shot out. |
Me the analogue guy again - my ever useful copy of NPFA 491M
Manual of Hazardous Chemical Reactions 1971 sez :—
MCA Case History 495 (1956); 1065. When moist chlorine
was passed over calcium carbide and potassium hydroxide,
a solution of 58% dichloroacetylene was collected in ether.
The solution burned spontaneously and filled the laboratory with
phosphgene. When the head was removed from a steel bomb
used for one of the experiments contact with air caused an
explosion that drove the base of the bomb through the floor.
R. Reemschneider and K Brendel, Ann. Chem 640: 5 (1961).
Ruthledge. p. 138 (1968)
At the risk of pandering to the pedestrian — Bretherick's has
several useful refs. including this which Google sez was posted
here!
www.sciencemadness.org/talk/files.php?pid=140857&aid=669...
[Edited on 26-11-2010 by The WiZard is In]
[Edited on 26-11-2010 by The WiZard is In]
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