Talk:Adamantane
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Quote: It melts at 270 °C and sublimates before boiling
Sublimation is the transition from solid directly to the gaseous phase, so that can't happen after melting. I guess it dissociates before it boils. 193.171.121.30 17:11, 25 Jan 2005 (UTC)
"It melts at 270 °C..." [in a vacuum? (see next line)] "and in atmospheric pressure..." [at what temperature, if different than above?] "sublimes..." [Is the correct word 'sublimates'?] "before boiling." [It sublimates, then boils? (solid -> gas -> liquid -> gas ) ???
What about "It sublimates (instead of boiling)"]
Suggestions: At 270 °C, it melts in a vacuum and sublimates at 1ATM. It melts in a vacuum at 270 °C, and sublimates at 1ATM at ??? °C. It sublimates in a vacuum at ??? °C, and melts at 1ATM at 270 °C. -Antonius- 23:44, 27 May 2006 (UTC)
"before boiling." In my oppinion the right way to put is before melting (see below)
@ Antonius : The process of sublimation depends on the vapor pressure of the material which again depends on the temperature. It does not really make sense to define something like a "sublimation point" comparable to a melting point. A better way to look at it is to compare it to some alcohol evaporating: It's not boiling and yet it disappears at a rate that depends on the temperature (and some other parameters, e.g. the degree of saturation of the surrounding space). Laslandes 11:08, 13 August 2006 (UTC)
- For now I removed the boiling/sublimation part (and the data that is available in chembox is removed from the article). I would suggest to put a short paragraph about the sublimation behaviour of the compound. What I think is that this is one of those compounds, which are solid around RT, melt at a certain temperature, but upon heating towards 'boiling' start to evaporate and sublimate onto any colder (RT or similar) surface (phenol is another one that springs to my mind). When lowering the pressure, one will get to a point where there is no liquid phase anymore, the solid simply sublimates, and sublimates again to a cold surface (unfortunately sublimation is both ways .. while for l/g we use boiling and condensing, and for s/l melting and freezing/crystallising, so here we talk about boiling/sublimation). The reason why there may not be a clear boiling point is that, at any given temperature below the boiling point, there is a certain vapour pressure (hence, there are molecules of adamantane in the gas-phase) .. when there is a cold surface close, the molecules that happen to be in the gas-phase condense onto the cold surface, thereby lowering the concentration of molecules in the gas-phase, which get repleneshed from the liquid phase. So while below boiling-point .. the compound will 'distill' towards the cold surface (maybe helped by energetically favourable crystallisation). Any thoughts anyone how to describe this process clearly? --Dirk Beetstra T C 11:34, 13 August 2006 (UTC)
[edit] Mountain crystals
The current article says that adamantane can be isolated from "some mountain crystals." That statement does not make sense, I work with a lot of crystals and we dont use the term mountain. Maybe a problem with translation from German.--Smokefoot 14:13, 24 June 2006 (UTC)
I just checked and I guess the right translation would be "rock crystal". --Laslandes 10:25, 13 August 2006 (UTC)
[edit] Solubility in water; org syn
- I weazeled out and left the mention that this stuff has some decent solubility in water. That property seems unlikely.
- several entries in Organic Syntheses (free on-line) describe various adamantanes. These references could be usefully incorporated.
--Smokefoot 14:45, 22 July 2006 (UTC)
[edit] Photoionisation
"...it cannot be photoionised because it lacks ultraviolet absorption bands."
Sorry, but this is simply wrong. Adamantane can very well be photoionized, only that the energies needed lie in the vacuum-ultraviolett regime of the spectrum. This means practically that it cant be photoionized within air because the air absorbs the rays before they reach the adamantane. I'll change that. Laslandes 15:52, 13 December 2006 (UTC)
