Mechanism of Glucose Isomerization Depends Upon Whether Sn is Isolated in the Framework or Extraframework SnOx in Zeolite Beta

In the isomerization of glucose into fructose in water, extraframework SnO_x located within the pores of hydrophobic Si-Beta by either direct synthesis or post-synthetic modification operate through the enolate mechanism, unlike framework Sn sites in Sn-Beta that operate by the Lewis acid mechanism.