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RISS 인기검색어
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- 저자 : Byung Hoo Kong (검색결과 4 건)
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PMO Theory of Orbital Interactions (Part 7). $\sigma-\pi$ Interactions
Kong, Byung-Hoo,Lee, Byung-Choon,Lee, Ik-Choon,Yang, Ki-Yull Korean Chemical Society 1985 Bulletin of the Korean Chemical Society Vol.6 No.5
Orbital interactions of the types, ${\sigma}-{\pi},\;{\sigma}^*-{\pi},\;{\sigma}-{\pi}^*\;and\;{\sigma}^*-{\pi}^*$ are investigated for the rotamers of ${\alpha}$-X-acetones (X = F and Cl) using STO-3G method of calculation. It was found that the interactions are possible only in gauche forms, and the ${\sigma}^*-{\pi}^*$ interactions are in general greater than the $\sigma-\pi$ interactions due to the greater overlap, in spite of the greater energy gap involved; the greater ${\sigma}^*-{\pi}^*$ interaction causes greater lowering of ${\pi}^*$ level relative to the lowering of ${\sigma}$ in the ${\sigma}-{\pi}$ interaction so that both ${\sigma}-{\pi}^*$ and $n-{\pi}^*$ interactions are enhanced in the gauche forms. The extra stability of the gauche form and the red shift in the $n-{\pi}^*$ transition are thus found to be natural corollaries of the greater ${\sigma}^*-{\pi}^*$ interaction in the gauche forms.
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채정병,공승환,김동재,김라진,김태영,이승후,Chae, Jung-Byung,Kong, Seung-Whan,Kim, Dong-Jae,Kim, La-Jin,Kim, Tae-Young,Lee, Seung-Hoo 대한고유수용성신경근촉진법학회 2008 PNF and Movement Vol.6 No.2
Purpose : This study was performed for find out temporal spatial parameter of the gait according to age. Method : Four groups of healthy people were allocated randomly in this study : group I(little child, 15), group II(child, 18) and group III(young people, 17), group(elder people, 16). This study was performed from 01 December to 31 December in 2007. Results : The results were as follows : 1. The swing phase was the longest group II, group IV was the shortest. Each groups, there was significant difference in swing phase(p<.05). 2. The stance phase was the longest group IV, group II was the shortest. Each groups, there was significant difference in stance phase(p<.05). 3. The single support time was the longest group II, group IV was the shortest. Each groups, there was significant difference in single support time(p<.05). 4. The double support time was the longest group IV, group II was the shortest. Each groups, there was significant difference in double support time(p<.05). 5. The gait velocity was the fastest group II, group I was the slowest. Each groups, there was significant difference in gait velocity(p<.05). 6. The toe in/out was very increased group IV, group I was very decreased. Each groups, there was significant difference in toe in/out(p<.05). 7. The cadence was the highest group I, group IV was the lowest. Each groups, there was significant difference in cadence(p<.05). 8. The step length was the longest group III, group I was the shortest. Each groups, there was significant difference in step length(p<.05). 9. The step length asymmetry ratio was the highest group IV, group III was the lowest. Each groups, there was no significant difference in step length asymmetry ratio(p>.05). 10. The single support time asymmetry ratio was the highest group I, group IV was the lowest. Each groups, there was no significant difference in single support time asymmetry ratio (p>.05). 11. The FAP was the highest group III, group I was the lowest. Each groups, there was significant difference in FAP(p<.05).
