• Bulletin of the Korean Chemical Society
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• v.20 no.5
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• pp.551-555
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• 1999

11-Deoxydaunomycinone 15 and 10-fluoroanthracyclinone derivatives 9, 10 were obtained. Naphthalenone 4 prepared from 2-(2,4-pentadienyl)-1,3-dioxane 2 with methyl vinyl ketone and hydrolysis with HClO4 was condensed with phthalidesulfone 5 through Michael type reaction, and was converted to 7 by epoxidation. Epoxide 7 was transformed to trione 12 using reduction-oxidation or hydrofluorination process, and then to 15 by introducing several functional groups. Compound 8 obtained in the course of the reaction of epoxide 7 and HF/ Pyr was used for the synthesis of compounds 9, 10.

• Bulletin of the Korean Chemical Society
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• v.12 no.6
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• pp.649-652
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• 1991

The reaction of primary aromatic amines with 1,7-heptanediol in the presence of a catalytic amount of ruthenium complex in dioxane at $180^{\circ}C$ for 24 hours gave the corresponding 1-substituted perhydroazocines in moderate yield.

• Proceedings of the PSK Conference
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• 2000.04a
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• pp.162.1-162.1
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• 2000

• Journal of Photoscience
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• v.12 no.1
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• pp.51-54
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• 2005

The electronic excitationenergy quenching of 2, 5-diphenyl-1, 3, 4-oxadiazole (PPD) by Carbon tetrachloride ($CCl_4$) in different solvents viz, n-hexane, n-heptane, toluene, benzene, cyclohexane, 1, 4- dioxane has been carried out at room temperature to understand the role of quenching mechanism. The Stern-Volmer plots have been found to be linear. As probability of quenching per encounter 'p' is less than unity, and the activation energy for quenching '$E_a$' is greater than the activation energy of diffusion '$E_d$', it is inferred that the fluorescence quenching mechanism is not due to material diffusion alone.

• Journal of the Korean Chemical Society
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• v.31 no.4
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• pp.352-358
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• 1987

Rate constants for the hydrolysis of para-substituted phenyl N-(p-chlorobenzoyl)chloroformimidate (I) derivatives in 1 : 4 dioxane-water at $25^{\circ}C$ have been determined. Rate data, substituent effect $(\rho\>{\rho}^+)$, product analysis and MO calculation indicate that the uncatalyzed reaction proceeds through an $S_N1$ mechanism involving the formation of azocarbonium ion (II) below pH 3.0, and the base-catalyzed reaction proceeds through an $S_N2$ mechanism via transition state (III) above pH 4.0. The relative stability of four peri planar conformational isomers were (E-ap) > (Z-ap) > (E-sp) > (Z-ap), respectively, and the most stable stereo structures shows that the Y-substituted phenyl group $(C_6H_4-Y)$ occupy vertical $(90^{\circ})$ position on the plane of the benzimidochloroformyl group in (E-ap) conformer. The nucleophilic substitution of water molecule occurs by sigma attack to the activatived azomethine carbon atom of (I) derivatives.

• Journal of the Korean Chemical Society
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• v.20 no.3
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• pp.221-228
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• 1976

The kinetics of hydrolysis of hydrazonyl bromides $(p-H,\;p-CH_3,\;p-OCH_3,\;p-Br,\;p-Cl\;&\;p-NO_2)$ have been investigated by UV spectrometry in $60{\%}$ dioxane-water at $25^{\circ}C$ and a rate equation which can be applied over wide pH range was obtained. Below pH2, the rate of hydrolysis of a series of hydrazonyl bromide is accelerated by electrondonating group (${\rho}$ = -0. 94) whereas at the pH values greater than 4, the ${\rho}$-value is 0.54. The rate equation, solvent-, substituent-and bromide ion-effect on the rate of hydrolysis are rationalized in terms of $S_N1$ and $S_N2$ mechanism: below pH 2, the hydrolysis proceed through $S_N2$, however, above pH 4, the hydrolysis is started by the attack of hydroxide ion and in the range pH 2{\sim}$4, these two reactions occur competitively.

• Applied Chemistry for Engineering
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• v.4 no.3
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• pp.497-504
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• 1993

The effect of DCCA (Drying Control Chemical Additives) on the drying of gel was investigated in order to determine an optimum drying condition of mullite precursor through sol-gel process. Aluminium sec-butoxide was synthesized from aluminium foil and then mullite powders were synthesized from Tetra-ethyl-ortho-silicate (TEOS) and the aluminium sec-butoxide. N, N-dimethyl formamide (DMF), Glycerol, 1, 4-Dioxane, and Oxalic acid were used as DCCA. Mullite powders that were calcined at 200, 900, 1100, and $1250^{\circ}C$ for 2hr were analysed by XRD, TG-DTA, FT-IR, and SEM in order to investigate structural change and characteristics of calcined powders. The results of this work showed that the drying time of gel was reduced to about half in the presence of 0.1mol DMF compared with the absence of DCCA and also calcined powders were obtained without remarkable structural change despite of the addition of DCCA.

