• Bulletin of the Korean Chemical Society
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• v.10 no.1
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• pp.102-103
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• 1989

Four coordinated rhodium(Ⅰ) complexes, Rh($ClO_4$)(CO)$(PPh_3)_2$ and [$Rh(CO)(PPh_3)_3$]$ClO_4$(2) catalyze the iosmerization of allylic alcohols to the corresponding carbonyl compounds at room temperature under nitrogen. The isomerization is faster with 2 than with 1, which is understood in terms of relative ease of the last step of the catalytic cycle, the reductive elimination of enol. Relative rates of the isomerization with 1 and 2 for different allylic alcohols are also explained by the relative ease of the enol elimination step in part. The first step of the catalytic cycle, the complex formation of the allylic alcohol through the ${\pi}-system$ of the olefinic group of the allylic alcohol and the following step, formation of hydridoallyl complex also seem to affect the overall rate of the isomerization.

• Bulletin of the Korean Chemical Society
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• v.13 no.1
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• pp.65-70
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• 1992

The hindered internal rotation effect of methyl group on chemical reaction was studied for cis-trans isomerization reaction of 1-bromopropene system using RRKM technique. A comparative study of the isomerization rates was also performed between the rigid and allowed internal rotations. The calculated rate of rigid cis-trans isomerization of 1-bromopropene was shown to be three times higher than its other halogenated propene homologues with its internal rotations and found to be in good agreement with experimental observations. These findings could be explained reasonably well in terms of the differences of the rotational barrier heights among halogenated propenes and correlated with the relatively low internal rotation barrier of cis-1-bromopropene, 230 cal/mol, compared to those of other cis-1-halopropenes, 700-800 cal/mol, and trans-1-halopropenes, 2.0-2.4 kcal/mol.

• Bulletin of the Korean Chemical Society
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• v.17 no.12
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• pp.1147-1149
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• 1996

The trans (2a)-cis (2b) isomerization of [Me2Al(μ-NHtBu)]2 (2) has been studied by 1H NMR spectroscopy. The equilibrium has been observed to follow reversible first order kinetics with ΔH0=2.22±0.07 kJmol-1 and ΔS0=2.85±0.07 JK-1mol-1. The activation parameters for the conversion 2a→2b are ΔH1=49.7±2.3 kJmol-1 and ΔS1=-126.3±0.2 JK-1mo1-1 and for the reverse reaction 2b→2a are ΔH-1=47.5±2.3 kJmol-1 and ΔS-1=-129.1±0.5 JK-1mol-1. The isomerization is markedly accelerated in the presence of Lewis bases. A crossover experiment indicates that the isomer interconversion is a unimolecular process. The large negative entropies of activation suggest either the existence of a sterically congested intermediate or the participation of solvent in the isomerization process.

• Bulletin of the Korean Chemical Society
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• v.26 no.3
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• pp.461-462
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• 2005

• Bulletin of the Korean Chemical Society
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• v.22 no.7
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• pp.659-660
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• 2001

• Korean Journal of Food Science and Technology
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• v.31 no.6
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• pp.1453-1457
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• 1999

The optimal conditions of alkali isomerization to obtain conjugated linoleic acid (CLA) concentrate from vegetable oils which have antioxidant and anticarcinogenic properties were studied. The result of alkali isomerization of various vegetable oils indicated that CLA content of safflower oil which contains more linoleic acid than any other vegetable oils was the highest of all experimental vegetable oils. During alkali isomerization, the amount of cis-9, trans-11 CLA and total CLA content in safflower oil was the highest at $8{\sim}11%$ KOH concentration and $180{\sim}185^{\circ}C$. But heating time had no effect on CLA formation after $20{\sim}40$ minutes. As a result of alkali isomerization of neutral lipid, glycolipid and phospholipid in safflower oil, CLA content of neutral lipid class was higher than any other lipid classes. By urea treatment and HPLC fractionation, total CLA content in alkali-isomerized safflower oil increased to 95.4% from 78.9%.

• Bulletin of the Korean Chemical Society
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• v.27 no.5
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• pp.776-778
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• 2006

• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.701-704
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• 2011

• Bulletin of the Korean Chemical Society
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• v.26 no.7
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• pp.1107-1108
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• 2005

• Bulletin of the Korean Chemical Society
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• v.30 no.3
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• pp.735-738
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• 2009