Synthesis of Ligands using Amino Acid Precursors for Applications in Lactide Polymerizations

ONU McIntosh Center; Activities Room

Amino acids were combined with various phenols and formaldehyde via a Mannich reaction to synthesize a variety of ligands. The ligands were produced in yields ranging from 63.49% - 0.83%. Reaction conditions were identical for each of the ligands containing D-aspartic acid; however, the workup procedure varied depending on the substitution pattern of the phenol moeity (2,4-Di-tert-amylphenol - yield = 30.95%; 2,4-di-methylphenol - yield = 0.84%, and 2,4-di-tert-butylphenol - yield = 53.53%). Modification to reaction conditions was required whenever a new amino acid was introduced. In addition to D-aspartic acid, a ligand was successfully isolated from D/L-alanine and 2,4-dimethyl phenol (yield = 63.49%). Once the ligands were synthesized and characterized by NMR spectroscopy, some were coupled to titanium isopropoxide and cupric acetate in an attempt to isolate the catalysts. The cupric acetate complexes were left to crystalize, while the bright orange titanium complex (2,4-di-tert-butylphenol with D-aspartic acid product coupled to titanium) will soon be used in an attempt to catalyze the polymerization of lactide.