Roles of hydroxyls in the noncatalytic and catalyzed formation of levoglucosan from glucose

- Hydroxyl groups in the cyclic sugar β-d-glucose are key to forming bicyclic levoglucosan.
- Levoglucosan forms by unimolecular reaction or by catalysis through external hydroxyls or acids.
- Hydroxyl-oxygen lone pairs shape the transition states, as shown by substituting NH2 and CH3 for OH.
- H-bonding is examined by calculations with explicit H2Os and implicit H2O solvation models.
- Enthalpy of activation of Brønsted acid molecules decreases with increasing acid strength.