Enzymatic polyesterification in organic media. Enzyme‐catalyzed synthesis of linear polyesters. I. Condensation polymerization of linear hydroxyesters. II. Ring‐opening polymerization of ϵ‐caprolactone

Abstract

SYNOPSISWith the object to synthesize polyesters by enzymatic catalysis in organic media, two directions have been investigated ( 1 ) the condensation polymerization of linear o-hydroxyesters and ( 2 ) the ring-opening polymerization of lactones. The commerciallyavailable crude porcine pancreatic lipase ( P P L ) , suspended in organic solvents, was the preferred enzyme for the reactions. In order to determine the optimal conditions for the condensation polymerization, the bifunctional methyl 6-hydroxyhexanoate was used as a model compound to study the influence of the following parameters: type of the enzymecatalyst, kind of solvent, concentration, temperature, duration, size of the reaction mixture, and stirring. Film-forming polyesters with a degree of polymerization ( D P ) up to about 100 were obtained from linear aliphatic hydroxyesters in n -hexane at reflux temperature (69°C ) . Yet concurrently with the intermolecular condensation polymerization, macrolactones were also formed by intramolecular reaction. Two aromatic hydroxyesters did not react under these conditions. For the ring-opening polymerization of lactones the reaction of t-caprolactone with methanol as the preferred nucleophile, was studied. Polyesters with a D P of up to 35 were obtained in n-hexane at temperatures between 25 and 40°C. The degrees of polymerization of the polyesters were determined by comparative analyses of the end groups in the 'H-NMR spectra and by determination of molecular weights either by vapor phase osmometry, gel permeation chromatography, or intrinsic viscosity. 0 1993 John Wiley & Sons, Inc.

Immobilization of biocatalysts for enzymatic polymerizations: Possibilities, advantages, applications

“…Gutman et al (1987) reported the first study on polyester synthesis by enzyme-catalyzed polymerization of A-B type monomers. Two independent groups in 1993 (Knani et al, 1993;Uyama and Kobayashi, 1993) were first to report enzyme-catalyzed ring-opening polymerization (ROP). Their studies focused on 7-and 6-membered unsubstituted cyclic esters e-caprolactone and d-valerolactone, respectively.…”

Enzyme-Catalyzed Polymerization Mechanism of Aliphatic Polyester Investigated by 1H NMR and MALDI-TOF Mass Spectrum

“…21,22 According to their result, AB unit plays a key roll to make the chain grow. The enzyme-substrate complex (Enz-O-AB) is attacked by B, and then the oligomer consists of hydroxyl terminated products such as BAB, B(AB) 2 , B(AB) 3 , and so on. Finally they concluded that the preferred product is hydroxyl terminated one.…”

“…Lots of investigations on different ring size of lactones, solvent effect, and an enzymatic activity of lipases immobilized on different matrix have been carried out. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] In case of condensation of diol and diacid with aliphatic chain, the high molecular weight polyester can be obtained by removing a leaving group. Klibanov et al have explored the enzymatic catalyzed asymmetric polymerization of aliphatic diol and diacid.…”

Neural Network Based Modeling for Polycaprolactone Synthesis by Bio-Polymerization of ε-caprolactone

“…Of all available lipases, by far the most used in organic chemistry is Candida Antarctica Lipase B (CALB). Enzyme catalyzed lactones ROP in organic media have been conducted for the polymerizations of -caprolactone (-CL) [1,2]. Recently several researches have been carried out in this field from creating new biopolymers with the exisiting lipases to synthesizing biopolymers using newly developed enzymes.…”