CHAPTER 12 Nuclear Magnetic Resonance Spectroscopy PRELAB EX

CHAPTER 12 Nuclear Magnetic Resonance Spectroscopy PRELAB EXERCISE: Outline the preliminary solubility experiments you would carry out using inexpensive solvents before preparing a solution of an unknown compound for nuclear magnetic resonance NMR) spec troscopy using expensive deuterated solvents

Solution

Commonly used solvents for NMR study are CDCl3, D₂O, d⁶- DMSO, d⁶- Acetone etc. d⁶ term means all the 6 H is substituted by Deuterium.

Why these expensive deuterated solvents are used and not the simple solvents like CHCl3, H2O, DMSO, Acetone? Because then you will get plenty of peaks of H of these solvents. So it will be very difficult to distinguish your unknown compound\'s H-atoms from them.

Now when to use which deuterated solvents to dissolve your unknown compound? The way out is first check whether its soluble in its simple and of course, cheap H containing solvents. e.g. if a compound is soluble in CHCl₃ then obviously it will be soluble in CDCl₃ as D is just an isotope so no different chemical property.

All deuterated solvents are very costly because we have to prepare it synthetically by substituting the H to D.