Temperature‐Dependent Immobilization of a Tungsten Peroxo Complex That Catalyzes the Hydroxymethoxylation of Olefins

Abstract

A tungsten peroxo complex stabilized by the bidentate picolinato ligand has been synthesized and then immobilized successfully on imidazole‐functionalized silica. The immobilized tungsten‐based catalyst was employed as an efficient catalyst for the one‐pot synthesis of β‐alkoxy alcohols from olefins and methanol with H2O2. Regarding the catalyst evaluation and the results of characterization by the various methods, it was demonstrated that the immobilization of tungsten peroxo complex was highly temperature‐dependent. The tungsten peroxo complex can dissociate and diffuse into the liquid phase at reaction temperature, resulting in a homogeneous reaction. Nevertheless, the catalytically active species was anchored on the imidazole‐functionalized silica by hydrogen bonding as the temperature was lowered to 0 °C after the reaction, which thus offered a highly effective approach for recycling the catalyst for consecutive cycles. In addition, various olefins can be converted to the corresponding β‐alkoxy alcohols with good conversion and selectivity under relative mild conditions by H2O2.

A Catalyst of Pd@MIL‐101@SGO Catalyzes Epoxidation and Hydroxymethoxylation Tandem Reactions of Styrene

“…β‐alkoxy alcohols are used as valuable organic solvents, finechemicals, versatile synthons, and pharmaceutical intermediates . The main strategy to synthesize β‐alkoxy alcohols is a two‐step reaction that epoxidation of olefins and sequential alcoholysis of epoxides under acidic conditions .…”

“…By analogy with the previous reports, mechanism of the tandem reaction is shown in Scheme . As already described above, the one‐pot direct conversion of styrene into β‐alkoxy alcohol requires two catalytic centers to complete the two different parts of reaction.…”

Temperature-Responsive Ionic Liquids: Fundamental Behaviors and Catalytic Applications

“…Similar POM-ILs (Figure ) with poly­(ethylene glycol)-functionalized alkylimidazolium cations and heteropolyacids as anion were further reported by Hou and co-worker. − Due to the special thermo-regulated behavior, they have proved to be efficient catalysts both in esterification and epoxidation reactions. Interestingly, silica immobilized tungsten peroxo complex was also proven to be thermoresponsive by the same group in 2015 . During the one-pot synthesis of alkoxy alcohols from olefin and methanol with H 2 O 2 , it was found that the catalytically active tungsten peroxo complex can dissociate from silica under the reaction temperature, resulting in a homogeneous reaction.…”

“…Interestingly, silica immobilized tungsten peroxo complex was also proven to be thermoresponsive by the same group in 2015. 282 During the one-pot synthesis of alkoxy alcohols from olefin and methanol with H 2 O 2 , it was found that the catalytically active tungsten peroxo complex can dissociate from silica under the reaction temperature, resulting in a homogeneous reaction. However, the soluble W-based species was anchored robustly on silica as the temperature was decreased to 0 °C.…”

“…The desulfurization rate only keeps a gradually slight drop in the catalyst recycling runs. Polymer supported POM (C 16 PM­(O 2 ) 2 /PNIPAM) was also successfully used for catalyzing the oxidation of refractory sulfur-containing compound dibenzothiophene into its corresponding sulfone with high selectivity in the presence of H 2 O 2 . Application of this catalyst brings about an efficient, useful, and green process in desulfurization through extraction and oxidation simultaneously.…”