• 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.

• Journal of Photoscience
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• v.9 no.2
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• pp.1-4
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• 2002

Hula-twist is a volume-conserving photoisomerization reaction mechanism postulated in 1985 to account for the rapid photoisomerization of the retinyl chromophore in rhodopsin. The requisite stereochemical consequence of simultaneous isomerization of a double bond and an adjacent single bond has recently been demonstrated in isomerization of pre-vitamin D in an organic glass and by many other examples of organic systems already reported in the literature This paper reports the consequence in applying the mechanism to the primary photochemical process of several photosensitive biopigments: bilirubin, photoactive yellow protein, bacteriorhodopsin and rhodopsin. It is shown that the anchored nature of the chromophores must first be taken into consideration.

• 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.

• Bulletin of the Korean Chemical Society
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• v.29 no.11
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• pp.2202-2204
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• 2008

• Bulletin of the Korean Chemical Society
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• v.7 no.6
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• pp.468-471
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• 1986

The isolated products from the reactions of $Rh(ClO_4)(CO)(PPh_3)_2$ (1) with CH_2$ = $CHCO_2C_2H_5$ (2) and trans-$CH_3CH$ = $CHCO_2C_2H_5$ (3) contain 80∼ 90% of $[Rh(CH_2 = CHCO_2C_2H_5)(CO)(PPh_3)_2]ClO_4$ (4) and [Rh(trans-$CH_3CH = CHCO_2C_2H_5(CO)(PPh_3)_2]ClO_4$ (5), respectively where 2 and 3 seem to be coordinated through the carbonyl oxygen. It has been found that complex 1 catalyzes the isomerization of $CH_2 = CH(CH_2)_8CO_2C_2H_5$ (6) to $CH_3(CH_2)_nCH = CH(CH_2)_{7-n}CO_2C_2H_5$ (n = 0∼7) under nitrogen at 25$^{\circ}C$. The isomerization of 6 is slower than that of $CH_2 = CH(CH_2)_9CH_3$ to $CH_3(CH_2)_nCH$ = $CH(CH_2)_{8-n}CH_3$ (n = 0∼8), which is understood in terms of the interactions between the carbonyl oxygen of 6 and the catalyst. It has been also observed that complex 1 catalyzes the hydrogenation of 2, 3, 6, trans-$C_6H_5CH = CHCO_2C_2H_5$ (7), $CH_3(CH_2)_7CH = CH(CH_2)_7CO_2C_2H_5$ (8) and $CH_2 = CH(CH_2)_9CH_3$ (9), and the isomerization (double bond migration) of 6 and 9 under hydrogen at 25$^{\circ}C$. The interactions between the carbonyl oxygen of the unsaturated esters and the catalyst affect the hydrogenation in such a way that the hydrogenation of the unsaturated esters becomes slower than that of simple olefins.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.231.1-231.1
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• 2002

The anaerobic pathway for unsaturated fatty acid biosynthesis was established in the 1960s in Escherichia coli. The double bond is introduced into the growing acyl chain by FabA., an enzyme capable of both the dehydration of ${\beta}$-hydroxdecanoyl-［acyl carrier protein］ (ACP) to trans-2-decenoyl-ACP. and the isomerization of trans-2 to cis-3-decenoyl-ACP. However. there are a number of anaerobic bacteria whose genomes do not contain a fabA homolog, but these organisms nonetheless produce unsaturated fatty acids. (omitted)

• The Korean Journal of Food And Nutrition
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• v.11 no.1
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• pp.26-30
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• 1998

It was determined the effect of deodorizing temperature on forming amount and its composition of trans fatty acids by GLC in corn oil. Trans fatty acids were detected a trace amount at the low temperature deodorizing as 240~25$0^{\circ}C$, but it s amounts were showed to 0.30, 0.57, 0.64 and 0.81% at the high temperature deodorizing as 255~27$0^{\circ}C$, respectively. The isomerization phenomenon was remarkably in order that double bond number might to increase, tt, and ttt type were not detected nearly, that the ct, tc, cct and tcc type were detected to the large amount, respectively.

• Archives of Pharmacal Research
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• v.29 no.10
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• pp.840-844
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• 2006

For the exploration of pharmacophoric moiety of malloapelta B (1) possessing the inhibitory activity of $NF-{\kappa}B$ activation, structural variation of ${\alpha},{\beta}-unsaturated$ carbonyl motif was attempted. 1 was reduced by catalytic hydrogenation, sodium borohydride, and lithium aluminumhydride. Catalytic hydrogenation with 30 psi or 15 psi of $H_2$ gas of 1 generated 8-butyl-5,7-dimethoxy-2,2-dimethylchroman (2) and 1-(5,7-dimethoxy-2,2-dimethylchroman-8-yl)butan-1-one (3), respectively. Reduction with sodium borohydride occurred at the double bond of ${\alpha},{\beta}-unsaturated$ ketone of 1 to give 1-(5,7-dimethoxy-2,2-dimethyl-2H-chromen-8-yl)butan-1-one (4). Reduction of 1 with lithium aluminumhydride and then quenched with methanol and water produced unexpected products, 1-(5,7-dimethoxy-2,2-dimethyl-2H-chromen-8-yl)-3-methoxy-1-butene (5) and 1-(5,7-dimethoxy-2,2-dimethyl-2H-chromen-8-yl)-3-hydroxy-1-butene (6). These are formed from the isomerization of initial product 9 through the continuous conjugate carbocation intermediate 11. Addition of ethylmagnesium bromide and dimethyl malonate anion to 1 gave the conjugate adducts 7 and 8. Ethylmagesium bromide and sodium borohydride reduction unusually gave the conjugate addition due to steric congestion around carbonyl group of 1. Compound 2 exhibits the reduced inhibitory activity against $NF-{\kappa}B$ activation and the others do not show the activity. Therefore ${\alpha},{\beta}-unsaturated$ carbonyl group of 1 should be important for its inhibitory activity.

• Journal of the Korean Wood Science and Technology
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• v.16 no.2
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• pp.79-89
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• 1988

This experiment was carried out to investigate the difference of compositions between petroleum ether extract and its tall oil in Pinus rigida Mill. xylem and to obtain the basic data on effective extraction and its utilization of by-product, resin and fatty acid, when pulp making. After both petroleum ether extract from wood meal and its tall oil in pitch pine were separated to the resin and fatty acid by using DEAE-Sephadex and aluminum oxide column, these were analyzed with gas chromatograph. The results obtained were as follows: 1. Fatty acids contained as ester form in living trees were varied by peroxide of organic solvent in petroleum ehter extraction and cooking chemicals in cooking. 2. Pimaric-type acid was eluted earlier than abietic-type acid in resin acids and the fewer the carbons, the earlier the elution in fatty acids. 3. The retention time of SE-30 column was even smaller than that of OV-101 column but the relative retention time obtained by using methyl pimarate and methyl stearate as internal standard was nearly identical. 4. Both petroleum ether extract and tall oil mainly consisted of resin acids, expecially abietic-type acid. 5. Tall oil had more fatty acid but less resin acid than petroleum ether extract. Also, the content of unidentified materials was increased owing to the isomerization and the shift of double bond position in unsaturated fatty acids by high temperature and cooking chemicals when cooking.