60624-63-7Relevant academic research and scientific papers
Alkylrhenium oxides as homogeneous epoxidation catalysts: activity, selectivity, stability, deactivation
Herrmann, Wolfgang A.,Fischer, Richard W.,Rauch, Monika U.,Scherer, Wolfgang
, p. 243 - 266 (1994)
Methyltrioxorhenium (VII) (MTO, 1a) and several congeners 1b and 2a-d of formula R-ReO3 and R-ReO3·L, respectively, qualify as olefin epoxidation catalysts of high activity and selectivity. Related alkylrhenium (VI) complexes form efficient catalyst precursors as well, since they get oxidized by H2O2 to the same active species CH3ReO(O2)2·H2O (3). The present paper presents a comparison of this novel class of catalysts with the performance of known, commonly used catalysts. Catalyst stability has been recorded and deactivation reactions are described. The synthesis and crystal structure (X-ray diffraction) of the (pale pink-coloured) monomeric amino-functionalized complex O3Re-CH2CH2CH2N (C2H5)2 (4A) and its (violet) polymeric form (4B) are reported. Only the latter is an active epoxidation catalyst with H2O2. An improved laboratory method of the standard catalyst MTO 1a is described.
Equilibria and kinetics of the reactions between hydrogen peroxide and methyltrioxorhenium in aqueous perchloric acid solutions
Yamazaki, Shigekazu,Espenson, James H.,Huston, Patrick
, p. 4683 - 4687 (2008/10/08)
In aqueous solutions the colorless compounds CH3ReO3 (=MTO) and H2O2 form 1:1 and 1:2 adducts. The latter is yellow, with ε360 = 1.1 × 103 L mol-1 cm-1. Peroxide binding to MTO shows cooperativity, as shown by the inversion of the usual order of binding constants. The stepwise equilibrium constants are K1 = 7.7 L mol-1 and K2 = 145 L mol-1 at 25°C. The buildup of product, which occurs on the stopped-flow time scale at 9-680 mM H2O2, is fit by biexponential kinetics. The equilibria and rates are independent of [H3O+] in the range 10-1-10-3 M. The peroxide complexes decompose more rapidly at lower [H3O+], particularly at pH > 3. Possible structures for 1:1 and 1:2 MOT-H2O2 adducts are presented and discussed.
