Sciencemadness Discussion Board

Using Diflouroethane instead of Nitrogen?

Db33 - 15-12-2016 at 15:20

I have seen some reactions where they say to use a Nitrogen atmosphere, usually a balloon or something allowing Nitrogen in to flush out the air. My question is, if the problem in these reactions is just the air, would the same result be able to be had by just spraying a can full of Air Duster (diflouroethane) in the flask? What would be wrong with that?

ficolas - 15-12-2016 at 18:51

There cant be a general rule for this.
Reactions that require an inert atmosphere require an atmosphere that wont interfere in it. Sometimes CO2 may be enough, sometimes N2 is needed, or sometimes argon is needed. It all depends on the reactives and the products.

Texium - 15-12-2016 at 19:07

It has to be determined on a case-by-case basis, but I absolutely would not use difluoroethane at all for this, as it is flammable and its combustion yields some very deadly compounds such as HF and fluorophosgene. If you should accidentally ignite it, that could be a disaster.

[Edited on 12-16-2016 by zts16]

Db33 - 15-12-2016 at 19:49

when i see people doing reactions like this with Nitrogen, they just fill a balloon and put that on one of the necks and then start the reaction. But what about the air thats already in there? how do you get that out, would you open one of the other 3 necks of the flask, let some of the nitrogen in to flush it out and then close it? or what

Texium - 15-12-2016 at 19:52

I don't use inert gasses at home, but at work where I have a manifold in the hood with an argon line, I stick two needles into the septum of my reaction flask: one to the argon line and one not connected to anything. I allow the headspace to be flushed with argon for 10 minutes or so, then remove the open needle. You could do something similar with a balloon.

claudiusthegod - 15-12-2016 at 22:48

What gas you use depends on what reaction you're doing.

I know you've just got some 4-piperidone and propionyl chloride (according to your posts), but making a fentanyl derivative would be very wrong, so I'm sure you're not doing THAT.

But just what reaction are you planning on using your 4-piperidone and propionyl chloride for?

Maybe artificial flavoring for snow-cones?

If so I would use Argon, because snow-cone flavorings can be quite dangerous. Especially the pineapple!



violet sin - 16-12-2016 at 00:52

Strikes me as quite odd, chiming in as a 1 post name to poke at someone... Or was that just the incentive needed to register? I don't like the idea that it's possible a member might slip into a new skin to say something they wouldn't want pinned on their standard name. Tell me that's not what's going on here?! I don't mean to be outwardly rude, but it's not too often some new recruit has such a good grasp of all the recent postings. So perhaps you can see why this doesn't fit right with me. Apologies if wrong, and I sincerely hope I am.

Back on topic, I would rather not use dust off as an inert blanket. Mainly because of degredation products if something were to happen. Even a standard flamable gas like butane would have less hazard, if only in the essence you know what you would be in for if things went south. Could prepare for it even. However that's not a suggestion to purge with flamable substances. A small nitrogen cylinder isn't too much. Found one NEW for 50$ in the local brew shop. CO2/N2 bottle actually, but I was told it could be filled with N2 only on request.




Scalebar - 16-12-2016 at 01:39

Could you perhaps generate crude nitrogen by burning a metal in a sealed container of air to strip out oxygen? Do it in a inverted cylinder with the mouth under water and you'd be able to extract the gas with a syringe.

Tsjerk - 16-12-2016 at 02:28

I learned to first flush with inert gas as Zts16 described, but afterwards put a balloon with gas in the septum via a needle, this way you keep a bit of over pressure which will last even over night.

You could do this with butane.

[Edited on 16-12-2016 by Tsjerk]

JJay - 16-12-2016 at 02:52

You can generate nitrogen with sodium nitrite and sulfamic acid, but it would probably be a good idea to purify it before using it as an inert atmosphere.

Various inert gases can be obtained from welding stores.

Texium - 16-12-2016 at 08:45

Quote: Originally posted by violet sin  
Strikes me as quite odd, chiming in as a 1 post name to poke at someone... Or was that just the incentive needed to register? I don't like the idea that it's possible a member might slip into a new skin to say something they wouldn't want pinned on their standard name. Tell me that's not what's going on here?! I don't mean to be outwardly rude, but it's not too often some new recruit has such a good grasp of all the recent postings. So perhaps you can see why this doesn't fit right with me. Apologies if wrong, and I sincerely hope I am.
I don't see anything disturbing about it. It's not rare for lurkers who haven't made accounts to read the forum for some time before creating an account. I think the poking was certainly deserved, too, if Db33 appears to be making drugs. I hadn't noticed because I haven't been reading every thread lately, but I'm glad that it was pointed out. I think it's highly unlikely that they're a sockpuppet. Since when has anyone here been afraid to make tongue-in-cheek comments to potential cooks or kewls under their regular account? I'd have said something similar had I noticed what the OP was working with.

@Tsjerk: Yes, I keep the argon line on at a lower flow rate to make sure that the flask stays purged

XeonTheMGPony - 16-12-2016 at 09:06

Only liquid diflouroethane (R-152a) flammable the gas burns very little takes effort, but yes very nasty decomp products. It is not that un reactive either, so not inert, fairy stable but far far from Inert.

OFN Nitrogen isn't that expensive from gas suppliers (Oxygen Free Nitrogen) For brazing you can get Nitrogen with 5% Hydrogen as an oxygen scavenger used in oven brazing.

violet sin - 16-12-2016 at 12:44

Zts16, "I don't see anything disturbing about it" ... " I'm glad that it was pointed out"

I'm not the type to encourage illicit manufacture of controlled substances either. It was the nature of the comment not cared for. Hope Claudiusthegod, becomes a regular poster, we can always use another active member. As noted in my above post, I was wishing to be wrong about the whole situation any way. Consider the mater dropped.