I have some questions concerning deuterated solvents in NMR spectroscopy. 1. If
ID: 1004315 • Letter: I
Question
I have some questions concerning deuterated solvents in NMR spectroscopy.
1. If deuterium is a magnetic nucleus (and it is), why can we use deuterated solvents for our NMR samples? Won't the magnetic heavy hydrogen screw things up?
2. I noticed that D2O has a higher boiling point than water itself. The same would be true for the other deuterated solvents when compared to their normal versions. Why is this? I thought isotopic replacement was not supposed to alter the properties of a molecule. So why is the boiling point changing, by a fair amount?
Please help me. I really would like to understand.
Explanation / Answer
1) Deuterated solvents are used as we know that the frequency (noted) is field dependant. The deuterium receiver can notice the fluctuations in the field by change of the observation frequency which is also known as lock frequency. This lock frequency can correct the field strength as per the changes. We may use other nuclei as well (19F) however the deuterated solvents are easily available.
2) This is due to bond strength of O-D..........O-D (corresponding to hydrogen bond) is stronger than O-H.......O-H
so the boiling point of D2O is more and so of other deuterated solvents.