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- Title
Solvent-Free Epoxidation of Olefins Catalyzed by '[MoO<sub>2</sub>(SAP)]': A New Mode of tert-Butylhydroperoxide Activation.
- Authors
Morlot, JuliEN; Uyttebroeck, Nicolas; Agustin, Dominique; Poli, Rinaldo
- Abstract
The mononuclear molybdenum complexes [MoO2(acac)2] ( 1, acac=acetylacetonate), [MoO2(SAP)(MeOH)] ( 2), and dinuclear oxomolybdic complexes [MoO2L]2 [L=salicylideneaminophenolato (SAP, 5), salicylideneaminoethanolato (SAE, 6), salicylideneaminomethylpropanolato (SAMP, 7)] have been investigated as (pre)catalysts for the epoxidation of olefins under solvent-free conditions, using tert-butylhydroperoxide (TBHP, 70 % in water) as an oxidant. Complexes 6 and 7, although active, are limited by ligand hydrolysis during the catalytic process, whereas complexes 2 and 5 are not altered under catalytic conditions and yield essentially the same selectivity and activity, which is not suppressed by excess MeOH. Although these catalysts are less active than 1, their selectivity is higher (97-98 %). DFT calculations are consistent with the active form of the catalyst being the 5-coordinate '[MoO2(SAP)]'. The oxidant is activated by forming a weak adduct stabilized by a very loose Mo⋅⋅⋅O interaction and a hydrogen bond, predisposing it to the oxygen transfer to external olefin by a mechanism closely related to Bartlett's epoxidation with peroxyacids.
- Subjects
ORGANIC solvents; EPOXIDATION; ALKENES; MOLYBDENUM compounds; METAL complexes; HYDROPEROXIDES; ACTIVATION (Chemistry); SCHIFF bases; HOMOGENEOUS catalysis; DENSITY functionals
- Publication
ChemCatChem, 2013, Vol 5, Issue 2, p601
- ISSN
1867-3880
- Publication type
Article
- DOI
10.1002/cctc.201200068