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Letters in Organic Chemistry

Editor-in-Chief

ISSN (Print): 1570-1786
ISSN (Online): 1875-6255

Research Article

Highly Selective Cyclohexane Oxidation Catalyzed by Ferrocene in Ionic Liquid Medium

Author(s): Luísa M.D.R.S. Martins*, Ana Paula C. Ribeiro and Armando J.L. Pombeiro

Volume 14, Issue 8, 2017

Page: [571 - 574] Pages: 4

DOI: 10.2174/1570178614666170420182508

Price: $65

Abstract

Background: Although economically very important in view of the significance of the oxidized products for the manufacture of adipic acid and caprolactam (precursors to polyamides widely used in several industries), the current cyclohexane oxidation industrial process leads to very low conversions (ca. 4%) to assure a reasonable selectivity (ca. 85%). Therefore, there is an urgent need to develop sustainable selective cyclohexane oxidation chemistry, which is the main objective of this work.

Methods: The partial oxidation of cyclohexane by aqueous tert-butyl hydroperoxide (TBHP, 70% aq. sol.) in phosphonium ionic liquid medium [P6.6.6.14][DCA] and in the presence of catalytic amounts of ferrocene was investigated. The reaction proceeded during 2 h at room temperature.

Results: It was found that TBHP, under the above conditions, oxidizeD cyclohexane with high selectivity (> 98%), yielding mainly cyclohexanone (up to 16%, based on the substrate) with total TOFs up to 1 x 104 h-1.

Conclusion: The combination of a commercial iron-complex catalyst (ferrocene) and well-adjusted unconventional reaction conditions led to a highly selective, fast and reusable catalytic system for the mild oxidation of cyclohexane. Moreover, the found [Fe(C5H5)2]/[P6.6.6.14][DCA] catalytic system can be of significance to produce polyamide 6.

Keywords: Alkane functionalization, ferrocene, ionic liquid, catalysis, cyclohexane oxidation, water, KA oil

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