Zuwei Xi

Technical Institute of Physics and Chemistry, Peping, Beijing, China

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Publications (18)40.38 Total impact

  • Jun Li, Shuang Gao, Zuwei Xi
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    ABSTRACT: Reaction-controlled phase-transfer catalysis is a new catalytic system This catalytic system is homogeneous during the reaction After the reaction the catalyst becomes insoluble solid and precipitates from the reaction medium. so that the catalyst can be easily separated and reused This paper presents recent progress made in reaction-controlled phase transfer catalysis for the epoxidation of olefins, oxidation of alcohols, hydroxylation, reductive carbonylation of nitroaromatics, esterification, and other reactions by us and other groups
    ChemInform 04/2011; 42(16). DOI:10.1002/chin.201116256
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 12/2010; 27(50). DOI:10.1002/chin.199650069
  • [Show abstract] [Hide abstract]
    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 08/2010; 31(33). DOI:10.1002/chin.200033080
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    ABSTRACT: Cyclohexene can be oxidized directly to 1, 2-cyclohexanediol with aqueous hydrogen peroxide under solvent-free condition using a heteropolyphosphatotungstate catalyst. And an isolated yield of 54% was obtained in this catalytic system.
    Research on Chemical Intermediates 05/2009; 35(5):563-571. DOI:10.1007/s11164-009-0068-y · 1.54 Impact Factor
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    ABSTRACT: [n-C16H33N(CH3)3]3PW12O40 (1a) catalyzed the oxidation of secondary alcohols with 27.5% aqueous hydrogen peroxide under solvent-free conditions. The isolated yields of all ketones were higher than 92%. The turnover number of the catalyst 1a was above 368, and the highest TON and TOF were up to 3840 and 320h−1. In this catalytic system, the catalytic active species was {PO4[WO(O2)2]4}3−, which was formed from 1a in the reaction. It was discovered that {PO4[WO(O2)2]4}3− (PW4) and [PW12O40]3− (PW12) kept an equilibrium during the alcohol oxidation by simultaneous monitoring the distribution of species in organic and aqueous phases. The analysis of the W content in the aqueous phase by ICP and the detection of the species transformation in the organic phase by 31P NMR revealed that the most of the PW4 species were transformed to the PW12 species again after the reaction. PW12 and PW4 were in the transform-and-retransform process.
    Journal of Molecular Catalysis A Chemical 06/2008; 289(1):22-27. DOI:10.1016/j.molcata.2008.04.004 · 3.68 Impact Factor
  • Jian Li, Zuwei Xi, Shuang Gao
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    ABSTRACT: In the absence of organic solvent, allyl chloride was epoxidized with aqueous hydrogen peroxide catalyzed by a heteropolyphosphatotungstate catalyst with very good activity and recycling activity. Under optimized conditions, an epichlorohydrin yield of 88.7% was achieved in the first run; after two recycles, the epichlorohydrin yield remained still above 85.0%. Various factors affecting the catalytic reaction were investigated systematically. The reaction rate of hydrogen peroxide in the epoxidation of allyl chloride is zero order with respect to hydrogen peroxide. The activation energy is 52.27 kJ/mol.
    Research on Chemical Intermediates 06/2007; 33(6):523-534. DOI:10.1163/156856707782565840 · 1.54 Impact Factor
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    ABSTRACT: With aqueous hydrogen peroxide as oxidant, secondary alcohols could be efficiently oxidized to ketones in the presence of hexadecyl trimethyl ammonium heteropolyphosphatotungstate ((n-C16H33N(CH3)(3))(3)[PW4O16]) under solvent-free conditions. The oxidation of alcohol over 0.5 mol% (based on molar amount of hydrogen peroxide) catalyst occurred at 90 degrees C to give the corresponding ketones with above 92% yield and 97% selectivity. The catalyst could be reused without loss of selectivity. (c) 2006 Elsevier B.V. All rights reserved.
