• Bulletin of the Korean Chemical Society
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• v.22 no.8
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• pp.842-846
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• 2001

Solvolyses of N-methyl-N-phenylcarbamoyl chlorides in aqueous binary mixtures of acetone, ethanol, methanol and in water, D2O, and 50% D2O-CH3OD are investigated at 25.0 $^{\circ}C.$ The Grunwald-Winstein plots of first-ord er rate constants for N-methyl-N-phenylcarbamoyl chlorides with YCl (based on 2-adamantyl chloride) show a dispersion phenomenon. The ring parameter (I) has been shown to give considerable improvement when it is added as an hI term to the original Grunwald-Winstein and extended Grunwald-Winstein correlations for the solvolyses of N-methyl-N-phenylcarbamoyl chlorides. This study has shown that the magnitude of l, m and h values associated with a change of solvent composition is able to predict the dissociative SN2 transition state. The kinetic solvent isotope effects determined in deuterated water are consistent with the proposed mechanism of the general base catalyzed and/or a dissociative SN2 mechanism channel for N-methyl-N-phenylcarbamoyl chlorides solvolyses.

• Bulletin of the Korean Chemical Society
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• v.15 no.12
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• pp.1064-1069
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• 1994

Chlorobis(isoprene)rhodium(Ⅰ) (3), prepared by olefin-exchange reaction of chlorobis(cyclooctene)rhodium dimer (2) with isoprene, reacted with benzaldimine 4 to give iminoacylrhodium(Ⅲ) ${\eta}^3$-1,2-dimethylallyl complex 6. Ligand-promoted reductive elimination of 6 by pyridine and P(OMe)$_3$ produced ${\beta},{\gamma}$-unsaturated ketimine 8, which was readily hydrolyzed to give ${\beta},{\gamma}$-unsaturated ketone 9. Other methyl branched dienes such as 2,3-dimethylbutadiene, 3-methyl-1,3-pentadiene, 2-methyl-1,3-pentadiene, 2,4-dimethyl-1,3-pentadiene, 3-methyl-1,4-pentadiene and 2-methyl-1,4-pentadiene, were applied the synthesis of ${\beta},{\gamma}$-unsaturated ketones. In case of 2,4-dimethyl-1,3-pentadiene, only ${\gamma},{\delta}$ -unsaturated ketone 25, 1,2-addition product, was obtained, may be due to the mono-olefin coordination.

• Bulletin of the Korean Chemical Society
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• v.11 no.4
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• pp.286-290
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• 1990

The surface enhanced Raman scatterings of Zn(Ⅱ) tetrakis (4-N-methyl pyridyl) porphyrins were studied in silver sol. Zn(Ⅱ) tetrakis (4-N-methyl pyridyl) porphyrin was found to be adsorbed on silver surface via flat-on geometry with some inhomogeneous distribution in the orientation of pyridyl groups. Both the selective enhancement of Raman modes depending on the mode character and the theoretical arguments of SERS are utilized to support the above conclusion. The surface induced substitution reaction of Mn(Ⅲ) tetrakis (4-N-methyl pyridyl) porphyrin chloride to Ag(Ⅱ) tetrakis (4-N-methyl pyridyl) porphyrin was detected via surface enhanced Raman spectrum.

• Bulletin of the Korean Chemical Society
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• v.20 no.3
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• pp.307-313
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• 1999

