O Chem questions

[kponenation]

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Hi,

I just took the sample DAT from ADA website. I got two questions wrong and I was wondering if anyone can explain these questions.

The question is asking for the most acidic proton and the answer is A. I picked B. Why is A more acidic than b? Isn't alpha carbon hydrogen more than A?

This question is asking which one is stabilized by resonance.
I picked A and the answer is E. Why is the answer E?

The sample org chem DAT was very easy. I'm sure the real thing isn't easy like this one.. right??

Thanks in advance.

 

[failedmagician]

A is more acidic because if you take that proton off, the two electronegative oxygen atoms will have resonance to stabilize the conjugate base.

The second one, you cannot move the electrons around. If you move a lone pair down to a double bond, then what will you do? Try drawing resonance structures of each. Only E will allow you to draw multiple structures.

 

[nze82]

Hi,

I just took the sample DAT from ADA website. I got two questions wrong and I was wondering if anyone can explain these questions.

The question is asking for the most acidic proton and the answer is A. I picked B. Why is A more acidic than b? Isn't alpha carbon hydrogen more than A?

It's true that Alpha hydrogens are highly acidic, but they can't be more acidic than the hydrogen that belongs to a carboxylic acid. This molecule is a Betha-Hydroxy Carboxylic Acid, so (a) is the most acidic one.

This question is asking which one is stabilized by resonance.
I picked A and the answer is E. Why is the answer E

The sample org chem DAT was very easy. I'm sure the real thing isn't easy like this one.. right??

Thanks in advance.

You never know! It might very well be as easy as this one, depending on the test you get.

 

[kponenation]

Thank you both of you!