Jimmymajesty
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Silent discharge in preparative chemistry?
Hi folks,
I am just wondering what useful chemicals could be made out of OTC chems with this method. As I understand you give energy to the molecule mainly
without heating the rectants too much, it is like the socalled "microwave effect" I saw some papers on preparation of amino acids and hydrazine, but
what else could be made with it?
It is completely doable with standard glassware so feel free to experiment and do not forget to post the results here!
Thanks!
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aga
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Please read what you typed and try again.
Your post makes almost no sense at all (maybe to you).
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Bert
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Please give a link to your source material?
I will put this thread into "beginnings", at least until you provide some background references/documentation-
Rapopart’s Rules for critical commentary:
1. Attempt to re-express your target’s position so clearly, vividly and fairly that your target says: “Thanks, I wish I’d thought of putting it
that way.”
2. List any points of agreement (especially if they are not matters of general or widespread agreement).
3. Mention anything you have learned from your target.
4. Only then are you permitted to say so much as a word of rebuttal or criticism.
Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
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Bert
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Thread Moved
12-4-2015 at 17:42 |
Jimmymajesty
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Hi,
I do not have references, the question is what woluld be the outcome if you refluxed simple chems like ethyl acetate through silent discharge, would
it decompose? Can you induce molecular rearrangements of any sort with it?
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blogfast25
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Explain what you understand by 'silent discharge'.
If you don't have any references at all, then where did the idea come from?
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Metacelsus
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I think he means dielectric barrier discharge.
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HgDinis25
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Dielectric Barrier Discharge is just a fancy name for Silent Discharge. There are a few papers out there, concerning the decomposition of certain
gases by Silent Discharge, like the two:
http://pubs.acs.org/doi/abs/10.1021/ja01550a021
http://pubs.acs.org/doi/abs/10.1021/i260069a019
I didn't understand your system, though. Are you talking about having a continuous discharge in a reflux apparatus, for gas-phase decomposition?
That's not easy. If you were able to get it working, though, Ethyl Acetate would probably decompose into dozens of different chemicals.
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Nicodem
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There is very little on preparative chemistry using silent discharge reactors. It's nearly only application in academic and industrial setting is for
the production of ozone. Otherwise, a similar technology found its use in the plasma reactors used for depositing materials or surface etching.
There was some research into use of (modified) silent discharge reactors for the partial oxidation of alkanes to alcohols mainly, or generation of
hydrogen from hydrocarbons. There was also some interest for their use in the decontamination of trace amounts of volatile organic compounds in the
exhaust gases. But there is almost nothing more complex or interesting.
The reason is probably in its limitation to vapour phase reactions and due to the limitations imposed by the reactivity and instability of cationic
species formed from the compounds being ionized. Any complex substrate, like organic compounds, would tend to undergo complex fragmentation (or
complete oxidation in the presence of oxygen).
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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violet sin
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after reading the opening post I looked into the silent discharge research in hydrazine production. the paper I found was using reduced pressure
oxidation of ammonia vapor. it stated that the hydrazine was produced exclusively in the positive column and was related to some of the other actions
happening but also independent of some species entirely.
http://pubs.acs.org/doi/abs/10.1021/ja01639a006#
_________________________________________
and this one has some interesting info as well,
" It has been found that sustained high yields of hydrazine may be obtained by passing a stream of ammonia through an extended glow discharge if the
stream of gas is maintained under conditions of highly turbulent flow in its passage through the discharge and is eificiently cooled while it is in
the discharge zone. "
http://www.google.com/patents/US2728723
_________________________________________
interested in this one also,
" The term electrolysis is conventionally applied to chemical changes brought about by passing an electric current between conducting electrodes
dipping into a liquid phase containing ions, where the changes can be satisfactorily explained by electron transfer between the ions and the
electrodes. If, however, the liquid phase is itself made an electrode and an electrical glow-discharge is passed to it from a conductor located in the
gas space above the surface, a completely different situation arises in which novel chemical reactions can be brought about in the liquid phase, and
this process is referred to as glow-discharge electrolysis (GDE). "
http://link.springer.com/chapter/10.1007/978-1-4684-3000-4_5
____________________________________________
looks like I might have some research and papers to request when I get time to look around more. I LOVE electrochem
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Jimmymajesty
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I finally had some time to try it out. I used 95% ethyl alcohol. Aluminum foil was wrapped around a column and a copper wire went all along in a
zig-zag way inside the tube. I used a flyback transformer as a power source, switching it on without Et-OH it generated ozone as it should.
