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CO2 revalorization for the organocatalytic synthesis of cyclic carbonates and vanillin-based non-isocyanate polyurethanes (NIPUs)
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Mosteirín, Marcos Noé Fanjul (2019) CO2 revalorization for the organocatalytic synthesis of cyclic carbonates and vanillin-based non-isocyanate polyurethanes (NIPUs). PhD thesis, University of Warwick.
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Official URL: http://webcat.warwick.ac.uk/record=b3492282~S15
Abstract
Chapter 1 describes a general introduction to all the contents exhibited in this thesis. In this chapter the CO2 potential for the synthesis of added-value chemicals is explored. A strong survey is made in the organocatalytic methodologies for the synthesis of five-membered cyclic carbonates. Later, the synthesis of non isocyanate polyurethanes (NIPUs) is discussed. One of the most used methods for the synthesis of the aforementioned polymers is by the step-growth polymerization of bis-cyclic carbonates with amines. This approach links with the CO2 revalorization above discussed and gives a more sustainable approach for the production of polyurethanes since this method bypasses the use of toxic isocyanates. Finally, a survey of the renewable polymer feedstock is done with special emphasis in vanillin, a key renewable building block obtained from lignin.
Chapter 2 shows a rational study for the organocatalysed synthesis of five-membered cyclic carbonates from CO2 and epoxides. Several alkylated and protonated DBU-based catalysts were prepared and tested for the synthesis of five-membered cyclic carbonates. A relationship between structure and reactivity is stablished, showing the importance of hydrogen bond donor moieties in the DBU core revealing that iodide salt of DBU, i.e. [HDBU]I, exhibited the highest activity for the cyclocarboxylation of a battery of terminal functionalised epoxides. The influence of the anion was studied displaying iodide the highest performance. In addition, the catalyst was recycled up to six times without significant losses of activity. Finally, DFT calculations further support the influence of the nucleophilicity and leaving ability of the counter anion and corroborates the experimental observations.
Chapter 3 describes a preliminary study for the cycloaddition of CO2 into epoxides using novel guanidinium halide salts based around DCC. Inspired on the findings of chapter 2, a battery of guanidinium iodide salts were synthesised and fully characterised. Then, they were tested for the synthesis of styrene carbonate from styrene oxide and CO2. The incorporation of an imidazole moiety in the guanidinium core improved the catalytic activity in comparison with the other catalysts tested. A systematic optimization of the reaction parameters was described, rendering so, an efficient methodology for the synthesis of five-membered cyclic carbonates. Finally, a discussion of the mechanism is described, the C2 proton of the imidazole ring is proposed to make a very efficient epoxide activation via hydrogen bond interactions compared to the other tested guanidinium salts.
Chapter 4 explores the synthesis of non-isocyanate polyurethanes (NIPUS) based around vanillin. Several modifications of the vanillin functionalities were performed rendering three different bis-cyclic carbonates. Subsequently, each of those monomers were reacted with two different bis-amines to yield six different NIPUs which were fully characterised by 1H and 13C NMR spectroscopy, FTIR and SEC. Furthermore, their thermal properties were characterised by DSC analysis and TGA.
Chapter 5 describes the synthesis of waterborne thermo-responsive non-isocyanate poly(hydroxyurethane) hydrogels. Those materials were prepared by the reaction of a bis-eight membered cyclic carbonate, a PEG bis-amine and a tris-amine which was used as a cross-linker. The presence of hydrophilic PEG moieties and the tuning of ratios of PEG bis-amine and cross-linker rendered materials able to be printed as a consequence of their reversible moduli decay when they are heated up and their subsequent moduli increase when they are cooled down.
Chapter 6 shows experimental protocols plus spectroscopy data presented in this thesis.
A final appendix is provided showing all the 1H and 13C NMR spectroscopy data in all chapters.
Item Type: | Thesis (PhD) | ||||
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Subjects: | Q Science > QD Chemistry T Technology > TP Chemical technology |
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Library of Congress Subject Headings (LCSH): | Carbon dioxide -- Reactivity, Polyurethanes -- Synthesis, Polycarbonates -- Synthesis, Polycondensation, Catalysts -- Synthesis | ||||
Official Date: | December 2019 | ||||
Dates: |
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Institution: | University of Warwick | ||||
Theses Department: | Department of Chemistry | ||||
Thesis Type: | PhD | ||||
Publication Status: | Unpublished | ||||
Supervisor(s)/Advisor: | Dove, Andrew P. | ||||
Format of File: | |||||
Extent: | xxiv, 200 leaves : illustrations (some colour) | ||||
Language: | eng |
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