Polymerization of 1,2:5,6‐di‐O‐isopropylidene‐α‐ D ‐glucofuranose and 1,2‐O‐isopropylidene‐α‐ D ‐glucofuranose

A new method for preparing D‐glucose polymers is described. Isopropylidene derivatives of D‐glucofuranose, particularly the 1,2‐mono‐O‐derivative, are treated with Lewis acids, such as boron trifluoride, to eliminate acetone and produce a highly branched polymer with a molecular weight of 12,700. Approximately one isopropylidene unit remains, possibly on the potential reducing end of the glucan. Up to 95% of the polymer units are D‐glucopyranoside units indicating that ring expansion occurs during the condensation.