• Journal of the Korean Chemical Society
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• v.12 no.3
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• pp.85-88
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• 1968

The resonance parameter value between the saturated carbon and unsaturated carbon atom in cyclopentadiene has been evaluated. And then cyclopentadiene has been investigated on the correlations between it's electronic structures and reactivities by means of the extended Huckel method proposed by R. Hoffmann.

• Bulletin of the Korean Chemical Society
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• v.29 no.6
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• pp.1224-1228
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• 2008

The reaction of internal diynes and cyclopentadiene in the presence of 5 mol % of cobalt catalysts proceeded under 5 atm of carbon monoxide pressure to give a high yield of the corresponding [2+2+2] cycloaddition product. By lowering carbon monoxide pressure from 30 atm to 5atm, cyclopentadiene can be used as a dienophile in the cobalt carbonyl-catalyzed [2+2+2] cycloaddition reaction between internal diynes and cyclopentadiene.

• Journal of the Korean Chemical Society
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• v.13 no.1
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• pp.75-82
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• 1969

4-Ethyltropolone has been prepared in three steps from cyclopentadiene by a dichloroketene process, and at the same time, a comparison has also been made with the case of tropolone synthesis. In the addition reaction of dichloroketene to cyclopentadiene as well as to ethylcyclopentadiene, and also in the separation of cycloadducts from reaction mixture, the best results were given by prevention of the reactants from dimerization. Under these condition, the yields of cycloadducts were around 70% for both. Tropolone and 4-ethyltropolone were obtained in the yield of 51% and 32%, respectively, by hydrolysis of cycloadducts with potassium acetate in aqueous acetic acid. These results revealed that the steric effect of ethylgroup was more sensitive to the hydrolysis than to the cycloaddition reaction. A comparison of UV, IR and NMR spectroscopic results of 4-ethyltropolone with those of tropolone was also made together with a brief discussion of the tropolone ring system and ethylgroup effect.

• Bulletin of the Korean Chemical Society
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• v.23 no.6
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• pp.829-837
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• 2002

Recently it was reported that cycloaddition of 6,6-disubstituted cyclohexa-2,4-dienone, 1 with cyclopentadiene gave solely the adduct of type 1.while its reaction with 1,3-cyclohexadiene gave both Ⅱ and Ⅲ. Semiempirical MO calculations were done to elucidate the origin of the selectivity difference between the two dienes. Cycloaddition of 1 with cyclopentadiene is controlled thermodynamically to give only 1-diene adduct by ΔGvalues of 10.6-20.3 kcal/mol, while its reaction with 1,3-cyclohexadiene does not show 1-diene/1-dienophile selectivity due to similar stabilities of the two adducts. Thermodynamic parameters also show that 두애 adducts are more fabourably fromed in the cycloadditions of 1 with both cyclopentadiene and 1,3-cyclohexadiene, which coincides with experimental observations. Cope rearrangements of endo adducts are another avenue to convert between 1-diene and 1-dienophile.

• Bulletin of the Korean Chemical Society
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• v.6 no.6
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• pp.348-350
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• 1985

The compound 1,1,3,4-tetramethyl-1-sila-3-cyclopentene was obtained through the reaction of 2,3-dimethylbutadiene and dichlorodimethyl-silane in THF in the presence of sodium metal. After the bromination of this compound at $0^{\circ}C$ for 2 hrs and dehydrobromination by using a base, we prepared 1.1.3.4-tetramethyl-1-sila-2,4-cyclopentadiene, Which could undergo dimerization. The identification has been done by using $^1H-,^{13}C-$ and C/H-Correlation two dimensional nmr spectroscopies.

• Environmental Engineering Research
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• v.12 no.5
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• pp.211-217
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• 2007

Polycyclic aromatic hydrocarbon growth from cyclopentadiene (CPD) pyrolysis was investigated using a laminar flow reactor operating in a temperature range of 600 to $950^{\circ}c$. Major products from CPD pyrolysis are benzene, indene and naphthalene. Formation of observed products from CPD is explained as follows. Addition of the cyclopentadienyl radical to a CPD $\pi$-bond produces a resonance-stabilized radical, which further reacts by one of three unimolecular channels: intramolecular addition, C-H bond $\beta$-scission, or C-C bond $\beta$-scission. The intramolecular addition pathway produces a 7-norbornenyl radical, which then decomposes to indene. Decomposition by C-H bond $\beta$-scission produces a biaryl intermediate, which then undergoes a ring fusion sequence that has been proposed for dihydrofulvalene-to-naphthalene conversion. In this study, we propose C-C bond $\beta$-scission pathway as an alternative reaction channel to naphthalene from CPD. As preliminary computational analysis, Parametric Method 3 (PM3) molecular calculation suggests that intramolecular addition to form indene is favored at low temperatures and C-C bond $\beta$-scission leading to naphthalene is predominant at high temperatures.

• Bulletin of the Korean Chemical Society
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• v.28 no.8
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• pp.1299-1304
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• 2007

New sulfur functionalized cyclopentadiene ligands, 1-[2-(thioanisole)]-2,5-dimethylcyclopentadiene (3), 1-[2- (thioanisole)]-2,3,5-trimethylcyclopentadiene (4), and 1-[2-(thioanisole)]-2,3,4,5-tetramethylcyclopentadiene (5), were prepared. In these ligands, the S-donor atom is connected to a cyclopentadiene ring by a rigid phenylene spacer. CpCo(III)-diiodo half-sandwich complexes (6-8) were obtained from reaction the ligands (3- 5) with Co2(CO)8, followed by treatment of I2. Substitution reaction of CpCo(III)-diiodo complexes with MeLi yielded the corresponding CpCo(III)-dimethyl complexes (9-11). Further transformation to the corresponding cationic cobalt complexes (12-14) were achieved by reaction of the CpCo(III)-dimethyl complexes with HB(ArF)4·2Et2O and trapping with CD3CN. The new sulfur functionalized cyclopentadiene ligands having a rigid phenylene spacer and the corresponding cobalt complexes were characterized by 1H, 13C and 19F NMR spectroscopy. The diiodo Complex 6 was also characterized by a single crystal X-ray diffraction method.

• Applied Chemistry for Engineering
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• v.23 no.6
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• pp.614-617
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• 2012

Ti-containing zeolite was synthesised and used in the epoxidation of di-cyclopentadiene (DCPD). Among various Ti-zeolite catalysts, Y contained Ti-zeolite showed the highest yield in the epoxidation of DCPD. The study was also investigated in terms of the Ti content in the catalysts, $H_2O_2$/substrate ratio, reaction temperature and applied time. The reaction conditions significantly influenced on both the catalytic activity and selectivity. In addition, Ti structure in the zeolite was analyzed using IR and UV-vis spectroscopy.

• Bulletin of the Korean Chemical Society
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• v.20 no.4
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• pp.389-391
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• 1999

• Journal of the Korean Chemical Society
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• v.13 no.1
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• pp.89-95
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• 1969

The structural investigations on the adducts, formed from dichloroketene with cyclopentadiene, methyl and ethylcyclopentadiene, have been carried out by means of infrared and nuclear magnetic resonance spectroscopy and also by their chemical behaviors. It was confirmed by this study that the adducts were formed by 1, 2-cycloaddition reaction and had the fundamental structure of bicyclo [3. 2. 0]-7,7-dichloro-2-heptene-6-one. These results were well agreed with the hypothesis that a diradical intermediate was formed as the first step in 1, 2-cycloaddition. The reaction mechanism for the process in which tropolones were formed from these adducts was also discussed.