@article { ISI:000256178900015, title = {Selective cis-dihydroxylation of olefins using recyclable homogeneous molybdenum acetylide catalyst}, journal = {Journal of Molecular Catalysis A-Chemical}, volume = {285}, number = {1-2}, year = {2008}, month = {APR}, pages = {111-119}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Selective cis-dihydroxylation of various olefins has been carried out using molybdenum acetylide complex CpMO(CO)(3)(C CPh) (1) as catalyst and hydrogen peroxide as an efficient and environmentally benign oxidant. In case of cyclohexene, very high conversion (95\%) and selectivity (86\%) for cis-dihydroxylated product has been achieved using H2O2 as an oxidant and t-butanol as a solvent. cis-Dihydroxylation of other substrates like styrene, a-methyl styrene, limonene and cyclopentene has also been carried out with very high selectivity for diol. The catalyst and intermediate species have been characterized using FT-IR, UV-vis spectral analysis and XPS studies as well as cyclic voltametric studies. These studies suggest that molybdenum oxo-peroxo complex is the catalytically active species. The intermediate blue complex when characterized by ESI MS suggested the formation of dimeric molybdenum complex and XPS and cyclic voltametric studies confirm the presence of mixed valence Mo(V) and Mo(VI) in the reaction intermediate. Based on the characterization results possible mechanism for dihydroxylation is proposed. Interestingly, even though the catalyst is homogeneous; it could be recovered quantitatively by extraction in aqueous phase and recycled five times without any appreciable loss in cyclohexene conversion and selectivity for cis-1,2-cyclohexanediol. (c) 2008 Elsevier B.V. All rights reserved.

}, keywords = {acetylide complex, cis-dihydroxylation, Homogeneous catalysis, Hydrogen peroxide, recyclable}, issn = {1381-1169}, doi = {10.1016/j.molcata.2008.01.034}, author = {Biradar, Ankush V. and Sathe, Bhaskar R. and Shubhangi B. Umbarkar and Dongare, Mohan K.} } @article { ISI:000256043100018, title = {Selective N-oxidation of aromatic amines to nitroso derivatives using a molybdenum acetylide oxo-peroxo complex as catalyst}, journal = {Tetrahedron Letters}, volume = {49}, number = {22}, year = {2008}, month = {MAY}, pages = {3616-3619}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

The molybdenum acetylide oxo-peroxo complex obtained in situ by the treatment of the corresponding molybdenum acetylide carbonyl complex, CpMo(CO)(3)(C CPh); Cp = eta(5-)C(5)H(5) with H(2)O(2), has been used as an efficient catalyst for selective N-oxidation of primary amines to nitroso derivatives. Excellent amine conversion (up to 100\%) and very high selectivity for nitroso compounds (99\%) have been obtained using 30\% hydrogen peroxide as an oxidant. The oxo peroxo, Mo(VI) complex has also been found to be very active for the oxidation of various substituted primary aromatic amines with electron donating as well as electron withdrawing substituents on the aromatic ring. (C) 2008 Elsevier Ltd. All rights reserved.

}, keywords = {aromatic amine, Homogenous catalyst, Hydrogen peroxide, Molybdenum complex, nitroso, Oxidation, Oxo-peroxo}, issn = {0040-4039}, doi = {10.1016/j.tetlet.2008.04.005}, author = {Biradar, Ankush V. and Kotbagi, Trupti V. and Dongare, Mohan K. and Shubhangi B. Umbarkar} } @article { ISI:000266188300010, title = {Selective oxidation of aromatic primary alcohols to aldehydes using molybdenum acetylide oxo-peroxo complex as catalyst}, journal = {Tetrahedron Letters}, volume = {50}, number = {24}, year = {2009}, month = {JUN}, pages = {2885-2888}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

Selective oxidation of various aromatic alcohols to aldehydes has been carried out with very high conversion (90\%) and selectivity (90\%) for aldehydes using cyclopentadienyl molybdenum acetylide complex, CpMo(CO)(3)(C CPh) (1) as catalyst and hydrogen peroxide as environmentally benign oxidant, Water-soluble Mo acetylide oxo-peroxo species is formed in situ after reaction of I with aqueous hydrogen peroxide during the Course of reaction as catalytically active species. Interestingly even though the catalyst is homogeneous it Could be recycled very easily by separating the products in organic phase and catalyst in aqueous phase using separating funnel. Even after five recycles no appreciable loss in alcohol conversion and aldehyde selectivity was observed. (C) 2009 Elsevier Ltd. All rights reserved.

