Lipases polyester synthesis

Lipase-catalyzed reaction is useful for polyester synthesis and IE was employed successfully as solvent. Uyama and Kobayashi demonstrated an efficient polyester synthesis lipase-catalyzed esterification of agipic acid with butan-1,4-diol proceeded smoothly in [bmim][BF4] solvent, particularly under reduced pressure conditions (Fig. 8). Further Russel " and Nara independently reported efficient examples of the lipase-catalyzed polyester synthesis in an IE solvent system. 

Figure 8 Lipase-catalyzed polyester synthesis using IL solvent system.

In polyester synthesis via ring-opening polymerizations, metal catalysts are often used. For medical applications of polyesters, however, there has been concern about harmful effects of the metallic residues. Enzymatic synthesis of a metal-free polyester was demonstrated by the polymerization of l,4-dioxan-2-one using Candida antarctica lipase (lipase CA). Under appropriate reaction conditions, the high molecular weight polymer (molecular weight = 4.1 x 10" ) was obtained. 

Polyester synthesis was carried out hy insertion-dehydration of glycols into polyanhydrides using lipase CA as catalyst (Scheme 6). The insertion of 1,8-octanediol into poly(azelaic anhydride) took place at 30-60°C to give the corresponding polyester with molecular weight of several thousands. Effects of the reaction parameters on the polymer yield and molecular weight were systematically investigated. The dehydration reachon also proceeded in water. The reaction behaviors depended on the monomer structure and reaction media. 

Lipase-catalyzed synthesis of polyesters from cyclic anhydrides and oxi-ranes was reported. The polymerization took place by PPL catalyst and the molecular weight reached 1 x 10" under the selected reaction conditions. During the polymerizahon, the enzymatically formed acid group from the anhydride may open the oxirane ring to give a glycol, which is then reacted with the anhydride or acid by lipase catalysis, yielding the polyesters. 

Berkane, C. Mezoul, G. Lalot, T. Brigodiot, M. Lipase-catalyzed polyester synthesis in organic medium. Study of ring-chain equilibrium. Macromolecules 1997, 30, 7729-7734. 

Takamoto T, Uyama H, Kobayashi S (2001) Lipase-catalyzed synthesis of aliphatic polyesters in supercritical carbon dioxide. e-Polymers no.004... 

Lipase-catalyzed transesterification to prepare polyesters (replacing the traditional chemical polymerization at >200 °C) has received considerable attention in recent years. CaLB was found to mediate polyester synthesis in the ionic liquids [BMIm][BF4], [BMIm][PF6], and [BMIm][ Tf2N] at 60°C [110, 111, 112], but the molecular weight of the product was rather low compared with that in a solventless system [113], perhaps owing to the high viscosity of ionic liquid media. 

Lipase catalyzed esterifications were performed favorably solvent-free [21] and were applied also to bulk polymerization for polyester synthesis [22]. 

Kobayashi, S. (2009). Recent developments in lipase-catalyzed synthesis of polyesters. Macromol. Rapid Commun., 30, 237-266. 

Lipase Transesterification and direct esterification (inch polyester synthesis) Ring-opening polymerization of 8-caprolactone Hydrolysis alcoholysis acetylation Higher stability of enzyme greater activity catalyst recyclable sometimes higher enantio- and regio-selectivity compared with VOCs... 

Fig. 7.5 Pseudomonas cepacia lipase supported on ceramic particles PS-C catalysed polyester synthesis using diethyl octane-1,8-dicarboxylate and 1,4-butanediol in [bmim]PF6 at room...

Nara SJ, Haijani JR, Salunkhe MM, Mane AT, Wadgaonkar PP (2003) Lipase-catalysed polyester synthesis in l-butyl-3-methyllmidazolium hexafluorophosphate ionic hquid. Tetrahedron Lett 44 1371-1373... 

Wang, Z. L., Hiltunen, K., Orava, R, Seppala, J., and Linko, Y. Y, Lipase-catalyzed polyester synthesis, Pure Appl. Chem., A33, 599-612, 1996. 

Candida antarctica lipase B chemically immobilized on epoxy-activated micro-and nanobeads Catalysts for polyester synthesis. Biomacromolecules, 9 (2), 463-471. 

Among enzymes, lipases proved to be the most efficient for the in vitro polyester synthesis. Lipases or triacylglycerol acylhydrolases are water-soluble enzymes that catalyze the hydrolysis of ester bonds in water-insoluble, lipid substrates, and therefore comprise a subclass of the esterases. 