• Textile Coloration and Finishing
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• v.11 no.5
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• pp.44-54
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• 1999

Poly(ethylene 2,6-naphthalate), PEN, is a relatively well-known polymer used for engineering purposes. Naphthalene ring provides rigidity to the polymer backbone, thus, it elevated the glass transition temperature and enhanced mechanical properties. The structure and properties of PEN affect a processing conditions severely, and the high-thermal stability have been had a poor thermal processibility. Hence, the basic mechanism of solvent drawing, is very much the same as that of thermal drawing from glassy state since both involve the inducement of segmental mobility. The former achieves the goal by use of chemical energy, and the latter does so by use of thermal energy. Generally, the sorption of the solvent by the polymer has a plasticizing effect, and leads to a lowering of the glass transition temperature, $T_g$. In this paper, the dynamic viscoelasticity behavior in liquid-drawing process of an unoriented amorphous PEN films were investigated using Rheovibron. The results are as follows ： (1) For the drawing in silicone oil, the drawing below $T_g$. had $\alpha{2}$-dispersion due to an inhomogeneous taut structure. (2) For the drawing in water, the inhomogeneous taut structure reduced by the effect of plasticization even below $T_g$. (3) For the drawing in butanol, the only aliphatic segment in PEN have some molecular mobility but the mobility of the aromatic segment having naphthalene ring is nearly impossible. (4) For the drawing in dioxane/water mixing solvent, the solvent effect is complementary each other and accordingly the entire molecular conformation have stable state. (5) For the drawing in dioxane/butanol mixing solvent, the inhomogeneity of the taut structure and the aromatic segment increase with increasing the temperature and this tendencies correspond with that of the draw ratio.

• Analytical Science and Technology
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• v.5 no.4
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• pp.443-454
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• 1992

The analysis, hydrolysis mechanism, oxidation, reduction, thermal decomposition and metabolism of irritant materials such as chloroacetophenone isomers, bromophenylacetonitrile isomers, o-chlorobenzylidenemalononitrile(CS), and ethylisothiocyanate, etc. are interested in forensic science. We had studied hydrolysis of CS in 10% MeOH-$H_2O$ and 10% dioxane-$H_2O$ at pH 1.0~11.0 and various temperatures. As a result, we identified o-chlorobenzaldehyde and malononitrile that were formed by hydrolysis of CS by using gas chromatography/mass spectrometry, UV/Vis spectrometry, and polarographic method.

• Journal of the Korean Applied Science and Technology
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• v.13 no.3
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• pp.61-71
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• 1996

In acid-catalyzed acetal cyclization of long aliphatic aldehydes($R=n-C_7H_{15}$ ; $n-C_9H_{19}$ ; $n-C_{11}H_{23}$) with 1,1,1-tris(hydroxymethyl)propane, 2-alkyl-5-hydroxymethyl-5-ethyl-1,3-dioxanes were obtained. The final products, sodium 2-alkyl-5-(sulfonatedpropylethermethyl)-5-ethyl-1,3-propanesultion in the presence of sodium hydride. These compounds were a new group of destructible surfactants which were readily hydrolyzed and oxidized in natural water reservoirs. Physical properties of these new compounds involved some surface properties such as Krafft point(Kp), critical micelle concentration(cmc), surface tension of aqueous solutions near cmc(${\gamma}_{min}$), foaming power, emulsion power and hydrolysis properties were determined. The destructible surfactants containing 1,3-dioxane ring were synthesized to about $85{\pm}5.5%$ yield. The cmc values of the compounds by ring method were assumed to $0.5{\sim}5.0{\times}10^{-3}mol/L$ range and surface tensions at cmc were $29.5{\sim}33.0dyne/cm$ respectively at $25^{\circ}C$. The foaming power and foam stability were $170{\sim}230mm$ and $52{\sim}135mm$ respectively at $1{\times}10^{-2}mol/L$, foam was occurred rarely below $1{\times}10^{-3}mol/L$. The emulsion property of liquid paraffin was better than that of soybean oil. For hydrolysis property with ph and time, these compounds were decomposed within about 200minutes at $ph1{\sim}2$. Hopefully these compounds are expected to be a good O/W emulsifier that have decomposability in acid and may be used in the process which do not need foaming.