Introduction to CH-acidic Compounds
Due to the acidity of the α hydrogens of enolizable carbonyl compounds, the α hydrogen may easily be exchanged for deuterium (H/D exchange). H/D exchange may, for instance, occur when the carbonyl compound is treated with heavy water (). The exchange can be detected through 1H NMR, as deuterium does not produce a signal in 1H NMR. As the exchange proceeds relatively rapidly, the α hydrogen of enolizable carbonyl compounds cannot be detected through 1H NMR if is used as a solvent. Whenever a carbonyl compound is treated with a large excess of , for instance, if it is dissolved in , virtually all α hydrogens of the carbonyl compound are exchanged. A large excess of is essential, since H/D exchange is an equilibrium reaction.