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Diels-Alder Reaction

Diels-Alder Reaction. Teacher : Prof. Guey -Sheng Liou Advisor : Prof. Ching -I Huang Speaker : Wei-Ting Li Date : 2014.1.3. Outline. Diels-Alder Reaction Diels-Alder P olymerization Furan and Maleimide Anthracene and Maleimide Functions of Diels-Alder Polymer Reversibility

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Diels-Alder Reaction

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  1. Diels-Alder Reaction Teacher : Prof. Guey-Sheng Liou Advisor : Prof. Ching-I Huang Speaker : Wei-Ting Li Date : 2014.1.3 N. Yoshie, Encyclopedia of Polymer Science and Technology. Diels-Alder Polymers: 1-18 (2013)

  2. Outline • Diels-Alder Reaction • Diels-Alder Polymerization • Furan and Maleimide • Anthracene and Maleimide • Functions of Diels-Alder Polymer • Reversibility • Healing Polymers • Conclusion

  3. Diels-Alder Reaction [4+2] Cycloaddition Otto Diels 1876~1954 GermanyNobel Prize in Chemistry (1950) Kurt Alder 1902~1958 Germany Nobel Prize in Chemistry (1950) Retro Diels-Alder Reaction Diels, O. .; Alder, K. . (1928). "Synthesen in der hydroaromatischen Reihe". Justus Liebig's Annalen der Chemie 460: 98–122.

  4. Diels-Alder Reaction ΔH < 0 ΔS < 0 • Via a one-step, cyclic transition state, with no intermidiates generated. • Converts two pi bonds into two sigma bonds. • Good control overregio- and stereochemicalproperties. • Favor spontaneous at low temperature. ΔG = ΔH – TΔS < 0 Diels, O. .; Alder, K. . (1928). "Synthesen in der hydroaromatischen Reihe". Justus Liebig's Annalen der Chemie 460: 98–122.

  5. Mechanism Electron withdrawing groups Electron donating groups L.G. Wade, Jr. Organic Chemistry

  6. Examples Electron withdrawing groups Electron withdrawing groups Electron donating groups Electron donating groups Electron withdrawing groups L.G. Wade, Jr. Organic Chemistry

  7. Orbital Symmetry Symmetry-allowed L.G. Wade, Jr. Organic Chemistry

  8. Stereochemical Requirements of the Transition State s-cis of the diene Syn addition The endo rule L.G. Wade, Jr. Organic Chemistry

  9. s-cis Conformation of the Diene Cyclopentadiene is fixed in the s-cis conformation, it is highly reactive. L.G. Wade, Jr. Organic Chemistry

  10. Syn Stereochemistry trans trans cis trans L.G. Wade, Jr. Organic Chemistry

  11. The Endo Rule L.G. Wade, Jr. Organic Chemistry

  12. Unsymmetrical Reagents 1,2-product 1,4-product L.G. Wade, Jr. Organic Chemistry

  13. Outline • Diels-Alder Reaction • Diels-Alder Polymerization • Furan and Maleimide • Anthracene and Maleimide • Functions of Diels-Alder Polymer • Reversibility • Healing Polymers • Conclusion

  14. Diels-Alder Polymerization • Representative diene-dienophile combinations for polymer synthesis • Furan and Maleimide • Anthracene and Maleimide • Cyclopentadiene • Dithioester and Dienes • Researchers have focused on the diene-dienophile combination. • Ease of reactant preparation. • Reaction rate. • Equilibrium constant at room temperature. • Temperaure above which the retro Diels-Alder reaction. N. Yoshie, Encyclopedia of Polymer Science and Technology. Diels-Alder Polymers: 1-18 (2013)

  15. Furan and Maleimide • Extensively used in synthesizing functional polymers owing to its thermoreversibility. • Although the relatively low thermal stability, reversibility at moderate temperature makes the reaction very attractive as a source of a dynamic bond. • General concern for environmental sustainability has stimulated much research toward green chemistry, including production of polymers from renewable resources. Aromatization A. Gandini, Prog. Polym. Sci.38, 1–29 (2013).

