| 1. |
- Bonjour, Olivier, et al.
(författare)
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Rigid biobased polycarbonates with good processability based on a spirocyclic diol derived from citric acid
- 2020
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Ingår i: Green Chemistry. - 1463-9270. ; 22:12, s. 3940-3951
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Tidskriftsartikel (refereegranskat)abstract
- Introducing biobased polymers from renewable sources for use as high-performance thermoplastics with high demands on mechanical rigidity, transparency, thermal stability, as well as good processability, is a significant challenge. In the present work we have designed and prepared a rigid biobased bis-spirocylic diol by di-cycloketalization of a bicyclic diketone (cis-bicyclo[3.3.0]octane-3,7-dione, obtained from citric acid) using trimethylolpropane. This spiro-diol monomer has two reactive primary hydroxyl groups and the synthesis from inexpensive biobased starting materials is straightforward and readily upscalable, involving no chromatographic purification. In order to explore the usefulness of the new monomer, it was employed in melt polycondensations with diphenylcarbonate at up to 280 °C to form rigid fully amorphous polycarbonates (PCs). Molecular weights (MWs) up to Mn = 28 kg mol-1 were achieved, and thermal and dynamic mechanical measurements showed glass transitions up to Tg = 100 °C, with no thermal decomposition until Td ~ 350 °C. Solvent cast films had excellent mechanical flexibility and strength, as well as a high transparency with only slight coloration. Results by dynamic melt rheology implied that the high-MW PCs had a good processability at 170 °C, with a stable shear modulus over time, but started to degrade via chain scission reactions when the temperature approached 200 °C. In conclusion, the present work demonstrates the straightforward preparation of the citric acid-based spiro-diol, and indicates that it is an efficient building block for the preparation of rigid biobased PCs and other condensation polymers.
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| 2. |
- Gathergood, Nicholas
(creator_code:cre_t)
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Synthesis and polymerization of isosorbide-based monomethacrylates
- 2019
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Patent (övrigt vetenskapligt/konstnärligt)abstract
- Isosorbide-5-methacrylate was obtained by enzymatic catalysis with Lipozyme RM IM in a highly regioselective manner in up to 87% yield. The process uses readily available acyl donors (methacrylic anydride or vinyl methacrylate), is easily scalable and chromatography free. Simple extractive workup followed by decoloration and filtration affords the monomer with up to > 99% purity. In addition, the developed enzymatic strategy was applied for the synthesis of a series of isosorbide 5- and 2-methacrylate derivatives. All the sythesized isosorbide monomethacrylates were radically polymerized with AIBN. The properties of these polymers with different side groups in either endo or exo configuration in the isosorbide structure was examined. The methacrylic isosorbide derivatives with OH-group were found to have very high glass transition temperature (Tg = 167 °C) and good thermal stability (at 5% weight loss under N2, Td,95 = 240 °C). The highest molecular weight (Mn = 80.6 kg/mol) was determined for the polymethacrylate with Ac-substitute.
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| 3. |
- Matt, Livia, et al.
(författare)
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Enzymatic synthesis and polymerization of isosorbide-based monomethacrylates for high-Tg plastics
- 2018
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Ingår i: ACS Sustainable Chemistry & Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 6:12, s. 17382-17390
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Tidskriftsartikel (refereegranskat)abstract
- Isosorbide is a stiff bicyclic diol derived from glycose-based polysaccharides, and is thus an attractive building block for novel rigid bioplastics. In the present work a highly regioselective biocatalytic approach for the synthesis of isosorbide 5-methacrylate was developed. The Lipozyme RM IM (Rhizomucor miehei lipase) catalyzed process is straightforward, easily scalable and chromatography-free; a simple extractive workup afforded the monomer at >99% purity and in 87% yield. The developed strategy was applied for the synthesis of a series of monomethacrylated isosorbide derivatives. Radical polymerization of the monomers produced rigid polymethacrylates with a certain side group in either endo or exo configuration, exclusively, which generated materials with great diversity of properties. For example, the two regioisomeric polymers carrying hydroxyl groups reached a glass transition temperature at Tg = 167 °C. The polymer tethered with dodecanoate chains in exo position showed crystallinity with an unexpectedly high melting point at Tm = 83 °C. In contrast, the corresponding sample with dodecanoate chains in endo positions was fully amorphous with Tg = 54 °C. Efficient biocatalytic synthesis combined with attractive polymer properties opens up possibilities for production of these bio-based polymers on an industrial scale.
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| 4. |
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| 5. |
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| 6. |
- Ragnarsson, Ulf, 1934-, et al.
(författare)
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An unprecedented rearrangement of a 1,1-diprotected hydrazine derivative. Structure revision of a catalyst-containing by-product
- 2014
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Ingår i: Tetrahedron Letters. - : Elsevier. - 0040-4039 .- 1359-8562. ; 55:51, s. 7019-7022
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Tidskriftsartikel (refereegranskat)abstract
- Treatment of 1-Boc-1-tosyl-hydrazine with 1,1,3,3-tetramethylguanidine (TMG) gave rise to twoproducts, one containing and the other not containing TMG. The latter was identified as 1-Boc-2-tosylhydrazine.This rearrangement provided useful insight into the nature of the first product that had previouslybeen isolated and assigned an incorrect tentative structure. To rationalize the results a plausiblemechanism via a common intermediate, involving TMG as a nucleophilic catalyst is proposed. A simplerprocedure for the preparation of the starting material is also presented.
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| 7. |
- Sedrik, Rauno, et al.
(författare)
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Chemically Recyclable Poly(β-thioether ester)s Based on Rigid Spirocyclic Ketal Diols Derived from Citric Acid
- 2022
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1526-4602 .- 1525-7797. ; 23:6, s. 2685-2696
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Tidskriftsartikel (refereegranskat)abstract
- Incorporating rigid cyclic acetal and ketal units into polymer structures is an important strategy towards high-performance materials from renewable resources. In the present work, citric acid, a widely used platform chemical derived from biomass, has been efficiently converted into diand tricyclic diketones. Ketalization with glycerol or trimethylolpropane afforded rigid spirodiols, which were obtained as complex mixtures of isomers. After a comprehensive NMR analysis, the spirodiols were converted into the respective di(meth)acrylates and utilized in thiol-ene polymerizations in combination with different dithiols. The resulting poly(β-thioether ester ketal)s were thermally stable up to 300 °C and showed glass transition temperatures in a range from -7 to 40 °C, depending on monomer composition. The polymers were stable in aqueous acids and bases, but in a mixture of 1 M aq. HCl and acetone, the ketal functional groups were cleanly hydrolyzed, opening the pathway for potential chemical recycling of these materials. We envision that these novel bioderived spirodiols have a great potential to become valuable and versatile bio-based building blocks for several different kinds of polymer materials.
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