02717nas a2200301 4500008004100000022001400041245010700055210006900162260007300231300001200304490000800316520171400324653001202038653001802050653002302068653001002091653000702101653001302108653002002121653001802141653002302159100001802182700001602200700002802216700001802244700003002262856012302292 2005 eng d a1381-116900aInsight into the mechanism of selective mono-N-methylation of aniline on Cu1-xZnxFe2O4: a DRIFTS study0 aInsight into the mechanism of selective monoNmethylation of anil aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcAPR a169-1800 v2313 a

Mechanism of selective mono-N-methylation of aniline with methanol on Cu1-xZn2FeO4 catalysts was investigated in detail. The interaction of reactants (aniline. methanol and methanol: aniline) and possible products (N-methylaniline (NMA), N,N-dimethylaniline (DMA) and o-toluidine (OT)) on catalysts surface was studied by temperature-dependent in situ FTIR spectroscopy. Methanol adsorbs dissociatively over catalysts surface at 373 K as methoxy species and is oxidized to formate species at high temperature through dioxymethylene and/or formaldehyde as a surface intermediate species. On the other hand, adsorption of aniline:methanol mixtures shows that methanol oxidation was completely hindered in the presence of aniline. Aniline adsorbs on the Lewis acid sites at <= 373 K with phenyl ring oriented in a perpendicular manner to the catalyst surfaced however, N-H bond scission occurs above 373 K. A comparison of adsorbed NMA and methanol: am line (3:1) mixture on Cu0.5Zn0.5Fe2O4 shows NMA forms from the reaction mixture at 473 K. However, maximum activity at 573 K in catalytic reaction studies suggests that desorption limits the methylation kinetics. FTIR study displays stable aniline and methyl species on ZnFe2O4 even at 573 K; however. no methyl species is detected on Cr0.95Zn0.05Fe2O4 at 473 K due to methanol reforming reaction and that limits the overall reaction and hence low catalytic activity. It is proposed that methanol is protonated on catalysts surface by the labile H+ due to N-H bond scission. Co-adsorption of acidity probes with aniline and methanol indicates that aniline methylation takes place at single acid-base site. (c) 2005 Elsevier B.V. All rights reserved.

10aAniline10aCu1-xZnxFe2O410adesorption limited10aDRIFT10aIR10aMethanol10aN-methylaniline10aN-methylation10areaction mechanism1 aVijayaraj, M.1 aMurugan, B.1 aUmbarkar, Shubhangi, B.1 aHegde, S., G.1 aGopinath, Chinnakonda, S. uhttps://library.ncl.res.in/content/insight-mechanism-selective-mono-n-methylation-aniline-cu1-xznxfe2o4-drifts-study-001756nas a2200253 4500008004100000022001400041245011100055210006900166260006900235300001400304490000800318520082900326653002301155653002001178653002701198653002301225653002301248653000701271100001801278700002501296700002501321700002901346856012701375 2005 eng d a0022-328X00aIsolation and characterization of an iodide bridged dimeric palladium complex in carbonylation of methanol0 aIsolation and characterization of an iodide bridged dimeric pall aPO BOX 564, 1001 LAUSANNE, SWITZERLANDbELSEVIER SCIENCE SAcMAR a1677-16810 v6903 a

Palladium-catalyzed carbonylation of methanol in presence of iodide promoters was investigated. Iodide bridged palladium dimeric complex, [PPh3CH3](2)[Pd2I6] was isolated from the carbonylation reaction mixture and characterized using X-ray crystallography. Reaction mechanism was proposed based on IR and UV spectroscopic characterizations of catalytic species involved in the catalytic cycle. The isolated dimeric palladium species, [Pd2I6](2-) underwent carbonylation to give monomeric species [PdI3CO](-) at atmospheric pressure of carbon monoxide. It was also observed that PPh3 plays an important role to avoid catalyst deactivation at higher temperatures. Turnover frequency (TOF) of 1052 h(-1) was achieved using Pd(OAC)(2)-HI-PPh3 catalyst system at 175 degrees C. (c) 2005 Elsevier B.V. All rights reserved.

