[Mrbazoun]

Both of these compounds are only slightly soluble, but which one is more soluble. Which of these drugs is more soluble in water and why? I don't know where to begin - i have no cluehow cyclohexanes affect solubility.

[nj_bartel]

Those aren't cyclohexanes, but that's the wrong part of te molecule to look at. Both molecules have analagous structures and both have different structures. Since there's a difference in solubility, you should look where for the difference in structures and go from there

[Mrbazoun]

Yes, I made it that far; however, what I meant to say is I don't know how the cyclohexene affects solubility. Sorry

[nj_bartel]

Well, they're phenyl rings, not cyclohexenes. At any rate, I mis-saw the structures.  What does that fluoride cause to happen to the electrons of the phenyl ring?

[mehc]

Both of these compounds are only slightly soluble, but which one is more soluble. Which of these drugs is more soluble in water and why? I don't know where to begin - i have no cluehow cyclohexanes affect solubility.

one of these can show hydrogen bonding in water, and will be more soluble.

[orgopete]

… What does that fluoride cause to happen to the electrons of the phenyl ring?

I think a pH effect is being suggested. If not, then I erred in that assumption.

I want to suggest an alternate explanation to explain I think would be more soluble. I had experience in the past with trying to improve the water solubility of some analogs. The solution ended up being to incorporate a trifluoromethyl group. I was simply copying a literature report that these compounds improved water solubility. I simply took this as an empirical fact.

Since I have been thinking about molecular properties, I still think the more soluble compound is the fluoro-compound and here is why. I think fluorine is an effective hydrogen bond acceptor thus improving water solubility. Organic chemists know that iodine has more protons in its nucleus, its electrons are compacted into a smaller volume, it is more dense, it is a better leaving group, it is more electron withdrawing, and HI is a stronger acid. Fluorine has fewer protons, it is less dense, it is a poorer leaving group, it is less electron withdrawing, HF is a weaker acid, and its electrons can extend further from the nucleus. If I am paying attention, then fluorine can donate its electrons to water in forming hydrogen bonds, hence improve water solubility.

Now, I hope someone can tell us which acid is more soluble so someone can tell me I am all wrong.

[nj_bartel]

pH effect and generally disequilibrating the electron density, but I like your explanation too, maybe better, although it could be both things.

Edit: I also couldn't find solubility data on the two, though I only checked wiki

[idieh]

Motrin should be Ibuprofen and Ansaid Flurbiprofen, so try and find their solubility.
So:

Ansaid 8 mg/L
Motrin 0.049 mg/ml

I'm not sure whether these values are right or wrong, cause this means that Ansaid has a solubility of 0,008 mg/ml which is less than the solubility of Motrin.
This isn't consistent with the fact, that Ansaid should be more polarized because of the inductive effects and the Fluorine, which can build H-Bonds.
And as you now more polarized molecules are better soluble in Water. "Similia Similibus solvuntur".

[orgopete]

Well, dang it. I just hate the facts, just when you have a good theory going.

I saw the same kind of solubility data here:
http://www.drugbank.ca/drugs/DB01050
http://www.drugbank.ca/drugs/DB00712

Given that the measured solubilities are so low, I am inclined to believe the calculated values which also show flurbiprofen to be less than half as soluble.

[nj_bartel]

Entropy effect maybe, with solvent cage around fluoride + phenyl?