Esterification of Salicylic acid with Succinylated Dextran Using ZrOCl2.8H(2)O over MCM-41: A Novel Strategy to Design Polysaccharide-Based Macromolecular Prodrugs

We are exploiting the use of a versatile catalyst taken from heterogeneous catalysis, i.e., ZrOCl2.8H(2)O to efficiently catalyze the reaction of dextran-succinate conjugate (Dex-SAn) with salicylic acid (SA) under homogeneous reaction conditions. Dextran was first linked with succinic anhydride using triethylamine as a base in DMAc to provide active functionalities (succinate moieties) situated away from the polymer chains. The resultant Dex-SAn conjugate was further esterified with SA using zirconium (IV) oxychloride octahydrate (ZrOCl2.8H(2)O) as a catalyst at 80 degrees C under N-2. Reaction conditions and amount of catalyst ZrOCl2.8H(2)O and chiral support MCM-41 were optimized. This reaction methodology resulted in macromolecular prodrugs of SA as Dex-SAn-SA conjugates in good yield. The structures of Dex-SAn and newly synthesized Dex-SAn-SA conjugates were characterized using various spectroscopic techniques, i.e., FT-IR, H-1, and APT-C-13 NMR spectroscopy. The degree of substitution of SA on to Dex-SAn-SA was determined by UV/Vis spectroscopic methods. This reaction methodology can be modeled as a new protocol for facile attachment of several drug molecules onto the highly potential and biodegradable drug carrier dextran.