Abstract
The selective catalytic synthesis of limonene-derived monofunctional cyclic carbonates and their subsequent functionalisation via thiol–ene addition and amine ring-opening is reported. A phosphotungstate polyoxometalate catalyst used for limonene epoxidation in the 1,2-position is shown to also be active in cyclic carbonate synthesis, allowing a two-step, one-pot synthesis without intermittent epoxide isolation. When used in conjunction with a classical halide catalyst, the polyoxometalate increased the rate of carbonation in a synergistic double-activation of both substrates. The cis isomer is shown to be responsible for incomplete conversion and by-product formation in commercial mixtures of 1,2-limomene oxide. Carbonation of 8,9-limonene epoxide furnished the 8,9-limonene carbonate for the first time. Both cyclic carbonates underwent thiol–ene addition reactions to yield linked di-monocarbonates, which can be used in linear non-isocyanate polyurethanes synthesis, as shown by their facile ring-opening with N-hexylamine. Thus, the selective catalytic route to monofunctional limonene carbonates gives straightforward access to monomers for novel bio-based polymers.
Original language | English |
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Pages (from-to) | 7405-7415 |
Number of pages | 11 |
Journal | Chemistry - A European Journal |
Volume | 26 |
Issue number | 33 |
Early online date | 20 Feb 2020 |
DOIs | |
Publication status | Published - 10 Jun 2020 |
Keywords
- biomass
- epoxidation
- polymers
- polyoxometalates
- renewable resources
ASJC Scopus subject areas
- Catalysis
- Organic Chemistry