• 약학회지
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• 제39권1호
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• pp.36-40
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• 1995

In order to investigate the biological activity of protoberberine derivatives, they were synthesized four derivatives (1-4) of 7,8 adduct of cycloberberine, two derivatives (5, 6) treated with alkylamine or phenylamine, four compounds (7, 8) and (9, 10) adduct with 1,3-dichloroacetone and oxalychloride. Antibacterial activity of these synthesized compounds was tested.

• Bulletin of the Korean Chemical Society
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• 제32권6호
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• pp.1921-1924
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• 2011

Nitrile-forming eliminations from $(E)-2,4,6-(NO_2)_3C_6H_2CH=NOC_6H_4-2-X-4-NO_2$ (1) promoted by $R_3NH/R_3NH^+$ in 70 mol % MeCN(aq) have been studied kinetically. When X = $NO_2$, the reactions exhibited second-order kinetics as well as Br$\"{o}$nsted ${\beta}$ = 0.63 and ${\mid}{\beta}_{lg}{\mid}$ = 0.34-0.46, and an E2 mechanism is evident. As the leaving group was made poorer (X = H, Cl, and $CF_3$), Br$\"{o}$nsted ${\beta}$ value increased from 0.63 to 0.85-0.89 without much change in the ${\mid}{\beta}_{lg}{\mid}$ value E2, indicating that structure of the transition state changed to an E1cb-like with extensive $C_{\beta}-H$ bond cleavage, significant negative charge development at the ${\beta}$-carbon, and limited $C_{\alpha}$-OAr bond cleavage.

• Bulletin of the Korean Chemical Society
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• 제29권8호
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• pp.1441-1442
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• 2008

• 한국의류학회지
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• 제13권1호
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• pp.59-66
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• 1989

This paper is concerned with formaldehyde release from durable press finished rayon fabrics. $100\%$ rayon fabrics were treated with 3 kinds of commercial N-methylol crosslinking agents using a pad-dry cure technique. Aqueous extractions of fabric samples were carried out at $40^{\circ}C$ under pH's of 4, 7, 10. Formaldehyde release was evaluated for the types of resins, catalyst concentrations and extraction conditions. Results indicated that the higher concentration of catalyst leads to the more fixation of resin on the fabric. Total formaldehyde released to the extract was decreased as the catalyst concentration increased. For the resin types, the amount of formaldehyde released was in the order of DMU>MDMDHEU>DMDHEU. Free formaldehyde content in the extract was in the order of pH10>pH4>pH7. This result proved that resins are least resistant to alkaline hydrolysis and the N-C bond cleavage under alkaline condition. Under acidic condition, however, N-methylol formaldehyde was accumulated before the release of free formaldehyde. This suggested the C·0 bond cleavalge to form carbonium - immonim intermediate.

• 대한화학회지
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• 제34권3호
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• pp.227-231
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• 1990

50-100% $CH_3CN-CH_3OH$ 혼합용매계에서 파라-치환된 질산벤질과 아닐린과의 친핵성 치환반응에 대한 2차 속도상수를 전기전도도법으로 구하였다. 속도자료를 이용하여 Hammett ${\rho}_N$과 ${\rho}_C$값, Bronsted $\beta$값 및 용매화 파라미터 계수들을 구하였으며 이들을 PES및 양자역학 모형에 적용하여 구조 변화를 논의하였다. 연구 결과 결합형성보다 결합절단이 비교적 많이 진행된 상태에서 치환기 변화에 따라 결합절단의 진척이 결합형성을 촉진하는 동시적 $S_N2$ 반응메카니즘으로 진행됨을 알았다.

• Bulletin of the Korean Chemical Society
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• 제7권2호
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• pp.111-113
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• 1986

The axial alcohol in trans-3,3,5-trimethylcyclohexanol was oxidized more readily than the equatorial alcohol in cis-3,3,5-trimethylcyclohexanol by NBS in aqueous dioxane. On the contrary, the equatorial alcohol was preferentially oxidized to the axial one by 10% aqueous sodium hypochlorite in the presence of tetrabutylammonium hydrogen sulfate (TBHS). The specificity indicates the presence of two different mechanism. In acidic medium, the cleavage of C-H bond is rate determining step while the reactivity of the alcohol is important in the presence of TBHS. The mechanism in basic medium without TBHS will be discussed.