    Catalysis Communications 03/2007; 8(3):531-534. DOI:10.1016/j.catcom.2006.02.020 · 3.32 Impact Factor
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    ABSTRACT: Allyl chloride was epoxidized to epichlorohydrin with H2O2 under solvent-free conditions in 94% selectivity using a new reversible supported catalyst, heteropolyphosphatotungstate/silanized silica gel. By the action of H2O2 the heteropolyphosphatotungstate dissolves from the carrier surface and forms an active homogeneous reagent. When all H2O2 is consumed, the reduced catalyst redeposits on the support carrier. The supported catalyst retains the character of a homogeneous catalyst during reaction but exhibits heterogeneous properties upon work-up. The solid-supported catalyst is easily isolated and can be reused. The reaction system for synthesis of epichlorohydrin therefore avoids the serious pollution issues known from the commercialized chlorohydrin methods. Some other olefins can also be epoxidized by this catalytic system under neat conditions.
    Organic Process Research & Development 07/2006; 10(5). DOI:10.1021/op060108k · 2.55 Impact Factor
  • Xiaoge Yang, Shuang Gao, Zuwei Xi
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    ABSTRACT: The epoxidation of styrene catalyzed by a reaction-controlled phase transfer catalyst [(C18H37 (30%)+C16H33(70%))N(CH3)3]3[PW4O16] with H2O2 in a biphasic medium was investigated. Under certain conditions, the selectivity for styrene oxide was 95%, the conversion of styrene based on H2O2 was 85%, and the reaction time was less than 1 h. During the reaction, this catalyst powder formed soluble active species by the action of H2O2, was recovered as a precipitate, and was reused after H2O2 was used up. After two times recycling, the catalyst kept almost the same activity.
    Organic Process Research & Development 03/2005; 9(3). DOI:10.1021/op050005m · 2.55 Impact Factor
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    ABSTRACT: A series of heteropolyphosphatotungstate catalysts with different W/P ratio were prepared by different means.31P MAS NMR spectra show every heteropolyphosphatotungstate contains several species with different W/P ratio. Combined with propylene epoxidation results, it is shown that the band at chemical shift ca. δ=5ppm maybe corresponds to a catalyst precursor which can be the most efficiently converted to the structure {PO4[WO(O2)2]4}3−. Characterization results of ICP show, the catalysts with low W/P ratio show a good reactivity for propylene epoxidation.
    Journal of Molecular Catalysis A Chemical 08/2004; 218(2):247-252. DOI:10.1016/j.molcata.2004.04.024 · 3.68 Impact Factor
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    ABSTRACT: The epoxidation of cyclohexene with hydrogen peroxide in a biphase medium (H2O/CHCl3) was carried out with the reaction-controlled phase transfer catalyst composed of quaternary ammonium heteropolyoxotungstates [π-C5H5N(CH2)15CH3]3[PW4O16]. A conversion of about 90% and a selectivity of over 90% were obtained for epoxidation of cyclohexene on the catalyst. The fresh catalyst, the catalyst under reaction conditions and the used catalysts were characterized by FT-IR, Raman and 31P NMR spectroscopy. It appears that the insoluble catalyst could degrade into smaller species, [(PO4){WO(O2)2}4]3−, [(PO4){WO(O2)2}2{WO(O2)2(H2O)}]3−, and [(PO3(OH)){WO(O2)2}2]2− after the reaction with hydrogen peroxide and becomes soluble in the CHCl3 solvent. The active oxygen in the [W2O2(O2)4] structure unit of these soluble species reacts with olefins to form the epoxides and consequently the corresponding WObW (corner-sharing) and WOcW (edge-sharing) bonds are formed. The peroxo group [W2O2(O2)4] can be regenerated when the WObW and WOcW bonds react with hydrogen peroxide again. These soluble species lose active oxygen and then polymerize into larger compounds with the WObW and WOcW bonds and then precipitate from the reaction solution after the hydrogen peroxide is consumed up. Part of the used catalyst seems to form more stable compounds with Keggin structure under the reaction conditions.