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혼합용매에서의 용매화 (제 5 보) : 메탄올-아세톤 혼합용매계에서 tert-Butyl Halides와 1-Adamantyl Tosylate의 가용매 분해반응
이익춘,나상무,공병후,이본수,손세철,Ikchoon Lee,Sang-Mu La,Byung Hoo Kong,Bon-Su Lee,Se Chul Sohn 대한화학회 1987 대한화학회지 Vol.31 No.1
Solvolysis of tert-butyl halides and 1-adamantyl tosylate in methanol-acetone mixtures and solvolysis of tert-butyl bromide in methanol-chloroform mixtures have been studied. Solvent ionizing power of methanol-acetone mixtures were calculated by the Grunwald-Winstein equation and discussed the Y value variation caused by substrate changes. Y values based on 1-adamantyl tosylate is superion to others since it varies in wide range for methanol-acetone mixtures. It was found that the order of electrophilic assistance to leaving group is OTs > Cl > Br > I. 메탄올-아세톤 혼합용매에서 tert-butyl halides와 1-adamantyl tosylate 가용매 분해반응과 메탄올-클로로포름 혼합용매계에서 tert-butyl bromide의 가용매 분해반응을 연구하였다. 메탄올-아세톤 혼합용매의 이온화 능력의 척도를 구하였으며 기질의 변화에 따른 Y값의 변화를 논의하였다. 메탄올-아세톤 혼합용매계의 Y값은 1-adamantyl tosylate를 이용하여 구한 값이 가장 좋은 결과를 줌을 알 수 있었으며 용매에 의한 이탈기의 OTs > Cl > Br > I순서로 커짐을 알 수 있었다.
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${\alpha}$-치환 아세톤의 궤도간 상호작용과 형태에 관한 이론적 연구
이익춘,양기열,김왕기,공병후,이병춘,Ikchoon Lee,Kiyull Yang,Wang Ki Kim,Byung Hoo Kong,Byung Choon Lee 대한화학회 1986 대한화학회지 Vol.30 No.1
${\alpha}$-치환아세톤($CH_2XCOCH_3$, X = F, Cl, OH, SH 및 $NH_2$)의 상대적 형태안정성을 결정하기 위하여 MNDO 및 STO-3G계산을 수행하였다. 계산결과 cis형이 더 안정한 F 및 $NH_2$ 치환 아세톤의 경우를 제외하고 모두 gauche형에 해당하는 형태이성체가 안정함을 밝혔다. gauche형에 대한 안정성은 ${\sigma}_{cx}$와 ${\pi}_{co}^*$궤도간의 two-orbital-two-electron상호작용에 의한 것으로 생각되며 이것은 gauche형에서의 vicinal overlap이 상당히 크다는 점과 두 궤도간의 에너지간격이 작다는 점에서 비롯된다. 아울러 이러한 에너지간격의 좁힘현상은 ${\sigma}_{cx}^*$-${\pi}_{co}^*$궤도간의 hyperconjugation상호작용 때문에 ${\pi}_{co}^*$궤도가 낮아졌기 때문이다. 또한 gauche형에서의 여러가지 ${\sigma}-{\pi}$상호작용들은 X가 Cl 및 SH인 3주기 원자들에게 더 강함을 보였다. 한편 질소원자의 비결합궤도함수 $n_N$과 인접 C-C ${\sigma}$결합의 상호작용은 cis일 경우 보다 trans배향일 경우에 더 강하였다. MNDO and STO-3G calculations were performed to determine relative stabilities of rotamers for ${\alpha}$-substituted acetones, $CH_2XCOCH_3$, X = F, Cl, OH, SH, and $NH_2$. It was found that rotamers corresponding to gauche forms are preferred for all the ${\alpha}$-substituents except for X = F and NH$_2$, for which the cis forms were the preferred ones. The stability of gauche form was dictated by the stabilizing two-orbital-two-electron interaction ${\sigma}_{cx}$-${\pi}_{co}^*$, operating uniquely in the gauche form due to the substantial vicinal overlap and energy gap narrowing between ${\sigma}_{cx}$ and ${\pi}_{co}^*$ orbitals. The energy gap narrowing was caused by the lowering of ${\pi}_{co}^*$ level due to the hyperconjugative ${\sigma}_{cx}^*$-${\pi}_{co}^*$ interactions; the red shift in the n-${\pi}^*$ transition was another effect of the relatively large ${\sigma}_{cx}^*$-${\pi}_{co}^*$ splitting. Various ${\sigma}-{\pi}$ interactions in the gauche form were found to be stronger in the third-row hetero atom system, X = Cl and SH. Interactions between nonbonding orbital on N, $n_N$ and vicinal C-C ${\sigma}$ bond were shown to be stronger in the trans than in the cis orientation.
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