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HERAVI Majid M. SADJADI Sodeh HEKMATSHOAR Rahim OSKOOIE Hossein A. BAMOHARRAM Fatemeh F. 《中国化学》2009,27(3):607-609
A mild, simple and high yielding procedure for the direct conversion of oximes to nitriles has been developed using heteropolyacid in acetic acid. Aromatic and aliphatic aldoximes were converted to the corresponding nitriles in the presence of Preyssler type heteropolyacid, which could be reused several times without any appreciable loss of activity. 相似文献
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Sweeney MA Smith TW Croucher M Langner A Miri M Klymachyov A Kaplan S Tshudy D 《Journal of colloid and interface science》2002,253(1):53-61
Stable, colloidal sols of submicron size were prepared by titration of aqueous solutions of alkylene oxide surfactants with phosphotungstic acid, H(3)PW(12)O(40) (PTA), followed by neutralization with ammonium or potassium hydroxide. The stoichiometry of the complex between phosphotungstic acid and the ethoxylated surfactant was determined by (1)H and (31)P NMR and was dependent upon the degree of ethoxylation. For example, in the ethoxylated octylphenol having 9-10 ethylene oxide units, Triton X-100, the mole ratio of surfactant to PTA was 4.5. In the ethoxylated octylphenol having 70 ethylene oxide units, Triton X-705, the mole ratio of surfactant to PTA was 1. Prior to nucleation of particles, phosphotungstic acid forms an apparent yellow charge transfer complex with ethoxylated alkylphenol surfactants, typified by Triton X-405. This complex is characterized by an absorption spectrum that is the sum of the spectra of Triton X-405 and PTA with a very weak shoulder at 400-500 nm. Particles were nearly monodisperse and their size was dependent on the nonionic surfactant employed, the heteropolyacid, and the rate of addition of heteropolyacid solution. 相似文献
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Physicochemical properties and compositions of KxH(3-x)PW12O40 salts, where 2 < or = x < or = 3, have been investigated. It has been found that freshly prepared K2HPW12O40 salt (drying at 313 K) contains particles of heteropolyacid and particles of the neutral potassium salt, the sample being in 78.6% amorphous. On aging at room temperature, the heteropolyacid spreads to form a surface layer covering the neutral potassium salt particles K3PW12O40. Heat treatment of KxH(3-x)PW12O40 salts, where 2 < or = x < 3, from 313 K to higher temperatures induces the transformation of the heteropolyacid-covering K(3) core into a well-dispersed, amorphous surface layer. On further heating of the acidic potassium salts, the surface layer decomposes between 855 and 915 K with the formation of a PW8O26-type bronze as a new phase, the K3PW12O40 salt remaining unchanged. The latter starts to decompose at 1093 K, and in the case of all samples, the process is completed at about 1183 K. Rietveld structure refinement, XPS, and 31P NMR measurements of acidic potassium salts indicate that the core of these salts is always formed by the K3PW12O40 salt, which is covered by a heteropolyacid. Comparison of lattice parameters of the K3 salt and HPW leads to the conclusion that the layer is composed of partially or completely dehydrated heteropolyacid molecules. The coverage of the core by HPW in the K2 sample was estimated to be equal to one monolayer. 相似文献
