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Issue 5, 2005
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Continuous reactions in supercritical fluids; a cleaner, more selective synthesis of thymol in supercritical CO2

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Abstract

Continuous fixed-bed catalytic Friedel–Crafts alkylation of m-cresol with different alkylating agents, isopropanol (IPA) and propylene, has been carried out using supercritical CO2, scCO2, as an alternative and more environmentally friendly reaction medium, for the synthesis of the fine chemical thymol. Both a solid Lewis acid catalyst (γ-Al2O3) and a solid Brønsted acid catalyst (Nafion® SAC-13) have been investigated over a range of reaction conditions to optimise yield and selectivity for thymol. The reaction product distribution was found to be related to the type of catalyst employed. This is likely to have been due to the different reaction pathways through which the reaction occurred, a direct Friedel–Crafts alkylation in the case of Brønsted type acids and a Fries rearrangement when employing the Lewis catalyst. The new technique of 2DCOR-GC analysis was employed to establish the order of formation of the different species generated in the reaction over the two catalysts in scCO2.

Graphical abstract: Continuous reactions in supercritical fluids; a cleaner, more selective synthesis of thymol in supercritical CO2

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Publication details

The article was received on 17 Dec 2004, accepted on 07 Mar 2005 and first published on 11 Apr 2005


Article type: Paper
DOI: 10.1039/B418983C
Green Chem., 2005,7, 288-293

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    Continuous reactions in supercritical fluids; a cleaner, more selective synthesis of thymol in supercritical CO2

    R. Amandi, J. R. Hyde, S. K. Ross, T. J. Lotz and M. Poliakoff, Green Chem., 2005, 7, 288
    DOI: 10.1039/B418983C

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