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-metathesis02337nas a2200253   4500008004100000022001400041245006900055210006800124260000800192490000700200520155700207653001501764653001501779653002101794653001601815653001801831100002101849700003301870700001901903700002601922700001701948700002001965856009801985       2025                        eng d  a1864-563100aDepolymerization of waste polycarbonates to value-added products0 aDepolymerization of waste polycarbonates to valueadded products  cJAN0 v183 a<p>
	Additive free aminolysis method developed for the depolymerization/upcycling of polycarbonates. We report here chemical recycling of polycarbonate under ambient conditions to get its monomer bisphenol A, monoaminocarbamate and biscarbamates in 1 : 2 : 1 ratio respectively. By employing the secondary amine as the aminating reagent, facilitates the depolymerization to work under additive/catalyst free conditions. The developed method deals with depolymerization of waste polycarbonates and works even with late-stage amine derivatives such as amoxapine and desloratadine which are drugs molecules known to treat neurotic disorders and allergies respectively. The reaction can be scaled up and works with similar efficacy which depicts the efficiency of the depolymerization of wasteend-of-life polycarbonate plastic waste. The biscarbamate and bisphenol-A was further subjected for the post functionalization to obtain amides and phenol in good yields. Developed additive/catalyst free aminolysis of waste polycarbonates to carbamates and monomer BPA at ambient conditions. Variety of secondary amines were screened including the late stage amine derivatives like amoxapine and desloratadine which delivered the expected products successfully. Later the developed methodology was even applied for the different end-of-life polycarbonates with the secondary amine and achieved the depolymerization without any obstacle. Further carried out the scale up reaction and derivatization of carbamates and BPA to amide and phenol synthesis. image</p>
10aAminolysis10acarbamates10adepolymerization10aEnd-of-life10aPolycarbonate1 aPadhi, Ganeshdev1 aPansare, Vaibhav, Ramachandr1 aBajpai, Priyam1 aKrishna, Gamidi, Rama1 aVanka, Kumar1 aBarsu, Nagaraju  uhttps://library.ncl.res.in/content/depolymerization-waste-polycarbonates-value-added-products