Kinetic study of the microflow synthesis of 4-hydroxyquinoline in supercritical ethanol

Kinetic study of the microflow synthesis of 4-hydroxyquinoline in supercritical ethanol Article history: Supercritical ethanol was used as a solvent for the thermal cyclization of ethyl 3-(phenylimino)-butanoate Received 14 September 2015 to 2-methyl-4-hydroxyquinoline; the reaction is of great importance in pharmaceutical and color indus- Received in revised form 30 March 2016 tries but conventionally needs specific solvents with high boiling points. The mechanism and the kinetics Accepted 30 March 2016 were studied with a microreactor by measuring the yield of the product at various temperatures up to Available online 30 March 2016 ◦ ◦ 350 C. The reaction in ethanol completed in 27 s at 350 C and 10.0 MPa giving the quinoline in 97% GC yield, although it required higher temperature than that in acetonitrile. The results were explained Keywords: by the mechanism consisting of the two steps: (i) a reversible elimination of ethanol from the reactant Supercritical alcohol yielding ketene intermediate followed by (ii) an irreversible ring closure into the quinoline. On the basis The Conrad-Limpach thermal cyclization of the reaction mechanism, the rate constant and the activation energy were determined from the yield- High-temperature and high-pressure ◦ −3 time profiles measured at temperatures of 300–350 C and a constant ethanol density of 0.11 g cm . The http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Supercritical Fluids Elsevier

Kinetic study of the microflow synthesis of 4-hydroxyquinoline in supercritical ethanol

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Publisher
Elsevier
Copyright
Copyright © 2016 Elsevier B.V.
ISSN
0896-8446
eISSN
1872-8162
D.O.I.
10.1016/j.supflu.2016.03.029
Publisher site
See Article on Publisher Site

Abstract

Article history: Supercritical ethanol was used as a solvent for the thermal cyclization of ethyl 3-(phenylimino)-butanoate Received 14 September 2015 to 2-methyl-4-hydroxyquinoline; the reaction is of great importance in pharmaceutical and color indus- Received in revised form 30 March 2016 tries but conventionally needs specific solvents with high boiling points. The mechanism and the kinetics Accepted 30 March 2016 were studied with a microreactor by measuring the yield of the product at various temperatures up to Available online 30 March 2016 ◦ ◦ 350 C. The reaction in ethanol completed in 27 s at 350 C and 10.0 MPa giving the quinoline in 97% GC yield, although it required higher temperature than that in acetonitrile. The results were explained Keywords: by the mechanism consisting of the two steps: (i) a reversible elimination of ethanol from the reactant Supercritical alcohol yielding ketene intermediate followed by (ii) an irreversible ring closure into the quinoline. On the basis The Conrad-Limpach thermal cyclization of the reaction mechanism, the rate constant and the activation energy were determined from the yield- High-temperature and high-pressure ◦ −3 time profiles measured at temperatures of 300–350 C and a constant ethanol density of 0.11 g cm . The

Journal

The Journal of Supercritical FluidsElsevier

Published: Aug 1, 2016

References

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