# Introduction to CH-acidic Compounds

## Hydrogen-Deuterium Exchange

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 ($D2O$). 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 $D2O$ is used as a solvent. Whenever a carbonyl compound is treated with a large excess of $D2O$, for instance, if it is dissolved in $D2O$, virtually all α hydrogens of the carbonyl compound are exchanged. A large excess of $D2O$ is essential, since H/D exchange is an equilibrium reaction.

Fig.1
Hydrogen-deuterium exchange.

Page 4 of 4>