Microwave irradiated synthesis and characterization of 1, 4-phenylene bis-oxazoline form bis-(2-hydroxyethyl) terephthalamide obtained by depolymerization of poly (ethylene terephthalate) (PET) bottle wastes

Abstract

The aminolytic depolymerization of PET bottle waste with ethanolamine by conventional heating and microwave irradiation heating method was attempted with heterogeneous, recyclable acid catalysts such as beta zeolite (SiO2/ AlO2= 15 Na-form) and montmorillonite KSF. The pure product bis-(2-hydroxyethyl) terephthalamide (BHETA) of aminolysis was obtained in good yield (85-88%). The BHETA, thus obtained, was subjected to cyclization reaction by heating with polyphosphoric acid as well as by chlorination (using phosphoryl chloride), bromination (using red phosphorous and liquid bromine) and nitration (conc. HNO3 + conc. H2SO4) followed by conventional and microwave irradiation heating in N,N-dimethyl formamide/ potassium carbonate solution. The product so obtained was 2, 2'-(1,4-phenylene)-bis-(2-oxazoline) (PBO), which has applications in polymer synthesis as a chain extender/ chain coupling agent or a cross linker. The productswere analyzed by FTIR, DSC, Mass and NMR (1H and 13C NMR).

Recovery of Terephthalic Acid by employing magnetic nanoparticles as a solid support

“…In our previously reported data, we glycolized PET by using DEG as the solvent and NaOH as the catalysts under microwave irradiation [5] . Parab et al [6] used ethanolamine for aminolytic depolymerization of PET bottles wastes with heterogeneous, recyclable acid catalysts such as beta zeolite and montmorillonite KSF under microwave irradiation. Siddiqui [2] reported the using of microwave irradiation as a convenient energy source for recycling of poly (ethylene terephthalate) waste through methanolic pyrolysis.…”

Recent Developments in the Chemical Recycling of Postconsumer Poly(ethylene terephthalate) Waste

“…Later they explored the catalytic activity of heterogeneous and recyclable β-zeolite acid catalyst and montmorillonite KSF clay catalyst in the aminolytic depolymerization of PET waste with ethanol amine. 100 The product, BHETA (85−88% yield), undergoes a cyclization reaction on refluxing with polyphosphoric acid to give the product, 2,2′-(1,4-phenylene)-bis(2-oxazoline) (PBO), which finds applications in polymer synthesis as a chain extender/chain coupling agent or a cross-linker. Shah et al 101 aminolyzed PET bottle waste flakes using 3-amino-1-propanol under conventional (5 h) and microwave heating (7 min) methods in the presence of sodium acetate/potassium sulfate as catalyst.…”

Microwave-Assisted Cationic Ring-Opening Polymerization of 2-Oxazolines

“…of 95% in the case of 1,4-phenylene-bis-2-oxazoline. Notably, this product can also be derived from PET bottle waste, the procedure of which was described by Shukla et al [25]. Bis-(2-hydroxyethyl) terephthalamide, which was obtained in moderate to high yield from the aminolysis of PET waste according to CH or MW-assisted protocols, was subsequently chlorinated, brominated or nitrated.…”