NMR Question

[stester77s]

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A scientist attempts to follow the progress of the α-deuteration shown in Figure 2 using proton NMR. Which of the following would be the best indicator that the reaction has proceeded to completion?

1. Singlet at 9.8 ppm
   
   
2. Quadruplet between 1.0 and 2.0 ppm
   
   
3. Doublet between 3.0 and 4.0
   
   
4. No signal
   

The answer is #4.

So this leads me to the question, what exactly is the difference between, say, proton NMR and carbon NMR? Deuterium can undergo NMR as well, but how does it differ from "proton NMR"?

 

[Entadus]

Deuterium is a hydrogen with a NEUTRON, that is, mass = 2 (proton + neutron)


When you realize that both of these nucleons can have a spin, these will cancel each other and you get no signal.

For NMR you need an odd number of nucleons. For example H+ (proton) is fine because 1 nucleon ---> spin = +/-1/2

Also acceptable is 15N (not normal 14N). F-19 works but not F-18. etc.

If the nucleus can act as a magnetic dipole (a little magnet), then in the presence of an external magnetic field (our NMR machine supplies this) the nucleus can arrange either WITH or AGAINST the field. These two nuclear spin states have distinct energies, that is, we can measure a difference in their energies. . . . ....The nucleus absorbs light(microwaves) of particular frequencies (oh, it is spectroscopy after all).......