Toluene Alkylation with Methanol to p-Xylene over Heteropoly Acids Supported by Clay

The alkylation of toluene with methanol for the selective formation of p-xylene was systematically studied. Very few studies have been reported on the use of superacids such as heteropolyacids on cheap supports, such as clay. This article deals with the use of different heteropoly acids （HPAs）, viz, Dodeca-Tungstophosphoric acid [H3PO4.12WO3.xH2O] （TPA）, Dodeca-Molyhdo phosphoric acid ammonium salt hydrate [H12Mo12N3O40P＋aq] （DMAA）, Dodeca-Molyhdo Phosphoric acid （PMA） on clay （MontmoriUonite, K-10） and as such plain clay. This comparative study reveals that 20%PMA/Clay shows 62% toluene conversion and 100% selectivity toward p-xylene.

Highly efficient synthesis of 2,3-dihydroquinazolin-4(1H)-ones catalyzed by heteropoly acids in water

Heteropoly acids efficiently catalyzed the cyclocondensation reaction of anthranilamide with aldehydes in water at ambient temperature and afforded the corresponding 2,3-dihydro-4（1H）-quinazolinones compounds in good to excellent yields.This method provides mild reaction conditions and clean reaction profiles,using a small quantity of catalyst and a simple workup procedure.

Hydroxylation of Benzene with Hydrogen Peroxide over Highly Efficient Molybdovanadophosphoric Heteropoly Acid Catalysts

Keggin type molybdovanadophosphoric heteropoly acids, H3＋nPMo12-nVnO40（n=1-3）, were prepared by a novel environmentally benign method, and their catalytic performances were evaluated via hydroxylation of benzene to phenol with hydrogen peroxide as oxidant in a mixed solvent of glacial acetic acid and acetonitrile. Various reaction parameters, such as reaction time, reaction temperature, ratio of benzene to hydrogen peroxide, concentration of aqueous hydrogen peroxide, ratio of glacial acetic acid to acetonitrile in solvent and catalyst con- centration, were changed to obtain an optimal reaction conditions. H3＋nPMo12-nVnO40（n=1-3） are revealed to be highly efficient catalyst for hydroxylation of benzene. In case of H5PMo10V2O40, a conversion of benzene of 34.5% with the selectivity of phenol of 100% can be obtained at the optimal reaction conditions.

CATIONIC RING-OPENING POLYMERIZATION OF TETRAHYDROFURAN WITH KEGGIN-TYPE HETEROPOLYCOMPOUNDS AS SOLID ACID CATALYSTS

Three Keggin-type heteropolyanions, namely H3PMo12O40-13H2O, （NH4）3PMo12O40·4H2O and H3PW12O40·13H2O were prepared and tested in the ring-opening polymerization reaction of tetrahydrofuran. The effects of the counter-cation （H＋, NH4＋） and the peripheral atoms （Mo, W） on the polymerization were investigated. It has been found that when the protons of H3PMo12O40·13H2O were replaced by the ammonium cations the polymerization rate decreased dramatically. Whereas, when the peripheral atoms （Mo） were replaced by their homologous （W）, the polymerization rate increased twofold. As for the viscosity average molecular weight （My） of polymer products, it was found that the high molecular weight （7930） was obtained by using H3PW12O40·13H2O. The molecular weight （My） obtained by H3PMo12O40·13H2O and （NH4）H3PMo12O40·13H2O was 6470 and 6810, respectively.

Synthesis of d,l-α-Tocopherol Catalyzed by Heteropoly Acids

,d,l-a-Tocopherol (vitamin E) isfound to be synthesized by condensingtrimethylhydroquinone with isophytol catalyzed by heteropoly acids (HPA) H3:PW12O40 andH3PMo12O40 at room temperature. These HPA are efficient catalysts for the synthesis of d l-a-Tocopherol and can easily be separated from the reaction mixture and roused,

Synthesis, Characterization and Inhibition Effects of Vanadium Substituted Dawson-type Heteropoly Acids(Mo, P)

Four new vanadium substituted Dawson-type heteropoly acids H7[P2Mo17VO62]·39H2O（1）, H8[P2Mo16V2O62]·41H2O（2）, H9[P2Mo15V3O62]·51H2O（3） and H8[P2Mo14V4O62H2]·45H2O（4） were prepared respec-tively. Their structures were determined by IR and ICP. The inhibition effects of vanadium substituted Dawson-type heteropoly acids（Mo, P） on free radical polymerization of methyl methacrylate（MMA） were investigated by dilatometry. The results show that the rate of the polymerization of MMA decreases and the inhibition effects of the four heteropoly acids reach the inhibitor performance of hydroquinone at a certain ratio.

