Nickdul
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Predicting the solubility of organic compounds. Hydroquinone.
How do you determine how soluble a compound will be in different organic solvents, in a relative way (i.e. X will be more soluble in EtOH than in
water, etc) ? I know the different types of solvents (polar, nonpolar / protic, aprotic), and that functional groups determine (partly?) the polarity
of a compound, so many hydroxyl groups would determine higher polarity, but are there any guidelines, algorithms to predict that?
My question was spurred from searching the solubility of hydroquinone (1.4-dihydroxy benzene, HQ) in various solvents:
Two -OH groups in the 1 and 4 positions of the benzene ring determine solubility in somewhat polar compounds, right? So, it will be relatively
insoluble in pet. ether, hexanes, more soluble in H2O, and most soluble in solvents somewhere in between.
Kodak's reference (attached) lists solubility in many types of solvents. So,
(% probably wt/wt, 24°C):
Benzene, Toluene, Xylene -Insoluble
Water - 7%
Methyl Alcohol - 30%
Ethyl Alcohol - 34%
Ethyl Acetate - 18%
Acetone - 17%
Methyl Ethyl Ketone - 30%
Cyclohexanone - 30%
How can I estimate such relations. For example, I expected HQ to be more soluble in methanol than in ethanol. Also, can I anticipate solubilities
based on dielectric constant? I wanted to figure a suitable solvent that is immiscible with water that I can use to extract hydroquinone from an
aqueous solution.
Similarly, what holds true quinone (1,4 benzoquinone) in that respect?
I apologize for a dilettante's question but this has been bothering me; I plan to start at the fundamentals and work my way up in organic chemistry
before going to college, but it isn't the easiest thing 
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kmno4
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Find and read/search this book:
Solvents and Solvent Effects in Organic Chemistry, 4 (or 3-rd)th ed (Wiley).
Possibly you will find some answers to your questions.
In my opinion it is one of the most interesting books about solvents/solvent effects.
PS. wt/wt says not much - mole fraction is natural measure of concentration and it should be comparing instead 'wt' values.
[Edited on 27-1-2014 by kmno4]
Слава Україні !
Героям слава !
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Nickdul
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Thanks kmno4
I know that molar concentration is clearer, but considering that I was comparing one compound across solvents, I decided it might not be worthwhile
(maybe molality?).
If anyone has something to add, please do. Meanwhile, I'll try to get the book and read it.
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