fusso
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Which organic compounds has the widest/smallest liquid range?
Which organic compounds has the widest/smallest (except those which sublime directly) liquid range?
[Edited on 25/09/18 by fusso]
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clearly_not_atara
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The liquid range varies with pressure. For nearly all compounds, liquidus is absent below a certain pressure, which is called the "triple point
pressure", a reference to the phase diagram. So for example the liquid range of water becomes arbitrarily small as the pressure is decreased to 0.006
atmospheres. Carbon dioxide has no liquid range at standard pressure, and neither does elemental carbon.
At standard pressure, iodine heptafluoride has a liquid range of just 0.27 Kelvin:
https://en.wikipedia.org/wiki/Iodine_heptafluoride
On the other hand, many ionic liquids have no stable gas phase and remain liquid until they decompose. In the case of 1-butyl-3-methylimidazolium
triflimide, the melting point is below 0 C and the compound decomposes above 400 C:
https://pubs.acs.org/doi/pdf/10.1021/ie5009597
Among compounds that do vaporize, propylene carbonate has a liquid range from -49 C to +242 C, which is the highest I've seen, but that's a common
solvent, so maybe you can do better.
[Edited on 25-9-2018 by clearly_not_atara]
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fusso
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Quote: Originally posted by clearly_not_atara  | At standard pressure, iodine heptafluoride has a liquid range of just 0.27 Kelvin:
https://en.wikipedia.org/wiki/Iodine_heptafluoride[Edited on 25-9-2018 by clearly_not_atara] |
Even though I
was asking about organic, I still thank your response.
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macckone
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propylene carbonate is a commonly used solvent because it has such a wide range where it is liquid.
Ethanol is -114 to 78 which is less than propylene carbonate but still very wide.
Ethanol is one of the most widely used solvents.
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chornedsnorkack
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Found an organic example with conspicuously narrow liquid range, i. e. triple point pressure near but below 1 bar. Tetramethylbutane.
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happyfooddance
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tert-butanol has a pretty small window, although it can exist as supercooled liquid at pretty low temp (r.t.)
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unionised
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If I was looking for long liquid ranges for simple organics I'd look at aromatics- because they are stable enough, not to fall apart. I'd try linking
two together so they can't easily form a planar molecule - so the melting point isn't too high, and I'd stick an alkyl group or two on somewhere to
lower the melting point a bit further.
Something like tolylnaphthalene or xylylnapthalene might be worth looking at.
The first one's a liquid at room temp and boils about 350C
I couldn't easily find data on the other.
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chornedsnorkack
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| Quote: Originally posted by unionised |
Something like tolylnaphthalene or xylylnapthalene might be worth looking at.
The first one's a liquid at room temp and boils about 350C
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Which one? There are 6 of them. Because naphthalene has 2 positions to substitute, and there are 3 tolyl groups.
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