01967nas a2200229   4500008004100000022001400041245010400055210006900159260007300228300001000301490000800311520116300319653001401482653001101496653001501507653001401522653001301536100001601549700002601565700001801591856012801609       2005                        eng d  a1381-116900aInfluence of silica source in the catalytic activity and heterogenity of mesoporous vanadosilicates0 aInfluence of silica source in the catalytic activity and heterog  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcSEP  a57-630 v2393 a<p>Vanadium-substituted ordered mesoporous silicates (V-OMS) were synthesized hydrothermally using two common silica sources, viz. fumed silica and tetraethyl orthosilicate, and their surface properties and catalytic activities were evaluated in the liquid phase oxidation of 1-napthol using aqueous H2O2 as an oxidant. The catalysts were characterized by XRD, N-2, adsorption-desorption, DRUV-vis and TPR to evaluate the mesostructural ordering and the local environment of vanadium in the MCM-41 matrix. Characterization data of the fresh calcined catalysts reveal a more ordered hexagonal structure for the V-MCM-41 catalyst prepared by using tetraethyl orthosilicate as the silica source while spent catalyst showed that the material is less stable than the V-MCM-41 catalyst prepared by using fumed silica as the silica source. Further, the observed differences in the selectivity behavior of extracted and calcined forms of both vanadium catalysts shows that the treatment conditions had a decisive role in the formation of extra framework metal species and further in the mesoscopic structural ordering. (c) 2005 Elsevier B.V. All rights reserved.</p>10a1-napthol10aMCM-4110aMesoporous10aOxidation10aVanadium1 aShylesh, S.1 aMirajkar, Subhash, P.1 aSingh, A., P.  uhttps://library.ncl.res.in/content/influence-silica-source-catalytic-activity-and-heterogenity-mesoporous-vanadosilicates-002343nas a2200277   4500008004100000022001400041245015600055210006900211260000900280300001400289490000700303520134000310653005801650653002101708653002801729653002601757653001701783100001701800700002001817700001901837700001801856700001801874700003101892700002001923856012201943       2025                        eng d  a1060-132500aAn improved one-pot synthesis of polydichlorophosphazene from ammonium sulfate and phosphorus pentachloride and assessment of its stability in solution0 aimproved onepot synthesis of polydichlorophosphazene from ammoni  cNOV   a1016-10260 v623 a<p>
	Polyphosphazenes, with their synthetic flexibilities, can be tailored to achieve various desirable properties. The synthesis of basic linear polymer polydichlorophosphazene (PDCP) free of branching and crosslinking is the most challenging step, and its extreme sensitivity to moisture makes storage and handling difficult. In the reaction of (NH4)2SO4and PCl5 (1:4.5 mole ratio) via one-pot two-step method, the monomer [Cl3PNP(O)Cl2] synthesized from the 1st step directly undergoes bulk polycondensation (2nd step) to produce PDCP. Due to impurities, the produced PDCP is afflicted by frequent branching, cyclic oligomers, and crosslinking. We are reporting an improved one-pot synthesis coupled with an in-situ purification step of the monomer (as confirmed by 31P NMR) with little excess PCl5 in mole ratio (1:4.6-1:4.8). Further, the stability of PDCP and its solutions in toluene and THF have been examined under an inert atmosphere at three different temperatures: room temperature, 0 degrees C-4 degrees C, and -25 degrees C. These stored samples were monitored for cross-linking, gelling, or any other degradation by characterizing through 31P NMR for the appearance of additional peaks. The PDCP can be stored at -25 degrees C for 2 months (pure) and 4 months (toluene) without any deterioration in its structure.</p>
10aP-trichloro-N-(dichloromonophosphoryl)monophosphazene10aPolycondensation10aPolydichlorophosphazene10astability in solution10astorage life1 aYadav, Abhay1 aYadav, Prashant1 aNewale, S., P.1 aSrivastav, V.1 aSingh, A., P.1 aShanmuganathan, Kadhiravan1 aSikder, Nirmala  uhttps://library.ncl.res.in/content/improved-one-pot-synthesis-polydichlorophosphazene-ammonium-sulfate-and-phosphorus