Hybrid Hydrogels Loaded with Palladium Nanoparticles – Catalysts for Environmentally-Friendly Sonogashira and Heck Cross-Coupling Reactions

Petr Slavik; David Kelham Smith

doi:10.1016/j.tet.2020.131344

Hybrid Hydrogels Loaded with Palladium Nanoparticles – Catalysts for Environmentally-Friendly Sonogashira and Heck Cross-Coupling Reactions

Petr Slavik, David Kelham Smith

Chemistry

Research output: Contribution to journal › Article › peer-review

Abstract

Palladium nanoparticles (PdNPs) were encapsulated within hybrid hydrogels made from an acylhydrazide-functionalised 1,3:2,4-dibenzylidene sorbitol (DBS-CONHNH2) low-molecular-weight gelator (LMWG) combined with agarose polymer gelator via in situ reduction of Pd(II). These heterogeneous gel-phase catalysts were successfully applied for copper-, amine- and phosphine-free Sonogashira cross-coupling reactions under environmentally-friendly conditions without the need for inert atmosphere reaction conditions. The PdNP-loaded gel was reused in Sonogashira couplings up to at least five times with no adverse effect on yield. The performance of solvated PdNP-loaded gel catalysts was compared with the dried xerogels. The xerogels can be used at higher temperatures, enhancing reaction kinetics albeit lowering reaction selectivity, but unlike the solvated gels, were unable to be easily recycled and reused. The PdNP-loaded gels also had good activity in Heck reactions, and although longer reaction times or higher temperatures were required than for the Sonogashira reaction, the reaction conditions were mild for a Heck coupling. In summary, we demonstrate a ‘waste-to-wealth’ methodology in which Pd(II) ‘waste’ is converted into a valuable gel-phase catalyst that can be used for green Sonogashira and Heck cross-coupling reactions.

Original language	English
Article number	131344
Journal	Tetrahedron
Early online date	26 Jun 2020
DOIs	https://doi.org/10.1016/j.tet.2020.131344
Publication status	E-pub ahead of print - 26 Jun 2020

Bibliographical note

Access to Document

10.1016/j.tet.2020.131344

Hybrid Hydrogels Loaded with Palladium Nanoparticles – Catalysts for Environmentally-Friendly Sonogashira and Heck Cross-Coupling Reactions
© 2020 Elsevier Ltd. All rights reserved. This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy.
Accepted author manuscript, 5.18 MBLicence: CC BY-NC-ND

Cite this

@article{292b0c1a1f094ae6a43281ed1e79a22b,

title = "Hybrid Hydrogels Loaded with Palladium Nanoparticles – Catalysts for Environmentally-Friendly Sonogashira and Heck Cross-Coupling Reactions",

abstract = "Palladium nanoparticles (PdNPs) were encapsulated within hybrid hydrogels made from an acylhydrazide-functionalised 1,3:2,4-dibenzylidene sorbitol (DBS-CONHNH2) low-molecular-weight gelator (LMWG) combined with agarose polymer gelator via in situ reduction of Pd(II). These heterogeneous gel-phase catalysts were successfully applied for copper-, amine- and phosphine-free Sonogashira cross-coupling reactions under environmentally-friendly conditions without the need for inert atmosphere reaction conditions. The PdNP-loaded gel was reused in Sonogashira couplings up to at least five times with no adverse effect on yield. The performance of solvated PdNP-loaded gel catalysts was compared with the dried xerogels. The xerogels can be used at higher temperatures, enhancing reaction kinetics albeit lowering reaction selectivity, but unlike the solvated gels, were unable to be easily recycled and reused. The PdNP-loaded gels also had good activity in Heck reactions, and although longer reaction times or higher temperatures were required than for the Sonogashira reaction, the reaction conditions were mild for a Heck coupling. In summary, we demonstrate a {\textquoteleft}waste-to-wealth{\textquoteright} methodology in which Pd(II) {\textquoteleft}waste{\textquoteright} is converted into a valuable gel-phase catalyst that can be used for green Sonogashira and Heck cross-coupling reactions.",

author = "Petr Slavik and Smith, {David Kelham}",

note = "{\textcopyright} 2020 Elsevier Ltd. All rights reserved. This is an author-produced version of the published paper. Uploaded in accordance with the publisher{\textquoteright}s self-archiving policy. ",

year = "2020",

month = jun,

day = "26",

doi = "10.1016/j.tet.2020.131344",

language = "English",

journal = "Tetrahedron",

issn = "0040-4020",

publisher = "Elsevier",

}

TY - JOUR

T1 - Hybrid Hydrogels Loaded with Palladium Nanoparticles – Catalysts for Environmentally-Friendly Sonogashira and Heck Cross-Coupling Reactions

AU - Slavik, Petr

AU - Smith, David Kelham

PY - 2020/6/26

Y1 - 2020/6/26

N2 - Palladium nanoparticles (PdNPs) were encapsulated within hybrid hydrogels made from an acylhydrazide-functionalised 1,3:2,4-dibenzylidene sorbitol (DBS-CONHNH2) low-molecular-weight gelator (LMWG) combined with agarose polymer gelator via in situ reduction of Pd(II). These heterogeneous gel-phase catalysts were successfully applied for copper-, amine- and phosphine-free Sonogashira cross-coupling reactions under environmentally-friendly conditions without the need for inert atmosphere reaction conditions. The PdNP-loaded gel was reused in Sonogashira couplings up to at least five times with no adverse effect on yield. The performance of solvated PdNP-loaded gel catalysts was compared with the dried xerogels. The xerogels can be used at higher temperatures, enhancing reaction kinetics albeit lowering reaction selectivity, but unlike the solvated gels, were unable to be easily recycled and reused. The PdNP-loaded gels also had good activity in Heck reactions, and although longer reaction times or higher temperatures were required than for the Sonogashira reaction, the reaction conditions were mild for a Heck coupling. In summary, we demonstrate a ‘waste-to-wealth’ methodology in which Pd(II) ‘waste’ is converted into a valuable gel-phase catalyst that can be used for green Sonogashira and Heck cross-coupling reactions.

AB - Palladium nanoparticles (PdNPs) were encapsulated within hybrid hydrogels made from an acylhydrazide-functionalised 1,3:2,4-dibenzylidene sorbitol (DBS-CONHNH2) low-molecular-weight gelator (LMWG) combined with agarose polymer gelator via in situ reduction of Pd(II). These heterogeneous gel-phase catalysts were successfully applied for copper-, amine- and phosphine-free Sonogashira cross-coupling reactions under environmentally-friendly conditions without the need for inert atmosphere reaction conditions. The PdNP-loaded gel was reused in Sonogashira couplings up to at least five times with no adverse effect on yield. The performance of solvated PdNP-loaded gel catalysts was compared with the dried xerogels. The xerogels can be used at higher temperatures, enhancing reaction kinetics albeit lowering reaction selectivity, but unlike the solvated gels, were unable to be easily recycled and reused. The PdNP-loaded gels also had good activity in Heck reactions, and although longer reaction times or higher temperatures were required than for the Sonogashira reaction, the reaction conditions were mild for a Heck coupling. In summary, we demonstrate a ‘waste-to-wealth’ methodology in which Pd(II) ‘waste’ is converted into a valuable gel-phase catalyst that can be used for green Sonogashira and Heck cross-coupling reactions.

U2 - 10.1016/j.tet.2020.131344

DO - 10.1016/j.tet.2020.131344

M3 - Article

SN - 0040-4020

JO - Tetrahedron

JF - Tetrahedron

M1 - 131344

ER -