Studies on the Solubility of Terephthalic Acid in Ionic Liquids

Abstract

Low solubility of terephthalic acid in common solvents makes its industrial production very difficult and not environmentally benign. Ionic liquids are known for their extraordinary solvent properties, with capability to dissolve a wide variety of materials, from common solvents to cellulose, opening new possibilities to find more suitable solvents for terephthalic acid. This work presents studies on the solubility of terephthalic acid in ionic liquids, and demonstrates that terephthalic acid is soluble in ionic liquids, such as 1-ethyl-3-methylimidazolium diethylphosphate, 1-butyl-3-methylimidazolium acetate, and dialkylimidazolium chlorides up to four times higher than in DMSO. Additionally, the temperature effect and correlation of ionic liquid structure with solubility efficiency are discussed.

Towards closed-loop recycling of multilayer and coloured PET plastic waste by alkaline hydrolysis

“…1-butyl-3-methylimidazolium acetate and 1-ethyl-3methylimidazolium diethylphosphate. 55,56 Afterwards the content of the flask is titrated with 0.5 N KOH solution to a phenolphthalein endpoint. 1 H-NMR and UV-VIS spectra of obtained TPA after degradation are shown in Appendix, Fig.…”

Sustainable Method for the Synthesis of Alternative Bis(2-Ethylhexyl) Terephthalate Plasticizer in the Presence of Protic Ionic Liquids

“…The bottom phase should consist of an ionic liquid and water, and the upper phase should be created by the ester and unreacted alcohol. We assumed, based on previous studies [14][15][16][17][18], that this system would overcome the equilibrium and obtain a product with a high yield.…”

“…The low solubility of terephthalic acid in common solvents makes its industrial production very difficult and not environmentally benign. In our previous work, the solubility of terephthalic acid in ionic liquids was studied, and the results showed that terephthalic acid is partially soluble in ionic liquids, such as 1-ethyl-3-methylimidazolium diethylphosphate, 1-butyl-3-methylimidazolium acetate, and dialkylimidazolium chlorides up to four times higher than in DMSO (20 g of terephtalic acid per 100 g DMSO at 25 • C) [14]. Even though the solubility of terephthalic acid increased in the ionic liquid, the problem was not entirely solved.…”

Primary Ammonium Terephthalate Salts with High Moisture Resistance and Their Use in the Detection of OH Radicals

“…Terephthalate salts with cations such as Na + , K + , and NH 4 + are also soluble in water [8] . On the other hand, terephthalic acid (TPA), which is not a salt, is poorly soluble in water and alcohols, but soluble in dimethyl sulfoxide (DMSO) [9] . The crystal structure of TPA is closely packed by the π‐π interactions between the benzene rings, [10] preventing OH radicals from penetrating into the crystal.…”

“…[8] On the other hand, terephthalic acid (TPA), which is not a salt, is poorly soluble in water and alcohols, but soluble in dimethyl sulfoxide (DMSO). [9] The crystal structure of TPA is closely packed by the π-π interactions between the benzene rings, [10] preventing OH radicals from penetrating into the crystal. Thus, the reaction between OH radicals and terephthalic acid occurs only on the crystal surface, which leads to low production efficiency of HTA.…”