345-92-6Relevant articles and documents
Mn(III) active site in hydrotalcite efficiently catalyzes the oxidation of alkylarenes with molecular oxygen
Wang, Anwei,Zhou, WeiYou,Sun, Zhonghua,Zhang, Zhong,Zhang, Zhihui,He, MingYang,Chen, Qun
, (2020/12/07)
Developing efficient heterogeneous catalytic systems based on easily available materials and molecular oxygen for the selective oxidation of alkylarenes is highly desirable. In the present research, NiMn hydrotalcite (Ni2Mn-LDH) has been found as an efficient catalyst in the oxidation of alkylarenes using molecular oxygen as the sole oxidant without any additive. Impressive catalytic performance, excellent stability and recyclability, broad applicable scope and practical potential for the catalytic system have been observed. Mn3+ species was proposed to be the efficient active site, and Ni2+ played an important role in stabilizing the Mn3+ species in the hydrotalcite structure. The kinetic study showed that the aerobic oxidation of diphenylmethane is a first-order reaction over Ni2Mn-LDH with the activation energy (Ea) and pre-exponential factor (A0) being 85.7 kJ mol?1 and 1.8 × 109 min?1, respectively. The Gibbs free energy (ΔG≠) was determined to be -10.4 kJ mol-1 K-1 for the oxidation based on Eyring-Polanyi equation, indicating the reaction is exergonic. The mechanism study indicated that the reaction proceeded through both radical and carbocation intermediates. The two species were then trapped by molecular oxygen and H2O or hydroxyl species, respectively, to yield the corresponding products. The present research might provide information for constructing highly efficient and stable active site for the catalytic aerobic oxidation based on available and economic material.
Zwitterion-induced organic-metal hybrid catalysis in aerobic oxidation
Hu, Rong-Bin,Lam, Ying-Pong,Ng, Wing-Hin,Wong, Chun-Yuen,Yeung, Ying-Yeung
, p. 3498 - 3506 (2021/04/07)
In many metal catalyses, the traditional strategy of removing chloride ions is to add silver salts via anion exchange to obtain highly active catalysts. Herein, we reported an alternative strategy of removing chloride anions from ruthenium trichloride using an organic [P+-N-] zwitterionic compound via multiple hydrogen bond interactions. The resultant organic-metal hybrid catalytic system has successfully been applied to the aerobic oxidation of alcohols, tetrahydroquinolines, and indolines under mild conditions. The performance of zwitterion is far superior to that of many other common Lewis bases or Br?nsted bases. Mechanistic studies revealed that the zwitterion triggers the dissociation of chloride from ruthenium trichloride via nonclassical hydrogen bond interaction. Preliminary studies show that the zwitterion is applicable to catalytic transfer semi-hydrogenation.
4,4 ’ - Difluorobenzophenone and preparation method and application thereof
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Paragraph 0057-0099, (2021/11/21)
The 4, 4 ’ difluorobenzophenone and the preparation method thereof comprise: mixing a molecular sieve and hydrogen peroxide and with fluorobenzaldehyde to form a mixed solution, oxidizing fluorobenzaldehyde into p-fluorobenzoic acid, wherein the molecular sieve is a catalyst. Hydrochloric acid and zinc chloride are added to the mixed solution to generate p-fluorobenzoyl chloride under the condition that the molecular sieve is used as a catalyst. Fluorobenzene was added to the mixed solution containing the p-fluorobenzoyl chloride to obtain the 4, 4 ’ - difluorobenzophenone. Thus, the synthetic method has the following advantages: 4, the yield of 4 ’ - difluorobenzophenone is not lower 98%, the purity is not lower than 99.999%, and the purity makes it available for preparation of medical grade polyether ether ketone. Reaction conditions are easy to control, and the risk of explosion is reduced to a certain extent.