    Journal of Molecular Catalysis A Chemical 03/2004; 210(1):197-204. DOI:10.1016/j.molcata.2003.09.018 · 3.68 Impact Factor
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    ABSTRACT: [-C5H5NC16H33]3[PW4O16] was reported to be an excellent epoxidation catalyst which exhibited a unique reaction-controlled phase transfer behavior. In the paper, the composition and structural changes of the reaction-controlled phase transfer catalyst during and after reaction have been investigated by 31P NMR spectroscopy. The 31P MAS NMR confirmed that the original catalyst was a mixture of heteropoly tungstophosphates. When the catalyst reacted with hydrogen peroxide, the species PO4[WO(O2)2]4 3–, [(PO4)WO(O2)2 2WO(O2)2(H2O)]3– and [(PO3(OH))WO(O2)2 2]2– were detected by in situ 31P NMR. It was also found that the P/W ratios and quaternary ammonium cations had great influence on the composition of heteropoly tungstophosphates. Although the catalyst with [(C18H37)2N(CH3)2]+ was not a reaction-controlled phase transfer catalyst, it could be precipitated from the reaction solution when acetone was subsequently added to the solution. The 31P MAS NMR spectra of the recovered catalysts revealed that they had more low P/W ratio heteropoly tungstophosphates than fresh catalysts.
    Catalysis Letters 01/2004; 93(1):41-46. DOI:10.1023/B:CATL.0000016947.14759.e9 · 2.29 Impact Factor
  • Organic Process Research & Development 11/2003; 8(1). DOI:10.1021/op0341014 · 2.55 Impact Factor
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    ABSTRACT: The epoxidation of propylene catalyzed by a reaction-controlled phase transfer catalyst [π-C5H5NC16H33]3[PW4O16] is investigated. The H2O2 is generated by the oxidation of 2-ethylanthrahydroquinone (EAHQ) with molecular oxygen in the organic solvent. Under mild conditions, the selectivity for propylene oxide, based on propylene, is 95%, and the yield, based on 2-ethylanthrahydroquinone, is 85%. During the epoxidation, the catalytic system is homogeneous. However, after the H2O2 is used up, the catalyst can be recovered as a precipitate and can be reused. After the epoxidation reaction, 2-ethylanthraquinone can be regenerated to 2-ethylanthrahydroquinone by catalytic hydrogenation, and no coproduct is produced.
    Applied Catalysis A General 09/2003; 250(2):239-245. DOI:10.1016/S0926-860X(03)00310-7 · 3.67 Impact Factor
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    ABSTRACT: A new epoxidation system is reported in this communication. Heteropolyoxometalates catalyst/recyclable reductant — 2-ethylanthrahydroquinone/O2 is employed for epoxidation of olefins. The reductant can be regenerated by catalytic hydrogenation without consumption.
    Journal of Molecular Catalysis A Chemical 03/2001; 168(1):299-301. DOI:10.1016/S1381-1169(00)00189-8 · 3.68 Impact Factor
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    Yu Sun, Zuwei Xi, Guoying Cao
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    ABSTRACT: In the epoxidation system of [π-C5H5NC16H33]3[PW4O16]/molecular oxygen/recyclable reductant (2-ethylanthrahydroquinone), cyclohexene, terminal olefins and allyl chloride all underwent epoxidation reactions smoothly under mild conditions. Good selectivities to epoxides and high reductant utilization efficiencies (72.6–94.5%) were achieved. From 1-dodecene to 1-hexene, the epoxidation reactivity of the olefin and the utilization efficiency of the reductant increased with the decrease of carbon atoms in terminal olefins. Studies showed that H2O2 produced by the oxidation of 2-ethylanthrahydroquinone with molecular oxygen was the key intermediate that afforded the direct epoxidation of the substrate.
    Journal of Molecular Catalysis A Chemical 02/2001; 166(2). DOI:10.1016/S1381-1169(00)00416-7 · 3.68 Impact Factor
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    ABSTRACT: Catechol reacted with β-methallyl chloride in the presence of base and phase transfer catalyst under microwave irradiation and gave 2-methallyloxyphenol within 1∼2 minutes. The yield of 2-methallyloxyphenol varied from 64%-68%.
    Synthetic Communications 01/2000; 30(7):1337-1342. DOI:10.1080/00397910008087156 · 0.98 Impact Factor
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    ABSTRACT: o-Chlorophenol reacted with ethanol in the presence of sodium hydroxide and phase transfer catalyst under microwave irradiation and gave o-ethoxyphenol conveniently within a few minutes, and the isolated yield of o-ethoxyphenol vary from 69% to 82%.
    Synthetic Communications 09/1996; 26(18):3425-3429. DOI:10.1080/00397919608003747 · 0.98 Impact Factor