• Bulletin of the Korean Chemical Society
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• 제9권3호
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• pp.144-149
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• 1988

Reaction of thianthrene cation radical perchlorate (1) with 1-methyl-4-benzenesulfonylaminobenzene (10) afforded thianthrene (5), N-(4-tolyl)-N-thianthrenylbenzenesulfonamide (14), 1-methyl-3-[N-(4-tolyl)-N-benzenesulfonyl-amino- 4-benzene-sulfonylaminobenzene (16), cis-thianthrene-5,10-dioxide (17), 5-(3'-methyl-6-benzenesulfonylaminobenzene)thian threnium perchlorate (18), and benzenesulfonate. In the meantime, reaction of 1 with 1-ethyl-4-benzenesulfonylaminobenzene (12) afforded 5, 1-ethyl-3-[N-(4-ethylphenyl)-N-benzenesulfonyl]a mino-4-benzenesulfonylaminobenzene (19), 1-benzenesulfonyl-amino-4-[1-(2-benzenesulfonyla mino-5-ethylphenyl)ethyl]benzene (20), and 1-(1-acetamidoethyl)-4-benzenesulfonylaminobenz ene (21). The formations of these products except for 18 and benzenesulfonate could be rationalized by assuming a sulfonamidyl radical as an intermediate.

• Journal of Microbiology and Biotechnology
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• 제17권7호
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• pp.1098-1105
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• 2007

Quantum mechanical and molecular dynamics simulation analysis has been performed on the model system for CALB (Candida antarctica lipase B) with esters to study the reaction mechanism and conformational preference of catalytic hydrolysis and the esterification reaction. Using quantum mechanical analysis, the ping-pong bi-bi mechanism was applied and energies and 3-dimensional binding configurations of the whole reaction pathways were calculated. Further molecular dynamics simulation analysis was performed on the basis of the transition state obtained from quantum mechanical study to observe the effect of structures of the substrates. Calculation results using substrates of different chain length and chiral configurations were compared for conformational preference. The calculated results showed very small influence on chain length, whereas chiral conformation showed big differences. Calculated results from molecular modeling studies have been compared qualitatively with the experimental data using racemic mixtures of (${\pm}$)-cis-4-acetamido-cyclopent-2-ene-1-ethyl acetate as substrates.

• 멤브레인
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• 제23권4호
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• pp.283-289
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• 2013

Poly(vinyl alcohol) (PVA)에 대하여 가교제로써 glutaraldehyde (GA), maleic anhydride (MA)를 이용하여 제조한 코팅용액을 알칼리로 가수분해 시킨 poly acrylonitrile (PAN) 중공사 막표면에 코팅하여 막을 제조하였다. 제조된 막의 투과특성평가를 위해서 물/에탄올 혼합액에 대한 투과증발 실험을 수행하였다. $60^{\circ}C$의 90 wt%의 물/에탄올 혼합액에 대하여 반응온도 및 가교제의 농도변화에 따른 투과도 및 선택도를 측정하였다. 일반적으로 반응온도, 가교제 농도가 증가할 경우 투과도는 낮아지고, 선택도는 증가하는 경향을 보여주었다. 가교제로 GA의 대표적 결과는 반응온도 $120^{\circ}C$, GA 11 wt%로 투과도는 $165g/m^2hr$ 선택도는 81이고, MA는 반응온도 $120^{\circ}C$, MA 11 wt%로 투과도는 $174g/m^2hr$ 선택도는 73의 결과를 얻을 수 있었다.

• 멤브레인
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• 제23권4호
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• pp.312-318
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• 2013

Poly vinylidene fluoride (PVDF) 중공사막을 polyethylenimine (PEI)와 p-xylylene dichloride (XDC)를 이용해 친수화 시킨 후 poly(vinyl alcohol) (PVA)과 가교제인 poly(acrylic acid-co-maleic acid) (PAM) 혼합용액을 코팅하여 막을 제조하였다. 중공사막 표면의 코팅여부는 scanning electron microscope (SEM)을 통해 관찰하였으며, 막의 특성평가를 위해 물/에탄올 혼합액에 대한 투과증발 실험을 수행하였다. 공급액 조성은 90 wt% 에탄올 수용액을 사용하였으며, 가교제 농도, 공급액과 반응온도 변화에 따른 투과도 및 선택도를 측정하였다. 투과도는 반응온도 $100^{\circ}C$, PAM 농도 3 wt%, 공급액온도 $70^{\circ}C$에서 $1,480g/m^2hr$, 그리고 선택도는 반응온도 $100^{\circ}C$, PAM 농도 15 wt%, 공급액온도 $25^{\circ}C$에서 ${\alpha}_{W/E}=82$의 결과를 얻을 수 있었다.

• 폴리머
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• 제34권5호
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• pp.391-397
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• 2010

폴리아믹산(PAA)은 가교가 가능한 2중 결합을 갖는 bicyclo(2,2,2)oct-7-ene-2,3,5,6-tetracarboxy-licdianhydride(BTDA)와 bis[4-(3-aminophenoxy)phenyl] sulfone(BAPS)을 N,N-dimethylacetamide(DMAc) 용매에서 반응하여 얻어졌으며, 폴리이미드(PI) 필름은 PAA를 캐스팅하여 각각 다른 반응 온도에서 열처리를 통해 얻었다. 가교 온도를 $250{\sim}350^{\circ}C$까지 증가하여 얻은 가교된 PI의 열적-기계적 성질, 가교도, 광학적 특성을 열처리 온도에 따라 조사하였다. 열적-기계적 성질은 $350^{\circ}C$에서 열처리되었을 때 최대 값을 나타냈으며, 광학적 특성은 $250^{\circ}C$에서 열처리된 필름이 가장 우수한 광학특성을 보였다. $250{\sim}350^{\circ}C$까지 열처리에 따른 가교도는 NMR 상에서 85~93%를 나타냈다.

