Ring-opening of γ-valerolactone with amino compounds

Diols obtained by the ring-opening of biomass-based γ-valerolactone (GVL) are potentially valuable building blocks that can be used as precursors in the manufacture of green polymers and resins. We report here a study on the ring-opening of GVL through adding amine compounds. The reactivity of the applied amine compounds in this ring-opening was tested by varying the structure of the amine compounds. Both mono-amines (ammonium, 2-aminoethanol, 2-phenylethylamine, and morpholine) and di-amines (1,2-diaminoethane, 1,2-diaminopropane, and piperazine) were used. The study showed that steric hindrance at the reacting amine-function plays a more prominent role than local point charge. To optimize the yield of the desired di-functional monomers, the ring-opening of GVL with 1,2-diaminoethane (1,2-DE) was studied in more detail. Reaction temperature (25-100°C), reaction time, and molar ratio of the reactants appeared to be the determining processing parameters. These were found to be more important than the use of catalysts (triphenylphosphine, Tin(II)-2-ethylhexanoate, Ytterbium(III)trifuoromethanesulfonate, AlCl ₃, and SnCl₂) and solvent polarity (methanol, DMA, DMSO, and water).