Thermal Behaviour of Some New Polyoxometalate Complexes of Ciprofloxacin with Keggin-type Heteropoly Acids

Four polyoxometalate complexes, (CPFX·HCl)_3H_4SiW_~12 O_~40 , (CPFX·HCl)_3H_3PW_~12 O_~40 , (CPFX·HCl)_3H_3PMo_~12 O_~40 and (CPFX·HCl)_4H_4SiMo_~12 O_~40 , were prepared from ciprofloxacin hydrochloride(CPFX·HCl) reacting with H_nXM_~12 O_~40 ·nH_2O(X=P,Si; M=W,Mo) in an aqueous solution, and characterized by elemental analysis, IR spectrometry and TG-DTA. The IR spectrum confirms the presence of Keggin-type anions of heteropoly acids and the characteristic functional groups of ciprofloxacin. The TG/DTA curves show that their thermal decomposition is a multi-step process including simultaneous collapse of the Keggin-type structure. At first, these compounds had a mass loss of water molecules, then several other mass losses occured due to the decomposition of ciprofloxacin hydrochloride and its fragments with the degradation of Keggin anions. The end product of decomposition is the mixture of WO_3(or MoO_3) and SiO_2(or P_2O_5), identified by X-ray diffraction and IR spectroscopy. The possible thermal decomposition mechanisms of these complexes are proposed. This study exemplified that the thermal stability of the complexes containing tungsten is much better than that of the complexes containing molybdenum.

Preparation and Conductivity of Triheteropoly Tungstozincoaluminic Acid

The ternary undecatungstozincoaluminic heteropoly acid H-7[Al(H2O)ZnW11O39](.)12H(2)O was prepared by the ion exchanging-cooling method. The optimal proportion of solutions of the component elements and the pH of the synthesis reaction were given. The product was characterized by chemical analysis, potentiometric titration, IR, UV, XRD and TG-DTA. AC impedance measurement results show that its proton conductivity is 1.37x10(-4) S/cm at 18 degreesC.

Synthesis and proton conductibility of ternary germanic heteropoly acids

The ternary germanic heteropoly acids H_5GeW_(11)O_(40) centre dot 22H_2O andH_5GeMo_(11)VO_(40) centre dot 24H_2O were synthesized for the first time by the stepwiseacidification and the stepwise addition of solution of the component elements. The products werecharacterized by ICP, IR, UV, XRD and TG-DTA. The proton conductibility and the activation energy ofproton conduction of the heteropoly acids were investigated.

Synthesis and Characterization of Vanadium Substituted Dawson-Type Heteropoly Acid (Mo, As)

Five novel vanadium substituted series of Dawson-type heteropoly acid H7 [As2Mo17VO62 ]·10H2O （1）, H8 [ As2Mo16 V2O62 ]· 7H2O（2）, Ha [ As2MO15 V3O62 ]·8H2O（3）, H8 [ As2Mo14 V4O62 H2 ]·7H2O（ 4 ）, H9[As2Mo13V5O62H2] ·10H2O（5） were prepared respectively in aqueous solution. When magnetic stirring and pH meter monitoring, all reactants mixed and controled different pH, then the mixture was refluxed for 10 h, later extracted by aether when it cooled, finally, it could be recrystaled by 0.5 % sulphuic acid solution, then yielded productions that we need. Compounds （ 1 ） - （5） were characterized by elemental analysis, thermogravimetic analysis （TGA）, infrared spectroscopy （IR）, ultraviolet and visible spectroscopy（UV-Vis）, X-ray powder diffraction analysis, ^51V nuclear magnetic resonance （SIV NMR） structure analysis. The study indicates that these compounds possess Dawson structures, ^51V NMR spectra reveals that V atom is polar-site substituted indeed.

