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gamma-Acyloxy-epsilon-Caprolactones: Synthesis, Ring-Opening Polymerization vs. Rearrangement by Means of Chemical and Enzymatic Catalysis
KTH, School of Biotechnology (BIO), Biochemistry (closed 20130101).
KTH, School of Biotechnology (BIO), Biochemistry (closed 20130101).ORCID iD: 0000-0002-2993-9375
KTH, School of Biotechnology (BIO), Biochemistry (closed 20130101).
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2008 (English)In: Macromolecular Symposia, ISSN 1022-1360, E-ISSN 1521-3900, Vol. 272, 28-38 p.Article in journal (Refereed) Published
Abstract [en]

gamma-Acyloxy-epsilon-caprolactones (3a-d) were prepared in two steps starting from 4-hydroxy-cyclohexanone (1). in the first step acylation of the hydroxyl group occurs and in the second step ring enlargement by Baeyer-Villiger oxidation. if this order of reaction is inverted rearrangement occurs in the Baeyer-Villiger oxidation Of 4-hydroxy-cyclohexanone leading to gamma-hydroxyethyl-gamma-butyrolactone. Using the first procedure gamma-acetyloxy- (33), gamma-benzoyloxy-(3B), gamma-acryloyloxy-(3c), and gamma-methacryloyloxy-epsilon-caprolactone (3d) were prepared. These monomers and for comparison reasons epsilon-caprolactone and gamma-methyl-epsilon-caprolactone were polymerized by means of chemical and enzymatic catalysis. The results were different depending on the monomer structure and catalyst used. in the presence of a chemical catalyst, all the monomers, except gamma-acetyloxy-epsilon-caprolactone, undergo controlled ring-opening polymerization. gamma-Acetyloxy-epsilon-caprolactone (3a), however, rearranges to a large extent under polymerization conditions to give gamma-acetyloxyethyl-gamma-butyrolactone (6a). in the presence of an enzyme (Novozyme 435, Lipase B from Candida antarctica (CALB) immobilized on a macroporous resin) all gamma-acyloxy-epsilon-caprolactones partly rearrange to result the corresponding gamma-acyloxy-gamma-butyrolactones, while epsilon-caproiactone and gamma-methyl-epsilon-caprolactone yield the corresponding polymers, the latter even in a stereoselective manner as reported earlier in the literature. A molecular dynamic study was performed with 3a and 3b as substrates to gain information on the substrate recognition displayed by CALB. A mechanism for the chemically and enzymatically catalyzed reactions of gamma-acyloxy-epsilon-caprolactones is proposed.

Place, publisher, year, edition, pages
2008. Vol. 272, 28-38 p.
Keyword [en]
enzyme and chemical catalysis, ring-opening polymerization, gamma-Acyloxy-epsilon-caprolactones
National Category
Biochemistry and Molecular Biology
Identifiers
URN: urn:nbn:se:kth:diva-24968DOI: 10.1002/masy.200851203ISI: 000261674400003Scopus ID: 2-s2.0-55849127376OAI: oai:DiVA.org:kth-24968DiVA: diva2:354711
Conference
International Conference on (Bio)degradable Polymers from Renewable Resources Vienna, AUSTRIA, NOV 18-21, 2007
Note

QC 20101004 (International Conference on (Bio)degradable Polymers from Renewable Resources Vienna, AUSTRIA, NOV 18-21, 2007)

Available from: 2010-10-04 Created: 2010-10-04 Last updated: 2014-10-21Bibliographically approved
In thesis
1. Lipase Specificity and Selectivity: Engineering, Kinetics and Applied Catalysis
Open this publication in new window or tab >>Lipase Specificity and Selectivity: Engineering, Kinetics and Applied Catalysis
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The specificity and selectivity of the enzyme Candida antarctica lipase B (CALB) were studiedfor several substrates and applications.With help of molecular modeling, the active site of CALB was redesigned for the ring openingpolymerization of D,D‐lactide. Two mutants, with about 90‐fold increase in activity ascompared to the wild‐type enzyme, were created. Changing a glutamine into alanineaccounted for this increase in both mutants by creating a larger space in the acyl donorpocket. The new space made it possible to accommodate the bulky substrate and improvethe transition state‐active site complementarity during polymer chain propagation.The enantioselectivity of CALB towards secondary alcohols was engineered by rationalredesign of the stereoselectivity pocket in the enzyme active site. A larger space created by asingle point mutation resulted in an 8’300’000 times change in enantioselectivity towards 1‐phenylethanol and the enantiopreference was inverted into S‐preference. The activitytowards the S‐enantiomer increased 64’000 times in the mutant as related to the wild‐type.The solvent and temperature effects on the enantioselectivity were studied for severalsubstrates and revealed the importance of entropy in the change in enantioselectivity.Substrate selectivity is of great importance for the outcome of enzyme catalyzed polymersynthesis. Ring opening polymerization (ROP) of γ‐acyloxy‐ε‐caprolactones will result in apolyester chain with pendant functional groups. CALB was found to have activity not onlytowards the lactone but also towards the γ‐ester leading to rearrangement of the monomersyielding γ‐acetyloxyethyl‐γ‐butyrolactone. This selectivity between the lactone and the γ‐ester was dependent on the type of group in the γ position and determined the ratio ofpolymerization and rearrangement of the monomers. Molecular dynamics simulations wereused to gain molecular understanding of the selectivity between the lactone and γ‐ester.In order to obtain (meth)acrylate functional polyesters we investigated the use of 2‐hydroxyethyl (meth)acrylate (HEA and HEMA) as initiators for ring opening polymerization.We found that, in addition to the ring opening polymerization activity, CALB catalyzed thetransacylation of the acid moiety of the initiators. The selectivity of CALB towards thedifferent acyl donors in the reaction resulted in a mixture of polymers with different endgroups. A kinetic investigation of the reaction showed the product distribution with timewhen using HEA or HEMA with ε‐caprolactone or ω‐pentadecalactone.The high selectivity of CALB towards lactones over (meth)acrylate esters such as ethyleneglycol di(meth)acrylate was used to design a single‐step route for the synthesis ofdi(meth)acrylated polymers. By mixing ω‐pentadecalactone with the ethylene glycoldi(meth)acrylate and the enzyme in solvent free conditions, we obtained >95 % ofdi(meth)acrylated polypentadecalactone.Taking advantage of the high chemoselectivity of CALB, it was possible to synthesizepolyesters with thiol and/or acrylate functional ends. When using a thioalcohol as initiatorCALB showed high selectivity towards the alcohol group over the thiol group as acyl acceptorfor the ROP reaction. The enzymatic ability of catalyzing simultaneous reactions (ROP andtransacylation) it was possible to develop a single‐step route for the synthesis ofdifunctionalized polyesters with two thiol ends or one thiol and one acrylate end by mixingthe initiator, lactone and a terminator.

Place, publisher, year, edition, pages
Stockholm: KTH, 2010. viii, 48 p.
Series
Trita-BIO-Report, ISSN 1654-2312 ; 2010:17
National Category
Medical Biotechnology (with a focus on Cell Biology (including Stem Cell Biology), Molecular Biology, Microbiology, Biochemistry or Biopharmacy)
Identifiers
urn:nbn:se:kth:diva-25039 (URN)978-91-7415-729-1 (ISBN)
Public defence
2010-10-22, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
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Note
QC 20101006Available from: 2010-10-06 Created: 2010-10-06 Last updated: 2010-10-06Bibliographically approved

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Martinelle, Mats

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