623-37-0Relevant articles and documents
Biomimetic alkane oxidation by iodosylbenzene and iodobenzene diacetate catalyzed by a new manganese porphyrin: Water effect
Da Silva, Vinícius Santos,Idemori, Ynara Marina,DeFreitas-Silva, Gilson
, p. 54 - 62 (2015)
This work describes the synthesis and characterization of the novel third-generation catalyst 5,10-(3,5-bromo,4-aminophenyl)-15,20-(phenyl)-2,3,7,8,12,13,17,18-octabromoporphyrinatomanganese(III) chloride, cis-[MnIIIBr12DAPDPP]Cl, and compares the catalytic activity of this compound with the catalytic activity of the first- and second-generation manganese porphyrins [MnIIITPP]Cl and cis-[MnIIIDAPDPP]Cl, respectively, in cyclohexane, adamantane and n-hexane, oxidation by iodosylbenzene (PhIO) or iodobenzene diacetate (PhI(OAc)2). This work also investigates how addition of water and imidazole influences the catalytic systems in the adamantane and cyclohexane oxidation. In the absence of water and imidazole, cis-[MnIIIBr12DAPDPP]Cl leads to higher product yields as compared with [MnIIITPP]Cl and cis-[MnIIIDAPDPP]Cl in cyclohexane oxidation. The third-generation (β-octabrominated) cis-[MnIIIBr12DAPDPP]Cl was not fully destroyed in reactions with PhI(OAc)2 as oxidant. In the presence of imidazole, [MnIIITPP]Cl and cis-[MnIIIDAPDPP]Cl give superior cyclohexanol yields as compared with cis-[MnIIIBr12DAPDPP]Cl. Addition of water during adamantane oxidation by PhI(OAc)2 increases 1-adamantanol yield. As for cyclohexane oxidation by PhIO or PhI(OAc)2, the presence of water raises product yields and diminishes catalyst destruction, especially in the case of cis-[MnIIIDAPDPP]Cl. The presence of water in systems employing PhI(OAc)2 as oxidant affords higher product yields as compared with systems that use PhIO as oxidant.
Synthesis of TS-1 zeolites from a polymer containing titanium and silicon
Xing, Jiacheng,Yuan, Danhua,Liu, Hanbang,Tong, Yansi,Xu, Yunpeng,Liu, Zhongmin
, p. 6205 - 6213 (2021/03/22)
The synthesis of TS-1 zeolites is regarded as a milestone in zeolite history, and it has led to the revolution of the green oxidation system of using H2O2as an oxidant, leaving only water as the byproduct. However, because of the highly hydrolyzable titanium source, the preparation of TS-1 requires complex synthesis conditions. Moreover, the difference in the hydrolysis rate between the silicon source and titanium source tends to increase the difficulty of titanium insertion into the framework, and it is easy to generate extra-framework Ti species during the synthesis. Here, a high-quality TS-1 zeolite with a large external surface area and free of extra-framework Ti species has been successfully synthesized by using a kind of novel polymer containing titanium and silicon. Due to the high hydrolysis resistance of the polymer reagent, a good matching of the hydrolysis rate between the silicon source and the titanium source is realized during crystallization, which facilitates the incorporation of titanium into the framework. Furthermore, the TS-1 zeolite exhibited excellent catalytic performance inn-hexane oxidation with hydrogen peroxide as the oxidant. This method of synthesizing zeolites from polymers is expected to be widely applied for the synthesis of other titanium-containing zeotype materials.
Hydrodeoxygenation of C4-C6 sugar alcohols to diols or mono-alcohols with the retention of the carbon chain over a silica-supported tungsten oxide-modified platinum catalyst
Betchaku, Mii,Cao, Ji,Liu, Lujie,Nakagawa, Yoshinao,Tamura, Masazumi,Tomishige, Keiichi,Yabushita, Mizuho
supporting information, p. 5665 - 5679 (2021/08/16)
The hydrodeoxygenation of erythritol, xylitol, and sorbitol was investigated over a Pt-WOx/SiO2 (4 wt% Pt, W/Pt = 0.25, molar ratio) catalyst. 1,4-Butanediol can be selectively produced with 51% yield (carbon based) by erythritol hydrodeoxygenation at 413 K, based on the selectivity over this catalyst toward the regioselective removal of the C-O bond in the -O-C-CH2OH structure. Because the catalyst is also active in the hydrodeoxygenation of other polyols to some extent but much less active in that of mono-alcohols, at higher temperature (453 K), mono-alcohols can be produced from sugar alcohols. A good total yield (59%) of pentanols can be obtained from xylitol, which is mainly converted to C2 + C3 products in the literature hydrogenolysis systems. It can be applied to the hydrodeoxygenation of other sugar alcohols to mono-alcohols with high yields as well, such as erythritol to butanols (74%) and sorbitol to hexanols (59%) with very small amounts of C-C bond cleavage products. The active site is suggested to be the Pt-WOx interfacial site, which is supported by the reaction and characterization results (TEM and XAFS). WOx/SiO2 selectively catalyzed the dehydration of xylitol to 1,4-anhydroxylitol, whereas Pt-WOx/SiO2 promoted the transformation of xylitol to pentanols with 1,3,5-pentanetriol as the main intermediate. Pre-calcination of the reused catalyst at 573 K is important to prevent coke formation and to improve the reusability.