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以三聚氰胺和磷酸为原料,以去离子水为溶剂,在杂多酸A催化下,制得改性三聚氰胺磷酸盐(MP);将MP在箱式气氛炉中进行多温度段热缩合反应合成了三聚氰胺聚磷酸盐(MPP),其结构经~(31)P NMR,IR和元素分析表征。通过TG对MPP的热稳定性和成炭性能进行了分析。结果表明:MPP失重1%时温度为372.1℃,失重5%时温度为382.7℃,700℃时残炭率为37.36%。 相似文献
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Fatemeh F.BAMOHARRAM Majid M.HERAVI Javad EBRAHIMI Ali AHMADPOUR Mojtaba ZEBARJAD 《催化学报》2011,32(5):782-788
An efficient and environmentally benign procedure for the catalytic esterification of salicylic acid with aliphatic alcohols, CnH2n+1OH(n=1-5)and benzylic alcohols,RC6H4CH2OH(R=H,NO2,OCH3,Br,Cl,Me)was developed using nano-SiO2-supported Preyssler heteropolyacid both under thermal conditions and microwave irradiation.Silica nanostructures were obtained through a sol-gel method and were characterized by transmission electron microscopy and powder X-ray diffraction.The effects of various parameters such as solvent type,molar ratio of substrates,Preyssler heteropolyacid loading on silica,catalyst amount,temperature,and reaction time were studied and the optimum conditions were obtained.It has been found that the catalyst with 30 wt%loading is highly active and shows high yields in esterification reactions.The use of nano-SiO2-supported Preyssler heteropolyacid coupled with microwave irradiation allows a solvent-free,rapid(3 min),and high-yielding reaction.This catalyst can be easily recovered and reused for many times without a significant loss in its activity. 相似文献
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三取代过渡金属钨镓杂多配合物的磁性及导电性能研究 总被引:16,自引:0,他引:16
合成了过渡金属三取代的钨镓杂多配合物:α-Na~nH~m[GaW~9O~3~7M~3(H~2O)~3]·xH~2O[M=Fe(Ⅲ), Cu(Ⅱ), Co(Ⅱ)]。通过元素分析、红外、紫外、^1^8^3W NMR以及热分析等手段进行了表征, 变温磁化率数据显示了配合物具有反铁磁特征。电导率测定结果表明所合成的配合物是迄今未见文献报道的过渡金属三取代杂多配合物高质子导体, 室温下GaW~9Fe~3的σ值可达10^-^3S·cm^-^1, 其特点是热稳定范围宽, 不易失水, 可望成为能实用化的杂多酸型固体电解质。 相似文献
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Mechanism and kinetics of gas phase synthesis of ethyl-tert-butyl ether (ETBE) over Wells–Dawson heteropolyacid H6P2W18O62 in an anhydrous system have been discussed. The rates of ETBE synthesis were measured in a differential reactor for ethanol–isobutene system, far from the limitation by chemical equilibrium. In the pressure range studied, kinetic measurements show that isobutene has an enhancing effect on the reaction while ethanol has an inhibitory one.
Catalytic and sorption experiments allowed to formulate the mechanism of ETBE synthesis which assumed isobutene adsorption and oligomerization at the surface of heteropolyacid crystallites and the formation of carbocation using protons supplied from the bulk of catalyst. Kinetic equations were deduced indicating that it is the concentration of protons forming inter-anionic bonds between heteropolyacid anions which determines the catalytic activity of heteropolyacid. 相似文献
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Majid M. Heravi Samaheh Sadjadi Hossein A. Oskooie Rahim Hekmatshoar Fatemeh F. Bamoharram 《中国化学会会志》2008,55(4):842-845
3H‐1,5‐benzodiazepines were synthesized by the condensation of o‐phenylendiamine and various 1,3‐diketones in the presence of various heteropolyacid (HPA) catalysts under mild conditions in very good yields and with high selectivity. 相似文献
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Ai Ren Tan Luisa Magno de Carvalho Ailton de Souza Gomes 《Macromolecular Symposia》2005,229(1):168-178