HYDROXYLATION OF BENZENE BY HETEROPOLY ACIDS(SALTS)CONTAINING VANADIUM

Direct hydroxylation of benzene catalyzed by vanadium-con- taining heteropoly compounds with Keggin or Dawson structure has been investigated.The effects of several factors upon the hydroxylation reaction have also been examined.It is indicated that the highest yield of phenol reached 76%(based on H_2O_(?))with 99.4～100% selectivity.

Trimethyl-1,4-Benzoquinone Synthesis via 2,3,6-Trimethylphenol Catalytic Oxidation by Oxygen in the Presence of Non-Keggin-Type Mo-V-Phosphoric Heteropoly Acid Solutions

In the present study, the modified （non-Keggin-type） aqueous solutions of Mo-V-phosphoric heteropoly acids HaPzMoyVx,Oh （HPA-x＇） were applied as homogeneous catalysts for the two-stage oxidation of TMP （2,3,6-trimethylphenol） by oxygen into TMQ （2,3,5-trimethyl-l,4-benzoquinone）, the latter being the key intermediate in the synthesis of vitamin E. The TMQ yield was analyzed regarding solvent type, reaction temperature, molar HPA-x ＇：TMP ratio, and the concentration of vanadium （V） in the HPA-x＇ solution. The TMQ yield was found to depend strongly on the catalyst redox potential and the rate of electron transfer. The results obtained enabled to establish the optimal reaction conditions as well as to suggest the reaction mechanism. In the target reaction, which proceeds in the two-phase system, the TMQ yield is higher than 99%. After phase separation, the catalyst is rapidly regenerated by oxygen and reused.

One-Pot Process of Anthraquinone Synthesis in the Presence of Mo-V-P Heteropoly Acid Solutions as a Bifunctional Catalysts

Acid-catalytic 1,3-butadiene condensation with para-quinones followed by the obtained product oxidation may be performed in one stage as one-pot process, if assisted by the aqueous solutions of Mo-V-P heteropoly acids with a composition of HaPzMoyVxOb. 1,4-naphthoquinone condensation with 1,3-butadiene in the HPA solutions with no organic solvents yields 9,10-anthraquinone (AQ) mixed with tetrahydro-AQ (THA) and dihydro-AQ (DHA). However, AQ yield and its purity may be considerably improved by using water-mixable organic solvents, e.g., acetone, 1,4-dioxane, as well as high vanadium content HPA such as H15P4Mo18V7O89 and H17P3Mo16V10O89. Process optimization provides 70% yield of reaction product containing no less than 90% AQ.

One-Pot Production of Substituted Anthraquinones via the Diene Synthesis in the Presence of Mo-V-P Heteropoly Acid Solutions

Acid-catalytic 1,3-butadiene condensation with para-quinones followed by the obtained product oxidation may be performed in one stage as one-pot process, if assisted by the aqueous solutions of Mo-V-P heteropoly acids with a composition of HaPzMoyVxOb. 1,4-naphthoquinone (NQ) condensation with 1,3-butadiene in HPA solutions (brutto-composition H15P4Mo18V7O89 and H17P3Mo16V10O89) in the presence of hydrophylic organic solvents (acetone, 1,4-dioxane) provides 70% yield of 9,10-anthraquinone (AQ) containing no less than 90% AQ. In the same conditions reaction NQ with substituted 1,3-butadienes in the presence of the aqueous H17P3Mo16V10O89 (HPA-10) solution allows to prepare substituted AQ with yield up to 90% and purity up to 99%. The catalysts are regenerated by oxygen in separate stage and are reused.

