• Journal of the Korean Chemical Society
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• v.21 no.4
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• pp.262-269
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• 1977

The solvolysis of 1-naphthalene-and 2-naphthalenesulfonyl chlorides in acetone-water mixtures have been studied by means of conductometry. The solvent effect and mechanism have been discussed in terms of variation in solvent composition and activation parameters. The reaction was predominantly $S_N2$ type, but bond breaking increased with the increase of water content. The rate constant for 1-naphthyl compound was smaller than that of 2-naphthyl compound due to the ground state stabilization effect and peri-hydrogen effect, and the latter effect was similar to that in ethanol-water mixtures.

• Journal of the Korean Chemical Society
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• v.37 no.8
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• pp.695-701
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• 1993

Rate constants of solvolysis of 2-thiophenesulfonyl chloride were determined in aqueous binary mixtures with methanol, ethanol, acetone in water and in methanol. These data are interpreted using the equation of Grunwald-Winstein and Kivinen relationship. Also, kinetic solvent isotope effects in water and in methanol and product selectivities in alcohol-water mixtures were determined. Kinetic solvent isotope effect for hydrolysis of 2-thiopenesulfonyl chloride was 2.24 and 1.47 for methanol and water, respectively. Selectivity values for formation of ester relative to acid in ethanol-water mixtures show maximum S value. From kinetic solvent isotope effect in methanol and water, selectivity data in aqueous alcoholic solvents and solvent effects, it is proposed that the reaction channel favoured in low polarity solvents is general-base catalysis and/or is possibly addition elimination (S$_A$N) reaction pathway and in high polarity solvents iS S$_N$2 reaction mechanism.

• Journal of the Korean Chemical Society
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• v.24 no.6
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• pp.413-420
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• 1980

Die Geschwindigkeitskonstanten der Solvolyse-Reaktionen von 9-Chlormethylanthracen wurden bei verschiedenen Temperaturen in unterschiedlichen binadren Losungsmittelgemischen (Wasser/Aceton, Wasser/Acetonitril, Wasser/Methanol, Wasser/Athanol) mit Hilfe der Leitfahigkeitsmeßungen bestimmt. Die Aktivierungsparameter $E_a$, ${\Delta}H^{\neq}$ und ${\Delta}S^{\neq}$ wurden berechnet. Die Meßergebnisse deuten darauf hin, daß die Solvolyse von 9-Chlormethylanthracen in protonischen Losungsmitteln schneller ablauft als in aprotonischen Losungsmitteln; in den Meßreihen mit protonsichen bzw. mit aprotonischen Losungsmitteln steigt die Reaktionsgeschwindigkeit mit der Zunahme der Dielektrizitatskonstanten des Losungsmittels an, und die Aktivierungsparameter nehmen mit steigendem Wassergehalt zu. Es wurde festgestellt, daß die Reaktion nach einem $S_N1$-Mechanismus ablauft. Die experimentellen Daten deuten darauf hin, daß Wasser einerseits als Nucleophil und andererseits als allgemeine Base am Reaktionsmechanismus beteiligt ist.

• Journal of the Korean Chemical Society
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• v.31 no.1
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• pp.25-30
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• 1987

Solvolysis of tert-butyl halides and 1-adamantyl tosylate in methanol-acetone mixtures and solvolysis of tert-butyl bromide in methanol-chloroform mixtures have been studied. Solvent ionizing power of methanol-acetone mixtures were calculated by the Grunwald-Winstein equation and discussed the Y value variation caused by substrate changes. Y values based on 1-adamantyl tosylate is superion to others since it varies in wide range for methanol-acetone mixtures. It was found that the order of electrophilic assistance to leaving group is OTs > Cl > Br > I.

• Journal of the Korean Chemical Society
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• v.34 no.1
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• pp.10-18
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• 1990

Solvolyses of p-substituted benzyl bromides have been studied in dimethylsulfoxide-water and N,N-dimethylformamide-water mixtures by kinetic method. To determine the ionizing power, Y and the nucleophilicity, $N_{BS}$, the solvolyses of 1-adamantyl halides, t-butyl halides, and methyl tosylate in the same solvent mixtures have been investigated. The solvatochromic parameters for each dimethylsulfoxide-water mixtures have been determined by substituting into the Taft's linear solvatochromic energy relationships with measured $ν_{max}$. The solvolyses of p-substituted benzyl bromides have been found to proceed by borderline mechanism in which bond formation is more advanced than bond cleavage in the transition state based on the m, l values and ${\beta},{\rho}_s$, values.

