[CBond007]

Does anyone know why in some cases oxime solubility in ethanol increases as the temperature decreases.  I would have thought it would have been the other way around. 

The compund I have synthesised behaves similar in methanol, ethanol, isopropanol, and acetonitrile.

I have searched ACS journals but only found the citation below and it doesnt explain why.  Please point me in the right direction.

J. Chem. Eng. Data 2001, 46, 838-841

Thanks
Marvin

[organoman]

Is there any reliable data to support it. I mean it is really strange. In case of solubility of gases in solvent this is true.
However one vague explanation could be that at higher temperature hydrogen binding between solvent and oxime might ruptured. This is what I can think of at moment.

[kiwi]

no i'd say at low temperatures you have a non-covalent complex of multiple oxime molecules, which cluster together (like a micelle) . At higher temperatures, the attractive forces between oxime molecules are increasingly overcome, and each molecule is forced to try and dissolve on its own. it can't, so it crashes out.

[organoman]

Hi kiwi,
looks OK of what you say. But your statement "At higher temperatures, the attractive forces between oxime molecules are increasingly overcome," is not clear. i mean at higher temperature any attractive forces should only diminish.

[kiwi]

exactly, as temperature increases, likelihood of clusters remaining around decreases. hence decreasing solubility at increasing T