02091nas a2200193   4500008004100000022001400041245010700055210006900162260000800231300001600239490000700255520138000262100002401642700002401666700003101690700002001721700002401741856013201765       2024                        eng d  a1463-926200aDepolymerization of waste polyethylene to linear alkenes via sequential dehydrogenation and metathesis0 aDepolymerization of waste polyethylene to linear alkenes via seq  cOCT  a10558-105660 v263 a<p>
	Polyethylene (PE) is the most abundantly sourced plastic and significant efforts are needed for its end-of-life management. The deconstruction of PE is an uphill task and requires the breaking of highly stable C-C bonds. Here we demonstrate that PE can be deconstructed to value-added dodecene, along with other long-chain alkenes. The PCP-iridium complex catalyzes the dehydrogenation of commercial and post-consumer polyethylene waste to produce dehydrogenated polyethylene (DHP) with 0.5-1.0% unsaturation. The DHP was subjected to an ethylene cross-metathesis reaction in the presence of suitable catalysts. Through meticulous optimization of reaction parameters, 63% selectivity toward dodecene, with 26% overall yield, was achieved. The practical significance of our method has been demonstrated by subjecting post-consumer plastic waste to dehydrogenation followed by ethylene metathesis to produce dodecene as a major product, together with long-chain alkenes. The PE deconstruction has been confirmed by recording molar mass before and after depolymerization using high-temperature gel permeation chromatography. The existence of dodecene has been unambiguously ascertained using GC, GC-MS, NMR, and IR spectroscopy. Thus, these results demonstrate the conversion of waste PE to value-added dodecene and long-chain alkenes under mild reaction conditions.</p>
1 aKhopade, Kishor, V.1 aRajput, Nikhita, S.1 aRangappa, Raghavendrakumar1 aBarsu, Nagaraju1 aChikkali, Samir, H.  uhttps://library.ncl.res.in/content/depolymerization-waste-polyethylene-linear-alkenes-sequential-dehydrogenation-and-metathesis01640nas a2200229   4500008004100000022001400041245012500055210006900180260000900249300001100258490000700269520081400276653002901090653002601119653001801145653002001163653002401183100002701207700002401234700002401258856012801282       2026                        eng d  a2365-654900aDirect synthesis of phosphine-phosphite ligand and its implication in asymmetric hydrogenation of functionalized olefins0 aDirect synthesis of phosphinephosphite ligand and its implicatio  cFEB   ae075480 v113 a<p>
	Phosphine-phosphite (P-OP) ligands constitute a privileged class of chiral ligands in asymmetric catalysis owing to their modular structures and tunable steric and electronic properties. Herein, we report a direct, one-pot, synthesis of a new flexible P-OP ligand (L) derived from BINOL-PCl and its in situ complexation with rhodium (Rh) for catalytic evaluation. The resulting Rh/L system efficiently hydrogenates a diverse library of 19 functionalized olefins under mild conditions, delivering moderate to excellent enantioselectivities, with ee values reaching up to 99%. Several of the hydrogenated products correspond to valuable chiral building blocks relevant to pharmaceutical synthesis, underscoring the practical utility of flexible P-OP ligand architectures in asymmetric hydrogenation.</p>
10aasymmetric hydrogenation10afunctionalized alkene10aligand design10ametal catalyzed10aphosphine-phosphite1 aChandanshive, Amol, C.1 aKhopade, Kishor, V.1 aChikkali, Samir, H.  uhttps://library.ncl.res.in/content/direct-synthesis-phosphine-phosphite-ligand-and-its-implication-asymmetric-hydrogenation