Epoxidation of α-pinene catalyzed by methyltrioxorhenium(VII): Influence of additives, oxidants and solvents
摘要:
The epoxidation of alpha-pinene employing methyltrioxorhenium as catalyst is examined. The influence of mono- and bidentate Lewis basic additives (e.g. (t)butylpyridine, 4,4'-dimethyl-2,2'-bipyridine, and Schiff-bases) is investigated. Additionally the impact of the oxidant (H2O2 in water or urea-hydrogen peroxide (UHP)) on the catalytic performance is studied. The effect of the solvent is also examined in order to determine the optimal conditions for the epoxidation of alpha-pinene. The best and straightforwardly applicable result is obtained when a ratio alpha-pinene:MTO:(t)butylpyridine:UHP of 200:1:40:600 is applied at 0 degrees C in nitromethane. In this case, alpha-pinene oxide is formed with 95% yield after 3 h with a turnover frequency (TOF) of 610 h(-1). (C) 2011 Elsevier B.V. All rights reserved.
Halide substituted Schiff-bases: Different activities in methyltrioxorhenium(VII) catalyzed epoxidation via different substitution patterns
作者:Philipp Altmann、Mirza Cokoja、Fritz E. Kühn
DOI:10.1016/j.jorganchem.2011.12.010
日期:2012.3
influence of halide substituted Schiff-bases as ligands of methyltrioxorhenium (MTO) in epoxidation catalysis. Therefore, selected Schiff-bases were prepared by the reaction of hydroxy-benzaldehydes and aniline derivates. These differently substituted Schiff-bases were tested as MTO-ligands in cyclooctene- and 1-octene-epoxidation. Although no great disparities among the substitution patterns have been
Methyltrioxorhenium-catalyzed oxidation of pseudocumene for vitamin E synthesis: A study of solvent and ligand effects
作者:Mónica Carril、Philipp Altmann、Markus Drees、Werner Bonrath、Thomas Netscher、Jan Schütz、Fritz E. Kühn
DOI:10.1016/j.jcat.2011.07.003
日期:2011.10
VitaminE is an essential food component of major economical relevance with important antioxidant properties and biological activity. The oxidation of pseudocumene to trimethyl-1,4-benzoquinone would be a key transformation in an alternative industrial production of α-tocopherol that is important for the antioxidant activity of vitaminE. The methyltrioxorhenium (MTO)-catalyzed oxidation of pseudocumene