• Applied Chemistry for Engineering
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• v.30 no.5
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• pp.615-619
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• 2019

Statistical design of experiments was performed to optimize MOF-235 synthesis process. Concentrations of terephthalic acid (TPA), iron (III) chloride hexahydrate, N,N-dimethylformamide (DMF) and ethanol were important factors to develop the crystal structure of MOF-235. MOF-235 was synthesized with various concentrations of the listed chemicals above and the crystallinity was measured by XRD. The effect of the composition on the synthesis of MOF-235 was evaluated using a statistical analysis. For the variance analysis using F-test, the concentration of ethanol showed the greatest effect on the crystallinity and TPA the least influential. A regression model for predicting the crystallinity of MOF-235 was derived and the prediction results for two synthetic variables were presented using contour plots. Finally, the crystallinity was predicted by a mixture method with $FeCl_3$, ethanol and DMF.

• Applied Chemistry for Engineering
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• v.33 no.4
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• pp.402-407
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• 2022

Statistical design of experiments was used to optimize the MOF-5 synthesis process. A mixture design was employed to optimize precursor concentration. The optimal composition of three chemical materials, terephthalic acid, zinc acetate dihydrate, and N,N-dimethylformamide for MOF-5 synthesis was determined by extreme vertices design methods as follows; 1 mol : 2.7 mol : 40 mol. A multilevel factorial design was selected to screen the significance of synthesis reaction conditions such as temperature, time, and stirring speed. Statistical analysis results suggested excluding stirring speed from further investigation. Using a central composition design, the synthesis time and temperature were optimized. The quadratic model equation was derived from 13 synthesis experiments. The model predicted that MOF-5 synthesized at 119 ℃ for 10.4 h had the highest crystallinity.

• Toxicological Research
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• v.27 no.4
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• pp.191-203
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• 2011

There has been growing concern about the toxicity of phthalate esters. Phthalate esters are being used widely for the production of perfume, nail varnish, hairsprays and other personal/cosmetic uses. Recently, exposure to phthalates has been assessed by analyzing urine for their metabolites. The parent phthalate is rapidly metabolized to its monoester (the active metabolite) and also glucuronidated, then excreted. The objective of this study is to evaluate the toxicity of phthalic acid (PA), which is the final common metabolic form of phthalic acid esters (PAEs). The individual PA isomers are extensively employed in the synthesis of synthetic agents, for example isophthalic acid (IPA), and terephthalic acid (TPA), which have very broad applications in the preparation of phthalate ester plasticizers and components of polyester fiber, film and fabricated items. There is a broad potential for exposure by industrial workers during the manufacturing process and by the general public (via vehicle exhausts, consumer products, etc). This review suggests that PA shows in vitro and in vivo toxicity (mutagenicity, developmental toxicity, reproductive toxicity, etc.). In addition, PA seems to be a useful biomarker for multiple exposure to PAEs in humans.

• YAKHAK HOEJI
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• v.38 no.3
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• pp.230-237
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• 1994

The structure-activity relationships of (E)-chalcone-4-carboxylic acids, flavone-4'-carboxylic acids, two types of aromatic amides, terephthalic monoanilides, and (arylcarboxamido)benzoic acids, which were made by Shudo group, are discussed by conformation analysis(AM1) of retinoic acid and those compounds. Conformer of each compound is superimposed on the conformationally restricted compound, 4-(6,7,8,9-tetrahydro-6,6,9,9-tetramethyl-4H-4-oxonaphto[ 2,3-b]pyran-2-yl) benzoic acid(Fv80), possessing the strongest differentiation-inducing activity on human promyelocytic leukemia cells HL-60. The results indicated that the lengths between the carboxylic carbon and the two 6, 9 carbons binding to dimethyl, 1.20 nm and 1.09 nm, as well as the planarity of molecule are very important factors for the activity, especially 1.20 nm. In the case of the recently synthesized azulenic retinoic acids by Sato, et al. in 1993, the distance probably is also important, resulted from superimposing them on a Ch55 conformer and Fv80. The distance 1.0 nm is also important in Ch55. Several conformers of all-trans retinoic acid (RA) are well superimposed on the almost non-flexible Fv80, RA, 9-cis RA, and, specifically s-10,12 cis RA. And a simple hexangular model of RA is suggested to draw RA conformers easily without computer drawing model or molecular model.

• Journal of the Korean Society of Industry Convergence
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• v.5 no.2
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• pp.147-152
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• 2002

Because of the difference of the relative reactivity between two hydroxyl groups of the hydroquinone due to the steric hindrance of the substituent, many combinations of the substituent direction in the polyesters derived from asymmetrical diphenols such as monosubstituted hydroquinones was expected. It was studied how the mode of the direction affected the properties of the resulting polyesters in terms of the transition temperatures of the thermotropic polyesters prepared from terephthalic acid, 2,4-dichloroterephthalic acid, and phenylhydroquinone by the reaction using p-Toluenesulfonylchloride in pyridine. The direction was tried to control the relative reactivity by changing the reaction temperature and addition time of the hydroquinone, and by modifying it through an association of the hydroquinones with DMF.

