• Korean Journal of Food Science and Technology
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• v.32 no.6
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• pp.1234-1243
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• 2000

A method for quantitative determination of styrene dimer and trimer, which are suspected as endocrine disruptors, in foods and containers was studied. For residual contents of styrene dimer and trimer in two-kinds of containers, which contained instant noodle and yogurt, sample pieces were completely dissolved in tetrahydrofuran. The polymer was precipitated with n-hexane, a portion of supernatant was concentrated for analysis. A sensitive method was also optimized for the quantification of styrene dimer and trimer in foods such as instant cup noodle and yogurt by using GC/MS. Limits of Detection were about 3.2-87.0 ppb for styrene dimers and trimers. The highest recovery was obtained by extraction with acetone/hexane(1:1), followed by florisil clean-up. The levels of styrene dimer and trimer migrated by food simulants were much higher in heptane.

• Bulletin of the Korean Chemical Society
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• v.14 no.4
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• pp.469-475
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• 1993

The approximate rates and stoichiometry of the reaction of excess lithium tris(diethylamino)aluminum hydride (LTDEA) with selected organic compounds containing representative functional groups under standardized condition (tetrahydrofuran, 0$^{\circ}C$) were examined in order to define the characteristics of the reagent for selective reductions. The reducing ability of LTDEA was also compared with those of the parent lithium aluminum hydride (LAH) and lithium tris(dibutylamino)aluminum hydride (LTDBA). In general, the reactivity toward organic functionalities is in order of LAH${\gg}$LTDEA${\geq}$LTDBA. LTDEA shows a unique reducing characteristics. Thus, benzyl alcohol and phenol evolve hydrogen slowly. The rate of hydrogen evolution of primary, secondary, and tertiary alcohols is distinctive: 1-hexanol evolves hydrogen completely in 6 h, whereas 3-hexanol evolves hydrogen very slowly. However, 3-ethyl-3-pentanol does not evolve any hydrogen under these reaction conditions. Primary amine, such as n-hexylamine, evolves only 1 equivalent of hydrogen. On the other hand, thiols examined are absolutely inert to this reagent. LTDEA reduces aldehydes, ketones, esters, acid chlorides, and epoxides readily to the corresponding alcohols. Quinones, such as p-benzoquinone and anthraquinone, are reduced to the corresponding diols without hydrogen evolution. However, carboxylic acids, anhydrides, nitriles, and primary amides are reduced slowly, where as tertiary amides are readily reduced. Finally, sulfides and sulfoxides are reduced to thiols and sulfides, respectively, without evolution of hydrogen. In addition to that, the reagent appears to be an excellent partial reducing agent to convert esters, primary carboxamides, and aromatic nitriles into the corresponding aldehydes. Free carboxylic acids are also converted into aldehydes through treatment of acyloxy-9-BBN with this reagent in excellent yields.

• Korean Chemical Engineering Research
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• v.57 no.1
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• pp.5-10
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• 2019

In this study, electrochemical characteristics of artificial graphite coated with petroleum pitch using solvent method as anode material of lithium ion battery were investigated. As the solvent, n-hexane, toluene, tetrahydrofuran and quinoline were used. The surface of the prepared anode material was analyzed by SEM and TEM. Also the electrochemical performances of the prepared anode materials were performed by constant current first charge/discharge, cycle, cyclic voltammetry and impedance tests in the electrolyte of $LiPF_6$ dissolved inorganic solvents (EC:DEC=1:1 vol%). The coating thickness of the prepared graphite was about 100-500 nm and the graphite coated with THF solvent had a smoother surface than that using other solvents. It was found that pitch-coated graphite (THF) show the low initial irreversible capacity (51 mAh/g), the high discharge capacity (360 mAh/g) and coulombic efficiency (99%).

• Applied Chemistry for Engineering
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• v.33 no.4
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• pp.367-372
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• 2022

The effect of the addition of a polyvinylchloride (PVC) non-solvent to a PVC-tetrahydrofuran (THF) solution on the surface properties of the PVC thin film was analyzed. The non-solvents used were composed of alcohol-based and non-alcoholic ones. Surface morphologies of PVC thin films according to the addition of the non-solvent were compared. In addition, the hydrophobic properties relying on the surface characteristics were compared. The micro-bubbles generated in the preparation of PVC-THF solution affected the surface morphology of the thin film. In order to implement the normal surface physical properties of the coating thin film at the relatively high concentration of PVC-THF solution, the selection of appropriate drying method was required. When an alcohol-based non-solvent was added, a PVC thin film having a granular porous surface was obtained and exhibited super hydrophobic properties. The volume ratio of the PVC-THF solution to the non-solvent affects the surface shape of the coating thin film. The larger the amount of non-solvent was added, the more advantageous it was to form a super hydrophobic PVC thin film.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1635-1639
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• 2011

An efficient and novel positive charge-doping on the sidewalls of multi-walled carbon nanotubes has been achieved in the presence of tetrahydrofuran as a dopant and Lewis acidic ionic liquids, [bmim]$Sb_nF_{5n+1}$ (n ${\geq}$ 2; bmim = 1-butyl-3-methylimidazolium), as an activator, leaving air-stable derivatives having positively charged sidewalls and the counter anions, [MWCNT$^{y+}$][SbF$_6^-$]$_y$ (MWCNT = multi-walled carbon nanotube). The derivatization took place very fast in one-pot and under mild reaction conditions. The ionic structure enabled a tunable dissolution of the derivatives in various solvents through anion exchange.

