Question from the OAT sample test

[fit2]

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Hello everyone!

I'm prepping for the DAT but I was really excited to take the OAT sample test. However, I was very disappointed because just like the 2009 DAT sample test it has mistakes.

I was wondering if someone could explain question 95. I knew the answer had to be B or D but I couldn't find a reason why B was the answer.

Thanks for the help!!!

 

[catsomgcats]

In D, the N has a lone pair and you would think that it would be able to accept a proton but it actually can't because that proton is involved in resonance with the double bond from C=O.

So therefore, the correct answer is B because the OH can accept a proton (it has lone pairs that aren't involved in resonance) and it can also donate the 1 proton that it does have.

 

[fit2]

Thanks! Also I think if you compare pka you see that OH is higher so weaker acid will be the stronger base. is that a good way to think about a problem like this?

 

[catsomgcats]

No, not really. Because something that acts as both an acid and a base (amphoteric) is something that can both accept and donate a proton. It doesn't really matter if it is a weaker acid or base.

 

[fit2]

That makes sense! Thanks a lot