The Lobry de Bruyn–van Ekenstein rearrangement is a classic carbohydrate reaction where aldoses and ketoses interconvert via an enediol intermediate, often under alkaline conditions. It explains the equilibrium between glucose, fructose, and mannose, and has important applications in sugar chemistry, food chemistry, and biochemistry.
The reaction is named after Cornelis Adriaan Lobry van Troostenburg de Bruyn and Willem Alberda van Ekenstein who reported it in 1895.
Mechanism
- Deprotonation: Hydroxide ion abstracts a proton from the α-carbon of the sugar.
- Enediol Formation: This generates an enediol intermediate (–C(OH)=C(OH)–).
- Reprotonation: The enediol can be reprotonated at different positions, leading to:
- Isomerization: Aldose ↔ Ketose (e.g., glucose ↔ fructose).
- Epimerization: Formation of stereoisomers (e.g., glucose ↔ mannose).
Premium PDF Notes Available
Your download will begin in 10 seconds...