• Applied Chemistry for Engineering
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• v.26 no.3
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• pp.366-371
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• 2015

The kinetic behavior of tetrahydrotricyclopentadiene (THTCPD) isomerization was studied by using two kinds of chloroaluminate ionic liquid (IL) catalyst with different Lewis acidity. THTCPD isomerization pathway was discussed under the different temperature and time as reaction parameters using IL catalysts consisting of 1-butyl-3-methylimidazolun chloride $(BMIC)/AlCl_3$ with low acidity and pyridine hydrochloride $(PHC)/AlCl_3$ with high acidity. The conversion of THTCPD isomerization increased with increasing Lewis acidity of IL catalyst. The THTCPD isomerization pathway changed as a function of reaction temperature and catalyst acidity. In the case of $BMIC/AlCl_3$ IL catalyst, THTCPD isomerization pathway was similar to that of using conventional $AlCl_3$ catalyst. However, two different types of additional pathways (endo, exo, endo-NB ${\rightarrow}$ exo, exo, endo-NB ${\rightarrow}$ exo, exo, exo-NB and endo, exo, endo-NB ${\rightarrow}$ exo, exo, endo-NB ${\rightarrow}$ exo, exo, exo-CP) were appeared when using $PHC/AlCl_3$ IL catalyst.

• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.1851-1858
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• 2011

Details of the double-bond isomerization of 1-hexene over H-ZSM-5 were clarified using density functional theory. It is found that the reaction proceeds by a mechanism which involves the Br${\o}$nsted acid part of the zeolite solely. According to this mechanism, 1-hexene is first physically adsorbed on the acidic site, and then, the acidic proton transfers to one carbon atom of the double bond, while the other carbon atom of the double bond bonds with the Br${\o}$nsted host oxygen, yielding a stable alkoxy intermediate. Thereafter, the Br${\o}$nsted host oxygen abstracts a hydrogen atom from the $C_6H_{13}$ fragment and the C-O bond is broken, restoring the acidic site and yielding trans-2-hexene. The calculated activation barrier is 12.65 kcal/mol, which is in good agreement with the experimental value. These results well explain the energetic aspects during the course of double-bond isomerization and extend the understanding of the nature of the zeolite active sites.

• Polymer(Korea)
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• v.34 no.1
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• pp.69-73
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• 2010

Effects of reaction time and temperature on the isomerization and dehydrobromination reactions of brominated butyl rubber were investigated. The structural composition of brominated butyl rubber was determined by Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance spectroscopy($^1H$-NMR), Density functional theory (DFT) was used to study on the isomerization and dehydrobromination mechanisms of model compounds. The geometries for model compounds of 3-bromo-5,5,7,7-tetramethyl-2(2',2',4',4'-tetramethyl)pentyl-1-octylene (3BrOE), 1-bromo-5,5,7,7-tetramethyl-2(2',2',4',4'-tetramethyl)pentyl-2-octylene (1Br2OE) and 5,5,7,7-tetramethyl-2(2',2', 4',4'-tetramethyl)pentyl-1,3-octadiene (CD) had been optimized by using density functional theory at B3LYP/3-21G and B3LYP/6-31G levels. The predicted energy of 3BrOE lies higher than that of 1Br2OE which suggests that 1Br2OE configuration is more stable than the 3BrOE configuration. Compared with the energy barrier, the pathway of dehydrobromination is less competitive than that of isomerization. This is qualitatively consistent with the experimental results.

• Korean Chemical Engineering Research
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• v.43 no.5
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• pp.566-570
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• 2005

The study on the hydrogenation and isomerization of unsaturated bicyclic hydrcarbon compounds using methylcyclopentadiene dimer (MCPD) was carried out. Exo compound was prepared through isomerization reaction after two hydrogenation reaction steps. In the first hydrogenation reaction which needs one mole of hydrogen, the formation rate of monomer was increased as dimer was decomposed at reaction temperature above $100^{\circ}C$. At first hydrogenation, DHDMCPD [dihydrodi(methylcyclopentadiene)] was formed and second hydrogenation was proceeded to produce THDMCPD [tetrahydrodi(methylcyclopentadiene)], the ratio of exo to endo THDMCPD was varied by the control of 2nd hydrogenation temperature. To improve the process, continuous 1st and 2nd hydrogenation conditions were established by using the 2nd stage heat controllable reactor. Also, catalytic activities were compared by the use of halogenized aluminum, metal halides and solid acids catalysts on the isomerization reaction from endo to exo THDMCPD.

