• YAKHAK HOEJI
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• v.53 no.5
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• pp.281-285
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• 2009

The retention of solutes in reversed-phase high-performance liquid chromatography depends on their hydrophobicity. Although the retention behaviors of alkyl benzenes have been reported so far, quite a few authors have mentioned the retention behavior of alkyl benzenes with plural hydrophobicity parameters. In this sense, we were interested in the retention behaviors of alkyl benzenes having benzene moiety and increasing alkyl chain. In this study, we therefore investigated the retention behavior of alkyl benzenes in reversed-phase high-performance liquid chromatography in order to obtain information concerning the effects of the aromatic moiety and the carbon chain on the retention mechanism by comparing their capacity factor (k') in relation to the carbon chain length. The eluent acetonitrile ($CH_3CN$) showed high selectivity on alkyl benzenes, showing the high difference of capacity factor (${\Delta}log\;k'$) between toluene and octyl benzene. Indeed, the ${\Delta}log\;k'$ of 80% $CH_3CN$ represented 1.42- and 4.25-times longer than 90% MeOH and 60% THF, respectively. The hydrophobicity parameters, van der Waals volume, bond constant, partition constant, $\pi$-energy effect and enthalpy were evaluated with the capacity factor (k') of alkyl benzenes eluted on 80% CH3CN, 90% MeOH and 60% THF, respectively. The best eluent for predicting retention behavior of alkyl benzenes was 90% MeOH ($R^2$ 0.999). The three parameters, van der Waals volume, bond constant and partition constant were well coincident to log k' by increasing alkyl benzenes. However, $\pi$-energy effect and enthalpy were severely disagreeable. Taken together, van der Waals volume, bond constant and partition constant were a reliable parameters to predict the retention behaviors of alkyl benzenes on reversed-phase column.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3073-3074
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• 2010

• Bulletin of the Korean Chemical Society
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• v.13 no.1
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• pp.45-48
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• 1992

A synthetic method for bis-carbonylation of bromo(bromomethyl)benzenes was described. Alkyl carboalkoxyphenylacetates were easily prepared by the carbonylation of benzylic and arylic bromide moieties in bromo(bromomethyl)benzenes with alcohols in the presence of $K_2CO_3,\;CH_3I$, and a catalytic amount of cobalt carbonyl under the atmospheric pressure of carbon monoxide at room temperature in good to excellent yields. The base played a decisive role in the selectivity of product and $K_2CO_3$ was the best one among bases used.

• Journal of ILASS-Korea
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• v.23 no.4
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• pp.185-191
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• 2018

Benzene, toluene, ethylbenzene and xylene (BTEX) were well known as ozone precursors from photochemical reactions and contribute to the formation of photochemical smog which pose health hazards. Also, some of these compounds directly affect the human health due to their toxicity such as benzene. In this study, BTEX ratios and correlation of $C_2$-benzenes (xylenes, ethylbenzene) in vehicle exhaust from recreational vehicle (RV) and multi-purpose vehicle (MPV) were characterized using a chassis dynamometer. VOCs were collected by tedlar bag and a GC/MS system was used for their quantification. Among all of the BTEX, toluene has the highest concentration(more than 30% in composition of BTEX). The average ratio of toluene to benzene emissions (T/B ratio=2.2) was found in vehicle exhaust. The average m,p-xylene/ethylbenzene and m,p-xylene/o-xylene ratios were 1.0 and 3.0 respectively. As a result, it showed a good correlation between the $C_2$-benzenes ($R^2=0.98{\sim}0.99$). In the future, it can be used as a marker for effect evaluation to atmospheric environment by vehicle exhaust.

