CNMR CMR

Problem 12.34 Why is spin-spin coupling between adjacent C s not observed  

Since the natural abundance of this isotope is so low, the chance of finding two C s next to each other is practically nil. However, if a compound were synthesized with only Cs, then coupling would be observed. 

Problem 12.35 How many peaks would be evidenced in the decoupled spectrum of (a) methylcyclohexane  

The 0=0 group is electron-withdrawing and causes a downfield shift of other attached C atoms. See Fig. 12-11. 

---