  16. Furan and Maleimide Linear Polymerization A. Gandini, Prog. Polym. Sci.38, 1–29 (2013).

  17. Non-linear Polymerization Furan and Maleimide Dendrimer Network Polymers A. Gandini, Prog. Polym. Sci.38, 1–29 (2013).

  18. Furan and Maleimide Cross-linking 80℃ A. Gandini, Prog. Polym. Sci.38, 1–29 (2013).

  19. Anthracene and Maleimide • Thermally more stable than the furan/maleimideDiels-Alder adduct. • The thermal stability also results in a higher rate of the cycloaddition. • Simple reaction conditions, high yield, and high selectivity, make the reaction valuable in polymer synthesis. • More often used in click reactions because of the thermal stability of the resultant products. N. Yoshie, Encyclopedia of Polymer Science and Technology. Diels-Alder Polymers: 1-18 (2013)

  20. Multiarm star terpolymer Anthracene and Maleimide Three-arm star block copolymer ABC-type linear terpolymer H. Durmaz, A. Sanyal, G. Hizal, and U. Tunca, Polym. Chem. 3, 825–835 (2012).

  21. Anthracene and Maleimide H-shaped quintopolymer Cyclic block copolymer Heterograft terpolymer H. Durmaz, A. Sanyal, G. Hizal, and U. Tunca, Polym. Chem. 3, 825–835 (2012).

  22. Anthracene and Maleimide Dendronized Graft B. Gacal, H. Durmaz, M. A. Tasdelen, G. Hizal, U. Tunca, Y. Yagci, and A. L. Demirel, Macromolecules39, 5330–5336 (2006). M. Tonga, N. Cengiz, M. M. Kose, T. Dede, and A. Sanyal, J. Polym. Sci., Part A: Polym. Chem. 48, 410–416 (2010).

  23. Outline • Diels-Alder Reaction • Diels-Alder Polymerization • Furan and Maleimide • Anthracene and Maleimide • Functions of Diels-Alder Polymer • Reversibility • Healing Polymers • Conclusion

  24. Reversibility • The thermoreversibility for Diels-Alder polymers to function as smart materials. • Repeatable bonding/debonding in Diels-Alder polymers confers stimuli-responsive properties to gels, organic-inorganic hybrids, and core-cross-linked micelles, and provides a route to surface modification. • Reworkability and recyclability of thermosets, adhesives, and foams. • The Diels-Alder network polymers has been applied to lithiography. • Nanoporous films were successfully fabricated by combining microphase separation in block copolymers and retro Diels-Alder reaction. N. Yoshie, Encyclopedia of Polymer Science and Technology. Diels-Alder Polymers: 1-18 (2013)

  25. Healing Polymers N. Yoshie, Encyclopedia of Polymer Science and Technology. Diels-Alder Polymers: 1-18 (2013)

  26. Outline • Diels-Alder Reaction • Diels-Alder Polymerization • Furan and Maleimide • Anthracene and Maleimide • Functions of Diels-Alder Polymer • Reversibility • Healing Polymers • Conclusion

  27. Conclusion • Some Diels-Alder reactions are thermally reversible. Enthalpically favorable forward cycloaddition proceeds at a low temperature, whereas the opposite cycloreversion proceeds at a moderate to high temperature. • Recently, the Diels-Alder reaction has been rerecognized as a member of the click-chemistry family. Because of the simple reaction condition, high yield, and high selectivity. • The Diels-Alder reaction is extensively used in polymer chemistry. Linear, network, and hyperbranched polymers as well as polymers with unique architectures have been prepared from monomers and prepolymers containing a diene and a dienophile. • Diels-Alder click chemistry is a powerful tool for synthesizing polymers with various advanced architectures (e.g., block and graft copolymers, star polymers, telechelic polymers, dendrimers, and dendronized polymers). N. Yoshie, Encyclopedia of Polymer Science and Technology. Diels-Alder Polymers: 1-18 (2013)

  28. Thanks for your attention.

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