• Bulletin of the Korean Chemical Society
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• v.26 no.8
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• pp.1214-1218
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• 2005

Ti-HMS samples in which titanium species exist in various forms of isolated tetrahedral state, finely dispersed $TiO_2$ cluster, and some in extra-framework anatase phase were prepared via a direct synthesis route using dodecylamine (DDS) as a structure directing agent by systematically varying the titanium loadings between 2 and 50 mol% Ti/(Ti+Si) in substrate composition. Physicochemical properties of the materials were evaluated using XRD, SEM/TEM, N2 adsorption, UV-vis and XANES spectroscopies. Catalytic properties of Ti-HMS in cyclohexene and 2,6-di-tert-butyl phenol (2,6-DTBP) oxidation using aqueous $H_2O_2$, and vapor phase photocatalytic degradation of acetaldehyde were evaluated. High $H_2O_2$ selectivity was obtained in cyclohexene oxidation, and cyclohexene conversion was found primarily dependent on the amount of tetrahedrally coordinated Ti sites. For bulky 2,6-DTBP oxidation and photocatalytic oxidation of acetaldehyde, on the other hand, conversions were found dependent on the total amount of Ti sites and maintaining an uniform mesoporous structure in the catalysts was not critical for efficient catalysis.

• Journal of Soil and Groundwater Environment
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• v.27 no.4
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• pp.37-48
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• 2022

Accurate analysis of petroleum hydrocarbons in soil is an important prerequisite for proper source tracking of contamination. Identification of petroleum compounds is commonly carried out by peak pattern matching in gas chromatography. However, this method has several technical limitations, especially when the soils underwent biological, physical and chemical transformation. For instance, it is very difficult to distinguish jet fuel (JP-8) from kerosene because JP-8 is derivatized from secondary reaction between chemical agents (e.g. anti-oxidants, antifreezer and so on) and kerosene. In this study, an alternative method to separately analyze JP-8 and kerosene in the petroleum hydrocarbon contaminated soil was proposed. Qualitative analyses were performed for representative phenolic antioxidants [2,6-di-tert-butyl phenol (2,6-DTBP), 2,4-di-tert- butylphenol(2,4-DTBP), 2,6-di-tert-butyl-4-methyl phenol (2,6-DTBMP)] using a two dimensional gas chromatograph mass spectrometer (2D GC×GC-TOF-MS). This qualitative analysis of antioxidants in soil would be a useful complementary tool for the peak pattern matching method to identify JP-8 contamination in soil.

• Journal of the Korean Chemical Society
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• v.37 no.7
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• pp.648-654
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• 1993

$[M(cyclam)X_2]Y(M=Co^{3+},\;Fe^{3+},\;Mn^{3+}\;:\;X=Cl-^,\;Br^-,\;NCS^-\;:\;Y=Cl^-,\;Br^-,\;NCS^-),\;[Co(trans-14-diene)X_2]Y(X=Cl^-,\;Br^-\;:\;Y=ClO_4^-)\;and\;[Co(trans-14-diene)](ClO_4)_2$ were able to activate an molecular oxygen under sodium borohydride. 2,4-di-tert-butylphenol and 2,6-di-tert-butylphenol reacted with activated molecular oxygen to give 2,4-tert-butyl-1,6-benzoquinone(BQ) and 3,5,3',5'-tetra-tert-butyldiphenoquinone(DPQ). The saturated tetraazamacrocyclic complexes, $[Co(cyclam)X_2]Y$, were more an effective catalyst than $[Co(trans-14-diene)X_2]Y$ the unsaturated complexes in the formation of BQ and DPQ. The mole ratio of $O_2$ vs. catalyst $(O_2/M)$ for $[Co(cyclam)X_2]Y$ and [Co(trans-14-diene)X_2]Y$ was 1/1, while it was 1/2 for $[M(cyclam)Cl_2]Cl(M=Fe(III),\;Mn(III))$. The results suggested that Co(III)-macrocyclic complexes activated molecular oxygen as superoxolike ${O_2}^-$ and $[M(cyclam)Cl_2]Cl(M=Fe(III),\;Mn(III))$ activated that as peroxolike $O_2^{2-}$.

