Diels alder reaction
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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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Diels alder reaction

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)


Outline

Outline

  • Diels-Alder Reaction

  • Diels-Alder Polymerization

    • Furan and Maleimide

    • Anthracene and Maleimide

  • Functions of Diels-Alder Polymer

    • Reversibility

    • Healing Polymers

  • Conclusion


Diels alder reaction1

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.


Diels alder reaction2

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.


Mechanism

Mechanism

Electron withdrawing

groups

Electron donating

groups

L.G. Wade, Jr. Organic Chemistry


Examples

Examples

Electron withdrawing

groups

Electron withdrawing

groups

Electron donating

groups

Electron donating

groups

Electron withdrawing

groups

L.G. Wade, Jr. Organic Chemistry


Orbital symmetry

Orbital Symmetry

Symmetry-allowed

L.G. Wade, Jr. Organic Chemistry


Stereochemical requirements of the transition state

Stereochemical Requirements of the Transition State

s-cis of the diene

Syn addition

The endo rule

L.G. Wade, Jr. Organic Chemistry


S cis conformation of the diene

s-cis Conformation of the Diene

Cyclopentadiene is fixed in the s-cis conformation, it is highly reactive.

L.G. Wade, Jr. Organic Chemistry


Syn stereochemistry

Syn Stereochemistry

trans

trans

cis

trans

L.G. Wade, Jr. Organic Chemistry


The endo rule

The Endo Rule

L.G. Wade, Jr. Organic Chemistry


Unsymmetrical reagents

Unsymmetrical Reagents

1,2-product

1,4-product

L.G. Wade, Jr. Organic Chemistry


Outline1

Outline

  • Diels-Alder Reaction

  • Diels-Alder Polymerization

    • Furan and Maleimide

    • Anthracene and Maleimide

  • Functions of Diels-Alder Polymer

    • Reversibility

    • Healing Polymers

  • Conclusion


Diels alder polymerization

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)


Furan and maleimide

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).


Furan and maleimide1

Furan and Maleimide

Linear Polymerization

A. Gandini, Prog. Polym. Sci.38, 1–29 (2013).


Furan and maleimide2

Non-linear Polymerization

Furan and Maleimide

Dendrimer

Network

Polymers

A. Gandini, Prog. Polym. Sci.38, 1–29 (2013).


Furan and maleimide3

Furan and Maleimide

Cross-linking

80℃

A. Gandini, Prog. Polym. Sci.38, 1–29 (2013).


Anthracene and maleimide

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)


Anthracene and maleimide1

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).


Anthracene and maleimide2

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).


Anthracene and maleimide3

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).


Outline2

Outline

  • Diels-Alder Reaction

  • Diels-Alder Polymerization

    • Furan and Maleimide

    • Anthracene and Maleimide

  • Functions of Diels-Alder Polymer

    • Reversibility

    • Healing Polymers

  • Conclusion


Reversibility

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)


Healing polymers

Healing Polymers

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


Outline3

Outline

  • Diels-Alder Reaction

  • Diels-Alder Polymerization

    • Furan and Maleimide

    • Anthracene and Maleimide

  • Functions of Diels-Alder Polymer

    • Reversibility

    • Healing Polymers

  • Conclusion


Conclusion

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)


Thanks for your attention

Thanks for your attention.


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