}, keywords = {Homogenous catalyst, Hydrogen peroxide, Molybdenum complex, Oxidation, Oxo-peroxo, Primary aromatic alcohol}, issn = {0040-4039}, doi = {10.1016/j.tetlet.2009.03.178}, author = {Biradar, Ankush V. and Dongare, Mohan K. and Shubhangi B. Umbarkar} } @article { ISI:000267381100014, title = {Synthesis of catalytically active porous platinum nanoparticles by transmetallation reaction and proposition of the mechanism}, journal = {Small}, volume = {5}, number = {12}, year = {2009}, month = {JUN}, pages = {1467-1473}, publisher = {WILEY-V C H VERLAG GMBH}, address = {PO BOX 10 11 61, D-69451 WEINHEIM, GERMANY}, abstract = {

A facile method for the synthesis of porous platinum nanoparticles by transmetallation reactions between sacrificial nickel nanoparticles and chloroplatinic acid (H(2)PtCl(6)) in solution, as well as at the constrained environment of the air water interface, using a Langmuir-Blodgett instrumental setup is presented. To carry out the transmetallation at the air-water interface hydrophobized nickel nanoparticles are assembled as a monolayer on the sub phase containing platinum ions. The porous Pt nanoparticles obtained as a result of the reaction are found to act as extremely good catalysts for hydrogenation reaction. The products are well characterized by TEM, HRTEM, EDAX, and STEM. Attempts are made to postulate the plausible mechanism of this reaction to generate this kind of nanoparticle with controllable geometric shape and structure. This simple strategy has the potential to synthesize other nanomaterials of interest too.

}, keywords = {Catalysts, Interfaces, Nickel nanoparticles, porous platinum, Transmetallation}, issn = {1613-6810}, doi = {10.1002/smll.200801863}, author = {Pasricha, Renu and Bala, Tanushree and Biradar, Ankush V. and Shubhangi B. Umbarkar and Sastry, Murali} } @article { ISI:000310744400011, title = {Selective oxidation of nonrefractory and refractory sulfides by cyclopentadienyl molybdenum acetylide complexes as efficient catalysts}, journal = {Catalysis Letters}, volume = {142}, number = {11}, year = {2012}, month = {NOV}, pages = {1352-1360}, publisher = {SPRINGER}, address = {233 SPRING ST, NEW YORK, NY 10013 USA}, abstract = {

{The synthesis and catalytic properties of molybdenum acetylide complexes CpMo(CO)(3)(-C CR)

}, keywords = {Homogeneous catalysis, Molybdenum acetylide, Oxo-peroxo species, Refractory sulfide oxidation}, issn = {1011-372X}, doi = {10.1007/s10562-012-0898-x}, author = {Chandgude, Macchindra G. and Biradar, Ankush V. and Kotbagi, Trupti V. and Puranik, Vedavati G. and Dongare, Mohan K. and Shubhangi B. Umbarkar} } @article { ISI:000350221600066, title = {Silica microspheres containing high density surface hydroxyl groups as efficient epoxidation catalysts}, journal = {RSC Advances}, volume = {5}, number = {27}, year = {2015}, month = {FEB}, pages = {21125-21131}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Uniformly sized silica microspheres were synthesized by a hydrolysis-condensation method. The obtained material was etched with a mild aqueous potassium hydroxide solution for different periods of time to break their Si-O-Si bonds and increases the density of hydroxyl groups on their surfaces. The resulting materials were then used as transition metal-free catalysts for oxidation of olefins in the presence of hydrogen peroxide as a green oxidant. The materials were thoroughly characterized using various physicochemical techniques. These highly populated hydroxyl groups on the surface of silica microspheres were proven to be responsible for excellent conversion (up to 93\%) and epoxide selectivity (up to 100\%) for various olefins. Quantum mechanical calculations also corroborate the experimental findings. Furthermore, both experimental and theoretical studies show that tertiary silanols were present at the active sites of the catalyst surface and were responsible for olefin epoxidation.

}, issn = {2046-2069}, doi = {10.1039/c5ra00374a}, author = {Chandra, Prakash and Doke, Dhananjay S. and Shubhangi B. Umbarkar and Vanka, Kumar and Biradar, Ankush V.} }