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thechemMo
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Propane as an inert-gas
I know there has kinda been a thread about that.I wanna make it a little bit more specific,though.
I’ve read a thread on HIVE about the demethylation of Ethylvanilin to give protocatechuic aldehyde https://chemistry.mdma.ch/hiveboard/novel/000291912.html .The paper mentioned in this thread used Argon as an inert.I wanna use propane because
it’s more excessebile and cheap.I don’t see anything against this „theory“ but I’m a little bit worried about explosion dangers.I‘d do it
like this:3 neck rb flask,left neck I’d attach the tube that is connected to my propane tank with a suitable Glas Adapter.In the middle neck I‘d
have my Friedrich condenser where I would on the top attach a „tube adapter“ made from Glas to let the propane gas get out of the apparatus(an
then it would be ignited with a torch or something so that nothing comes into the atmosphere ).On the right neck Id just have my thermometer quick
fit.Do u think that would work?
[Edited on 30-9-2018 by thechemMo]
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Sulaiman
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You could consider bubbling the exhaust gas through water to act as a flame trap ?
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unionised
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Did you consider CO2?
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macckone
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Argon is available as 'wine preserving' gas in fine wine stores.
If argon is unavailable, I would suggest butane rather than propane.
Butane can be bought without odorant.
To my knowledge propane cannot.
The thiol used as an odorant may cause issues.
If you use butane make sure you do it outside and use a flame arrestor on the outlet.
Unless you are working in a real lab and it is ethyl ether rated.
Butane has similar LEL and a higher activation energy than ethyl ether.
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zed
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It is possible CO2 will serve?
Might be sufficiently inert under your reaction conditions, and it is easy to generate.
I've seen Argon tanks at "Harbor Freight", in the past.
But, a current search of their site, shows none advertised.
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ninhydric1
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Or use nitrogen gas. Remove the O2 from the atmospheric air with a flame and use water to absorb CO2. Send the gas through sulfuric acid to dry it. Or
you could buy it if you have access to it.
The philosophy of one century is the common sense of the next.
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morganbw
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I would try the reaction without the inert gas. Maybe it is needed but sometimes it becomes a habit that is used with all trials.
I did not see any results shown without the inert gas.
For me (skip the inert) would be the first trial, then if that sucked I would think that, yay maybe it needs to be inert.
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Tsjerk
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With these phenols I would advise using a inert gas. They are prone to polymerizationand somehow it seems oxygen induced. Propane should work, just
don't set it on fire
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morganbw
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Quote: Originally posted by Tsjerk  | | With these phenols I would advise using a inert gas. They are prone to polymerizationand somehow it seems oxygen induced. Propane should work, just
don't set it on fire |
You are more than likely right. I really understand this and respect this.
I am however a little reckless at times and am willing to trash a few grams of a substance just to satisfy my curiosity.
Dang, it looks as if I have just decided on a future experiment/synthesis for myself. No worries, I have failed a few times in the past. Still?
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deep_dreamer
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I have read a post (probably here on Sciencemadness) by a knowledgeable user that inert gas is not always necessary with catechols. Sadly, I can't
find it anymore. It stated that the main problem is the oxygen already dissolved in the solvent, which could be fixed by boiling the solvent prior
usage or by addition of a small amount of (I believe) a bisulfite salt (not too much, as to not interfere with the aldehydes).
Takes this with a grain of salt because:
1) I am not experienced enough to say if this works
2) I can not remember the original post
3) Even the original post was not backed up with any scientific data and merely anecdotal!
I believe it's better to be safe than sorry and use a decent inert gas.
PS: If someone finds the post I am referring to, please provide it.
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Swinfi2
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I've worked with catechols, their stable enough dry in air and in degassed water, it is the wet oxygen that kills them.
[Edited on 7-10-2018 by Swinfi2]
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wg48
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Catechol and other phenol derivatives were and probable still are used as silver halide developers. Meaning they were used in water solutions in
baths open to the air for many hours. Typically the developers included sulphite to prevent air oxidation of the catechol.
I don’t know if the sulphite was able to reduce oxidised catechol or if it only acted as a oxygen scavenger being oxidised in preference to the
catechol.
Borosilicate glass:
Good temperature resistance and good thermal shock resistance but finite.
For normal, standard service typically 200-230°C, for short-term (minutes) service max 400°C
Maximum thermal shock resistance is 160°C
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CaptainPike
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Another OTC argon
There is also another retail source of argon, five nines
http://www.bloxygen.com/
You don't get very much – it's a low pressure container, but it's very pure. Maybe you could just fill the headspace occasionally during the
reaction.
[Edited on 9-10-2018 by CaptainPike]
[Edited on 9-10-2018 by CaptainPike]
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walruslover69
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I don't know what is available where you live, but every Walmart near me sells helium tanks. They aren't that expensive.