• 대한화학회지
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• 제23권1호
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• pp.37-41
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• 1979

Benzyl m-nitrobenzenesulfonate와 N,N-dimethylaniline類와의 反應速度를 아세톤 溶媒에서 電氣傳導度法으로 測定하였다. N,N-디메틸아닐린의 反應性에 關한 置換基效果와 直線 自由에너지 關係를 考察하였다. 反應速度常數 k는 2.55∼487 $10^{-4}l{\cdot}mol^{-l}{\cdot}sec^{-1} (35^{\circ}C)$였으며 置換基가 電子를 주는 能力이 클수록 反應은 빨랐다. Hammett 도시에서 置換基常數 ${\sigma}$와 ${\sigma}p$-MeO = -0.35의 새로운 값을 使用했을때 ${\rho}$ = -1.37의 좋은 直線이 얻어졌다. 本反應의 경우 r값은 브롬화벤질에 比해 큰 값을 가졌다. Bronsted 圖示에서 溶媒效果에 基因된 p-MeO基를 除外하고는 좋은 直線이 얻어졌으며 C${\cdot}{\cdot}{\cdot}$O 結合의 쪼개짐이 結合 形成보다 優先的인 $S_N2$ 轉移狀態를 갖는다고 推定된다.

• 대한화학회지
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• 제35권6호
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• pp.673-679
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• 1991

N-Tert-butylbenzothiazole-2-sulfenamide (TBBS;가황촉진제)의 전기화학적 환원을 직류와 시차펄스 폴라로그래피, 순환 전압전류법, 조절전위 전기량법으로 연구하였다. TBBS의 전극환원과정은 단일 환원파(-2.31 volts vs. Ag/0.1M AgN$O_3$)에서 비가역으로 4전자가 이동하는 E-C-E-C 반응기구로 진행되었다. 조절전위 전기분해 결과 sulfenamide(-S-N=)결합이 끊어지고 mercaptobenzothiazole (MBT)과 유리된 황 그리고 benzothiazole disulfide (MBT dimer) 등이 생성물로 얻어졌다. 생성물의 분석결과와 pH변화에 따른 폴라로그램의 해석을 바탕으로 전기화학적 반응기구를 제안하였다.

• 대한화학회지
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• 제35권6호
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• pp.680-688
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• 1991

N-Oxyldiethylenebenzothiazole-2-sulfenamide (ODBS;가황산촉진제)의 전기화학적 환원을 직류와 시차펄스 폴라로그래피 순환 전압전류법, 조절전위 전기량법으로 연구하였다. ODBS의 전극환원과정은 단일 환원파(-1.86 volts vs. Ag/0.1 M AgN$O_3$in AN)에서 비가역으로 3전자가 이동하는 E-C-E-C 반응 메카니즘으로 진행되었다. 조절전위 전기분해 결과 SULFENAMIDE(-S-N=) 결합이 끊어지고 mercaptobenzothiazole(MBT)과 benzothiazole disulfide(MBT dimer) 그리고 유리된 sulfur 등이 생성물로 얻어졌따. pH 변화에 따른 폴라로그램의 해석과 생성물 분석의 결과를 바탕으로하여 전기화학적 반응 메카니즘을 제안하였다.

• Bulletin of the Korean Chemical Society
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• 제26권4호
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• pp.641-644
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• 2005

Nucleophilic addition reactions of benzylamines $(XC_6H_4CH_2NH_2)\;to\;{\beta}$-cyanostilbenes ($YC_6H_4CH=C(CN)C_6H_4$Y’) have been studied in acetonitrile at 30.0 oC. A greater degree of N-$C_{\alpha}$ bond formation (larger ${\beta}_X$) is obtained with a stronger electron-withdrawing substituent in either ${\alpha}-\;(\delta\sigma_Y\;{\gt}\;0)\;or\;{\beta}-ring\;(\delta\sigma_{Y'}\;{\gt}$ 0). A stronger charge development is observed in the TS on $C_{\beta}\;(\rho_{Y'}$= 1.06 for X=Y=H) rather than on $C_{\alpha}\;(\rho_{Y}$ = 0.62 for X=Y’H) indicating the lag in the resonance development into the activating group (CN) on $C_{\beta}$ in the transition state. Similarly, the magnitude of $\rho$$_{XY'}$(−0.72) is greater than $\rho_{XY}$ (−0.66) due to a stronger interaction of the nucleophile with $\beta$-ring than $\alpha$-ring. The positive sign of $\rho_{YY'}$correctly reflects $\pi$ bond cleavage between the two rings in the TS. Relatively large kinetic isotope effects ($k_H/k_D\;{\geq}$ 2.0) involving deuterated nucleophiles ($XC_6H_4CH_2ND_2$) suggest a four-membered cyclic TS in which concurrent N-C$_{\alpha}$ and H(D)-C$_{\beta}$ bond formation occurs.