diels-alder reaction teacher : prof. guey-sheng liou advisor : prof. ching-i huang speaker :...

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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

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

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Outline• Diels-Alder Reaction

• Diels-Alder Polymerization

• Furan and Maleimide

• Anthracene and Maleimide

• Functions of Diels-Alder Polymer

• Reversibility

• Healing Polymers

• Conclusion

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Diels-Alder Reaction

Kurt Alder1902~1958GermanyNobel Prize in Chemistry (1950)

Otto Diels1876~1954GermanyNobel Prize in Chemistry (1950)

Diels, O. .; Alder, K. . (1928). "Synthesen in der hydroaromatischen Reihe". Justus Liebig's Annalen der Chemie 460: 98–122.

[4+2] Cycloaddition

Retro Diels-Alder Reaction

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Diels-Alder Reaction

Diels, O. .; Alder, K. . (1928). "Synthesen in der hydroaromatischen Reihe". Justus Liebig's Annalen der Chemie 460: 98–122.

• Via a one-step, cyclic transition state, with no intermidiates generated.

• Converts two pi bonds into two sigma bonds.

• Good control over regio- and stereochemical properties.

• Favor spontaneous at low temperature.

ΔH < 0

ΔS < 0

ΔG = ΔH – TΔS < 0

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Mechanism

L.G. Wade, Jr. Organic Chemistry

Electron

donating

groups

Electron withdrawi

nggroups

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Examples

L.G. Wade, Jr. Organic Chemistry

Electron

donating

groups

Electron withdrawi

nggroups

Electron

donating

groups

Electron withdrawi

nggroups

Electron withdrawi

nggroups

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Orbital Symmetry

L.G. Wade, Jr. Organic Chemistry

Symmetry-allowed

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Stereochemical Requirements of the Transition State

L.G. Wade, Jr. Organic Chemistry

Syn addition

s-cis of the diene

The endo rule

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s-cis Conformation of the Diene

L.G. Wade, Jr. Organic Chemistry

Cyclopentadiene is fixed in the s-cis

conformation, it is highly reactive.

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Syn Stereochemistry

L.G. Wade, Jr. Organic Chemistry

trans

trans

trans

cis

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The Endo Rule

L.G. Wade, Jr. Organic Chemistry

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Unsymmetrical Reagents

L.G. Wade, Jr. Organic Chemistry

1,4-product

1,2-product

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Outline• Diels-Alder Reaction

• Diels-Alder Polymerization

• Furan and Maleimide

• Anthracene and Maleimide

• Functions of Diels-Alder Polymer

• Reversibility

• Healing Polymers

• Conclusion

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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)

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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.

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

Aromatization

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Furan and Maleimide

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

Linear Polymerization

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Furan and Maleimide

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

Non-linear Polymerizatio

n Dendrimer

NetworkPolymer

s

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Furan and Maleimide

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

Cross-linking

80℃

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Anthracene and Maleimide

• Thermally more stable than the furan/maleimide Diels-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)

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Anthracene and Maleimide

H. Durmaz, A. Sanyal, G. Hizal, and U. Tunca, Polym. Chem. 3, 825–835 (2012).

ABC-type linear terpolymer

Three-arm star block

copolymer

Multiarm star terpolymer

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Anthracene and Maleimide

H. Durmaz, A. Sanyal, G. Hizal, and U. Tunca, Polym. Chem. 3, 825–835 (2012).

Heterograftterpolymer

H-shaped quintopolyme

r

Cyclic block copolymer

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Anthracene and Maleimide

B. Gacal, H. Durmaz, M. A. Tasdelen, G. Hizal, U. Tunca, Y. Yagci, and A. L. Demirel, Macromolecules 39, 5330–5336 (2006).

Graft

Dendronized

M. Tonga, N. Cengiz, M. M. Kose, T. Dede, and A. Sanyal, J. Polym. Sci., Part A: Polym. Chem. 48, 410–416 (2010).

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Outline• Diels-Alder Reaction

• Diels-Alder Polymerization

• Furan and Maleimide

• Anthracene and Maleimide

• Functions of Diels-Alder Polymer

• Reversibility

• Healing Polymers

• Conclusion

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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)

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Healing Polymers

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

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Outline• Diels-Alder Reaction

• Diels-Alder Polymerization

• Furan and Maleimide

• Anthracene and Maleimide

• Functions of Diels-Alder Polymer

• Reversibility

• Healing Polymers

• Conclusion

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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)

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Thanks for your attention.