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VSEPR_VOID
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I am not sure if that helium is very pure.
Nitrogen is cheap and you can get it from welding supply stores locally.
Propane sounds like a bad idea. If there is any O2 remaining in the reaction vessel, you just made a bomb.
Within cells interlinked
Within cells interlinked
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Twospoons
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A lot of the OTC helium has oxygen in it to stop people suffocating while playing the voice changing game.
You should be able to get Ar or Ar/CO2 shield gas in single use cylinders at a welding supply shop.
[Edited on 19-10-2018 by Twospoons]
Helicopter: "helico" -> spiral, "pter" -> with wings
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Morgan
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That would be an experiment to try to test for oxygen in helium for balloons. I know one thing, it makes you dizzy when you do the squeaky voice
thing. What percentage of O2 is cited in helium for balloons, from what reference if anyone knows or if any at all? Would it support combustion for
example?
I should say I've only tried the store-bought balloons, not those lower volume, round tanks the public can buy for parties.
[Edited on 19-10-2018 by Morgan]
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BromicAcid
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Use nitrogen?
http://www.sciencemadness.org/talk/files.php?pid=505259&...
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VSEPR_VOID
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| Quote: Originally posted by Morgan | That would be an experiment to try to test for oxygen in helium for balloons. I know one thing, it makes you dizzy when you do the squeaky voice
thing. What percentage of O2 is cited in helium for balloons, from what reference if anyone knows or if any at all? Would it support combustion for
example?
I should say I've only tried the store-bought balloons, not those lower volume, round tanks the public can buy for parties.
[Edited on 19-10-2018 by Morgan] |
I bet it would not be hard to do an assay and find out. Find a reaction that requires bubbling oxygen through a solution to get a precipitate, put a
liter of store bought He in, weight the precipitate, calculate O2 content
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macckone
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The walmart helium literally says on the tank that it contains oxygen.
If you are going to get a tank from a gas supplier, argon is way cheaper.
Propane is not any more dangerous than ethyl ether.
In fact ethyl ether is in some respects more dangerous.
Any reaction needing inert gas is likely going to be using either ether or another organic
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Morgan
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I see Balloon time helium is or says it's a "mixture of helium and air containing not less than 80% helium" that's for sale at PartyCity looking at
the literature written on a tank from a photo from their site.
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macckone
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Morgan: that is the same stuff. In 2011 NZ corner Ian Smith recommended that helium from balloon time contain a minimum of 10% oxygen to prevent both
accidental and intentional death. Shortly after the new mix started hitting shelves. Here is the worthington datasheet which provides the product
for Balloon Time. I suspect Air is actually straight oxygen and they are shooting for 10-15% oxygen.
Attachment: wc042-helium-blend.pdf (30kB)
This file has been downloaded 298 times
[Edited on 21-10-2018 by macckone]
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Morgan
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Macckone I guess if it was just a He and air mix, then it would contain less than 5% O2. But yes, it does seem suspect in that the way foods and
products are labeled these days, you never know if there may be obfuscations.
As an aside, there's something ironic about a person ending their life with a product called Balloon time. When I worked for a library, we had the
book Final Exit in Large Print and that too was in a sense quirky.
https://exitinternational.net/?wysija-page=1&controller=...
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unionised
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| Quote: Originally posted by Morgan | What percentage of O2 is cited in helium for balloons, from what reference if anyone knows or if any at all?
[Edited on 19-10-2018 by Morgan] |
In principle, none.
They do not add oxygen to "balloon gas".
That idea is a dangerous myth.
The safety data sheet for Balloon gas is the same as the one for higher grades of helium.
https://www.boconline.co.uk/en/images/10021690_tcm410-84477....
If they added oxygen they would be expected to ensure that the rest of it was "breathing grade" and that would make it much more expensive.
Balloon gas is cheap "dirty" helium.
When a research lab or whoever returns an "empty" cylinder to the supplier, they first thing they have to do is empty it y hooking it to a vacuum
pump.
Similarly, when they fill high purity helium cylinders, they have to purge air out of the manifolds with helium.
Both those processes give rise to He containing a bit of air.
That's "balloon gas".
The specification that was cited earlier includes 0% air as a possibility.
[Edited on 21-10-18 by unionised]
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Morgan
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I was wondering if you put Balloon time helium in a burette with an electrically heated platinum wire or gauze you could slowly introduce hydrogen to
keep it below any possible lower explosive limit and burn up the oxygen to confirm what volume of helium and nitrogen remains.
I can't think of any simple getters for oxygen the way limewater works for CO2.
[Edited on 21-10-2018 by Morgan]
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