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Author: Subject: Perfluorooctanesulfonic acid (PFOS) from KPFOS
Nicodem
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[*] posted on 10-8-2010 at 13:18


Quote: Originally posted by Mister Junk Pile  
I know what a melting point apparatus is but I am certain that all of the ones I have used thus far would in no way be able to reach temperatures needed to melt metal salts (734*C for KBr). The glass (capilary tube) would even begin to soften at that point, right?

Look, I'm not going to search for the mp of tetraethylammonium perfluorooctylsulfonate in the literature. I think it is your business to do that, so do that. But expecting its melting point to be comparable to that of inorganic salts like KBr is extremely naive. With a perfluoroalkyl group and being a quat salt you can be sure it will be bellow 200°C, possibly even bellow 100°C. Actually, it would not even be a surprise if was a ionic liquid (though ethyl groups are too short for a tetraalkylammonium type of ionic liquid).
Anyway, just to answer your question about measuring high temperatures, some thermocouples can be used up to 1600°C or more (depending on the two metals used). Where no material resists any more, IR thermometers are used. But don't worry, you will never have to resort to such things when measuring the mp of organic substances.

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This might lead to publication but all of the stuff I have been discussing is already in the literature (it's where I got the TEAPFOS idea). Anything unique has not been mentioned. This was part of a question that I asked earlier: is it usually okay to discuss this as long as I don't divulge anything unique that is not already out there?

All but this preparation of tetraethylammonium perfluorooctylsulfonate. I'm sure your mentor would dislike this, but that is none of my business. It is not about divulging anything that is not already out there, it is about academic paranoia which is a conglomerate of many factors, including compromised authorship, research competition, novelty factor, loyalty factor, etc.
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Mister Junk Pile
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[*] posted on 10-8-2010 at 15:09



Quote:

Look, I'm not going to search for the mp of tetraethylammonium perfluorooctylsulfonate in the literature. I think it is your business to do that, so do that. But expecting its melting point to be comparable to that of inorganic salts like KBr is extremely naive.


Haha! Come on man! This was a question out of curiosity to see how one would measure the m.p. of KBr! I know that TEAPFOS will not have a m.p. anywhere near that temperature.

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All but this preparation of tetraethylammonium perfluorooctylsulfonate. I'm sure your mentor would dislike this, but that is none of my business. It is not about divulging anything that is not already out there, it is about academic paranoia which is a conglomerate of many factors, including compromised authorship, research competition, novelty factor, loyalty factor, etc.


Noted. Thanks.
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[*] posted on 11-8-2010 at 12:02


Quote: Originally posted by Mister Junk Pile  

Haha! Come on man! This was a question out of curiosity to see how one would measure the m.p. of KBr! I know that TEAPFOS will not have a m.p. anywhere near that temperature.

Every person I know would simply measure a DSC (or a TGA/DTA) since the measurement is set up in a few minutes. Added benefit: you get the enthalpy of fusion and an idea of the change of the heat capacity from solid to liquid phase and all phase transitions.
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[*] posted on 11-8-2010 at 14:38


Like this? I wish...

How would this particular model function?
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