Lipase-Catalyzed Synthesis of Poly(1,4-Butanediol Succinate) in Organic Solvent

During the last decade, lipase has gained interest as a biocatalyst for synthesis in organic solvent systems. The paper describes the lipase catalyzed oligocondensation of bis(2-chloroethyl) succinate and 1,4-butanediol to obtain poly (1,4-butanediol succinate). The reaction was carried out at 37°C in organic solvents without any addition of water. Various lipases and solvents were screened to obtain a maximum degree of polymerization. Based on gel permeation chromatography, the highest average molecular weight of the oligomer obtained was 1570 g/mol with a polydispersity of 1.2 when a mixture of 70% diisopropyl ether and 30% chloroform was used as a solvent. The degree of polymerization was 8 in this case. According to thin-layer chromatography, a trimer (HO(CH₂)₄OCO(CH₂)₂COO(CH₂)₄OH) was formed at an early stage, with a subsequent condensation with bis(2-chloroethyl) succinate to give higher oligomers. The structure of the oligomers was confirmed by ¹³C NMR and IR spectra.