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  • 51. Vaida, Cristian
    et al.
    Takwa, Mohamad
    KTH, School of Biotechnology (BIO), Biochemistry (closed 20130101).
    Martinelle, Mats
    KTH, School of Biotechnology (BIO), Biochemistry (closed 20130101).
    Hult, Karl
    KTH, School of Biotechnology (BIO), Biochemistry (closed 20130101).
    Keul, Helmut
    Möller, Martin
    gamma-Acyloxy-epsilon-Caprolactones: Synthesis, Ring-Opening Polymerization vs. Rearrangement by Means of Chemical and Enzymatic Catalysis2008In: Macromolecular Symposia, ISSN 1022-1360, E-ISSN 1521-3900, Vol. 272, p. 28-38Article in journal (Refereed)
    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.

  • 52. Xiao, Yan
    et al.
    Takwa, Mohamad
    KTH, School of Biotechnology (BIO), Biochemistry.
    Hult, Karl
    KTH, School of Biotechnology (BIO), Biochemistry.
    Koning, Cor E.
    Heise, Andreas
    Martinelle, Mats
    KTH, School of Biotechnology (BIO), Biochemistry.
    Systematic Comparison of HEA and HEMA as Initiators in Enzymatic Ring-Opening Polymerizations2009In: Macromolecular Bioscience, ISSN 1616-5187, E-ISSN 1616-5195, Vol. 9, no 7, p. 713-720Article in journal (Refereed)
    Abstract [en]

    Two initiators (HEA and HEMA) containing a cleavable ester bond were compared in the lipase-catalyzed ROP of CL and PDL. HEA and HEMA displayed similar reaction efficiencies as initiators (acyl acceptors) in the enzymatic ROP. However, transacylation reactions were found to be 15 times faster on the HEA-initiated polyesters as compared with the HEAAA initiated polyesters (HEA/HEMA moieties as acyl donors). While in both cases the amount of HEA- and HEMA-initiated polymers could be maximized by H short reaction times, a well-defined (meth)acrylation by this approach was not possible. Our results show that trans esterification reactions are present at high rates throughout the enzyme-catalyzed ROP.

  • 53. Çakir, S.
    et al.
    Eriksson, Magnus
    KTH, School of Biotechnology (BIO), Industrial Biotechnology.
    Martinelle, Mats
    KTH, School of Biotechnology (BIO), Industrial Biotechnology.
    Koning, C. E.
    Multiblock copolymers of polyamide 6 and diepoxy propylene adipate obtained by solid state polymerization2016In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 79, p. 13-22Article in journal (Refereed)
    Abstract [en]

    Polyesteramide multiblock copolymers based on polyamide 6 and diepoxy propylene adipate blocks were synthesized. For this purpose a carboxyl-terminated polyamide 6 (Mn = 2400 g/mol, Tm = 205.5 °C) and diepoxy propylene adipate (Mn = 450 g/mol) were separately synthesized and characterized. The incorporation of the oligoester into the polyamide 6 backbone was performed by solid state polymerization (SSP) well below the melting temperature of the polyamide (80-140 °C) so that the physical and thermal properties of the original polyamide 6 block were retained. Formation of the multiblock structure was confirmed by following the increase in molecular weight by SEC, reaction of the end groups by 1H NMR and by following the maintained melting temperature after the copolymerization. These segmented copolymers have molecular weights up to 10 kg/mol, thermal stability of 325 °C at 5% weight loss and a melting temperature of 205 °C.

  • 54.
    Öhrner, Niklas
    et al.
    KTH, Superseded Departments (pre-2005), Biochemistry and Biotechnology.
    MARTINELLE, Mats
    KTH, Superseded Departments (pre-2005), Biochemistry and Biotechnology.
    Mattson, Anders
    Norin, T
    Hult, K
    Displacement of the equilibrium in lipase catalysed transesterification in ethyl octanoate by continous evaporation of ethanol1992In: Biotechnology letters, ISSN 0141-5492, E-ISSN 1573-6776, Vol. 14, no 4, p. 263-268Article in journal (Refereed)
    Abstract [en]

    A simple method to overcome low equilibrium conversion in lipase catalysed resolution of alcohols by transesterification was developed. Ethyl octanoate was used as acyl donor as well as solvent and the reaction equilibrium was shifted by applying reduced pressure, forcing the co-product ethanol to evaporate during the reaction. Using a lipase from Candida antarctica 2-octanol, 1-phenyl ethanol, 1-cyclohexyl ethanol and trans-2-methylcyclohexanol were resolved in good optical and chemical yields.

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