@article {49291,
	title = {Depolymerization of waste polyethylene to linear alkenes via sequential dehydrogenation and metathesis},
	journal = {Green Chemistry},
	volume = {26},
	year = {2024},
	month = {OCT},
	pages = {10558-10566},
	type = {Article},
	abstract = {<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>
},
	issn = {1463-9262},
	doi = {10.1039/d4gc03646h},
	author = {Khopade, Kishor V. and Rajput, Nikhita S. and Rangappa, Raghavendrakumar and Barsu, Nagaraju and Chikkali, Samir H.}
}
@article {49417,
	title = {Designing of imine thiophene-ligated metal-complexes and implication in ethylene polymerization},
	journal = {Journal of Macromolecular Science Part A-Pure and Applied Chemistry},
	year = {2024},
	month = {SEP},
	type = {Article; Early Access},
	abstract = {<p>
	Polyethylene is the single largest volume polymer produced globally using Ziegler-type catalysts. Numerous modifications have been reported in search of a better catalyst that can control molecular weight, polydispersity, and branching. In our attempts to identify a suitable imine thiophene-ligated chromium complex, we examined 9 different titanium complexes computationally. The DFT investigations considered barriers for insertion, propagation, and termination by beta-H elimination or chain transfer, and identified N-(4-methoxyphenyl)-2-phenyl-1-(thiophen-2-yl)ethan-1-imine(L9) as the most suitable ligand. Subsequently, L9 was prepared in good yield (70\%) by condensing 2-phenyl-1-(thiophen-2-yl)ethan-1-one with 4-methoxyaniline. Ligand L9 was treated with early transition metal precursors (Ti, Cr, Zr) to generate a homogenous catalyst. The identity of these catalysts was unambiguously ascertained using a combination of NMR, ICP, FT-IR, UV-Vis spectroscopy, and ESI-MS. The performance of L9-ligated titanium complex [Cat.1] was examined in ethylene polymerization using MMAO as a co-catalyst. Insertion of ethylene was tracked using high-pressure NMR experiments and Cat.1 was found to be active in the polymerization. Ethylene polymerization conditions were optimized to obtain high activity and molecular weight polyethylene. The chromium complex [Cat.2] outperformed the Ti and Zr-derived catalysts with the highest TOF of 6294 mol of PE/mol of Cr/h. Cat.2 produced high molecular weight, high-density polyethylene.</p>
},
	keywords = {Cr-complexes, DFT, high-density polyethylene, Imine thiophene ligand, Polyethylene},
	issn = {1060-1325},
	doi = {10.1080/10601325.2024.2409753},
	author = {Shaikh, Maulali H. and Ramekar, V. Rohan and Jawoor, Shailaja and Dash, Soumya R. and Birajadar, Rajkumar S. and Pawal, Sandip B. and Thenmani, Nandakumar and Vanka, Kumar and Chikkali, Samir H.}
}