• Polymer(Korea)
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• v.35 no.6
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• pp.593-598
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• 2011

The IPA-co-HDO-co-(TPA/MA) copolymers for all-vanadium redox flow battery were synthesized by melt condensation polymerization using isophthalic acid(IPA), 1,6-hexandiol (HDO), terephthalic acid(TPA) and maleic anhydride(MA). The amination of chloromethylated IPA-co- HDO-co-(TPA/MA)(CIHTM) copolymer was carried out using trimethylamine, and the anion exchange membrane was also prepared by UV crosslinking reaction. The structure and thermal stability of IHTM copolymers were confirmed by FTIR, $^1H$ NMR, and TGA analysis. The anion membrane properties such as water uptake, ion exchange capacity, electric resistance and electrical conductivity, were measured by gravimetry, titration and LCR meter. The efficiency of the all-vanadium redox flow battery was analyzed. The ion exchange capacity, electric resistance and electrical conductivity were 1.10 meq/g, $1.98{\Omega}{\cdot}cm^2$, and 0.009 S/cm, respectively. The efficiency of charge-discharge, voltage, and energy for the allvanadium redox flow battery were 96.5, 74.6, 70.0%, respectively.

• Korean Chemical Engineering Research
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• v.46 no.6
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• pp.1130-1134
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• 2008

Acetic acid has been used as a solvent in the process of manufacturing terephthalic acid. Although the used acetic acid has been mainly separated and recovered through the distillation process, adsorption process can be applied to recover a small amount of acetic acid remaining in the stream after the distillation process. In this study, activated carbon was selected as an adsorbent for acetic acid and the effects of temperature and acid treatment on adsorption capacity were investigated. The adsorption capacities of activated carbon for acetic acid were 0.176 mmol/g at 303 K and 0.118 mmol/g at 343 K, respectively. Adsorption capacity decreased with increasing temperature. The acid treatment of the activated carbon induced the increase in adsorption capacity, which was ascribed to increase in surface functional groups such as phenolic hydroxyl groups and carboxilic acid groups on the carbon surface. In the results of acetic acid desorption, 89% of adsorbed acetic acid was desorbed from activated carbon.

• Macromolecular Research
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• v.17 no.3
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• pp.149-155
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• 2009

The thermal decomposition behavior and degradation characteristics off our different thermotropic liquid crystalline polymers (TLCPs) were studied. The thermal decomposition behavior was determined by means of thermogravimetric analysis (TGA) at different heating rates in nitrogen and air. The order of the thermal stability was as follows: multi-aromatic polyester > hydroxybenzoic acid (HBA)/hydroxynaphthoic acid (HNA) copolyester > HNA/hydroxyl acetaniline (HAA)/terephthalic acid (TA) copolyester > HBA/Poly(ethylene terephthalate) (PET) copolyester. The activation energies of the thermal degradation were calculated by four multiple heating rate methods: Flynn-Wall, Friedman, Kissinger, and Kim-Park. The Flynn-Wall and Kim-Park methods were the most suitable methods to calculate the activation energy. Samples were exposed to an accelerated degradation test (ADT), under fixed conditions of heat ($63{\pm}3^{\circ}C$), humidity ($30{\pm}4%$) and Xenon arc radiation ($1.10\;W/m^2$), and the changes in surface morphology and color difference with time were determined. The TLCPs decomposed, discolored and cracked upon exposure to ultraviolet radiation.

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.335-336
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• 2003

The synthesis of poly(trimethylene terephthalate) (PTT), whose application is being expanded very rapidly to new apparel and carpet materials, was investigated by melt condensation polymerization using 1,3-propanediol (PDO) and terephthalic acid (TPA). No catalyst was used in the 1st step reaction (esterification), but tetrabutyl titanate(TBT) was used as a polyesterification catalyst ranging from 25 to 75 ppm based on the weight of TPA used in the 2nd step reaction (polyesterification). The molar ratio of PDO to TPA was set as 2.2:1. The effect of reaction conditions on the color and intrinsic viscosity of the final product was investigated. (omitted)

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.377-382
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• 2004

This paper presents a novel optimization method for the air- and gas-supplying network comprised of several air compression systems and air and gas streams in an industrial chemical plant. The optimization is based on the hybrid model developed by Han and $Han^1$ for predicting the power consumption of a compression system. A constrained optimization problem was formulated to minimize the total electric power consumption of all the compression systems in the air- and gas-supplying network under various operating constraints and was solved using a successive quadratic optimization algorithm. The optimization approach was applied to an industrial terephthalic acid manufacturing plant to achieve about 10% reduction in the total electric power consumption under varying ambient conditions.