Summary: Composite polymer membranes based on sulfonated poly(arylene ether sulfone) (SPSU) containing benzimidazole derivatives (BIzD) and heteropolyacid for use in fuel cells were prepared. The effects of both the increment in BBIzD component and the procedure of mixing on the morphology and proton conductivity were investigated. The heteropolyacid (HPA) extracted in water decreased with the addition of BBIzD in the composite. The interactions developed among the sulfonate groups, the benzimidazole derivatives and the HPA were verified by Fourier transform infrared (FTIR). The network of interactions established in the composite membrane based on SPSU containing benzimidazole derivatives and phosphotungstic acid (HPW) in the ratio of SPSU/BBIzC4(8:1) in equivalents and SPSU/HPW(7:3) in mass resulted in a very high proton conductivity at 110 °C. 相似文献
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以1-丁基苯并咪唑为起始原料,合成了1-丁基-3-(4-磺酸基丁基)苯并咪唑內盐(1),1-丁基-3-羧甲基苯并咪唑氯盐(2)和1,3-二丁基苯并咪唑溴盐(3);1~3分别与硅钨酸、磷钨酸和磷钼酸在水或者乙醇中反应,合成了5种新型的杂多酸盐离子液体——1-丁基-3-(4-磺酸基丁基)苯并咪唑硅钨酸盐(4a),1-丁基-3-(4-磺酸基丁基)苯并咪唑磷钨酸盐(4b),1-丁基-3-(4-磺酸基丁基)苯并咪唑磷钼酸盐(4c),1-丁基-3-羧甲基苯并咪唑硅钨酸盐(5)和1,3-二丁基苯并咪唑硅钨酸盐(6),其结构经1H NMR,13C NMR和IR表征。并考察了4~6在30%H_2O_2催化氧化环己烯制备己二酸反应中的催化效果。实验结果表明:4b的催化效果最好。在最佳反应条件[环己烯20 mmol,4b 0.16 mmol,n(环己烯)∶n(H2O2)∶n(ILs)=1∶4.4∶0.008]下,己二酸产率71%。 相似文献
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硅钨杂多酸与牛血红蛋白相互作用的研究 总被引:4,自引:0,他引:4
多金属氧酸盐作为抗艾滋病病毒、抗流感病毒和抗肿瘤的药物,引起了人们对多金属氧酸与蛋白质之间相互作用的极大关注。蛋白质空间结构的任何变化引起的构象变化都意味着蛋白质分子的活性改变,因此,蛋白质与内源性化合物及许多药物分子之间相互作用的研究一直受到人们关注[1 ̄3]。血红蛋白是动物及人体内执行输氧任务的蛋白质,是生命机体进行各种生理活动的主要承担者。血红蛋白分子中每条α链和β链含有的色氨酸(Trp)残基分别为α-14Trp、β-15Trp、β-37Trp。Alpert[4]等认为位于疏水腔内的β-37Trp是血红蛋白内源荧光的主要来源,同时β… 相似文献
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磷钨杂多酸及其铯盐上的常温正戊烷异构化反应 总被引:2,自引:0,他引:2
制备了一系列用于正戊烷异构化的磷钨杂多酸及其铯盐催化剂,并对它们进行了详细的物性表征。实验结果表明, Cs含量对催化剂的比表面、孔结构、热稳定性和表面酸量有显著的影响。考察了所制备的催化剂上常温下正戊烷异构化反应的活性和选择性。利用催化剂表征结果讨论了活化温度和Cs含量等因素对催化性能的影响。磷钨杂多酸及其铯酸式盐属固体超强酸。根据35℃时正戊烷异构化反应速率常数估测H~3PW~1~2O~4~0和Cs~2~.~2~5H~0~.~7~5PW~1~2O~4~0的酸强度H~0约在-13~-12.4之间。 相似文献
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用自然沉降法组装成规则排列的聚苯乙烯胶晶,并以此作为模板剂,用Keggin结构的杂多酸SiW12和正硅酸乙酯组成溶胶作为先驱物,成功制备了三维有序大孔(3DOM)SiW12/SiO2杂化材料. XRD和IR等测试结果表明,所得样品中的杂多酸SiW12能够保持其Keggin结构,SEM观察显示,样品具有三维大孔规则排列的结构. 研究发现,溶胶组成对杂化材料的3DOM结构影响很大,纯SiW12难以形成3DOM结构,随着SiO2含量的增加,样品的孔结构三维规整性和强度明显增强,而且引入SiO2可有效提高杂多酸的热稳定性. 相似文献
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L.F. Chen J.A. Wang J. Aguilar P. Salas P. Del Ángel 《Journal of solid state chemistry》2007,180(10):2958-2972
For the first time, modifications of the surface and framework of Si-MCM-41 by depositing a heteropolyacid on the surface and by introducing foreign Zr4+ ions into the framework are investigated. The Zr-modified Si-MCM-41 mesoporous materials (hereafter referred as WSZn, n=Si/Zr=25, 15, 8, 4) were synthesized through a surfactant-templated preparation approach, using low-cost fumed silica as the Si precursor. After impregnation with 25 wt% of H3PW12O40, the surface Brönsted acidity of the Pt/H3PW12O40/WSZn catalysts was greatly enhanced by 2-10 times relative to the bare WSZn support. Two kinds of supported heteropolyacids were formed: (i) bulk-like heteropolyacid crystals with unchanged Keggin structures, and (ii) highly dispersed heteropolyacid with distorted Keggin units. The formation of various kinds of heteropolyacid structures is closely related to the interaction between the heteropolyanions and the hydroxyl groups in the host support. 相似文献