Trityl-based alkoxyamines as NMP controllers and spin-labels
Gérard Audran1, Elena G Bagryanskaya2,3, Paul Brémond1
1Aix-Marseille Univ, CNRS, ICR, UMR 7273, case 551, Avenue Escadrille Normandie-Niemen, 13397 Marseille Cedex 20 France.
Researchers developed the first spin-labelled alkoxyamines by attaching trityl radicals. These novel compounds are effective initiators for nitroxide-mediated polymerization (NMP), demonstrating high biradical yields.
Area of Science:
- Polymer Chemistry
- Organic Synthesis
- Radical Chemistry
Background:
- Trityl-nitroxide biradicals have emerging applications in various chemical fields.
- Alkoxyamines are crucial components in controlled radical polymerization techniques like nitroxide-mediated polymerization (NMP).
- Developing novel initiators/controllers can enhance the efficiency and scope of NMP.
Purpose of the Study:
- To synthesize and characterize novel trityl-labelled alkoxyamines for the first time.
- To investigate the C-ON bond homolysis kinetics and identify the primary reaction pathway.
- To evaluate the performance of these spin-labelled alkoxyamines in nitroxide-mediated polymerization.
Main Methods:
- Synthesized trityl-alkoxyamines by attaching trityl radicals to alkoxyamine structures.
- Measured the rate constants (k_d) for C-ON bond homolysis using kinetic studies.
- Utilized Electron Paramagnetic Resonance (EPR) spectroscopy to analyze homolysis products and estimate exchange interactions.
- Demonstrated the application in nitroxide-mediated polymerization (NMP) of styrene.
Main Results:
- The rate constants for C-ON bond homolysis in trityl-alkoxyamines were comparable to non-tritylated analogues.
- Decomposition of trityl-alkoxyamines yielded over 80% biradicals, confirming C-ON bond homolysis as the dominant reaction.
- Successful nitroxide-mediated polymerization (NMP) of styrene was achieved using the newly synthesized spin-labelled initiators.
Conclusions:
- This study reports the first successful synthesis of spin-labelled alkoxyamines incorporating trityl radicals.
- The synthesized compounds exhibit efficient C-ON bond homolysis, making them suitable for controlled polymerization.
- These novel trityl-alkoxyamines represent a new class of initiators/controllers for nitroxide-mediated polymerization.
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