I set up the Et-OH for reflux, waited for 10 mins. Then switched on the H.V. source, the blue glow was apparent inside the tube but small to zero gas
evolution could be observed (~2ml/min). I smelled inside the condenser but apart from the ozone-ish smell nothing special.
I do not really know how to do a better trial... The electric power trasferred to the Et-OH molecules was too little I think.
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violet sin
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Did you see the last link I provided? It said different effects take place when one electrode is below the surface. Could be more reactive and not
too different that you would have to scrap the first setup entirely. At least worth a try I would wager
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Jimmymajesty
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Yup, I tried it out out today with Et-OH, but nothing really happened apart from after some time the ethanol started to boil. I really do not see how
this could be used to make anything at all, at least with my stuff.
I did another experiment today inspired by the patent attached.
I mixed ozone and acetaldehyde gas then bubbled them into 20°C water. The gas flow was around 5ml/sec for each feed.
But again nothing really happened... I even prepared for an explosion but the ozone and the acetaldehyde did not even react. After 30mins I put some
KI crystals into the water and it turned yellow, so there were some ozone dissolved but also there was a strong smell of acetaldehyde. Thought they
are easily forming acetaldyde monoperacetate so I boiled the resulting liquid but not a single trace of acetic acid, just acetaldehyde, so it appears
they not.
Attachment: acetaldehyde monoperacetate GB877662A.pdf (393kB)
This file has been downloaded 560 times
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violet sin
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well that sucks( scientific term lol) I had hoped to see some results of some kind.
good one with pic's and diagrams
http://iesj.org/html/service/ijpest/vol1_no1_2007/4_Moon.pdf
" The effects of the third electrode on the discharge and ozone generation characteristics of a wire-plate type
nonthermal plasma reactor, with a slit dielectric barrier, have been investigated. When a third electrode is installed just
above the slit of the slit dielectric barrier, where an intense surface corona discharge occurred, it is found that a
significantly-increased ozone can be obtained, especially from a negative corona discharge. "
oxidative coupling of methane with AC and DC coronal discharge
http://coecs.ou.edu/Richard.G.Mallinson/PDFs/96iecr3295Liu.p...
plating in a coronal discharge
http://pubs.acs.org/doi/abs/10.1021/ba-1969-0080.ch016
" It has been demonstrated that boron can be deposited on tungsten in a corona discharge. "
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Jimmymajesty
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violet sin, thanks for the papers.
I tried out couple of things in the last days mainly with acetaldehyde.
I mixed ozonized air with acetaldehyde and let the gases into a temp. controlled reactor.
Above 100°C a bleach like smell was indicating that something was happening still I could not really condense anything after the reactor, (after 1
hour 0,1ml of oily liquid that was flammable and strongly smelled of formaldehyde+bleach) this was at 120°C, then I went above the ignition temp. of
acetaldehyde (to 220°C) but this time nothing condensed at all.
Also I tried to use ozone as a catalyst in water at 40°C. I let the acetaldehyde into the water together with ozonized air, the acetaldehyde escaped
as it entered, the smell again was somewhat formadehyde-ish but I think my nose was tricked by the smell of ozone because its smell is way stronger
than that of acetaldehyde.
Then I added 2 ml of saturated copper acetate into the sparger without any detectable effect. The time frame for each experiment was around 1 hr, so
they either proceeded very slowly or I was doing something wrong.
It seems the thread does not deseve much attention afterall...
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WGTR
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I have experienced silent discharges in the lab before. Thankfully, I was positioned in front of the fume hood. I merely opened the sash a little
wider, and no one was the wiser.
This was a topic that I found fascinating back when I was trying to synthesize liquid hydrocarbons from common materials. The silent discharge was a
general area of research in the late 1800's to early 1900's, but as others have mentioned, the main application today is ozone generation.
The following reference contains several experiments and experimental conditions with the silent discharge. It seems that the procedure works better
when the electrodes are as close as possible together, a few mm at most. Enjoy.
https://books.google.com/books?id=1902AQAAMAAJ&pg=PA1542...
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