Malic Acid → HCID 70298316, compound

Participants

Reaction Conditions

Reaction Steps

A flame-dried resin kettle equipped with a mechanical stirrer and an argon inlet was charged with glycolide (2.586 mole, 300 g), anhydrous malic acid (0.172 mole, 23 g), and stannous octoate (0.2 M in toluene, 862 ml, 0.172 m mole). The polymerization reactor and its contents were purged with dry argon several times. After melting the polymerization charge, the reactants were heated to and stirred at 160° C. until the polymer started to precipitate from the melt. Shortly after partial precipitation, the stirring was terminated and the reaction was continued at 160° C. for 2 hours. At the conclusion of the polymerization, the temperature was lowered below 120° C. and excess monomer was removed under reduced pressure. The composition of the isolated polymer was verified using infrared and NMR spectroscopy. Differential Scanning Calorimetry was used to determine the polymer melting temperature (Tm=206° C.). The solid polymer was ground to achieve average particle diameter of about 125 μm using a Wiley mill. Further reduction of the particle size to 5-10 μm diameter was achieved using a jet-mill receiving pressurized dry nitrogen. The resulting microparticles were rinsed with acetone to remove trace monomer and low molecular weight oligomers. The product was then dried under reduced pressure at 40° C. until used. The average diameter of the dry microparticle was determined using a particle size analyzer.

Provenance & Evidence