• Korean Chemical Engineering Research
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• v.45 no.3
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• pp.209-214
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• 2007

Sr hexaaluminate($Sr_{1-x}La_xMnAl_{11}O_{19-\alpha}$) were prepared by sol-gel method of metal alkoxide with 1-butanol or ethylene glycol as a solvent. The physical properties of prepared hexaaluminates were examined by TG/DTA, XRD and $N_2$ adsorption. When ethylene glycol was used as a solvent, the decomposition reaction and dehydroxylation reaction was observed above $400^{\circ}C$ and the temperature of the formation of a crystal structure of hexaaluminate was also increased resulting in small specific surface area and low catalytic activity of methane compared to Sr-hexaaluminate with 1-butanol.

• Journal of the Korean Chemical Society
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• v.24 no.4
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• pp.288-294
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• 1980

Methanolysis rate constants were determined for $CH_3O(CO)Cl,\;CH_3S(CO)Cl\;and\;CH_3S(CS)Cl\;in\;CH_3OH-CH_3CN$ mixtures. Results show that the rates are not predominantly influenced by the bulk solvent properties but are partly influenced by specific electrophilic solvation.Polarity of the solvent is not a dominant factor but it nevertheless plays a role in charge stabilization of the $S_N1$ like transition state. The methanolysis proceeds through $S_N1$ mechanism for $CH_3S(CS)Cl$ for which both specific solvation of leaving group by methanol and charge stabilization by a high dielectric medium are important, while for $CH_3O(CO)Cl\;methanolysis occurs\;via\;S_N2$ mechanism in which both of the solvent effects are unimportant.

• Journal of the Korean Chemical Society
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• v.31 no.5
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• pp.419-424
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• 1987

Kinetic studies on the solvolysis of para-methyl benzyl nitrate and benzyl nitrate were carried out in aqueous methanol, ethanol, acetonitrile, acetone, tetrahydrofuran and dioxane mixtures at 60$^{\circ}$C. The rates were faster in protic solvent mixtures than in aprotic solvent mixtures. This was considered in the light of transition state stabilization by hydrogen bonding solvation of protic solvent mixtures. Grunwald-Winstein equation, extended Grunwald-Winstein equation and correlation between E$_T$(30) and rate constant were applied in order to discuss the transition state variations caused by changing benzyl substituents and solvents. The results showed that strong electrophilic assistance of solvent is operative in the the water-rich solvents.

• The Korean Journal of Mycology
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• v.11 no.3
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• pp.115-119
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• 1983

The bioconversion of progesterone by Aspergillus phoenicis has been studied. The metabolism in the conditions of experiment gave $11{\alpha}-hydroxyprogesterone$ as main product. The concentration of $11{\alpha}-hydroxyprogesterone$ increased monotonically and leveled off after 40 hours of incubation. Addition of glucose into the medium reduced considerably the time for attaining limiting concentration of $11{\alpha}-hydroxyprogesterone$. The increase in initial progesterone concentration did not affected the percentage of conversion nor the time required for termination of the reaction. But it could not be represented as first order reaction with respect to progesterone concentration. The degree of inhibition of enzymes by organic solvents depended upon the concentration of solvents. At low solvent concentration, acetone proved to yield the highest conversion.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.230-230
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• 2003

Chalcopyrite 구조를 가진 CuInSe$_2$ (CIS) 나노입자를 유기용매인 diethylamine을 사용하여 autoclave안에서 용매열법(solvothermal method)으로 제조하였다. 180 $^{\circ}C$에서 36시간 반응시켜 길이가 10-30 nm, 폭이 5-10 nm인 rod-Eke 형상을 한 CIS 나노입자를 얻었다. 반응온도를 25$0^{\circ}C$로 증가시키고 동일한 반응시간에서 보다 미세하고 균일한 구형의 CIS 나노입자를 관찰할 수 있었다. 한편, 190 $^{\circ}C$에서 얻어진 CIS 나노입자는 36시간을 반응시킨 경우 구형으로 관찰되었으나 60시간 반응시킨 경우는 길이가 50-100 nm 인 rod-like 입자로 성장하였다. 이와 같이 반응시간과 온도를 달리하여 나노입자의 형상이 바뀌는 것을 입자성장기구의 관점에서 고찰하였다. 반응시간과 온도에 따라 얻어진 CIS 나노 입자들의 결정성, 미세구조 그리고 정량 및 정성분석을 XRD, SEM, TEM, EDS등으로 각각 행하였다.