• Korean Chemical Engineering Research
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• v.45 no.4
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• pp.351-355
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• 2007

It is necessary to convert butene-2 into butene-1 with higher added-values through positional isomerization. In this study, hydro-isomerization of butene-2 with hydrogen over Pd/alumina catalysts was investigated in a fixed bed reactor. The yield of butene-1 over Ld-265 catalyst was higher than that over other catalysts. The yield of butene-1 was highest (5.3%) under the conditions of reaction temperature of $75^{\circ}C$, reaction pressure of 150 psig, 2-butene flow rate of 48 cc/h and hydrogen flow rate of 3 cc/min. We conducted simulation for the process composed of a hydro-isomerization reactor and a distillation tower. In the case of 78% of tray efficiency, we obtained over 99% pure butene-1 through a distillation tower with 171 steps (R=120).

• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.692-696
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• 2008

There is not much method of using C4 Raffinate III, despite having high olefin contents. The majority of the C4 Raffinate III have been converted into n-butane through hydrogenation, and sold as LPG. The C4 Raffinate III is rich 2-butenes with very low isobutene and isobutene contents. The 2-butenes are converted into 1-butene in the vicinity of thermodynamic equilibrium yield through positional isomerization with n-almumina catalyst calcinated at $400{\sim}600^{\circ}C$. The overall process is composed of isomerization-reactor, de-1-buteneizer to prepare the reactants and to enrich reactive products, and 1-butene column to product a high purity 1-butene. The production of 1-butene increases by 40~60 wt% with the selective positional isomerization from the existing separation method.

• Journal of Photoscience
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• v.5 no.2
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• pp.47-51
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• 1998

Direct irradiation of 1Z,3E-1-cyano-1,4-diphenylbutadiene (2) and 1Z,3E-1-cyano-3-methyl-1,4-diphenylbutadiene (3) in organic solvents viz. n-hexane, methanol and acetonitrile results in preferential isomerization of the double bond substituted with cyano group via one-photon-one-bond isomerization process. The quantum efficiency of the isomerization of 3 is more than 2 in all the three solvents. Photoproducts of 2 and 3 (viz. 2a, 2b, 3a, 3b) also exhibited similar photoisomerization trends. The results are discussed in terms of the effects of substituents on the potential energy surface of the excited singlet states of $\alpha$,$\omega$-diphenylpolyenes, and the role of zwitterionic dipolar species in the photoisomerization process of linearly conjugated C=C polyenes is highlighted.

• Journal of the Korean Chemical Society
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• v.20 no.4
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• pp.290-294
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• 1976

Radiation-induced cis-trans isomerization of ${\beta}$-styrylnaphthalene is studied by determination of G values and the radiostationary states. The results are compared with data obtained in direct and sensitized photoisomerization of the compound. Both the excited singlet and triplet states are involved in the isomerization of ${\beta}$-styrylnaphthalene in the radiolysis of benzene solution.

• Bulletin of the Korean Chemical Society
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• v.33 no.11
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• pp.3740-3744
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• 2012

We synthesized three different derivatives of bis-spiropyran using simple organic reactions with high yields. BSP1, a derivative of bis-spiropyran having a connection at the position 6' and BSP2, a derivative of bis-spiropyran having a connection at the position 5 and BSP3, a derivative of bis-spiropyran containing a dithienylethene group between two spiropyran moieties were synthesized. The optical properties of BSPs were characterized. UV-Vis spectra showed that BSPs exhibit reversible photo-isomerization and the efficiency of photo-isomerization is highly dependent on the position of nitro group. BSPs having nitro group at para position of hydroxy group showed the higher efficiency of photo-isomerization that the one having nitro group at ortho position. The optical microscope images obtained under ultraviolet or visible light exposure demonstrated that the formation of nanorods can be reversibly controlled by optical signal.

• Proceedings of the KAIS Fall Conference
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• 2004.11a
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• pp.280-283
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• 2004

Effect of H2 spillover rate as function of reduction temperature on reaction kinetics was evaluated. Reaction kinetics including yield, conversion, activation energy and selectivity of 1-butene isomerization over Pt/HxMoO/SiO were measured as reaction temperature was increased. While conversion of 1-butane was decreased, yield of iso-butene was increased. Two kinds of reaction mechanism were proposed from the change of selectivity as function of temperature.