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Deconstruction of rubber via C–H amination and aza-Cope rearrangement

Nature volume 640, pages 384–389 (2025)Cite this article

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Abstract

Limited strategies exist for chemical recycling of commodity diene polymers, like those found in tyres1,2,3. Here we apply C–H amination and backbone rearrangement of polymers to deconstruct these materials into precursors for epoxy resins. Specifically, we develop a sulfur diimide reagent4,5 that enables up to about 35% allylic amination of diene polymers and rubber. Then, we apply the cationic 2-aza-Cope rearrangement to deconstruct aminated diene polymers. In a model system, we see molecular weight reduction from 58,100 to approximately 400 g mol−1, and aminated post-consumer rubber is deconstructed over 6 hours into soluble amine-functionalized polymers, which can be utilized to prepare epoxy thermosets with similar stiffnesses to commercial bisphenol A-derived resins6. Altogether, this work demonstrates the power of C–H amination and backbone rearrangement to enable chemical recycling of post-consumer materials.

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Fig. 1: Overview of our strategy for rubber deconstruction.
Fig. 2: Allylic amination on model substrates 1, 5 and 9.
Fig. 3: Results from ACR deconstruction studies.
Fig. 4: Deconstruction of crosslinked materials and application of products.

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Data availability

All data are available in the main text or the Supplementary Information. Provisional patent numbers of applications associated with this work are as follows: 63/454,452; Filing Date: 03-27-2023 (M.R., A.V.Z.) and 63/710,916; Filing Date: 10-24-2024 (S.E.T., A.V.Z.).

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Acknowledgements

This research was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Catalysis Science Program, under award DE-SC0022898. S.E.T. is also supported by the National Science Foundation Graduate Research Fellowship. We thank F. Leibfarth (UNC-CH) for discussion and for the use of his group’s ATR-FTIR and dogbone cutter. We thank the Sheiko group and J.-J. Wang (UNC-CH) for help with DMA data collection. We thank the Becker laboratory (Duke University) for the use of their cryomill. We thank M. ter Horst (UNC-CH) for NMR-related discussion, C. Chen (UNC-CH) for X-ray diffraction advice and B. Ehrmann (UNC-CH) for MS advice and assistance with the MALDI-TOF. We thank the UNC Chemistry NMR facility (NSF grant no. CHE-0922858), UNC Chemistry X-Ray Diffraction facility (NSF grant no. CHE-2117287) and the UNC Chemistry Mass Spectrometry facility (NIH grant no. R35GM118055, DOD grant no. FA9550-23-1-0077) for the use of their instrumentation. We thank K. Sharp-Knott (Virginia Tech) and the Virginia Tech Chemistry NMR Facility for collection of all solid-state NMR spectroscopy data. We thank the physics machine shop (UNC-CH) for creating our Teflon moulds for materials testing.

Author information

Author notes

  1. These authors contributed equally: Sydney E. Towell, Maxim Ratushnyy

Authors and Affiliations

  1. Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA

    Sydney E. Towell, Maxim Ratushnyy, Lauren S. Cooke & Aleksandr V. Zhukhovitskiy

  2. Center for Sustainable Systems, University of Michigan, Ann Arbor, MI, USA

    Geoffrey M. Lewis

Authors
  1. Sydney E. Towell
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Contributions

Conceptualization: A.V.Z. Methodology: S.E.T., M.R., L.S., G.M.L. Investigation: S.E.T., M.R., L.S., G.M.L. Visualization: S.E.T., M.R., L.S., A.V.Z. Funding acquisition: A.V.Z. Project administration: A.V.Z. Supervision: A.V.Z. Writing—original draft: S.E.T., M.R., A.V.Z. Writing—review and editing: S.E.T., M.R., L.S., G.M.L., A.V.Z.

Corresponding author

Correspondence to Aleksandr V. Zhukhovitskiy.

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Competing interests

Two patent applications have been filed on sulfur diimide-mediated amination and aza-Cope deconstruction.

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Nature thanks Ciaran Lahive, Christophe Thomas and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Extended data figures and tables

Extended Data Fig. 1 Results from ACR deconstruction studies.

ACR of 15 showing deconstruction products 16a–20a. (Left) 1H NMR spectra of deconstruction of 15 at zero h and 48 h; (Right) Associated GPC differential refractive index (dRI) traces of 1H NMR samples after Boc-protection using conditions c.

Supplementary information

Supplementary Information

This file contains Supplementary materials, methods, figures and data.

Supplementary Data

Supplementary Data

Check-CIF file for the X-ray crystal structure of S31.

Supplementary Video 1

PBD rubber deconstruction.

Supplementary Video 2

Post-consumer rubber deconstruction.

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Towell, S.E., Ratushnyy, M., Cooke, L.S. et al. Deconstruction of rubber via C–H amination and aza-Cope rearrangement. Nature 640, 384–389 (2025). https://doi.org/10.1038/s41586-025-08716-6

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