• 멤브레인
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• 제23권2호
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• pp.170-175
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• 2013

지지체인 Polyacrylonitrile (PAN) 중공사에 Poly (vinyl alcohol) (PVA)과 가교제인 Glutaraldehyde (GA)를 코팅하여 막을 제조하였으며, 특성평가를 위해 물/Isopropyl alcohol (IPA) 혼합액에 대한 투과증발 실험을 수행하였다. 코팅용액의 조성변화와 반응온도의 조건변화에 따른 투과도 및 선택도를 측정하였고, 공급액의 조성은 85 wt% IPA 수용액을 사용하였으며, 온도는 30, 50, 70, $90^{\circ}C$로 변화시켰다. 투과도는 PVA 3.5 wt%, 공급액 온도가 $90^{\circ}C$일 때 1,870 $g/m^2{\cdot}hr$, 선택도는 PVA 7 wt% 공급액 온도가 $30^{\circ}C$일 때 804로 가장 높은 값을 얻을 수 있었다.

• 대한화학회지
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• 제37권2호
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• pp.220-227
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• 1993

Lithiated 화합물인 $Cl_3$Si=$CHCH_2^tBu$로부터 LiCl의 제거반응에 의해 생성된 준안정 반응중간체인 Silaethene, $Cl_2$Si=$CHCH_2^tBu$은 propene, 2-methylpropene, 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, anthracene과 반응하여 엔반응 생성물, 2 + 2-, 2 + 4- 고리화부가생성물을 생성한다. 이들을 분별진공증류법에 의해 분리하였고 분광학적으로 확인하였다.

• Bulletin of the Korean Chemical Society
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• 제11권1호
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• pp.49-54
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• 1990

The gas-phase thermolysis reactions of ${\alpha}$- and ${\beta}$-methylated ethyl formates, Y = $CH-X-CHR_1CH_2R_2$ where X = Y = O or S and $R_1\;=\;R_2$ = H or $CH_3$, are investigated theoretically using the AM1 method. The experimental reactivity order is reproduced correctly by AM1 in all cases. The thermolysis proceeds through a six-membered cyclic transition state conforming to a retro-ene reaction, which can be conveniently interpreted using the frontier orbital theory of three-species interactions. The methyl group substituted at $C_{\alpha}\;or\;C_{\beta}$ is shown to elevate the ${\pi}$-HOMO of the donor fragment (Y = C) and depress the ${\sigma}^{\ast}$-LUMO of the acceptor fragment ($C_{\beta}$-H), increasing the nucleophilicity of Y toward ${\beta}$-hydrogen which in turn increases the reactivity. The two bond breaking processes of the $C_{\alpha}$-X and $C_{\beta}$-H bonds are concerted but not synchronous so that the reaction takes place in two stages as Taylor suggested. The initial cleavage of $C_{\alpha}$-X is of little importance but the subsequent scission of $C_{\beta}$-H occurs in a rate determining stage.

• Macromolecular Research
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• 제9권5호
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• pp.247-252
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• 2001

Tricyclic aliphatic dianhydride monomer, tricycle[4.2.2.0]dec-9-ene exo, endo-3,4: 7,8-tetra-carboxylicdianhydride (TCDDA), was synthesized by photochemical reaction and poly(amic acid)s from TCDDA and diamines such as 1,4-bis-(4-aminophenoxy)benzene (BAB), 2,2-bis(4-(4-aminophenoxy) phenyl) propane (BAPP), 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane (BAPHF), bis(4-(4-ami-nophenoxy) phenyl)sulfone (BAPS), and 1,4-bis-(4-aminophenoxy)biphenyl (BABP) were prepared. The inherent viscosities of the poly(amic acid)s were between 0.39 and 0.50 dL/g. The poly(amic acid)s were converted to polyimide films by thermal imidization. The glass transition temperatures (T$\_$g/) of the polyimides were in the range of 201-263$\^{C}$. The thermogravimetric analysis (TGA) thermogram of these polyimides showed the temperatures of 5% weight losses between 375 and 393$\^{C}$ in nitrogen atmosphere. To show their utility for image generation, degradations of these polyimides in UV exposure were investigated by UV spectroscopy.

• Bulletin of the Korean Chemical Society
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• 제11권1호
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• pp.31-33
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• 1990

We synthesized the novel complexes of (1,1-dimethyl-3,4-diphenyl-1-silacyclopenta-2,4-di ene-2,5-yldibenzene)bis(tricarbonylchromium) and tricarbonyl (R,R'-3,4,5-triphenyl-1-silacyclopenta-2,4-diene-2 -ylbenzene)chromium(R,R' = Me, R = Me/R' = Cl, R = Ph/R' = Cl) from the reaction of the corresponding R,R'-2,3,4,5-Tetraphenyl-1-silacyclopenta-2,4-dien e (abr. R,R'-TPSCp) with chromiumhexacarbonyl. These results reveal that chromium prefer to coordinate to the phenyl substituents of 1-silacyclospentadiene rather than the butadiene moiety of the ring.