How many signals would you expect to find in the ¹³C NMR spectrum of the following compounds?

Question

Quizplus · Accepted Answer

There are two sets of signals, one for each unique type of proton in the molecule. 
I. S1U1P11S1S1P0S1U1P13
- S: singlet (1 signal)
- U: unspecified (could be singlet, doublet or other, so no prediction possible)
- P11: pentet (5 signals)
- S: singlet (1 signal)
- S: singlet (1 signal)
- P0: no proton (no signal)
- S1U1P13: doublet (2 signals)
Total signals for set I = 10
II. S1S1P0C
- S: singlet (1 signal)
- S: singlet (1 signal)
- P0: no proton (no signal)
- C: complex (usually appears as multiple overlapping signals)
Total signals for set II = 2-3 (assuming the complex signal is split into multiple signals)
Therefore, the total number of signals expected in the NMR spectrum is 10 + 2-3 = 12-13. The closest answer choice is D, which predicts 5 signals for set I and 6 signals for set II, for a total of 11 signals.

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