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Author: Subject: Propane as an inert-gas
thechemMo
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[*] posted on 30-9-2018 at 01:45
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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[*] posted on 30-9-2018 at 10:00


You could consider bubbling the exhaust gas through water to act as a flame trap ?
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[*] posted on 30-9-2018 at 10:04


Did you consider CO2?
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macckone
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[*] posted on 30-9-2018 at 22:36


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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[*] posted on 2-10-2018 at 12:21


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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[*] posted on 2-10-2018 at 19:49


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.



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morganbw
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[*] posted on 5-10-2018 at 13:50


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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[*] posted on 5-10-2018 at 13:56


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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[*] posted on 5-10-2018 at 14:53


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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[*] posted on 6-10-2018 at 01:14


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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[*] posted on 6-10-2018 at 20:07


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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[*] posted on 6-10-2018 at 23:39


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.




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[*] posted on 8-10-2018 at 19:38
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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[*] posted on 9-10-2018 at 06:09


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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[*] posted on 18-10-2018 at 16:29


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.




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[*] posted on 18-10-2018 at 16:51


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]




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Morgan
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[*] posted on 18-10-2018 at 17:14


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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[*] posted on 18-10-2018 at 17:27


Use nitrogen?

http://www.sciencemadness.org/talk/files.php?pid=505259&...




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[*] posted on 18-10-2018 at 18:10


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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[*] posted on 19-10-2018 at 20:27


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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[*] posted on 20-10-2018 at 05:17


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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[*] posted on 20-10-2018 at 19:33


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 212 times

[Edited on 21-10-2018 by macckone]
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Morgan
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[*] posted on 21-10-2018 at 06:19


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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[*] posted on 21-10-2018 at 06:55


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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[*] posted on 21-10-2018 at 07:11


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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