• Applied Chemistry for Engineering
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• v.7 no.6
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• pp.1204-1208
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• 1996

The organic impurities are formed in the p-xylene oxidation process to terephthalic acid(TPA) and they are present in the filtrate(mother liquor) solution or the TPA particles. The organic impurities present in the p-xylene oxidation are formed through side reactions or incomplete reaction. In this study, the main organic impurities, such as benzoic acid, p-toluic acid, p-tolualdehyde, 4-carboxybenzaldehyde, phthalic acid, isophthalic acid, trimellitic acid, and 4-hydroxymethyl benzoic acid were identified simultaneously by gas chromatograghy. The above impurities were reacted with bis(trimethylsilyl)trifluoroacetamide in the mixture of internal standard solution and pyridine solution by trimethylsilylation, where the internal standard solution was made by 99% bis (trimethylsilyl)trifluoroacetamide and 1% trimethylchlorosilane. The main organic impurities above mentioned can be analyzed quantitatively within 50 min.

• Journal of the Korean Applied Science and Technology
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• v.23 no.3
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• pp.177-184
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• 2006

Because of the difference in 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 diphenol such as monosubstituted hydroquinone 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 diphenyl chlorophosphate in pyridine. The direction was tried to control the relative reactivity by changing the reaction temperature and the addition time of hydroquinone, and by modifying it through an association of hydroquinone with LiCl.

• Korean Journal of Pharmacognosy
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• v.19 no.3
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• pp.188-192
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• 1988

An aromatic hydrocarbon, $mp\;79{\sim}80^{\circ},\;C_{11}H_{12}O_5$, was first isolated from Phyllostachys sp. and identified as 1, 4-benzenedicarboxylic and 2'-hydroxyethylmethyl ester. Five compounds isolated after alkali hydrolysis were identified as vanillin, 4-hydroxyacetophenone, terephthalic acid, 4-hydroxybenzaldehyde and friedelin.

• Proceedings of the Korean Fiber Society Conference
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• 1991.06a
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• pp.11-11
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• 1991

• Bulletin of the Korean Chemical Society
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• v.23 no.3
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• pp.503-506
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• 2002

• Journal of the Korean Chemical Society
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• v.46 no.1
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• pp.57-63
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• 2002

The hydropurification reaction of CTA (crude terephthalic acid) was carried out with hydrogen over PdRu/CCM (carbon-carbonaceous composite material) catalyst in a batch reactor at high temperature. The first order kinetics of hydropurification is confirmed with the linear dependence of ln(4-CBA; 4-carboxybenzaldehyde) with reaction time. The reaction condition studied is thought to represent the hydropurification well because of the linear dependence of catalytic activity on the catalyst weight. The p-toluic acid (p-tol) in solid and liquid increases with the conversion of reaction or the decrease of 4-CBA. However, the benzoic acid (BA) concentration does not depend much on the conversion. The AT (alkali transmittance) does not depend on the 4-CBA when the concentration is higher than about 0.2% which shows the 4-CBA, in itself, does not cause the coloring effect. The AT of PTA depends inversely with the concentration of 4-CBA when the 4-CBA is less than about 0.15%. This may show the coloring materials are removed in parallel with the hydrogenation of 4-CBA. The (0.3%Pd-0.2%Ru)/CCM shows larger residual catalytic activity than a commercial catalyst, 0.5%Pd/C, after using in a commercial reactor even though the former has smaller fresh activity than the latter. The palladium and ruthenium in PdRu/CCM show the synergetic effect in activity when the ruthenium concentration is about $0.2{\sim}0.35$ wt%. It may be supposed that the PdRu/CCM catalyst can be a promising candidate to replace the commercial Pd/C catalyst.

• Journal of the Korean Society of Safety
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• v.15 no.1
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• pp.121-125
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• 2000

This study was executed by dust explosion experiment of terephthalic acid which was widely used for various purposes of food packing material and film etc. and the demand was rapidly increasing. The particle size and concentration of dust affected the minimum ignition energy largely and the lean concentration and the minimum ignition energy in the range of this study were obtained 50$g/m^3$ and 19mJ respectively. Minimum ignition energy was shown at the 4 and 5mm gap distance of discharge electrode, and when the gap distance was below 2mm the explosion could not generated although the sufficient energy was given. It was also found that the ignition energy decreased linearly with the decreasing of dust mean particle size.

• Applied Chemistry for Engineering
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• v.3 no.3
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• pp.464-470
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• 1992

The copolyester was prepared by melt polycondensation varying the amount of ethylene glycol(EG) and pentanediol from terephthalic acid(TPA), EG and pentanediol isomers were. used as the third monomer. The chemical structure and the compositions of the copolyester were determined by nuclear magnetic resonance spectroscopy. Thermal properties were investigated with the aid of differential scanning calorimetry and thermogravimetric analyzer.

• Proceedings of the Korean Fiber Society Conference
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• 2001.04a
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• pp.343-346
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• 2001

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.6
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• pp.2311-2316
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• 2010

Three series of copolyterephthalamides having biphenyl-2,2'-diyl structure in the main chain, were synthesized from p-phenylene-containing diamines such as p-phenylene diamine, 4,4'-oxydianiline or 1,4-bis(4-aminophenoxy)benzene, with mixed diacids of terephthalic acid and 2,2'-bibenzoic acid by the direct polycondensation method. The resulting copolymers had inherent viscosities ranging from 0.46 to 0.93dL/g, and most of them could be readily dissolved in polar aprotic solvents including N,N-dimethyl acetamide and N-methyl-2-pyrrolidone. These copolymers had glass transition temperatures between 239 and $326^{\circ}C$, and their 10% weight loss temperatures were recorded in the range of $410{\sim}485^{\circ}C$ in nitrogen atmosphere.