solubility
January 26, 2015 8:54 AM   Subscribe

how is benzonitrile less soluble than methylbenzene? I'm baffled

I'm trying to rank the solubility of molecules and running across various problems. the nitrogen is triple bonded to the carbon and leaves it a lone pair for creating a hydrogen group. I get that the rest of the molecule will get in the way and lower the solubility, but why would it be less than methyl benzene which has no polarity?
This leads me to another question... how do London forces affect solubility? I keep finding examples where they are really talking about London dispersion forces in gas and that adds density leading it to be more soluble and I'm a bit mixed up and not trusting what I think I know.
posted by iamcharity to Science & Nature (3 answers total)
 
Solubility in what?
posted by tchemgrrl at 9:37 AM on January 26, 2015 [4 favorites]


how is benzonitrile less soluble than methylbenzene?

I don't think it is. If you're going by the solubility listed in Wikipedia, I don't think the unsourced number they give for benzonitrile is correct. I found a literature citation which gives the solubility of benzonitrile in water at 20°C as 0.4% by mass, which would be about 4 g/L. (Compared to 0.52g/L for toluene, a figure which is sourced in Wikipedia.)

Stephenson RM. Mutual Solublity of Water and Nitriles. J. Chem. Eng. Data 39:225-7 (1994).
(Article may be paywalled, check your local institution for availability.)

(On preview, yes, I'm assuming solubility in water — if it's some other solvent, my answer does not apply.)
posted by DevilsAdvocate at 9:48 AM on January 26, 2015 [1 favorite]


Response by poster: Yeah, I should check my sources better. I usually use msds sheets. Sorry if I caused stress.
posted by iamcharity at 10:35 AM on January 26, 2015


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