@article { ISI:000253450900068, title = {Alkene epoxidation catalyzed by vanadomolybdophosphoric acids supported on hydrated titania}, journal = {Catalysis Communications}, volume = {9}, number = {5}, year = {2008}, month = {MAR}, pages = {931-938}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Vanadomolybdophosphoric acids wet-impregnated oil hydrated titania (TiO(2) - xH(2)O), make ail efficient catalytic system for the epoxidation of a variety of alkenes with organic solvent extracted TBHP as the oxidant. By,in appropriate choice of solvent, the catalyst call be reused at least three times without much loss in the activity for subsequent runs. XRD shows that the heteropoly acid is uniformly dispersed over the support and up to 15 wt\% loading of the heteropoly acid, no additional peak of the same call be seen in the XRD pattern of the catalyst. The reactivity varied with the nature of alkene but the major product was always the corresponding epoxide. The catalytic system is free of high temperature calcination steps and tedious multi-step procedures, normally encountered in the heter-ogenization of heteropoly acids. (c) 2007 Elsevier B.V. All rights reserved.

}, keywords = {alkenes, epoxidation, heteropoly acids, TBHP, titania, vanadomolybdophosphoric acids}, issn = {1566-7367}, doi = {10.1016/j.catcom.2007.09.022}, author = {Ingle, Rohit H. and Vinu, A. and Halligudi, Shivaraj B.} } @article { ISI:000326900600016, title = {Highly efficient povidone-phosphotungstic acid catalyst for the tandem acetalization of aldehydes to bis- and tris(indolyl)methanes}, journal = {ChemPlusChem}, volume = {78}, number = {11}, year = {2013}, month = {NOV}, pages = {1393-1399}, publisher = {WILEY-V C H VERLAG GMBH}, address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY}, abstract = {

A novel, nonleachable hybrid of heteropoly acid and polyvinylpyrrolidone (or povidone) catalyzes the acetalization of aldehydes in methanol at room temperature followed by reaction with indole to give bis(indolyl)methanes (BIMs) and tris(indolyl)methanes (TIMs) in quantitative yields (90-97\%). The catalyst was shown by pyridine FTIR spectroscopy to possess BrOnsted acidity, and the hybrid formation was confirmed by XRD and (PNMR)-P-31 studies. Friedel-Crafts alkylation of indole as well as the tandem synthesis of BIMs and TIMs were established with several types of carbonyl and indole substrates to give the corresponding products quantitatively. The catalyst was recycled efficiently for three successive runs without losing its original activity.

}, keywords = {acetals, Acidity, aldehydes, heterogeneous catalysis, heteropoly acids}, issn = {2192-6506}, doi = {10.1002/cplu.201300248}, author = {Kamble, Sumit B. and Swami, Rameshwar K. and Sakate, Sachin S. and Rode, Chandrashekhar V.} } @article { ISI:000345975300012, title = {Titania nanoparticles stabilized HPA in SBA-15 for the intermolecular hydroamination of activated olefins}, journal = {ChemCatChem}, volume = {6}, number = {12}, year = {2014}, month = {DEC}, pages = {3347-3354}, publisher = {WILEY-V C H VERLAG GMBH}, address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY}, abstract = {

A liquid phase hydroamination (HA) of alpha,beta-ethylenic compounds with amines was investigated with TiO2 nanoparticles stabilized 12-tungstophosphoric acid (TPA) in SBA-15. The catalysts were prepared by wet impregnation of TPA/TiO2 nanoparticles into the SBA-15 and calcined at different temperatures. The characterization results reveal that the textural properties and the acidity of the prepared catalysts can be finely controlled with the simple adjustment of the calcination temperature and the structure of the support, decorated with the TiO2 and TPA nanoparticles, was intact even after the modification. The prepared catalysts were investigated for HA of ethyl acrylate with different aromatic and aliphatic amines over a wide range of reaction conditions to optimize the yield and the selectivity of product. It was found that this process is 100\% atom efficient and the catalytic performance depended significantly on the loading of TPA over the catalyst and the calcination temperature. Under optimized reaction conditions, the best catalyst, 15 wt\% TPA/22.4 wt\% TiO2/SBA-15 calcined at 1123 K, offered the highest conversion of p-ethylaniline (70\%) with 100\% chemo-selectivity to the anti-Markovnikov product, i.e., the mono-addition product. The reaction was heterogeneously catalyzed and no contribution from leached TPA into the reaction was observed.

}, keywords = {heteropoly acids, hydroamination, mesoporous materials, nanocatalysts}, issn = {1867-3880}, doi = {10.1002/cctc.201402449}, author = {Sawant-Dhuri, Dhanashri and Balasubramanian, Veerappan V. and Ariga, Katsuhiko and Park, Dae-Hwan and Choy, Jin-Ho and Cha, Wang Soo and Al-deyab, Salem S. and Halligudi, Shivappa B. and Vinu, Ajayan} }