• Applied Chemistry for Engineering
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• v.20 no.3
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• pp.335-338
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• 2009

As important intermediates for blue emitting materials of organic light-emitting diodes, bromotriphenylethylene derivatives for distrylarylenes are prepared by reactions of bromobenzophenone with benzylphosphonates. The reaction produces a 60 : 40 mixture of (Z)- and (E)-geometric isomers that are difficult to be resolved. The (Z)-isomer is successfully isolated by a selective recrystallization process using 2-propanol as a solvent. The X-ray structure analysis of (Z)-isomer shows that dihedral angles between tert-butylphenyl ring and bromophenyl ring and between bromophenyl ring and phenyl ring are $56.5(4)^{\circ}$ and $74.1(4)^{\circ}$, respectively.

• Applied Chemistry for Engineering
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• v.20 no.3
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• pp.339-345
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• 2009

The graft copolymerization of acrylonitrile-EPDM-styrene (AES) was investigated under various reaction conditions such as the concentration of initiator, the content of diene and viscosity of EPDM, and the concentration of solvents. The conversion increased but the molecular weight and the rubber particle size decreased with the concentration of initiator. The graft ratio(GR) increased at low concentrations of the initiator but, after the maximum value, it gradually decreased with the concentration of initiator. Toluene as a single solvent gave the highest conversion and the mixture of ethyl benzene and toluene was better than toluene. The rubber particle size increased with the viscosity of EPDM and the graft ratio and the number of rubber particles with occluded SANs increased with the content of diene.

• Polymer(Korea)
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• v.32 no.4
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• pp.366-371
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• 2008

The controlled/living cationic polymerization of $\alpha$-methylstyrene (${\alpha}MeSt$) and sequential block copolymerization of isobutylene (IB) with ${\alpha}MeSt$ were achieved using 2-chloro-2,4,4-trimethylpentane (TMPCl)/titanium tetrachloride ($TiCl_4$)/titanium isopropoxide ($Ti(OiPr)_4$)/2,6-ditert-butylpyridine (DtBP) initiating system in $CH_3Cl$/hexane(50/50 v/v) solvent mixture at $-80^{\circ}C$. The polymerization rate decreased with increasing $[Ti(OiPr)_4]/[TiCl_4]$ ratio in the homopolymerization of ${\alpha}MeSt$. The effects of $[Ti(OiPr)_4]/[TiCl_4]$ ratios and $PIB^+$ molecular weight on the polymerization rate and blocking efficiency were also investigated. Well-defined poly(isobutylene-b-$\alpha$-methylstyrene)s were demonstrated by $^1H$-NMR and triple detection SEC; refractive index (RI), multiangle laser light scattering (MALLS) and ultraviolet (UV) detectors. Blocking efficiencies for the poly(isobutylene-b-$\alpha$-methylstyrene)s of almost 100% were obtained when ${\alpha}MeSt$ was induced by PIB's of $M_n\;{\geq}\;41000$ at $[Ti(OiPr)_4]/[TiCl_4]=1$. Differential scanning calorimetry (DSC) of the block copolymers showed two glass transition temperatures, thereby demonstrating microphase separation.

• Bulletin of the Korean Chemical Society
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• v.31 no.7
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• pp.1997-2002
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• 2010

ZnSe and ZnS:Mn nanocrystals were synthesized via the thermal decomposition of their corresponding organometallic precursors in a hot coordinating solvent (TOP/TOPO) mixture. The organic surface capping agents were substituted with EDTA molecules to impart hydrophilic surface properties to the resulting nanocrystals. The optical properties of the water-dispersible nanocrystals were analyzed by UV-visible and room temperature solution photoluminescence (PL) spectroscopy. The powders were characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), and confocal laser scanning microscopy (CLSM). The solution PL spectra revealed emission peaks at 390 (ZnSe-EDTA) and 597 (ZnS:Mn-EDTA) nm with PL efficiencies of 4.0 (former) and 2.4% (latter), respectively. Two-photon spectra were obtained by fixing the excitation light source wavelengths at 616 nm (ZnSe-EDTA) and 560 nm (ZnS:Mn-EDTA). The emission peaks appeared at the same positions to that of the PL spectra but with lower peak intensity. In addition, the morphology and sizes of the nanocrystals were estimated from the corresponding HR-TEM images. The measured average particle sizes were 5.4 nm (ZnSe-EDTA) with a standard deviation of 1.2 nm, and 4.7 nm (ZnS:Mn-EDTA) with a standard deviation of 0.8 nm, respectively.

• Journal of the Korean Chemical Society
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• v.24 no.6
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• pp.444-451
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• 1980

In order to further elucidate the process of electron solvation in liquids, the medium effect, as the difference between the free energy of $H^+$ in aqueous and non-aqueous states (${\Delta}{\Delta}G_0$), of THF-water mixtures has been investigated. (${\Delta}{\Delta}G_0$) were determined by electromotive force masurements of the cell Pt$H_2Q$, Q, HCI, THF, $H_2O$|KC1 | $Hg_2Cl_2$|Hg(Pt), where $H_2Q$ and Q are hydroquinone and quinone respectively. The effect of dielectric constant on the difference of free energy and the absorption energy of solvated electrons have been studied. For the consideration of these effect the polymerization of water in THF has been studied. Near infrared spectrum of O-H stetching energy has been used to measure the extent of water aggregates. The expermental results indicate that at least in some composition of binary mixtures the electrons or other ions are solvated preferentially with one component of solvents.

