Rates of alkene epoxidation and oxidant decomposition were measured using batch reactors (100 cm 3 , three-neck round-bottom flasks) equipped with reflux condensers to minimize evaporative losses. An alkene and H 2 O 2 were added to a solution of CH 3 CN and decane (used as an internal standard for GC analysis) and heated to the desired temperature (303 -348 K) while stirring at 700 rpm. The reactions were initiated by the addition of a catalyst, and small aliquots (~500 μL) of the reaction solution were extracted through a syringe filter (0.22 μm, polypropylene) at predetermined time intervals. The concentrations of the organic components within these aliquots were quantified via gas chromatography. All species were identified, and calibration factors were quantified using standards of known concentration. In all reported data, the standard uncertainty for measured reaction rates was below 10%. For all reactions, only the 1,2epoxyalkane products were observed, which reflects the intentionally low conversion over which these experiments were conducted. Rates for the conversion of alkene and oxidant were determined using the method of initial rates and were measured as functions of reactant concentrations. All reported results were obtained at differential conversion (i.e., <0.5% conversion of the limiting reagent); consequently, all reported rates do not reflect artifacts associated with catalyst deactivation. 1-Alkene epoxidation kinetics were measured in the absence of mass-transfer artifacts as indicated by turnover rates that depend linearly on the concentration of the alkene (data not shown).