Solubility and esterification kinetics of terephthalic acid in ethylene glycol III. The effects of functional groups

Abstract

SYNOPSISClear time (tcl), the time required for the turbid mixture of terephthalic acid (TPA) and ethylene glycol (EG) to be clear, was measured to examine the effect of poly(ethy1ene terephthalate) (PET) prepolymer (DP of 1-5) on the kinetics of dissolution and/or esterification of TPA with EG. The tcl of the mixture of TPA/EG (1 : 1.5 in molar ratio) was reduced to 1 : 2.2 or 1 : 3.5 by addition of 30 w t % of PET prepolymer or bis-(2-hydroxyl ethyl) terephthalate (BHET), respectively. Diethyl terephthalate (DET) as an additive was used as a model compound to examine the effects of the -OH group on the esterification reaction of TPA/EG. The tcl value increased with addition of DET. The effect of the carbonyl group was also examined by determining esterification rates of benzoic acid (BA) with either ethylene glycol monobezoate (EGMB) as a compound with carbonyl group, or 2penoxyethanol (2-PhE) as a compound without the carbonyl group. The reaction rate of BA with EGMB was much higher than that of BA with 2-PhE, which indicates that the carbonyl group gave an increasing effect of the esterification rate. Fourier transform infrared spectra showed that the -OH group in both BHET and EGMB formed intramolecular hydrogen bonding with the ester carbonyl group. On the basis of these observations, we concluded that the electron density of oxygen in the hydroxyl group increased through the formation of the intramolecular hydrogen bond. The increased electron density gave the -OH group easier access to the carbonyi carbon in BA, leading to an increase in the esterification rate.

Circularizing PET-G Multimaterials: Life Cycle Assessment and Techno-Economic Analysis

“…The composition of PET-G cards was determined by weighing individual components and thermogravimetric analysis (Figures S1 and S2). In the absence of an inventory database for BHET, CHDM, and DBU, the published literature , and patents were consulted for data related to the synthesis of these chemicals. The inventory data for EG, metals (scrap copper), acetone, and water were sourced from the ecoinvent database.…”

Improved polymerization and depolymerization kinetics of poly(ethylene terephthalate) by co-polymerization with 2,5-furandicarboxylic acid

“…During the copolymerization, the comonomer diacid may compete with TPA for the esterication reaction with EG and may affect the dissolution and reaction kinetics, especially at higher molar contents. While detailed studies on the role of solubility in the esterication kinetics of PET have been reported, [10][11][12] to the authors' knowledge, no published study on the effect of copolymerization on the esterication step of PET synthesis is available.…”

Metodologia para detectar a presença do PET reciclado em embalagens PET para alimentos

“…A razão molar do TPA : EG e a faixa de temperatura reacional usadas são 1:1,5 -3 e 240 -260 o C, respectivamente. A utilização de uma menor razão entre os monômeros e uma maior temperatura, em comparação com o método de transesterificação, é imprescindível para alcançar uma excelente solubilidade do monômero TPA em EG [20][21][22][23][24].…”

“…Compton kα (19,20 keV) e kβ(21,56 keV); e composição), o meio passa a interagir de forma diferenciada com a radiação incidente, ocorrendo um significativo aumento da intensidade do espalhamento da fonte primária de raios-X. Além do Ródio (Rh), são observados linhas kα para: S (2,28 keV), Cl (2,62 keV), Mn (5,82 keV), Fe (6,32 keV), Cu (7,94 keV) e Sb(26,28 keV).…”