title: Macrolactones and polyesters from ricinoleic acid.
abstract: A systematic study on the synthesis, characterization, and polymerization of ricinoleic acid (RA) lactone is reported. Ricinoleic acid lactones were synthesized by refluxing pure ricinoleic acid in chloroform (10 mg/mL) with dicyclohexylcarbodimide and (dimethylamino)pyridine as catalyst. Purification of RA lactones was performed by silica gel chromatography. The reaction resulted in a 75% yield of ricinoleic acid lactones. IR and NMR analysis confirmed the formation of cyclic compounds. Polymerization of the ricinoleic acid lactones with catalysts commonly used for ring-opening polymerization of lactones, under specific reaction conditions, resulted in oligomers. Copolymerization with lactide (LA) by ring-opening polymerization, using Sn(Oct) as catalyst, yielded copolyesters with molecular weights (M(w)) in the range of 5000-16000 and melting temperatures of 100-130 degrees C for copolymers containing 10-50% w/w ricinoleic acid residues. Degradation studies of the copolymers were performed in 0.1 M phosphate buffer solution, pH 7.4, at 37 degrees C. P(LA-RA)s with up to 20% w/w RA slowly degraded and released only approximately 7% of its lactic acid content after 60 days of study, while pure PLA under similar conditions released more than 20% of its lactic acid content. On the other hand, copolyesters containing more then 20% w/w RA degraded and released lactic acid faster than pure PLA due to the low crystallinity of the copolymers.
authors.affiliation: Department of Medicinal Chemistry and Natural Products, School of Pharmacy-Faculty of Medicine, The Hebrew University of Jerusalem, 91120 Jerusalem, Israel.
authors.forename: Raia
authors.initials: R
authors.lastname: Slivniak
authors.forename: Abraham J
authors.initials: AJ
authors.lastname: Domb
mesh_terms: D007783:Lactones / Q000032:analysis / Q000138:chemical synthesis*; D011091:Polyesters / Q000032:analysis / Q000138:chemical synthesis*; D012277:Ricinoleic Acids / Q000032:analysis / Q000138:chemical synthesis*
chemical_list: D007783:Lactones; D011091:Polyesters; D012277:Ricinoleic Acids; C030521:ricinoleic acid