- Synthesis of core-shell Ce-modified mixed metal oxides derived from P123-templated layered double hydroxides
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Layered double hydroxides are a promising platform material which can be combined with a variety of active species based on their characteristic features. Silicon@P123-templated Ce-doped layered double hydroxide (SiO2@CeMgAl-LDH(P123)) composites were synthesizedviaa facilein situco-precipitation method, and characterized by TEM, X-ray diffraction, FTIR, XPS, CO2-,etc.in detail. Meanwhile, the calcined powder (SiO2@CeMgAl-LDO(P123)) possessed an excellent core-shell structure and a high surface area inherited from the LDH structure, which led to an outstanding catalytic activity (99.7% conversion of propylene oxide, 92.4% selectivity of propylene glycol methyl ether) under mild reaction conditions (120 °C). Cerium oxide provides a large number of oxygen vacancies and significantly improves the medium basic strength of the material, which facilitates the selective ring-opening of PO. Furthermore, the introduction and removal of P123 make the cerium oxide uniformly dispersed on the LDH layers, providing more reaction sites for the reaction of methanol and propylene oxide. The core-shell structure prepared by thein situco-precipitation method could solve the shortcomings of agglomeration of layered double hydroxides and prolong the catalytic life evidently.
- Wang, Kaijun,Mao, Qifan,Fei, Weimin,Kong, Lingxin,Cao, Xiaoyan,Gu, Zhenggui
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- Method for synthesizing gamma-alkoxy alcohol
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The invention provides a synthesis method of gamma-alkoxy alcohol. The method comprises the following steps: in a synthesis gas atmosphere, sequentially carrying out hydroformylation and a hydrogenation reaction on an enol ether substrate under the action of a catalyst to obtain the gamma-alkoxy alcohol by a one-pot method. The method has the main advantages that a synthesis route is novel, the enol ether is creatively used as the raw material to prepare the gamma-alkoxy alcohol in one step, and compared with other synthesis methods used at present, the method of the invention has obvious advantages; and cobalt and alkyl phosphine with high hydrogenation activity are selected as catalyst ligands, and Lewis acid is selected as a carbonyl activation reagent, so the hydrogenation reaction activity of the system is further improved, the gamma-alkoxy alcohol is obtained by the one-pot method, the separation and purification of an unstable intermediate gamma-alkoxy aldehyde are avoided, andoperation is simpler, more convenient and safer.
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Paragraph 0037-0051; 0061-0066
(2020/10/12)
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- Acetolysis of Cyclic Acetals: Regioselective Acylative Cleavage of Cyclic Formals
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The acid-catalyzed reaction of cyclic acetals with acetic anhydride has been investigated.Acylative cleavage of cyclic formals has been found to be a clean, high-yield reaction involving rupture of the C(2)-O bond with loss of stereochemical integrity at the C(2)-position to give hemiacetal acetate products.Ring cleavage of unsymmetrically substituted cyclic formals with either acetic anhydride or acetyl chloride occurs via preferential rupture of the less congested C(2)-O bond (Scheme I, path A).Such cleavage is totally regiospecific for 1,3-dioxanes and displays high (75-85percent) regioselectivity for smaller and larger ring systems.Acetolysis of cyclic acetals other than formals is a slow process that leads to loss of the aldehyde derived fragment and formation of simple diacetates.These results are rationalized in terms of rate-limiting electrophilic attack that is acutely sensitive to steric effects engendered by substituents located at positions adjacent to ring oxygens.
- Bailey, William F.,Rivera, Alberto D.
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p. 4958 - 4964
(2007/10/02)
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