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Triphenylphosphine-grafted, RAFT-synthesised, porous monoliths as catalysts for Michael addition in flow synthesis

journal contribution
posted on 2015-11-01, 00:00 authored by Kristine Barlow, V Bernabeu, X Hao, T C Hughes, O E Hutt, A Polyzos, K A Turner, G Moad
We describe the preparation and application of triphenylphosphine functional polystyrene-based porous monolithic catalysts for use as flow reactors. RAFT (reversible addition-fragmentation chain transfer)-crosslinking polymerisation of styrene and divinylbenzene provided monoliths which were then functionalized by RAFT “grafting from” polymerisation of 4-styryldiphenylphosphine mediated by the retained thiocarbonylthio functionality. Under the chosen conditions, the retention of the RAFT functionality was proved by chain extension experiments in which the monoliths were five times re-subjected to the grafting conditions. Importantly, the bound triphenylphosphine-functionality was demonstrated to be catalytically active when the monoliths were used as flow reactors in performing Michael addition of 1-hexanethiol to tert-butyl acrylate and of acetyl acetone to diethyl azodicarboxylate. Conversions from reagent to product of up to 77% were achieved. The monoliths were susceptible to oxidation of the phosphine groups most likely caused by adventitious oxygen in the non-degassed reaction medium, but were successfully regenerated by trichlorosilane reduction and reused.

History

Journal

Reactive and Functional Polymers

Volume

96

Pagination

89 - 96

Publisher

Elsevier

Location

Amsterdam, The Netherlands

ISSN

1381-5148

eISSN

1873-166X

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

2015, Elsevier