• Food Science and Preservation
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• v.6 no.2
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• pp.206-215
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• 1999

Volatile flavor components in five varieties, Bekdo, Chundo, Yumung, Daegubo and Hwangdo, of peach (Prunus persica L.) were extracted by SDE (Simultaneous steam distillation and extraction) method using the mixture of n-pentane and diethylether(1:1, v/v) as an extract solvent. Analysis of the concentrate by capillary gas chromatography and gas chromatography-mass spectrometry led to the identification of 83, 85, 70, 74 and 66 components in Bekdo, Chundo, Yumung, Daegubo and Hwangdo, respectively. Aroma patterns (29 alcohols, 27 ketones, 18 aldehydes, 9 esters, 5 ethers, 3 acids, 6 terpene and derivatives, and 26 miscellaneous) were identified and quantified in five cultivars. Ethyl acetate, hexanal, o-xylene, (E)-2-hexenal, hexanol, (E)-2-hexen-1-ol, benzaldehyde, r-decalactone and r-dodecalactone were the main components in each samples, though there were several differences in composition of volatile components. Beside C$\_$6/ compounds, a series of saturated and unsaturated r- and $\delta$-lactones ranging from chain length C$\_$6/ to C$\_$l2/, with concentration maxima for r-decalactone and r-dodecalactone, were a major class of constituents. Lactones and peroxidation products of unsaturated fatty acid (i.e. C$\_$6/ aldehydes and alcohols) were major constituents of the extract.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.3
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• pp.211-215
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• 2000

Lipid extraction preceding fatty acid methyl esters preparation for gas-liquid chromatography is time-consuming and cumbersome. We performed one-step extraction/methylation method with a mixture of methanol-heptane-benzene-DMP-H$_2$SO$_4$ without prior fat extraction. The simultaneous digestion and lipid transmethylation takes place at 8$0^{\circ}C$ in a single phase. After cooling till room temperature, two phases are formed. The upper one of the phases contains the fatty acid methyl esters ready for GLC. The fatty acid composition of major industrial crops obtained by the one step extraction/methylation method (method 1 and 2) was almost identical with the fatty acid composition of the pure fats extracted with hexane by the Soxtec instrument (method 3). Due to its simplicity, speed, and reduced organic solvent the one-step extraction/methylation method (method 1 and 2) should be useful to determine overall fatty acid composition, especially in situations where many samples have to be analyzed.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.5
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• pp.116-125
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• 2014

Pyrolysis oil (PO), derived from biomass through fast pyrolysis process have the potential to displace significant amounts of petroleum fuels. The PO derived from wood has been regarded as an alternative fuel to be used in diesel engines. However, the use of PO in a diesel engine is very limited due to its poor properties like low energy density, low cetane number, high acidity and high viscosity of PO. Therefore, one of the easiest way to adopt PO to diesel engine without modifications is blended with other fuels that have high centane number. However, PO that has high amount of polar chemicals is immiscible with non polar hydrocarbons of diesel or biodiesel. Thus, to stabilize a homogeneous phase of diesel/biodiesel-PO blends, a proper surfactant should be used. Nevertheless, PO which was produced from different biomass type have varied characteristics and this complicates the selection of a suitable additive for a specific PO-diesel emulsion. In this regard, a more simple approach such as the use of a co-solvent like ethanol or butanol to induce a more stable phase of the PO-diesel mixture could be a promising alternative. In this study, a diesel engine operated with diesel/biodiesel-PO-butanol blends was experimentally investigated. Performance and gaseous & particle emission characteristics of a diesel engine were examined under the engine loads of IMEP 0.2 ~ 0.8MPa.

• Polymer(Korea)
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• v.27 no.3
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• pp.242-248
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• 2003

PP-g-(AN/Sty) was synthesized by grafting with acrylonitrile (AN) and styrene (Sty) onto PP staple fiber using an electron beam accelerator and followed by amidoximination and phosphorylation. Mole fraction of AN in the graft chain increased with the increase of the AN content in the monomer mixture. The highest AN grafting yield of 45% was obtained at a monomer ratio of 40 vol% AN/60 vol% Sty. Mole fraction of AN in the graft chain decreased with the increase of methanol amount used its solvent. As reaction temperature increased, the grafting yield of copolymer increased and reached equilibrium at 50$^{\circ}C$. Amount of amidoxime group in fibrous ion exchanger was increased as increasing amount of hydroxylamine, and the maximum content of amidoxime group was observed at 5.8 mmol/g with the 9 wt% hydroxylamine concentration. Content of phosphorous group in fibrous ion exchanger increased up to 0.5 N phosphoric acid concentration, and then leveled off. The adsorption ability of the copolymer for uranyl ion by the chelating adsorbents was in the following order : bifunctional PP-g-(AN/sty) > amidoximated PP-g-(AN/Sty) > phosphorylated PP-g-(AN/Sty).

• Applied Biological Chemistry
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• v.24 no.4
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• pp.238-244
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• 1981

The thin Layer chromatographic determination of ${\alpha}-solanine $ in potato tuber was investigated. The solanine was extracted with methanol-chloroform mixture (2 : 1, v/v) and precipitated as the crude glycoalkaloid by the addition of ammonium hydroxide. The solanine in the crude precipitate was separated by TLC using a solvent system of 1% $NH_4OH-absolute$ ethanol-chloroform (1:2:2, v/v). The purity of ${\alpha}-solanine $ was confirmed by infrared spectrophotometry. The ${\alpha}-solanine $ separated by TLC was determined at the wavelength of 310nm after coloration with concentrated sulfuric acid-1% paraformaldehyde, with the molar absorptivity of 2,090.