• Bulletin of the Korean Chemical Society
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• v.34 no.9
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• pp.2623-2628
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• 2013

Three di-acyl chlolide reagents, adipoyl chloride, terephthaloyl chloride and isophthaloyl chloride, were used as spacer reagents to prepare bonded type of three cellulose (3,5-dimethylphenyl)carbamate (CDMPC) chiral stationary phases (CSPs). The CDMPC CSPs were prepared using these three acid chlorides as spacer agents at the 6-position of the primary hydroxyl group on the glucose unit of cellulose regioselectively. The chiral recognition ability of the prepared CSPs for five racemates was evaluated by normal-phase high-performance liquid chromatography (HPLC) with the following mobile phases: hexane/isopropanol (IPA), hexane/IPA/tetrahydrofuran (THF) and hexane/IPA/chloroform. The result showed that these prepared CSPs can be used in THF and chloroform solutions and the chiral recognition abilities of the CSPs were improved depending on the eluents and chiral samples.

• Journal of the Korean Ceramic Society
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• v.38 no.8
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• pp.755-760
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• 2001

본 연구에서는 카본전극의 표면개질에 따른 리튬이온 전지의 전지특성 변화에 대해서 연구하였다. 즉, mesocarbon microbeads(MCMB) 카본에 에폭시 수지(resin)를 코팅시킴으로서 카본전극 표면에 개질시켰으며, 이에 따른 전극의 전기화학적 특성을 고찰하였다. 에폭시 수지에 의한 카본의 표면코팅은 30%의 H$_2$SO$_4$용액에서 2시간 동안 refluxing한 MCMB를 에폭시 수지를 용해시킨 THF(tetrahydrofuran) 용액에 넣어 혼합함으로써 MCMB 표면에 에폭시 수지가 코팅되도록 하였다. 이렇게 에폭시 수지가 코팅된 MCMB를 약 1000-130$0^{\circ}C$로 열처리하여 고분해능 투과전자현미경으로 관찰한 결과, 코팅층은 비정질 카본 구조를 갖게됨을 알 수 있었다. 또한, 에폭시 수지에 의하여 코팅된 MCMB는 코팅되지 않은 MCMB보다 더 높은 BET 비표면적을 나타내었다. Li/MCMB 전지 cell을 만들어 충방전시험을 수행한 결과, 에폭시 수지에 의하여 코팅된 MCMB로 만든 전극이 더 우수한 충방전 용량과 싸이클 특성을 나타내었다. 에폭시 수지 코팅으로 전극 표면을 개질시킴으로서 전지특성이 개선된 원인에 관하여 에폭시 코팅의 결정구조와 전극계면에서의 부동태 피막(passivation film) 형성과 연계하여 논의하였다.

• Proceedings of the Korean Fiber Society Conference
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• 2002.04a
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• pp.187-190
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• 2002

Poly(vinyl alcohol) (PVA) is a representative hydrophilic and water-soluble polymer and widely employed in various applications such as fibers for clothes and industries, films, membranes, medicines for drug delivery system, and cancer cell-killing embolic materials. Moreover, PVA fibers, gels, and films are potentially high-performance materials because they have high tensile and impact strengths, high tensile modulus, high abrasion resistance, excellent alkali resistance, and oxygen barrier property which are superior to those of any known polymers[1,2]. (omitted)

• Proceedings of the Membrane Society of Korea Conference
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• 1993.10a
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• pp.61-62
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• 1993

고분자 분리막의 투과성과 선택성을 향상시키기 위하여 IPN막, 고분자/액정 복합막을 다양한 기능을 가진 재료가 개발되고 있다. 본 연구에서는 알칼리메탈이온을 분리하기 위하여 고분자 지지체에 운반체로써 crown ether(macro-cyclic polyether)류를 분산시킨 고분자/운반체 복합박막을 제조하였다. 고분자/운반체 복합박막은 고분자와 운반체의 혼합용액을 수면에 전개시켜 제조하였다. 고분자는 PVC(M.W 60000, Aldrich), PS(M.W 280000, Aldrich)와 CA(M.W 30000, Sigma)를 사용하였고, 운반체로는 crown ether 중 $K^+$이온과 선택성을 가지는 18-Crown-6(Sigma)를 사용, 고분자와 18-Crown-6의 증량분을 달리하는 혼합용액을 제조하였다. 이때 용매는 Tetrahydrofuran를 사용하였다. 수면에 생성된 박막을 다공성 지지막에 적층시킨 후 감압 건조시켜 복합막을 제조하였다. 고분자와 운반체가 혼합되어 있는 용액의 점도와 표면장력을 각각 fluid spectrometer와 tensionmeter를 사용, 용액이 수면위에서 완전한 막을 형성하면서 분산될 수 있는지 조사하였으며, 고분자 지지체에 분산 고정된 운반체의 분산형태와 표면농도를 조사하기 위하여 ESCA를 이용하였다.

• YAKHAK HOEJI
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• v.40 no.2
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• pp.149-154
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• 1996

A high-performance liquid chromatographic method for the determination of ${\beta}$-sitosterol in the unsaponifiable fraction of Zea mays L. and its related drug preparations using a cholesterol as an internal standard was investigated. They were saponified with 20% methanolic KOH solution. Phytosterols in the reaction mixture were extracted with diethyl ether and separated on silica gel TLC plate with n-hexane-diethyl ether(40:60) as the solvent and then were scraped off. They were separated by reversed phase high perfomance liquid chromatography on Inertsil ODS-2 column with detection at 205nm. Cholesterol and ${\beta}$-sitosterol were resolved from interferences by adjusting the acetonitrile content in the MeOH-tetrahydrofuran-$H_2O$ eluent. The detection limit of ${\beta$-sitosterol was 0.43${\mu}$g.