SUIDIES ON SOME PROPERTIES AND CATALYSIS OF RARE EARTH HETEROPOLY ACIDS

INTRODUCTIONThough potassium salts of rare earth substituted silicotungsticacids were synthesized early in 1971 by R.D.Peacock etc.,sofar the reports about the application of the corresponding acidshave not been found.We prepared fourteen rare earth substitutedsilicotungstic acids and determined their thermal stability,IRabsorption Spectra and x-ray diffraction spectra.Furthermore,thecatalytic activities of the fourteen heteropoly acids in acid cata-lytic reaction were investigated.Our experimental results demonstrated rare earth substituted silico-tungstic acids have very high catalytic activity in the reaction of

杂多酸催化合成2-甲萘醌的研究

2-甲萘醌可应用于止血剂、饲料添加剂等,用途广泛。本实验以2-甲基萘为原料,30 wt.%过氧化氢水溶液为氧化剂,磷钨杂多酸作为催化剂,冰乙酸为溶剂,合成的2-甲萘醌最高收率为82.3%。考察了催化剂用量、氧化剂用量、反应温度、氧化剂滴加时间和反应时间对产品收率的影响,得到最佳的实验条件;同时对过氧化氢浓度、溶剂用量、重结晶溶剂的种类和用量、搅拌速度等其他影响产品纯度和收率的因素做了说明。红外光谱表征了产品结构。

多酸基UiO-66的合成及其对硫化氢的脱除性能

硫化氢具有较强的毒性和腐蚀性,高效脱除硫化氢对于工业生产、环境治理等过程意义重大。该文基于钼基杂多酸(HPAs),以UiO-66为载体,一步水热合成HPAs@UiO-66,构建不同活性中心多酸基固相脱硫体系,考察杂多酸结构(Keggin、Dawson)、中心原子(P、Si)、取代原子(V、W)对脱硫的影响,并通过BET、FT-IR、XRD、SEM、TEM进行理化性质分析。结果表明,PMo_(12)@UiO-66脱硫活性最高,且其脱硫能力在100℃时最佳,吸附量可达到17.18 mg/g,同时发现水分对其脱硫具有促进作用。与PMo_(12)和UiO-66相比,PMo_(12)@UiO-66表现出明显脱硫优势,其吸附量分别为PMo_(12)和UiO-66的7.5和14.2倍,证明了PMo_(12)与UiO-66具有协同脱硫作用。XPS结果表明,PMo_(12)与H_(2)S之间发生了氧化还原反应,H_(2)S在PMo_(12)氧化作用下被转化成单质硫。研究表明PMo_(12)的引入对UiO-66脱硫性能的强化作用最为显著,可为开发新型多酸基固相脱硫剂提供参考。

Researches into the Proton Conductivity of Molybdovanadophosphoric Acids with Wells－Dawson Structure

Five kinds of molybdovanadophosphoric acids H_7[P_2Mo_(17)VO_(62)],H_8[P_2Mo_(16)·V_2O_(62)],H_9 [P_2Mo_(15)V_3O_(62)],H_8[P_2Mo_(14)V_4O_(61)(H_2O)]and H_9[P_2Mo_(13)V_5O_(61)(H_2O)]have been synthesized.Their protop conductivities(C) have been measured.The effects of three main factors (frequency,hydration numbers,temperature)on the conductivity have been investigated.In some degree,heteropoly compounds with different structures give a different conductivity.

Organophosphonotungstic HPA of Keggin Type with Sulfo,Taurine and Glycine Substituted Ethylphosphonic Acids as the Coordinate Center

The title compounds 2ac were synthesized and characterized for the first time. Their proton numbers are around 3.2±0.15 and are not in proportion with the valid acidity-basicity of the central phosphonic acids. The entirety of phosphonic acids 1a-c is as the coordinate center of heteropoly anions of 2ac.

A new route to the synthesis of thieno[2,3-d]pyrimidin-4(3H)-one derivatives catalyzed by 12-tungstophosphoric acid (H_3PW_(12)O_(40))

Heteropoly acid H3PW12040 （PW） has been used as an effective catalyst for the synthesis of thieno[2,3-d]pyrimidin-4（3H）-one derivatives. The present methodology offers several advantages, such as high yields, short reaction times, mild reaction condition and a recyclable catalyst with a very easy work up.