Peroxyacetic Acid Oxidation of Olefins and Alkanes Catalyzed by a Dinuclear Manganese(IV) Complex with 1,4,7-trimethyl-1
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Peroxyacetic Acid Oxidation of Olefins and Alkanes Catalyzed by a Dinuclear Manganese(IV) Complex with 1,4,7-trimethyl-1,4,7-triazacyclononane Dalmo Mandelli Æ Yuriy N. Kozlov Æ Camilla C. Golfeto Æ Georgiy B. Shul’pin
Received: 31 May 2007 / Accepted: 13 June 2007 / Published online: 17 July 2007 Springer Science+Business Media, LLC 2007
Abstract Natural terpenes, (–)-limonene and (+)-carvone, can be epoxidized by peroxyacetic acid (PAA) at room temperature if a dinuclear manganese(IV) complex with 1,4,7-trimethyl-1,4,7-triazacyclononane (L), [Mn2L2O3] [PF6]2, is used as a catalyst. The total yield of the epoxides based on the consumed olefins are 97 and 95%, respectively. A kinetic study of the dec-1-ene and cyclohexane oxygenations including the investigation of their simultaneous competitive oxidation was carried out. The olefin epoxidation rate does not depend on dec-1-ene concentration and the dec-1-ene concentration does not affect the rate of cyclohexane oxidation. The cyclohexane oxidation rate is proportional to the alkane concentration. The kinetic analysis led to the conclusion that two species X1 and X2 are generated in the system, and there is no their mutual interconversion. The rate equation for the dec-1-ene epoxidation was proposed: W = k+1[cat][PAA], where cat is the initial manganese complex or its derivative, and the constant was determined: k+1 = 3.5 mol–1 dm3 s–1. Species X1 is apparently an effectively epoxidizing manganese peroxo derivative whereas species X2 is an alkane hydroxylating manganese oxo complex. Keywords Alkanes Alkyl hydroperoxides Carvone Epoxidation Homogeneous catalysis Limonene
Manganese complexes Olefins Oxidation Peroxyacetic acid Terpenes
1 Introduction Peroxy acids are known to oxidize olefins [1–3] and alkanes [4–7]. Metal complexes significantly accelerate such processes: olefin epoxidation [8–12] and alkane hydroperoxidation and hydroxylation [13–27]. Earlier we have demonstrated that synthesized and characterized by Wieghardt et al. [28] a dinuclear manganese(IV) complex with 1,4,7-trimethyl-1,4,7-triazacyclononane (complex 1), is a very efficient catalyst for oxidation of alkanes, olefins, alcohols and sulphides by hydrogen peroxide in the presence of a carboxylic acid as a co-catalyst [15, 16, 29–38]. Usually acetonitrile was used as a solvent and acetic or oxalic acids played the role of the co-catalyst. Compound 1 is also known to catalyze some other oxidations (see reviews [39, 40]). This compound catalyzes bleaching of stains with hydrogen peroxide [41]. It has been recently shown that absorbed on the cotton surface compound 1 exhibits catalase activity [42]. Peroxy acids were also employed as oxidizing reagents in alkane reactions catalyzed by compound 1 [15, 16]. Me
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D. Mandelli C. C. Golfeto Faculdade de Quı´mica, Pontifı´cia Universidade Cato´lica de Campinas, Campus I, Rod. D. Pedro I, km 136, Pq. das Universidades, Campinas, SP 13086-900, Brazil
IV
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Complex 1
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