@article { ISI:000260095800003, title = {Synthesis of substituted styrenes and stilbenes mediated by palladium on zirconia}, journal = {Journal of Chemical Research-S}, number = {9}, year = {2008}, month = {SEP}, pages = {495-499}, publisher = {SCIENCE REVIEWS LTD}, type = {Article}, address = {PO BOX 314, ST ALBANS AL1 4ZG, HERTS, ENGLAND}, abstract = {

Palladium on zirconia has been found to be an effective catalyst for the synthesis of various substituted styrenes and stilbenes, including biologically active natural products, by reaction of aryl halides with olefins.

}, keywords = {heterogeneous catalyst, palladium on zirconia, stilbenes, styrenes}, issn = {0308-2342}, doi = {10.3184/030823408X340807}, author = {Borate, Hanumant B. and Dumbre, Deepa K. and Wakharkar, Radhika D. and Choudhary, Vasant R.} } @article { ISI:000269259100007, title = {Supported nano-gold catalysts for epoxidation of styrene and oxidation of benzyl alcohol to benzaldehyde}, journal = {Topics in Catalysis}, volume = {52}, number = {12}, year = {2009}, month = {NOV}, pages = {1677-1687}, publisher = {SPRINGER/PLENUM PUBLISHERS}, address = {233 SPRING ST, NEW YORK, NY 10013 USA}, abstract = {

Nano-gold particles supported on different alkaline earth oxides (viz. MgO, CaO, BaO and SrO), Gr. IIIa metal oxides (viz. Al(2)O(3), Ga(2)O(3), In(2)O(3) and Tl(2)O(3)), transition metal oxides (viz. TiO(2), Cr(2)O(3), MnO(2), Fe(2)O(3), CoO(x), NiO, CuO, ZnO, Y(2)O(3) and ZrO(2)), rare earth metal oxides (viz. La(2)O(3), Ce(2)O(3), Nd(2)O(3), Sm(2)O(3), Eu(2)O(3), Tb(2)O(3), Er(2)O(3) and Yb(2)O(3)) and U(3)O(8) [all prepared by depositing gold on corresponding metal oxide support by deposition precipitation (DP) and/or homogeneous deposition precipitation (HDP) method] were evaluated for their catalytic performance in the liquid phase epoxidation of styrene by tert-butyl hydroperoxide (TBHP) to styrene oxide and also in the solvent-free benzyl alcohol-to-benzaldehyde oxidation (by molecular oxygen or TBHP) reactions. For the epoxidation, the catalytic performance (styrene oxide yield) of the most promising nano-gold catalysts prepared by the HDP method was in the following order: Au/MgO \> Au/Tl(2)O(3) \> Au/Yb(2)O(3) \> Au/Tb(2)O(3) \> Au/CaO (or TiO(2)). However, for the oxidation of benzyl alcohol to benzaldehyde by molecular oxygen, the order of choice for the most promising catalysts (based on benzaldehyde yield) was Au/U(3)O(8) \> Au/Al(2)O(3) \> Au/ZrO(2) \> Au/MgO. Whereas, when TBHP was used as an oxidizing agent for the benzyl alcohol oxidation, the order of choice for the most promising catalysts was Au/U(3)O(8) \> Au/MgO \> Au/TiO(2) \> Au/ZrO(2) \> Au/Al(2)O(3). The catalytic performance of a particular supported nano-gold catalyst was thus found to depend on the reaction catalysed by them. Moreover, it is strongly influenced by a number of catalyst parameters, such as the metal oxide support, the method of gold depositon on the support, the gold loading and also on the catalyst calcination temperature. Nano-gold particles-support interactions seem to play an important role in controlling the deposition of gold ( amount of gold deposited and size and morphology of gold particles), formation of different surface gold species (Au(0), Au(1+) and Au(3+)) and electronic properties of gold particles and, consequently, control the catalytic performance (both the activity and selectivity) of the supported nano-gold catalysts in the reactions. The nano-gold catalysts prepared by the HDP method showed much better catalytic performance than those prepared by the DP, coprecipitation or impregnation method; in general, the HDP method provided supported gold catalysts with much higher gold loading and/or smaller size gold particles than that achieved by the DP and other methods.

