Methyltrioxorhenium pyrazole

W. A. Herrmann, R. M. Kratzer, H. Ding, W. R. Thiel, H. Gras, Methyltrioxorhenium/ pyrazole-a highly efficient catalyst in the epoxidation of olefins, J. Organometal. Chem. 555,293-295 (1998). 

In methyltrioxorhenium-catalysed reactions, residual pyridine, pyrazole or imidazole may deactivate the active catalyst and the ionic liquid should be purified accordingly.118 191 The nature of the ionic liquid may decide the success or failure of a given reaction and, for example, Ru-catalysed alcohol oxidations appear to be very sensitive to the type and quality of ionic liquid used. 

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