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이익춘;박형연;한인숙;김창곤;김찬경;이본수
- Bulletin of the Korean Chemical Society
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- v.20 no.5
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- pp.559-566
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- 1999
Gas-phase alkylations of delocalized ambident anions, Y---CH---X- where X, Y=CH2, O, or S, have been investigated theoretically at the MP2/6-31+G*//MP2/6-31+G* and QCISD/6-31+G*//MP2/6-31+G* lev-els. O-and S-alkylations (X=O and S) are more favored kinetically by ΔE^≠ = 4.6 and 9.8 kcal mol-1 than the respective C-alkylations even though they are thermodynamically less favored by 22.4 and 6.0 kcal mol-1 respectively. It was found that the transition structures for the C-alkylations are imbalanced due to the endoergic rehybridi-zation of the carbon center from sp2 to sp3 which leads to premature bond contraction of the C-Y bond and delayed bond stretching of the C-X bond. In the O-, or S-alkylation, such endoergic process is not required since the σ-lone pair on O or S is involved in the initial stage of alkylation. The imbalanced TSs for the C-alkylation are accompanied by higher intrinsic barriers and deformation energies.
https://doi.org/10.5012/bkcs.1999.20.5.559 인용 PDF

Hong, Sung Hee;Lee, Wha Young;Song, In Kyu
- Applied Chemistry for Engineering
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- v.8 no.2
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- pp.211-219
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- 1997
Liquid or gas phase alkylation of isobutane with 1-butene for i-octane production was carried out over Cs- or $NH_4$-exchanged $H_3PW_{12}O_{40}$. Pretreatment temperature of the catalyst played an important role on the catalytic activity of heteropoly acids in the liquid phase alkylation. Cation-exchanged $H_3PW_{12}O_{40}$ showed a better total yield and i-octane selectivity than the mother acid in the liquid phase alkylation, and $(NH_4)_{2.5}H_{0.5}PW_{12}O_{40}$ was more efficient than $Cs_{2.5}H_{0.5}PW_{12}O_{40}$ in terms of i-octane selectivity. It was found that the acidic property (deactivation of acid sites) of the catalyst was closely related to the catalytic activity of Cs- or $NH_4$-exchanged $H_3PW_{12}O_{40}$ in the gas phase alkylation. $C_5-C_7$ were mainly formed in the early stage of gas phase alkylation due to the strong acidic property of the catalyst, whereas $C_8$ and $+C_9$ were mainly produced as the reaction proceeded due to the deactivation of acid sites. $Cs_{2.5}H_{0.5}PW_{12}O_{40}$ showed the highest total yield in the gas phase alkylation among the catalysts examined.
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Jew, Sang-Sup;Lee, Jeong-Hee;Yoo, Mi-Sook;Lee, Yeon-Ju;Jeong, Byeong-Seon;Park, Boon-Saeng;Kim, Myoung-Goo;Park, Hyeung-Geun
- Proceedings of the PSK Conference
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- 2003.04a
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- pp.252.1-252.1
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- 2003
Systematic investigations to develop an efficient enantioselective synthetic method for a-alkyl-alanine by the catalytic phase-transfer alkylation were performed. The alkylation of 2-naphthyl aldimine tert-butyl ester, 1 E with RbOH and O(9)-allyl-N-2'3'4'-trifluorobenzylhydrocinchonidinium bromide, 6, at \ulcorner5 \ulcorner\ulcorner showed the highest enantioselectivities, up to 96％ ee.
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Park, Hae-Sun;Park, Myung-Sook;Choi, Hee-Jeon;Kwon, Soon-Kyoung
- Proceedings of the PSK Conference
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- 2003.04a
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- pp.244.2-244.2
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- 2003
For the development of new synthetic method for unnatural amino acid esters, alkyl ${\alpha}$-anilinophenylacetates were synthesized through base-catalyzed hydrolysis of 1,5-diphenylhydantoins in methanol and O-alkylation of sodium ${\alpha}$-anilinophenylacetate with alkyl halides in DMF. Even though hydrolysis of hydantoin ring was undertaken under about 30-40$^{\circ}C$ in methanol, the hydantoic acid sodium salt was continuously converted to the sodium ${\alpha}$-anilinophenylacetate. (omitted)
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