}, keywords = {Benzaldehyde, Benzyl alcohol, epoxidation, Metal oxide supports, Nano-gold catalysts, Oxidation, styrene, Styrene oxide}, issn = {1022-5528}, doi = {10.1007/s11244-009-9306-1}, author = {Choudhary, Vasant R. and Dumbre, Deepa K.} } @article { ISI:000275580600010, title = {Solvent-free selective oxidation of benzyl alcohol to benzaldehyde by tert-butyl hydroperoxide over U3O8-supported nano-gold catalysts}, journal = {Applied Catalysis A-General}, volume = {375}, number = {2}, year = {2010}, month = {MAR}, pages = {252-257}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Liquid-phase oxidation of benzyl alcohol to benzaldehyde by tertiary butyl hydroperoxide over different uranium oxide supported nano-gold catalysts in the absence of a solvent has been thoroughly investigated. The influences of catalyst parameters [viz, method of gold deposition (impregnation, co-precipitation, deposition-precipitation and homogeneous deposition-precipitation), gold loading (08 wt\%) and catalyst calcination temperature (100-900 degrees C)] on the catalyst performance have been investigated. The influence of reaction conditions [viz, reaction time (0-2 h) and temperature (25-94 degrees C)] on the process performance has also been studied. The Au/U3O8 catalyst prepared by the homogeneous deposition-precipitation and calcined at 400 degrees C showed very high activity (100\% benzyl alcohol conversion with \>85\% selectivity for benzaldehyde) in the process for a short reaction period (0.5 h) at 94 degrees C. The catalyst also showed excellent reusability in the process. (C) 2010 Elsevier B.V. All rights reserved.

}, keywords = {Au/U3O8 catalyst, Benzaldehyde, Benzyl alcohol, Nano-gold, Partial oxidation, tert-Butyl hydroperoxide}, issn = {0926-860X}, doi = {10.1016/j.apcata.2010.01.007}, author = {Choudhary, Vasant R. and Dumbre, Deepa K.} } @article { ISI:000295757900019, title = {Solvent-free selective oxidation of primary alcohols-to-aldehydes and aldehydes-to-carboxylic acids by molecular oxygen over MgO-supported nano-gold catalyst}, journal = {Catalysis Communications}, volume = {13}, number = {1}, year = {2011}, month = {OCT}, pages = {82-86}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Magnesium oxide supported nano-gold catalyst (prepared by the homogeneous deposition precipitation technique) showed high activity/selectivity and excellent reusability in the oxidation of different primary alcohols and aldehydes to corresponding aldehydes and carboxylic acids, respectively, by molecular oxygen (under atmospheric pressure) in the absence of any solvent. Influence of the catalyst calcination temperature (400-900 degrees C), reaction temperature (50-120 degrees C) and use of different solvents (viz. toluene. p-xylene, DMF or DMSO) on the oxidation reaction has also been studied. (C) 2011 Published by Elsevier B.V.

}, keywords = {Alcohols, aldehydes, Au/MgO, Molecular oxygen, Solvent-free oxidation}, issn = {1566-7367}, doi = {10.1016/j.catcom.2011.07.001}, author = {Choudhary, Vasant R. and Dumbre, Deepa K.} } @article { ISI:000302535600002, title = {Solvent-free one-pot synthesis of sulfonephthaleins from saccharin and phenols}, journal = {Synthetic Communications}, volume = {42}, number = {8}, year = {2012}, month = {OCT}, pages = {1101-1107}, publisher = {TAYLOR \& FRANCIS INC}, address = {325 CHESTNUT ST, SUITE 800, PHILADELPHIA, PA 19106 USA}, abstract = {

Sulfonephthaleins can be synthesized in a single pot from saccharin and phenol via the in situ formation of 2-sulfobenzoic anhydride, followed by its reaction with phenol using H2SO4 as the condensing agent, in the absence of any solvent. This solvent-free synthesis is more economical and environmentally benign.

}, keywords = {H2SO4, Phenols, saccharin, sulfonephthalein}, issn = {0039-7911}, doi = {10.1080/00397911.2010.535946}, author = {Tillu, V. H. and Dumbre, Deepa K. and Borate, Hanumant B. and Wakharkar, R. D. and Choudhary, Vasant R.} } @article { ISI:000308345800010, title = {Solvent-free oxidation of aldehydes to acids by TBHP using environmental-friendly -exchanged Mg-Al hydrotalcite catalyst}, journal = {Journal of Chemical Sciences}, volume = {124}, number = {4}, year = {2012}, month = {JUL}, pages = {835-839}, publisher = {INDIAN ACAD SCIENCES}, address = {C V RAMAN AVENUE, SADASHIVANAGAR, P B \#8005, BANGALORE 560 080, INDIA}, abstract = {

A number of hydrotalcite (Mg-Al, Mn-Al, Co-Al, Ni-Al, Mg-Fe, Mg-Cr and Cu-Al) catalysts, with or without MnO-exchange, were evaluated for their performance in the solvent-free oxidation of benzaldehyde to benzoic acid by tert-butyl hydroperoxide under reflux in the absence of any solvent. The MnO-exchanged Mg-Al-hydrotalcite (Mg/Al = 10) showed high activity in the oxidation of different aromatic and aliphatic aldehydes to their corresponding acids and also showed excellent reusability in the oxidation process which is environmental-friendly.