• Journal of Korean Society on Water Environment
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• v.20 no.3
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• pp.245-250
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• 2004

This study investigated the micropollutants present in raw water supplied for the several drinking water treatment plants in Seoul. The target sample waters were collected from the several sites, such as Jayang (JY), Kuui (KI), Paldang (PD) and Kangbuk (KB) at the Han-River stream. The analytical method used in this study enable us to detect about 300 kinds of chemicals commonly found in surface water at ppt level by GC-ion trap MS. In this study, the consideration on the analytic results focused on the four hazardous organics, such as benzenes, phenols, phthalates and pesticides. The numbers of each detected micropollutant were 1~8 kinds for benzenes, 1~7 kinds for phenols, 5~7 kinds for phthalates and 1~9 kinds for pesticides. For the pesticides, the higher concentration was detected in the water samples collected from PD and KB adjacent to the farming area, and at June and July, which is the busy farming season. The total concentrations of each micropollutants detected at all the sites were significantly lower than those of drinking water regulation in Korea as well as other advanced countries. However, the frequently detected micropollutants requires the steady and precise monitoring for the effective management of drinking water source.

• Journal of the Korean Chemical Society
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• v.32 no.2
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• pp.135-143
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• 1988

The correlations between chromatographic parameters of monosubstituted benzenes and several physical parameters in reversed phase liquid chromatography were studied. The relationships between retention data and polarity index were investigated by plotting $log(log k'_S/k'_B)$ vs. $P'_S/P'_B$ which were relative retention and relative polarity index of monosubstituted benzenes with respect to benzene, respectively. The linear relationship between relative retention and polarity index was observed for the monosubstituted benzenes having polar group, while in case of those having nonpolar group, the good linearity was observed by combination with relative molecular weight i.e. $(P'_S/P'_B)/(MW_S/MW_B)$. Multivariant regression analysis, $a(P'_S/P'_B)+b(MW_S/MW_B)$+c did not give significantly better correlations compared to single variant analysis, $a[(P'_S/P'_B)/(MW_S/MW_B)]$+c, but multiple stepwise regression analysis was recommended when several physical parameters simultaneously were chosen. The best correlation between retention data for monosubstituted benzenes taken from the literature and substituent constant(${\pi}$), derived from hydrophobic parameter and the first order molecular connectivity index$(^1{\chi}^{\nu})$, was established for methanol/water mobile phase system. The larger the surface coverage of the stationary phase, the higher was the correlation coefficient between these two parameters and retention data.

• Proceedings of the Microbiological Society of Korea Conference
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• 2000.05a
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• pp.79-86
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• 2000

• Bulletin of the Korean Chemical Society
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• v.19 no.6
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• pp.607-608
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• 1998

• Journal of the Korean Chemical Society
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• v.41 no.2
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• pp.82-87
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• 1997

The 1,4-bis(alkyldichlorosilyl)benzene was synthesized to be a precursor of the bis(silacyclopentadienyl) aromatic system. The cyclization reaction of the precursor with 1,4-dilithio-1,2,3,4-tetraphenyl-1,3-butadiene produced the 1,4-bis(1'-alkyl-2',3',4',5'-tetraphenyl-1'-silacyclopentadienyl)benzene as the ligand of organotransition metal compound and the precursor of the stable silacyclopentadienyl anion.

• Bulletin of the Korean Chemical Society
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• v.1 no.3
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• pp.109-112
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• 1980

Ultraviolet spectrophotometric investigations were carried out on monoalkylbenzene-iodine systems in carbon tetrachloride. The results reveal the formation of one-to-one molecular complexes. On the basis of the equilibrium constants for these complexes of representative monosubstituted benzenes, the following order of increasing stability is obtained: i-propyl- ${\Delta}$H, ${\Delta}$G and ${\Delta}$S for the interaction of a number of monoalkyl substituted benzenes with iodine have been determined. In general, it can be said that as ${\Delta}$H becomes increasingly negative, corresponding decreases in the ${\Delta}$G and the ${\Delta}$S values are observed, and these variations are linear. The thermodynamic constants become increasingly negative with increasing monoalkyl substitution of the aromatic donor nucleus. The complex bond is therefore weak, and its formation is accompanied by relatively small entropy changes. Thus, analysis of these findings is discussed.