10adirneric palladium10aIR spectroscopy10amethanol carbonylation10apalladium catalyst10areaction mechanism10aUV1 aTonde, S., S.1 aKelkar, Ashutosh, A.1 aBhadbhade, Mohan, M.1 aChaudhari, Raghunath, V. uhttps://library.ncl.res.in/content/isolation-and-characterization-iodide-bridged-dimeric-palladium-complex-carbonylation-101879nas a2200193 4500008004100000245011500041210007100156260000800227300001500235490000600250520119000256653001201446653001801458653002301476653002101499100001501520700001401535856013601549 2017 eng d00aLess frustration, more Activity—theoretical insights into frustrated lewis pairs for hydrogenation catalysis0 aLess frustration more Activity—theoretical insights into frustra cAUG a 3013-30220 v93 aThe field of frustrated Lewis pair (FLP) chemistry has seen rapid development in only a few years. FLPs have performed most spectacularly in hydrogenation catalysis: a wide variety of FLP-based systems can catalyze the hydrogenation of a range of different substrates, including imines, enamines, ketones, alkynes, and alkenes. However, FLP-based hydrogenation catalysts are yet to match the efficiency of their transition-metal counterparts. The current investigation reveals an important aspect of FLPs that can be exploited to improve their efficiency, that is, the more sterically hindered the FLP catalyst is, the lower is its turnover frequency. Full quantum chemical calculations with DFT for a family of different, experimentally known hydrogenation FLP catalysts shows that superior FLP catalysts can be designed by reducing the frustration (by reducing the steric demand and acid/base strength) in the FLP. However, as lowering the steric demand without reduction in the frustration can result in unwanted side reactions, the design of the most efficient FLP catalysts depends on tuning the system so that both the steric demand and the frustration are reduced appropriately.10aBoranes10aHydrogenation10areaction mechanism10aSteric Hindrance1 aMane, M.V.1 aVanka, K. uhttps://library.ncl.res.in/content/less-frustration-more-activity%E2%80%94theoretical-insights-frustrated-lewis-pairs-hydrogenation01982nas a2200241 4500008004100000022001400041245010800055210006900163260000800232300001400240490000600254520113500260653001801395653003001413653001301443653002501456653002301481653003301504653003401537100002501571700001701596856012701613 2018 eng d a2155-543500aB(C6F5)(3): catalyst or initiator? insights from computational studies into surrogate silicon chemistry0 aBC6F53 catalyst or initiator insights from computational studies cJUL a6163-61760 v83 a

One of the most promising recent developments in catalysis has been the use of the metal-free Lewis acid B(C6F5)(3) as a catalyst for a range of different chemical transformations. Perhaps the most impressive achievement in this regard is the recently accomplished in situ generation of SiH4 from surrogates (Simonneau and Oestreich, Nat. Chem., 2015,7, 816). However, what the current computational work, with density functional theory, reveals is that this process, in addition to being catalyzed by B(C6F5)(3), is also significantly dominated by a series of autocatalytic reactions. The results are further corroborated by the use of the energetic span model, which shows that the turnover frequency is higher for the newly proposed autocatalytic pathway in comparison to the conventional B(C6F5)(3)-catalyzed pathway. The current work therefore provides interesting new insights into surrogate silicon chemistry. But, more importantly, the current studies indicate that B(C6F5)(3) is likely to function more as an initiator rather than a pure catalyst in many metal-free transformations that have been reported to date.

10aautocatalysis10aDensity functional theory10aion-pair10aLewis acid catalysis10areaction mechanism10asurrogate silicone chemistry10atris(pentafluorophenyl)borane1 aBanerjee, Subhrashis1 aVanka, Kumar uhttps://library.ncl.res.in/content/bc6f53-catalyst-or-initiator-insights-computational-studies-surrogate-silicon-chemistry