}, keywords = {acid, Aldehyde, MnO4-1-exchanged Mg-Al-hydrotalcite catalyst, Oxidation, TBHP}, issn = {0974-3626}, doi = {10.1007/s12039-012-0268-7}, author = {Choudhary, Vasant R. and Dumbre, Deepa K. and Narkhede, Vijay S.} } @article { ISI:000318332300017, title = {Suzuki-Miyaura cross-coupling reaction between aryl halides and phenylboronic acids over gold nano-particles supported on MgO (or CaO) and other metal oxides}, journal = {Journal of Catalysis}, volume = {301}, year = {2013}, month = {MAY}, pages = {134-140}, publisher = {ACADEMIC PRESS INC ELSEVIER SCIENCE}, address = {525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA}, abstract = {

Gold nano-particles-supported alkaline earth metal oxides, particularly MgO or CaO, show high catalytic activity in the Suzuki-Miyaura cross-coupling reaction in the presence of K2CO3 and DMF (as a solvent). The catalytic activity is strongly influenced by the nature or type of metal oxide support (viz, alkaline earth oxide, Group IIIA metal oxide, transition metal oxide, or rare earth oxide actinide oxide). It is also strongly influenced by the nature of aryl halide (aryl iodide, bromide, chloride, or fluoride), amount of K2CO3 in the reaction mixture and catalyst calcination temperature. Influence of reaction parameters viz, temperature and time and different substituents in aryl halides and/or phenylboronic acids on the biphenyl product yield in the reaction over Au/MgO catalyst has also been investigated. The catalyst showed excellent reusability in the reaction. Moreover, it is ligand-free and also has much lower cost than the commonly used homogeneous and heterogeneous Pd catalysts. (C) 2013 Elsevier Inc. All rights reserved.

}, keywords = {Aryl halides, Au/MgO (or CaO) catalyst, Biphenyls, Gold nano-particles, phenylboronic acids, Suzuki-Miyaura coupling reaction}, issn = {0021-9517}, doi = {10.1016/j.jcat.2013.01.012}, author = {Dumbre, Deepa K. and Yadav, P. N. and Bhargava, Suresh Kumar and Choudhary, Vasant R.} } @article { ISI:000381165300025, title = {Studies of synergy between metal-support interfaces and selective hydrogenation of HMF to DMF in water}, journal = {Journal of Catalysis}, volume = {340}, year = {2016}, month = {AUG}, pages = {248-260}, publisher = {ACADEMIC PRESS INC ELSEVIER SCIENCE}, address = {525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA}, abstract = {

Metal-support interfaces play a very important role in heterogeneous catalysis. The interfacial interactions not only are responsible for stabilizing the necessary oxidation state to facilitate the reaction but also enhance the stability of the catalyst system. Nano dispersion of Ni on mesoporous nitrogen-rich carbon material has been achieved using two different synthesis methods. It was observed that nickel (0) gets stabilized by strong interfacial interaction with the nitrogen atoms of the support material, and the material was found to be very economic and efficient for the conversion of HMF to DMF in aqueous medium. The material shows \>= 99\% conversion to 5-(hydroxymethyl) furfural (HMF) within 6 h of reaction with 98.7\% DMF selectivity. A unique correlation between synthesis methods and particle sizes with catalytic performance has been observed for these newly developed materials. Furthermore, a DFT calculation has been performed to predict the reaction mechanism. (C) 2016 Elsevier Inc. All rights reserved.

}, keywords = {biofuels, Biomass, Hydrogenation, mesoporous carbon, Ni-CNx}, issn = {0021-9517}, doi = {10.1016/j.jcat.2016.05.012}, author = {Goyal, Reena and Sarkar, Bipul and Bag, Arijit and Siddiqui, Nazia and Dumbre, Deepa K. and Lucas, Nishita and Bhargava, Suresh Kumar and Bordoloi, Ankur} }