• Journal of the Korean Chemical Society
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• v.35 no.3
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• pp.226-232
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• 1991

Adsorption and oxidation of polychlorinated phenols by suspended ${\sigma}-MnO_2$ in aqueous solution have been studied. Of the proposed mechanism, adsorption reaction of chlorophenols onto ${\sigma}-MnO_2$(s) depended upon the pH of the solution and the concentration of chlorophenol. Adsorption isotherms showed a reasonably good fit to the Langmuir isotherm. From the pH dependence of adsorption partition coefficient and the linear relationship between octanol-water partition coefficient and adsorption partiton coefficient of chlorophenol, it is estimated that adsorption is dominated by its hydrophobicity. The rate of electron transfer reaction evaluated from the rate of reductive dissolution of ${\sigma}-MnO_2$(s) depended linearly upon the concentration of chlorophenol and the pH of medium. Observed rate constants ($K_0$) of the meta-substituted chlorophenol were lower than that of the ortho-or para-chlorophenol because of resonance effect of chlorophenoxy radical. It is indicated that this radical is produced in the adsorption process and the electron transfer reaction is rate determining.

• Journal of the Korean Chemical Society
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• v.65 no.1
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• pp.62-66
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• 2021

• Applied Chemistry for Engineering
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• v.25 no.1
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• pp.20-26
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• 2014

The interaction of p-halogenated phenol derivatives with the micellar system of tetradecyltrimethylammonium bromide (TTAB) was studied by the UV/Vis spectrophotometric method. Effects of substituents, additives, and temperatures on the solubilization of phenol derivatives have been measured. The results show that all the values of ${\Delta}G^o$ and ${\Delta}H^o$ were negative and the values of ${\Delta}S^o$ were positive for all phenol derivatives within the measured temperature range. The calculated thermodynamic parameters depended on the size, the electro-negativity, and the hydrophobic property of halogen substituents. The addition of n-butanol results in the decrement in tthe Ks values and the addition of NaCl caused the increment in the Ks values for all the phenol derivatives. From these changes we can postulate that the solubilization sites of the phenol derivatives in the micelle depend severely on properties of the halogen-substituent.

• Journal of the Korean Chemical Society
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• v.38 no.8
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• pp.562-569
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• 1994

The retention data of twenty one monosubstituted phenols in the eluent systems containing 30∼70% of methanol or acetonitrile as organic modifiers, on $ C_{18}$ and Phenyl columns were collected to investigate the effect of the substituted groups on the retention of phenols. The capacity factors of the solutes except amino phenols are greater on $ C_{18}$ than on Phenyl column. And all the solutes have shown greater capacity factors in methanol-water than that in acetonitrile-water as a mobile phase. Generally the elution order between meta and para isomers of monosubstituted phenols in consistent (p < m) regardless of the polarity of the substituted group. But the elution order between ortho and meta isomers of phenol varies with regard to the polarity of the substituted group. The retention of the monosubstituted phenols has been influenced by the interaction between the solute and unreacted silanol of columns as well as the interaction between the solute and $ C_{18}$ or phenyl group of columns. And then, the effect of unreacted silanol on the retention of the monosubstituted phenols is greater on $ C_{18}$ than on Phenyl column. And the greater hydrogen bonding acceptor basicity(${\beta}$) of the substituted group is, the greater this effect is. The relationship between the retention of the monosubstituted phenols and their parameters such as van der Waals volume(VWV) and hydrogen bonding acceptor basicity(${\beta}$) has been investigated. The good linearity has been observed in the plot log k' vs. (1.01VWV/100-1.84${\beta}$). In consequence, the retention of the monosubstituted phenols on $ C_{18}$ and Phenyl columns can be easily predicted by the parameter (1.01VWV/100-1.84${\beta}$).

• Korean Chemical Engineering Research
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• v.46 no.2
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• pp.301-309
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• 2008

In this study, the effect of formaldehyde to phenol (F/P) molar ratios, catalyst wt%, and reaction temperature on the chemical structure was studied utilizing a two-level full factorial experimental design. The effect of three variables on the chemical structure was analyzed by using three-way ANOVA of SPSS. Concentration of methyrol-substituted phenols after 300 min addition reaction increased with higher the F/P mole ratio, lower the reaction temperature and lower the catalyst wt%. Resol catalysed by barium hydroxide showed higher addition of formaldehyde onto ortho positions of phenolic rings. A simplified elementary reaction model for resole type phenolic resin formation which do not consider the dissociation of phenolic compounds and the fraction of formaldehyde in the form of methylene glycol was proposed and compared with Zavitsas' type models. Elementary reaction model showed error of 2.79% compared to the error of 3.27% in Zavitsas' type models. It was thought that the elementary reaction model could be used to predict the behavior of addition reaction in resol formation.

• Journal of the Korean Chemical Society
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• v.31 no.5
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• pp.464-470
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• 1987

7-Substituted 2-aminophenazine-5,10-dioxides were synthesized by the reaction of 4-aminophenol with 6-substituted benzofuroxan derivatives which had been obtained from aniline derivatives bearing methoxy, methyl, acetyl, and nitro group at the para position. 2-Aminophenazine-5,10-dioxide was also prepared by the reaction of 4-aminophenol with benzofuroxan. The antimicrobial activities of these phenazine dioxide derivatives were investigated in terms of minimum inhibitory concentration by the common twofold dilution technique. It was observed that the antimicrobial activity of the phenazine dioxides bearing electron releasing substituents was stronger than that of those bearing electron withdrawing substituents. From this result, it was concluded that the antimicrobial activity of phenazine dioxide derivative has a direct relationship with the electronic effect of the substituents.

• Journal of the Korean Chemical Society
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• v.43 no.5
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• pp.11-606
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• 1999

• Journal of the Korean Chemical Society
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• v.24 no.5
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• pp.337-341
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• 1980

Radical formation reaction of phenolic antioxidants were examined MO theoretically. Results show that substitution of electron-donating alkyl groups in phenol increases the rate of phenoxy radical formation when attacked by an electrophilic radical by stabilization of cationic transition state.

• Journal of the Korean Chemical Society
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• v.43 no.2
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• pp.237-240
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• 1999

• Journal of the Korean Chemical Society
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• v.45 no.5
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• pp.500-504
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• 2001