Secondary α‐deuterium isotpe effect on the hydration of p ‐nitrobenzaldehyde

The secondary α‐deuterium isotpe effect on the equiliburium constant ( K D / K H ) for the hydration of p ‐nitrobenzaldehyde is 1·39 ± 0·05. The Kinetic secondary α‐deuterium isotope effect ( K D / K H ) for the addition of water to p ‐nitrobenzaldehyde is 1·18 ± 0·07. This result demonstrates that there is extensive carbon–oxygen bond formation in the transition state for addition of water to the carbonyl group of p ‐nitrobezaldehyde.