80717-22-2Relevant articles and documents
Understanding the mechanism of N coordination on framework Ti of Ti-BEA zeolite and its promoting effect on alkene epoxidation reaction
Liang, Xiaohang,Liu, Dan,Luo, Yibin,Peng, Xinxin,Shu, Xingtian,Xia, Changjiu
, (2021/07/31)
The function of ammonium salts on the epoxidation performance over Ti-BEA zeolite was investigated in detail. Experiments of alkene epoxidation, side reactions of epoxide and decomposition of H2O2 with or without ammonium salts were designed, and the UV-Vis spectroscopy was employed to analyze the structure of Ti-hydroperoxo species. It is revealed that the ammonia (or amines) dissociated from the ammonium salt would chelate with the linear Ti-η1(OOH) species and form a bridged Ti-η2(OOH)-R species, which is more stable, more weaker in epoxide adsorption and acidity as well. Therefore, side reactions and H2O2 decomposition would be suppressed, and both alkene conversion and epoxide selectivity would be promoted simultaneously. On the other hand, the excessive NH3?H2O (NH3/Ti>1) or NaOH bond with the Ti-η2(OOH)-R species and generate salt-like Ti-η2(OO)-M+ species, resulting in the deactivation of Ti active center. While for ammonium salts, e.g. NH4Cl, the limited dissociation degree along with the acidic environment help the Ti active center to maintain in highly active. In short, this work provides a practical Ti active center tuning method for Ti-BEA zeolite, as well as a thorough understanding of its Ti-hydroperoxo species.
Temperature-dependent immobilization of a tungsten peroxo complex that catalyzes the hydroxymethoxylation of olefins
Chen, Jizhong,Hua, Li,Chen, Chen,Guo, Li,Zhang, Ran,Chen, Angjun,Xiu, Yuhe,Liu, Xuerui,Hou, Zhenshan
, p. 1029 - 1037 (2015/06/08)
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. Running hot and cold: A tungsten peroxo complex (see picture) can dissociate and diffuse into the liquid phase at the reaction temperature, resulting in a homogeneous reaction. After reaction, the catalytically active species was anchored on the functionalized silica by hydrogen-bonding as the temperature was lowered to 0°C. This offers an effective approach for catalyst recovery and recycling.
Cyclopentadienyl and pentamethylcyclopentadienyl ruthenium complexes as catalysts for the total deoxygenation of 1,2-hexanediol and glycerol
Thibault, Michelle E.,Dimondo, Domenico V.,Jennings, Michael,Abdelnur, Patricia Verardi,Eberlin, Marcos N.,Schlaf, Marcel
supporting information; experimental part, p. 357 - 366 (2011/04/18)
The ruthenium aqua complexes [cp*Ru(OH2)(N-N)](OTf) (cp* = η5-pentamethylcyclopentadienyl, N-N = 2,2′-bipyridine, phen = 1,10-phenanthroline, OTf- = trifluoromethanesulfonate) and the acetonitrile complex [cpRu(CH 3CN)(bipy)](OTf) (cp = η5-cyclopentadienyl) are water-, acid-, and thermally stable (>200°C) catalysts for the hydrogenation of aldehydes and ketones in sulfolane solution. In the presence of HOTf as a co-catalyst, they effect the deoxygenation of 1,2-hexanediol to 1-hexanol and hexane. Glycerol is deoxygenated to 1-propanol in up to 18% yield and under more forcing conditions completely deoxygenated to propene. The structure of the acetonitrile pro-catalyst [cpRu(CH3CN)(bipy)](OTf) has been determined by X-ray crystallography (space group P1 (a = 9.3778(10) A; b = 10.7852(10) A; c = 11.1818(13) A; α = 101.718(5)°; β = 114.717(4)°; γ = 102.712(5)°; R = 3.95%).
