Catalytic synthesis of α-methylene-γ-valerolactone:: a biomass-derived acrylic monomer

alpha-Methylene-gamma-valerolactone (MeMBL) is an attractive, new, acrylic monomer that imparts high thermal stability to polymers. The absence of an economically attractive catalytic process for its preparation has prevented commercial development. Previous methods have used stoichiometric, expensive reagents. We now report a two-step process for its synthesis from a biomass-derived starting material, levulinic acid. The first step is a high yield hydrogenation of levulinic acid to gamma-valerolactone (GVL) in nearly quantitative yield using a Ru/c catalyst. The second step is a heterogeneous, gas phase catalytic condensation of formaldehyde with GVL over basic catalysts, prepared from Group 1 and 2 metal salts on silica. While the reaction is very selective to lactone derivatives, the process suffers form rapid catalyst deactivation, however regeneration can be accomplished under relatively mild conditions. Although an isomer of the desired product is highly favored over a wide temperature range, proper choice of catalyst gives the thermodynamically unfavorable, yet desirable product in very high yield. (C) 2004 Elsevier B.V. All rights reserved.