ãOlefin Epoxidation Catalyzed by Titanium-Salalen Complexes: Synergistic H2O2 Activation by Dinuclear Ti Sites, Ligand H-Bonding, and Ï-Acidityã?was written by Engler, Hauke; Lansing, Markus; Gordon, Christopher P.; Neudoerfl, Joerg-M.; Schaefer, Mathias; Schloerer, Nils E.; Coperet, Christophe; Berkessel, Albrecht. Reference of 2-Hydroxyphenylboronic acidThis research focused ontitanium Salalen Complex catalyst preparation crystal structure Epoxidation DFT; oxidation kinetics titanium Salalen Complex catalyst. The article conveys some information:
Titanium-salalen complexes have recently solved a long-standing problem in homogeneous epoxidation catalysis by enabling the selective catalytic epoxidation of terminal, nonconjugated olefins with hydrogen peroxide. The authors disclose the mechanism of this intriguing catalyst system, based on XRD analyses, kinetic studies, and NMR elucidation of intermediate structures, complemented by DFT computations. Titanium-salalen catalysts are typically prepared/stored as bis-μ-oxo or μ-oxo-μ-peroxo dimers. Under reaction conditions, while the μ-oxo bridged catalyst dimers remain intact, the epoxidation occurs through an octahedral, yet altered, coordination geometry of the homochiral monomeric subunits. This catalytically active coordination mode is accessed by a slow pre-equilibrium, involving uptake of hydrogen peroxide, and subsequent rearrangement of the coordination sphere of the dinuclear complex. This configuration allows a three-pronged electrophilic activation of hydrogen peroxide, which enables oxygen transfer by the joint action of (i) the Lewis acidic titanium center, (ii) H-bond donation by the ligand’s NH, and (iii) π-chalcogen interaction with the ligand’s pentafluorophenyl moieties. This efficient activation of H2O2 by a dinuclear site parallels recent findings on the active sites of the industrial heterogeneous titanium silicalite TS-1 catalyst. The experimental part of the paper was very detailed, including the reaction process of 2-Hydroxyphenylboronic acid(cas: 89466-08-0Reference of 2-Hydroxyphenylboronic acid)
2-Hydroxyphenylboronic acid(cas: 89466-08-0) belongs to acyl phenylboronic acid. Phenylboronic acid (PBA), a synthetic molecule applied in RNA affinity chromatography, is able to form reversible covalent ester bonds with 1,2- or 1,3-cis-doils on the ribose ringReference of 2-Hydroxyphenylboronic acid
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