Functionalized 1,5,7-triazabicyclo [4.4.0] dec-5-ene (TBD) as Novel Organocatalyst for Efficient Depolymerization of Polyethylene Terephthalate (PET) Wastes

Abstract

Poly(ethyleneterephthalate) waste was efficiently depolymerized through glycolysis and aminolysis reactions in the presence of functionalized 1,5,7-triazabicyclo [4.4.0] dec-5-ene (TBD) catalyst. The new catalyst of monoamide-ester type, was synthesized through reaction of dimethylterephthalate (DMT) with TBD in refluxing benzene. It was developed as a consequence of the mechanistic investigations of the transesterification reaction of isosorbide with DMT. To test the stability of functionalized TBD compound towards possible amide bond breakage, reactions with primary and secondary glycols as well as primary amines were performed when only the carboxymethyl group reacted. Moreover, it was found that the depolymerization of poly(ethyleneterephthalate) wastes proceeds faster in the presence of this novel organocatalyst by comparison with the hygroscopic TBD precursor.

Chemical Recycling of PET Using Catalysts from Layered Double Hydroxides: Effect of Synthesis Method and Mg-Fe Biocompatible Metals

“…Chemical shifts are observed in both spectra with a pronounced peak at δ 8.1 ppm (chemical group 1 in the structural formula of BHET), which are related to protons of aromatic rings of BHET. The protons of the methyl group (-CH 2 ) closest to the ester group (-COO) and-OH are recorded between the δ signals 4.7 ppm (chemical group 2) and 3.9 ppm (chemical group 3) [ 56 , 58 ].…”

Attempts to Upcycle PET Wastes into Bio-based Long-lasting Insulating Materials

“…In the 1 H-NMR spectra 5 zones can be identified: -the aromatic proton zone: 8,15 ppmterephthalic acid (AT) from PET, usually split into a sharp peak indicating the presence of monomers and an envelope corresponding to several populations of oligomers of different molecular weights and 7.5 -7.68 ppm doublet corresponding to PA (fig. 2a); the area of double bonds protons in sunflower oil (SO) at 5.3 ppm, deformed signal, indicating several bonding modalities; 5.47 ppm and 5.21 ppm -the IS proton area indicates esterification with both aromatic and aliphatic structural units but also significant amounts of free IS at 4.6 ppm [43,46]; glycolic proton area, indicating the following sequences: 4.7 ppm -ethylene glycol interchain (EG ic ), 3.7 ppm -free EG (EG f ), 2 triplets at 3.58 ppm and 2.72 ppm -free DEG (DEG f ) and in the same area, between 4.0-3.3 ppm, one can notice end chain methylene protons (fig. 2a belonging to propyl and butyl moieties from diTMP and N-BuDEA that could not be certainly assigned.…”

“…1,5,7-triazabicyclo [4.4.0] dec-5-ene -TBD) for aminolysis of PET are the most popular and their applications are also patented [40,41]. The organocatalytic transesterification of PET in the presence of TBD or TBD derivatives as catalysts (preformed or generated in situ during the PET depolymerization reaction) with ethylene glycol, diethylene glycol, isosorbide, ethanolamine, are also mentioned in some studies [42][43][44].…”