Is acidity strength increased or decreased when a hydroxyl group is added adjacent to the OH group in 2-hydroxyphenyl acetic acid? In this case the acid functional group is not attached directly to the ring.
The pKas of the above you mentioned are comparable but since I am concerned about the minor details, dihydroxybenzoic acid has a slightly higher pKa because the hydroxyl group tends to destabilise the ring and this might as well occur for the 2-hydroxylphenylacetic acid?Well, I doubt it will have much effect on pKa1 because the carboxylic acid functionality is attached at the benzylic and not at a phenyl position. Therefore, it is one carbon removed from being able to be stabilized/destabilized by anything on the ring and so even an electron-rich ring won't do much to destabilize the charge.
Even if you look at a comparable example - hydroxybenzoic acid as compared to dihydroxybenzoic acid - where the carboxylic acid is attached at a phenyl position, the pKa's are comparable. This is because the phenyl ring also does not really stabilize the negative charge developed on the oxygen - that charge stays on the carboxylic acid.
The pKas of the above you mentioned are comparable but since I am concerned about the minor details, dihydroxybenzoic acid has a slightly higher pKa because the hydroxyl group tends to destabilise the ring and this might as well occur for the 2-hydroxylphenylacetic acid?
Why make the questions debate able like this? Obviously it will increase the pka, the question is whether it will do it "much"
Well, MCAT questions will generally not be debateable like this. They go through to make sure it's not debateable. Because if you know pre-meds, anything debateable would cause an uproar. In this case, it's not obvious at all that it will increase pKa. In fact, it likely does not. What I mean is that you would be not be able to measure a difference in pKa that cannot also be fully accounted for by error in your measurement.
This issue is what instrument you are using. I dunno, I just really dont like the question
It will definitely raise the pka a finite amount. I agree that it probably wouldnt be detectable. But....