@article {46838, title = {Palladium-catalyzed insertion of ethylene and 1,1-disubstituted difunctional olefins: an experimental and computational study}, journal = {ChemPlusChem}, volume = {85}, year = {2020}, month = {JUN}, pages = {1200-1209}, type = {Article}, abstract = {

Insertion or coordination copolymerization of ethylene with di-substituted olefins is challenging and the choice of di-substituted mono-functional olefin versus di-substituted di-functional olefin (DDO) appears to be decisive. Here we show that DDO-inserted species are amenable to ethylene insertion and polymerization. DDOs such as 2-acetamidoacrylic acid (AAA), methyl 2-acetamidoacrylate (MAAA), and ethyl 2-cyanoacrylate (ECA) were treated with palladium complex [{P perpendicular to O}PdMe(L)] (P perpendicular to O=kappa(2)-P,O-Ar2PC6H4SO2O with Ar=2-MeOC6H4; L=C2H6OS) and the existence of respective insertion intermediates in moderate yield (up to 37 \%) was established. These intermediates were exposed to ethylene and corresponding ethylene-inserted products were isolated and characterized. A careful comparison with three model compounds confirmed ethylene insertion and polymerization. Thus, the combined experimental and computational investigations show that DDO-inserted species can undergo ethylene insertion and polymerization.

}, keywords = {Homogeneous catalysis, insertion copolymerization, Olefins, Palladium, Polyethylene}, issn = {2192-6506}, doi = {10.1002/cplu.202000309}, author = {Gaikwad, Shahaji R. and Patel, Ketan and Deshmukh, Satej S. and Mote, Nilesh R. and Birajdar, Rajkumar S. and Pandole, Satish P. and Chugh, Jeetender and Chikkali, Samir H.} } @article {47038, title = {Phosphorus ligands in hydroformylation and hydrogenation: a personal account}, journal = {Chemical Record}, year = {2021}, month = {MAR}, type = {Article; Early Access}, abstract = {

Metal-catalyzed hydroformylation and hydrogenation heavily rely on ligands, among which phosphorous ligands play a pivotal role. This personal account presents a selection of three distinct classes of phosphorous ligands, namely, monodentate meta-substituted phosphinites, bis-phosphites, and P-chiral supramolecular phosphines, developed in our group. The synthesis of these ligands, isolation, characterization, and their performance in transition metal-catalyzed hydroformylation, isomerizing hydroformylation, and asymmetric hydrogenation of olefins is summarized. The state of the art development in iron-catalyzed hydroformylation of alkenes and our contributions to the field is discussed. Use of phosphines enabled iron-catalyzed hydroformylation of alkenes under mild conditions. Thus, this account demonstrates the central role of phosphorus ligands in industrially relevant transformations such as hydrogenation and hydroformylation. The seemingly matured field of ligand discovery still holds significant potential and will steer the field of homogeneous catalysis.

}, keywords = {Homogeneous catalysis, Hydroformylation, Hydrogenation, Olefins, Phosphorus ligands}, issn = {1527-8999}, doi = {10.1002/tcr.202100007, Early Access Date = MAR 2021}, author = {Tewari, Tanuja and Kumar, Rohit and Chandanshive, Amol C. and Chikkali, Samir H.} } @article {49522, title = {Ruthenium-catalyzed deconstruction of polyolefins: a strategy to up-cycle waste polyethylene to value-added alkene}, journal = {Angewandte Chemie-International Edition}, volume = {64}, year = {2025}, month = {APR}, type = {Article}, abstract = {

Synthesis of value-added products from post-consumer waste polyolefins is fascinating as well as challenging. Here we report ruthenium-catalyzed up-cycling of the polyethylene to long-chain alkene derivatives. The developed methodology mainly involves two steps i.e., dehydrogenation of polyethylene through hydrogen atom transfer and its metathesis using the HG-II catalyst. The dehydrogenation of polyethylene using ruthenium catalysis derived up to 3.38 \%, of double bonds; with 90 \% of the recovered polyolefin material. The obtained unsaturated polyethylene was subjected to cross-metathesis with ethylene using HG-II catalytic system. This resulted in the synthesis of predominantly dodecene (C12) derivatives, with 58 \% selectivity, along with other derivatives of varying chain lengths. The overall reaction produced terminal and internal olefins in the ratio 1:0.8 respectively. The dehydrogenation of polyethylene and its deconstruction was confirmed by NMR spectroscopy, Gel Permeation Chromatography (GPC) and Differential Scanning Calorimetry (DSC). The origin of C12 selectivity has been demonstrated by control experiments. The scope of the methodology was extended to post-consumer waste polyethylene which gave high conversion to value-added dodecene derivatives as a major product.

}, keywords = {Deconstruction, Homogeneous catalysis, ruthenium, Upcycling, Waste plastic}, doi = {10.1002/anie.202422609}, author = {Padhi, Ganeshdev and Khopade, Kishor V. and Moyilla, Nageswararao and Rangappa, Raghavendrakumar and Chikkali, Samir H. and Barsu, Nagaraju} }