Research Commons
      • Browse 
        • Communities & Collections
        • Titles
        • Authors
        • By Issue Date
        • Subjects
        • Types
        • Series
      • Help 
        • About
        • Collection Policy
        • OA Mandate Guidelines
        • Guidelines FAQ
        • Contact Us
      • My Account 
        • Sign In
        • Register
      View Item 
      •   Research Commons
      • University of Waikato Theses
      • Masters Degree Theses
      • View Item
      •   Research Commons
      • University of Waikato Theses
      • Masters Degree Theses
      • View Item
      JavaScript is disabled for your browser. Some features of this site may not work without it.

      Derivatisation of Polyphenols

      Bridson, James Hadley
      Thumbnail
      Files
      thesis.pdf
      5.018Mb
      Citation
      Export citation
      Bridson, J. H. (2007). Derivatisation of Polyphenols (Thesis, Master of Science (MSc)). The University of Waikato, Hamilton, New Zealand. Retrieved from https://hdl.handle.net/10289/4952
      Permanent Research Commons link: https://hdl.handle.net/10289/4952
      Abstract
      Polyphenols, such as tannins, offer potential as a bio-derived chemical feedstock. Their present utilisation is limited mainly to leather tanning and wood panel adhesives. However, appropriate derivatisation may alter both the chemical and physical properties and thereby allow further utilisation of polyphenols.

      Derivatisation of polyphenols was achieved by esterification and etherification of the phenol groups. Esterification was achieved by alcoholysis of acid chlorides and transesterification with vinyl esters, while etherification was achieved by the ring opening of propylene oxide. The polyphenols used were resorcinol, catechin, Pinus radiata bark tannin, and Schinopsis lorentzii tannin. The products were characterised using a range of techniques including NMR (1H, 13C and 2D NMR in both the solution and solid state), ESI-MS, GPC, DSC, TGA, and rheology.

      The preparation of polyphenolic esters by alcoholysis provided model compounds to establish the key chemical, spectroscopic, and physical features. A range of simple polyphenol esters such as resorcinol dilaurate and catechin pentalaurate were prepared using lauroyl chloride. Furthermore, tannin lauroyl esters were prepared with varying degrees of substitution. A transesterification method was developed for the preparation of polyphenol esters. Ester interchange occurred effectively in the presence of base catalyst in aqueous solution or dimethyl sulfoxide with short or long chain vinyl esters. This included the first report of the base-catalysed transesterification of flavonoids by vinyl esters to give products such as catechin mono- and di-laurate. Transesterification occurred preferentially at the B-ring as shown by NMR spectroscopy. Subsequently, this transesterification procedure was used to prepare tannin esters. The chemical and physical properties of polyphenol esters were assessed using thermal, antioxidant, and UV/VIS light absorption analysis. Thermal analysis indicated melt/flow properties for some of the polyphenol esters. In some cases, the thermal stability was also shown to increase upon esterification. The antioxidant activity was shown to decrease upon transesterification of pine bark tannin with vinyl laurate, while the UV/VIS absorption was shown to increase. These properties may lend the products towards applications as polymer additives or pharmaceuticals.

      Polyphenol ethers were prepared by the Williamson ether synthesis and ring opening of propylene oxide. However, the Williamson ether synthesis, a common route to prepare ethers, proved unsuitable for flavonoids. Catechin and tannin hydroxypropyl ether derivatives of varying substitution were prepared by the ring-opening of propylene oxide in the presence of triethylamine. Upon hydroxypropylation the thermal properties of the polyphenol were altered. For example, catechin hydroxypropyl ethers showed a glass transition, which was dependent upon the molar substitution, while rheology showed melt behaviour for several of the tannin hydroxypropyl ethers.
      Date
      2007
      Type
      Thesis
      Degree Name
      Master of Science (MSc)
      Supervisors
      Main, Lyndsay
      Publisher
      The University of Waikato
      Rights
      All items in Research Commons are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated.
      Collections
      • Masters Degree Theses [2158]
      Show full item record  

      Usage

      Downloads, last 12 months
      183
       
       

      Usage Statistics

      For this itemFor all of Research Commons

      The University of Waikato - Te Whare Wānanga o WaikatoFeedback and RequestsCopyright and Legal Statement