• YAKHAK HOEJI
• /
• v.39 no.1
• /
• pp.36-40
• /
• 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
• /
• v.32 no.6
• /
• pp.1921-1924
• /
• 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
• /
• v.29 no.8
• /
• pp.1441-1442
• /
• 2008

• Journal of the Korean Society of Clothing and Textiles
• /
• v.13 no.1 s.29
• /
• pp.59-66
• /
• 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.

• Journal of the Korean Chemical Society
• /
• v.34 no.3
• /
• pp.227-231
• /
• 1990

Kinetic studies on the nucleophilic reactions of p-substituted benzylnitrates with substituted anilines have been conductometically carried out in 50-100% $CH_3CN-CH_3OH$ mixtures. From the kinetic data, Hammett ${\rho}_C$ and ${\rho}_N$ values, Bronsted $\beta$ values, and solvatochromic coefficients were determined in order to examine the transition state variations caused by changes in substituents and solvent properties. It is concluded that the reaction proceeds via a synchronous $S_N2$ mechanism in which bond formation is more advanced than bond cleavage.

• Bulletin of the Korean Chemical Society
• /
• v.7 no.2
• /
• pp.111-113
• /
• 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.

• Journal of the Korean Chemical Society
• /
• v.23 no.1
• /
• pp.37-41
• /
• 1979

The kinetics of the reaction of benzyl m-nitrobenzenesulfonate with m-and p-substituted N,N-dimethylanilines in acetone have been investigated by an electric conductivity method. The effects of substituents on the reactivity of N,N-dimethylaniline and the existence of linear free energy relationship were discussed. The rate constants k were in the range 2.55∼487 $10^{-4}l{\cdot}mol^{-l}{\cdot}sec^{-1} (35^{\circ}C)$ and increased with the electron donating ability of substituents. In the present reaction, the Hammett plot was correlated with ${\sigma}$ substituent constant, especially using the new ${\sigma}$ value of 0.35 in p-MeO and it's ${\rho}$ value was found to be -1.37. r value for the reaction was very large than the value obtained in the reaction of benzyl bromide. $Br{\"{o}}nsted$ linear relationship was shown between rate constant and basicites except for p-MeO resulted from solvent effect. From the Bronsted plot, this reaction was suggested that the cleavage of the C${\cdot}{\cdot}{\cdot}$O bond in the $S_N2$ transition state proceed the bond formation.

• Journal of the Korean Chemical Society
• /
• v.35 no.6
• /
• pp.673-679
• /
• 1991

The electrochemical reduction of N-tert-butylbenzothiazole-2-sulfenamide (TBBS; vulcanization accelerator) was investigated by direct current, differential pulse polarography, cyclic voltammetry and controlled potential coulometry. The electrode reduction of TBBS proceeded E-C-E-C reaction mechanism by four electrons transfer at irreversible one wave (-2.31 volts vs. Ag/0.1M AgN$O_3$ in AN). As the results of controlled potential electrolysis, mercaptobenzothiazole (MBT), benzothiazole disulfide (MBT dimer) and extricated sulfur were products which followed by cleavage of the sulfenamide (-S-N=) bond. Upon the basis of products analysis and polarogram interpretation with pH variable, electrochemical reaction mechanism was suggested.

• Journal of the Korean Chemical Society
• /
• v.35 no.6
• /
• pp.680-688
• /
• 1991

The electrochemical reduction of N-oxyldiethylenebenzothiazole-2-sulfenamide (ODBS; vulcanization accelerator) was investigated by direct current polarography, differential pulse polarography, cyclic voltammetry and controlled potential coulometry. The irreversible electrode reduction of ODBS proceeded E-C-E-C reaction mechanism by three electrons transfer with irreversible one wave (-1.86 volts vs. Ag/0.1 M AgN$O_3$ in AN). As the results of controlled potential electrolysis, mercaptobenzothiazole (MBT), benzothiazole disulfide (MBT dimer) and extricated sulfur were products which followed by cleavage of the sulfenamide (-S-N=) bond. Upo the basis of products analysis and polarogram interpretation witli pH variable, electrochemical reaction mechanism was suggested.

• Bulletin of the Korean Chemical Society
• /
• v.26 no.4
• /
• pp.641-644
• /
• 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.