This question is about the H NMR spectrum of creatine.
Creatine is a supplement taken by athletes to increase body mass. Recently, supplements containing derivatives of creatine have been marketed. These are usually more lipophilic in an attempt to improve uptake.
The 1 H NMR spectrum of one of these supplements in D2O is shown, with some parts magnified:
This particular supplement exists in an ionised form at pH1 but does not exist in an ionised form at pH 12 (I am unsure about this and will come back to it in my question below!)
Using this information we are asked to suggest a structure for the supplement. I was almost right. The answer is:
The mark scheme says that three things can be extracted from the NMR spectrum and the information given:
I don't understand the relevance of the pH statement. How does that relate to the structure? How does that relate to the ester group? (this is mentioned in the mark scheme which is attached just above this)
How can we use the integrals to calculate that there are 10 C-H protons? I measured the heights of the traces and got, 2.7cm, 4.75cm and 6.9cm but I'm not sure how this leads to '10 C-H protons'...
Would really appreciate help on this question and a breakdown of the key points discussed. Many thanks!