02206nas a2200253 4500008004100000022001400041245012800055210006900183260000900252300001000261490000800271520131100279653002001590653002301610653002601633653003301659653002301692100002401715700002401739700002001763700002201783700002101805856012601826 2017 eng d a0926-860X00aEfficient oxidation of ethyl benzene using in situ generated molybdenum acetylide oxo-peroxo complex as recyclable catalyst0 aEfficient oxidation of ethyl benzene using in situ generated mol cFEB  a45-510 v5313 a

Selective oxidation of various alkanes/alkyl aromatics to corresponding carbonyl compounds has been carried out with very high conversion (similar to 98%) and selectivity (up to 100%) for carbonyl compounds using cyclopentadienyl molybdenum acetylide complex, CpMo(CO)(3)(C CPh) (1) as catalyst and tert-butyl hydrogen peroxide (TBHP) as an oxidant and turnover number (TON) of 88 was obtained with turnover frequency (TOF) of 2.45 h(-1). Mo acetylide oxo-peroxo species is formed in situ by reaction of 1 with TBHP during the course of reaction as catalytically active species. Interestingly even though the catalytically active species is homogeneous in nature it could be recycled very easily by recovering the catalytically active species as solid after addition of diethyl ether, and separating the products into organic phase. In the case of ethyl benzene oxidation, even after three recycles no appreciable loss in ethyl benzene conversion and acetophenone selectivity was observed. This complex showed high catalytic activity for the oxo functionalization of other alkyl aromatics and alkanes such as substituted ethyl benzenes, toluene as well as cyclohexane. TBHP was found to be more efficient oxidant than hydrogen peroxide for this oxidation. (C) 2016 Elsevier B.V. All rights reserved.

10aAlkyl aromatics10aCarbonyl compounds10aHomogeneous catalysis10aMolybdenum acetylide complex10aOxo-peroxo species1 aKhomane, Sonali, B.1 aDoke, Dhananjay, S.1 aDongare, M., K.1 aHalligudi, S., B.1 aUmbarkar, S., B. uhttps://library.ncl.res.in/content/efficient-oxidation-ethyl-benzene-using-situ-generated-molybdenum-acetylide-oxo-peroxo11349nas a2200181 45000080041000002450122000412100069001632600008002324900008002405201065400248100002010902700002410922700002010946700002310966700002210989700002411011856013211035 2019 eng d00aVanadium-based highly active and selective catalysts for oxidative dehydrogenation of ethyl lactate to ethyl pyruvate0 aVanadiumbased highly active and selective catalysts for oxidativ cSEP0 v5873 a

Pyruvates are important intermediates for various bioactive and pharmaceutical molecules. Synthesis of pyruvates is challenging due to low selectivity, as the pyruvates are prone to polymerisation. In the present work, oxidative dehydrogenation of ethyl lactate to ethyl pyruvate was carried out under very mild conditions using vanadium-based homogeneous and heterogeneous catalysts in the presence of aqueous t-butyl hydroperoxide as an oxidant. Homogenous vanadium-based catalyst, VO(acac)2 in acetonitrile solvent, gave excellent conversion (upto 83%) with 100% selectivity to ethyl pyruvate at room temperature. However, the heterogeneous catalyst, V2O5 exhibited very high activity for oxidative dehydrogenation of ethyl lactate only at higher temperature (80 °C). At higher temperature, significant TBHP decomposition was observed if all TBHP was added in one lot. In case of ethyl lactate dehydrogenation using V2O5 catalyst at 80 °C with two equivalents TBHP, 60% ethyl lactate conversion with 100% TBHP conversions were observed after 5 h when all TBHP was added initially in the reaction mixture. However, the ethyl lactate conversion at 80 °C, after 5 h increased to 72% when the same amount of TBHP was added batch wise over a period of 4 h, indicating improved conversion of TBHP to ethyl pyruvate. The heterogeneous catalyst, V2O5 exhibited up to 98% conversion with 100% ethyl pyruvate selectivity at 80 °C after 10 h with 3 equivalent TBHP added batch wise. The homogeneous catalyst could not be reused while V2O5 could be successfully recycled five times without catalytic performances loss. Oxidation proceeds by radical mechanism, as proved by experiment with radical scavenger.

1 aDoke, Dhananjay1 aKhomane, Sonali, B.1 aPandhare, Swati1 aDongare, Mohan, K.1 aDumeignil, Franck1 aUmbarkar, Shubhangi uhttps://library.ncl.res.in/content/vanadium-based-highly-active-and-selective-catalysts-oxidative-dehydrogenation-ethyl-lactate