Synthesis of poly(p‐phenylene sulfide) from bis(4‐bromophenyl) disulfide

Improved reaction conditions for the preparation of poly(p‐phenylene sulfide) (PPS) directly from bis(4‐bromophenyl) disulfide (BBD) have been established. Heating BBD with magnesium metal afforded only a low molecular weight polymer. PPS with a melting temperature around 280 °C was obtained from BBD in the presence of sodium carbonate or zinc metal. The best results were obtained with the addition of a catalytic amount of KI to the zinc–BBD mixture. Polymers prepared by the above methods are semicrystalline and dissolve in 1‐chloronaphthalene and have properties comparable to commercial PPS. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 900–904, 2006     

THE AROMATIZATION MECHANISM OF METHANE OVER Mo/HZSM-5 ZEOLITE CATALYSTS WITHOUT USING OXIDANTS

IntroductionMethancisthcmaJorcomponcntofnaturalgasanditscatalyticconvcrsiontodcsiredchemicalproductsorliquidfiJcIisnotonl}'apromisingapproachtotheutilizationofnaturalgasrcsourccbutalsoagrcatsubjcctforcatalysissciencctt'hichdcaIst"iththcactivationofsmallmolcculesThcx"orldrcscrvcofnaturalgashasbccnexplorcdasaboutl382562xl()8m3IllTheMTGprocessdcvclopedbythcMobilcorpcangctliquidfuelfrommethancthroughsteamreformingofmethanctoproduccsynthcsisgaswhichisassociatedt'ithamaJorityofthecostsofthcprocc…     

还原温度对超细K－Co－Mo催化剂合成低碳醇性能的影响

 用溶胶－凝胶法合成了K－Co－Mo催化剂．样品经不同温度还原后，用于低碳醇的合成．XRD和HRTEM结果表明，样品是超细粒子，粒子尺寸为2～5nm．考察了催化剂的还原温度和反应条件对催化剂性能的影响．实验结果表明，还原温度对催化剂的活性有较大的影响，最佳还原温度为500℃．最佳反应温度范围为310～330℃．升高压力和空速可以提高醇的收率和选择性．在空速14400h－1，压力6．0MPa和温度310℃的条件下，醇的选择性为55．8％，收率为520．0g／（kg·h），MeOH／C2＋OH为0．27．催化剂稳定性良好，在200h的寿命实验中，活性基本不变．与文献中催化剂相比，超细K－Co－Mo催化剂对合成醇具有较高的活性和选择性，尤其是对C2＋OH的合成明显高于其他合成醇催化剂体系．     

WS2 超细粉体的固相法合成

WS2 超细粉体的固相法合成;WS2;固相反应;过硫系数;高能球磨;粒度     

Rational synthesis of covalently bonded organic-inorganic hybrids

Hybrid materials based on covalently linked inorganic polyoxometalates (POMs) and organic species containing a delocalized pi system have drawn increasing attention. These hybrids, traditionally prepared by cluster assembly approaches that lack predictability and controllability, can now be synthesized through common organic reactions by using organically functionalized POM clusters as building blocks. This minireview highlights some of the most recent advances on a particular type of hybrids where the organic and inorganic components are connected by an imido linkage.     

Robust core-shell supramolecular assemblies based on cationic vesicles and ring-shaped [Mo154] polyoxomolybdate nanoclusters: template-directed synthesis and characterizations

Substantial progress has been made recently in extending the supramolecular assembly of biomimetic structures to vesicle-based sophisticated nanocomposites and mesostructures. We report herein the successful preparation of unilamellar surfactant vesicles coated with a monolayer of ring-shaped [Mo(154)] polyoxometalate (POM) nanoclusters, (NH(4))(28)[Mo(154)(NO)(14)O(448)H(14)(H(2)O)(70)]. approximately 350 H(2)O, by coulomb attractions using preformed didodecyldimethylammonium bromide (DDAB) surfactant vesicles as templates. The resultant vesicle-templated supramolecular assemblies are robust (they do not disintegrate upon dehydration) both at room-temperature ambient and vacuum conditions, as characterized by conventional transmission electron microscopy (TEM) and atomic force microscopy (AFM). The flexibility of the complex soft assemblies was also revealed by AFM measurements. The effect of POM-vesicle coulomb attractions on the dimensions of the templating vesicles was also investigated by using dynamic light scattering (DLS). Although origins of the structure stability of the as-prepared supramolecular assemblies are not clear yet, the nanometer scale cavities and the related properties of macroions of the POM clusters may play an important role in it.     

Microchannel-assisted thermal-lens spectrometry for microchip analysis

We present a new method for homocysteine quantitation in human plasma based on in-capillary reaction of homocysteine with 2,2′-dipyridyl disulfide. Homocysteine is in this so-called thiol-exchange reaction quantitatively transformed in mixed disulfide concomitantly with formation of an equimolar amount of 2-thiopyridone that is further separated by micellar electrokinetic chromatography and determined specifically at 343 nm. The concentration of homocysteine is thus estimated indirectly from the result of 2-thiopyridone determination. The linear detection range for concentration versus peak area for the assay was from 0.03–3 mM (correlation coefficient 0.994) with a detection limit of 6 μM and a limit of quantitation 20 μM. The inter-day reproducibility of the peak area and the migration time were 1.37% and 0.05%, respectively. The method is simple, relatively rapid and can be easily automated. Moreover the common capillary electrophoresis apparatus with a UV detector can be used to distinguish between normal and pathological hyperhomocysteinemia plasma samples.     

罗丹明B-Mo(V)-SCN~--PVA体系荧光熄灭法测痕量钼

在聚乙烯醇存在下,用罗丹明B-Mo(V)-SCN~-荧光熄灭法测Mo,能消除过量的SCN-对罗丹明B的熄灭作用。加入聚乙烯醇后体系的荧光熄灭倍数比未加入时大14倍。此法灵敏度高、稳定性好、操作简便,检测下限0.12ng/ml Mo.可用于测水和头发中的钼。