Destroyer ochem question

[Decan]

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Please look at q.158 in the ochem section in the destroyer. I selected choice c because I figured that the quartet would be most deshielded because it is next to the most electron withdrawing group. I dont understand why b is the correct choice. I thought that the carbonyl group had a bigger deshielding effect than oxygen...

Can anyone clarify this for me? Thanks for any help!

 

[TermiNadder2012]

Not sure what the question is but if you are talking about proton NMR know that the carbonyl groups do not show up at all on the NMR Hydrogen graphs.

 

[Decan]

I know that carbonyl groups do not show up on proton NMRs, but wouldnt they have a bigger deshielding effect than an oxygen?