Although there are notable exceptions as given below, the most common lipase-catalyst used for polyester synthesis is Candida antarctica lipase B (CALB) (please refer to Chapter 14 for more information on the structure and reaction mechanisms of CALB). The immobilized CALB catalyst that has been primarily used is Novozym 435, manufactured by Novozymes (Bagsvaerd, Denmark). Novozym 435 consists of CALB physically adsorbed within the macroporous resin Lewatit VPOC 1600 (poly[methyl methacrylate-co-butyl methacrylate], supplied by Bayer) (please refer to Chapter 3 for more information on Novozym 435). 

Scheme 4.6 Porcine pancreatic lipase-catalyzed synthesis of enantio-enriched polyester with epoxy groups in the main chain.

Lipase-catalyzed synthesis of polyesters came to the focus after two major breakthroughs in 1984, novel lipase-catalyzed polycondensation to give oli-goesters in 1993, discovery of the catalysis for ring-opening polymerization of lactones. 

Olsson, A., Lindstrom, M., and Iversen, T. (2007) Lipase-catalyzed synthesis of an epoxy-functionalized polyester from the suberin monomer cis-9,10-epoxy-18-hydroxyodadecanoic acid. Biomacromolecules, 8 (2), 757-760. 

J. (1995) Lipase-catalyzed linear aliphatic polyester synthesis in organic solvent. Enzyme. Microb. Technol., 17 (6), 506-511. 

Uyama, H., Inaka, K., and Kobayashi, S. (2000) Lipase-catalyzed synthesis of aliphatic polyesters by polycondensation of dicarboxylic acids and glycols in solvent-free system. Polym. J., 32 (5), 440-443. 

P.P. (2003) Lipase-catalyzed polyester synthesis in l-butyl-3-methylimidazolium hexafluorophosphate ionic liquid. Tetrahedron Lett., 44 (7), 1371-1373. 

In recent years, the enzymatic synthesis of biodegradable polyesters was focused on the polycondensation method (22,23). Among the very few successful example of enzymatic ring-opening polymerization for polyesters synthesis, Novozyme-435 (immobilized lipase B from Candida antartica) has been proved an effective catalyst for polycaprolactone (PCL) synthesis in toluene (24). Considering the low cost and high recyclablity of IPPL, we also... 

Effects of Porous Polyacrylic Resin Parameters on Candida antarctica Lipase B Adsorption, Distribution, and Polyester Synthesis Activity... 

Polyacrylic resins were employed to study how immobilization resin particle size influences Candida antarctica Lipase B (CALB) loading, fraction of active sites, and catalytic properties for polyester synthesis. CALB adsorbed more rapidly on smaller beads. Saturation occurred in less than 30 seconds and 48 h for beads with diameters 35 and 560-710 pm, respectively. Infrared microspectroscopy showed that CALB forms protein loading fronts for resins with particle sizes 560-710 and 120 pm while CALB appears evenly distributed throughout 35 pm resins. The fraction of active CALB molecules adsorbed onto resins not influenced by particle size was less than 50 %. At about 5% w/w CALB loading, decrease in the immobilization support diameter from 560-710 to 120,75 and 35 pm increased conversion of s-CL to polyester (20 to 36, 42 and 61%, respectively, at 80 min). Similar trends were observed for condensation polymerizations of 1,8-octanediol and adipic acid. 

Lipase-catalyzed synthesis of aliphatic polyesters via diacid/diol polycondensation reactions have been explored by us and others at temperatures of 90°C and below (4,5). The substrates used in previous studies are a,a)-linear aliphatic diacid and/or diol monomers with six or more carbons. Herein we report a new method that allowed the first lipase-catalyzed synthesis of high molecular weight PBS fi om practical monomer precursors. 

More recently, Lopez-Luna et al. [54] reported the successful enzyme-mediated syntheses of polyester structures in SCCO2 and R-134a. Lipase-mediated synthesis of relatively high molecular weight poly(S-valerolactone) (PVL) was reported in SCCO2 and liquid R-134a solvent media. However, they found that polymers and copolymers... 

Lipase-catalyzed polyester synthesis has received considerable interest [31] due to the harsh conditions used in traditional chemical polymerization (> 200 C), and has also been subjected to reaction in ILs. Both CaLB and PcL lipases have been found to catalyze polyester synthesis in [BMIM][BF4] and [BMIM][PF6], but this approach does not seem to offer any advantages over state-of-the-art lipase-mediated polyester synthesis [32, 33] [Eq. (3)]. Still, the polydispersity index of the polymers formed in ILs were remarkably affected, giving values close to 1, which indicate a very narrow molecular weight range compared to material prepared by conventional polymerization processes [33]. 

Yang, Y., Yu, Y., Zhang, Y., Liu, C., Shi, W., Li, Q. Lipase/esterase-catalyzed ring-opening polymerization A green polyester synthesis technique. Process Biochem. 2011,46,1900-1908. 

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