• Bulletin of the Korean Chemical Society
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• v.3 no.1
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• pp.13-18
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• 1982

The new substituent constants $({\sigma}^{\ast})$ are calculated from the acidity constants $(pK^{\ast})$ of phenol derivatives in the excited state ($^1L_b$). These substituent constant are applied to the Hammett equations and found good correlation with $pK^{\ast}$ of 2,6-di-tert-butyl phenol, benzamide, nitroaniline, thiophenol, azobenzene, and benzoic acid derivatives. The correlation was much better than that of ground state substituent constants such as ${\sigma},\;{\sigma}^+$, and ${\sigma}^-$. From these results, the new substituent constants $({\sigma}^{\ast})$are proposed to be used for the linear free energy relationship in the $^1({\pi},{\pi}^{\ast})$ excited states of phenyl compounds.

• Tribology and Lubricants
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• v.18 no.6
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• pp.396-401
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• 2002

ln this paper, the fuction of molybdenum dialkyl dithiophosphate (MoDTP) as an oxidation inhibitor of mineral oils was investigated and compared with 2,6-Di-tert-Butyl-4-Methylphenol (DBMP). Oxidation tests were conducted using an oxygen absorption apparatus. MoDTP showed anti-oxidation property, and length of induction time prolonged by increasing MoDTP concentration. However the induction time of DBMP was longer than those of MoDTP. The anti-oxidation property of MoDTP was found to be inferior to that of DBMP The capability of hydroperoxide decomposition ability with MoDTP was much greater than that with DBMP. However the rate constant of radical scavenging with MoDTP was much better than that with DBMP. It was found that the performance of MoDTP is exellent with respect to hydroperoxide decomposition but it is susceptible to chemical decomposition. From the fact that formation of phenol was observed when MoDTP was added to hexane solution of cumene hydroperoxide (CHPO), it is indicated that the decomposition of hydroperoxide with MoDTP occurs by means of ionic mechanism.

• Korean Journal of Food Science and Technology
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• v.28 no.2
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• pp.316-323
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• 1996

Flavor components in mash of Takju prepared by different raw materials such as nonglutinous rice, glutinous rice, barley and wheat flour were detected by GC and GC-MS method using non-polar column. Seven alcohols, 15 esters, 10 organic acids, 1 aldehyde, 4 benzenes, 3 phenols, 8 alkans, 2 ketones and 5 others were found in takju after 16 day of fermentation. takju by wheat flour had the most various components of volatile flavor. Treatment with addition starter had less flavor component than that without addition starter in takju by nonglutinous rice. Nine kinds of flavor components including acetic acid ethyl ester, 3- methyl-1-butanol, acetic acid, ethyl benzene, acetic acid 3-methyl butyl ester, 2-phenylethanol, 2,6-di-tert-butyl-4-methyl phenol. plumbagic acid and 1,2-benzenedicarboxylic acid dibutyl ester were commonly detected in all the treatments. Especially, 2,4,0-trimethyl-1,3-benzenediamine was isolated in takju that was made of nonglutinous rice without addition starter. Diethyl sulfide, 4-methoxy benzaldehyde, docosane and 2-methyl propyl octadecanoic acid were isolated from takju by nonglutinous rice with addition starter. Propionic acid ethyl ester, acetic acid butyl ester, 2-methyl butane and 3-methyl pentane were isolated from takju glutinous rice. 2-Hydroxy-4-methyl pentanoic acid and 2-methyl tridecane were isolated from akju by barley 3-(Methylthio)-1-propanol. hexanoic acid ethyl ester, butanoic acid monomethyl ester, tridecanoic acid, ethyl tetramethyl cyclopentadiene and 1,5-diaza-2,9-diketocyclotetradecane were isolated from takju by wheat flour. Major volatile flavor components were acetic acid ethyl ester, 3-methyl-1-butanol, acetic acid and 2-phenylethanol.