2,4-Di-(2'-vinyloxyethoxy)benzylidenemalononitrile (la), methyl 2,4-di-(2'-vinyloxyethoxy)benzylidenecyanoacetate (lb), 3,4-di-(2'-vinyloxyethoxy)benzylidene malononitrile (2a), methyl 3,4-di-(2'-vinyloxyethoxy)benzylidenecyanoacetate (2b), 2,5-di-(2'-vinyloxyethoxy)benzylidenemalononitrile (3a), methyl 2,5-di-(2'-vinyloxyethoxy)benzylidenecyanoacetate (3b), 2,3-di-(2'-vinyloxyethoxy)benzylidenemalononitrile (4a), and methyl 2,3-di-(2'-vinyloxyethoxy)benzylidenecyanoacetate (4b) were prepared by the condensation of 2,4-di-(2'-vinyloxyethoxy)benzaldehyde, 3,4-di-(2'-vinyloxyethoxy)benzaldehyde, 2,5-di-(2'-vinyloxyethoxy) benzaldehyde, and 2,3-di-(2'-vinyloxyethoxy)benzaldehyde with malononitrile or methyl cyanoacetate, respectively. Trifunctional divinyl ether monomers 1-4 were polymerized readily with boron trifluoride etherate as a cationic initiator to give optically transparent swelling poly(vinyl ethers) 5-8 havina oxybenzylidenemalononitrile and oxycyanocinnamate, which is presumably effective chromophore for second-order nonlinear optical applications. Polymers 5-8 were not soluble in common organic solvents such as acetone and DMSO due to crosslinking. Polymers 5-8 showed a thermal stability up to 300 ℃ in TGA thermograms, which is acceptable for electrooptic device applications.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.6
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• pp.465-468
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• 2000

Methyl mercaptan oxidase was successfully induced from Rhodococcus rhodochrous IGTS8 using methyl mercaptan gas and purified to homogeneity for the detection of mercaptans. The purification procedure involved DEAE-Sephacel and Superose 12 column chromatography with recovery yields of 85.8 and 83.3%, and a specific activity of 92.7 and 303.4 units/mg-protein, respectively. The molecular weight of purified methyl mercaptan oxidase was determined to be 64.5 kDa by SDS-PAGE. The extract from gel filtration chromatography oxidizes methyl mercaptan to produce formaldehyde, which can be easily detected by the purpald-coloring method. Optimum temperature for activity was achieved at 60$^{\circ}C$. This enzyme was inhibited by both K$_2$SO$_4$and NaCl at concentration of less than 100mM and recovered to original activity at concentration of 200mM. In the presence of methanol, the activity decreased by 33%.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.820-829
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• 2017

Vegetable oil dielectrics have been used in transformers as green alternatives to mineral insulating oils for about twenty years, because of their advantages of non-toxic, biodegradability, and renewability. However, the viscosity of vegetable oils is more than 3 times of mineral oils, which means a poor heat dissipation capacity. To get low-viscosity dielectrics, transesterification and purification were performed to prepare vegetable oil methyl esters in this study. Electrical and physical properties were determined to investigate their potential as dielectrics. The results showed that the methyl ester products had good dielectric strengths, high water saturation and enough fire resistance. The viscosities (at $40^{\circ}C$) were 0.2 times less than FR3 fluid, and 0.7 times less than mineral oil, which indicated superior cooling capacity as we expected. With the assistance of 0.5 wt% pour point depressants, canola oil methyl ester exhibited the lowest pour point ($-26^{\circ}C$) among the products which was lower than FR3 fluid ($-21^{\circ}C$) and 25# mineral oil ($-23^{\circ}C$). Thus, canola oil methyl ester was the best candidate as a low-viscosity vegetable oil-based dielectric. The low-viscosity fluid could extend the service life of transformers by its better cooling capacity compared with nature ester dielectrics.

• Journal of the Korean Chemical Society
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• v.47 no.4
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• pp.354-362
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• 2003

A strategy for synthesis of the furan-fused tetracyclic system of xestoquinone was explored through a model study. Using 3-butyn-1-ol as a starting material, 5-iodo-1-methoxymethoxy pentyne (5) was prepared in 5 steps. Reaction of ethyl 2-phenylpropanoate with 5 gave ethyl 7-methoxymethoxy-2-methyl-2-phenyl-5-heptynoate (6) in 88% yield, and then methyl 9-oxo-4-methyl-4-phenyl-2,7-nonadiynoate (13), the key intermediate, was synthesized in 6 steps from the ester 6. Intramolecular cycloaddition reaction of 13 afforded isobenzofuran 14 in 5% yield, which was converted to the tetracyclic structure 15 in the presence of Lewis acid.

• Journal of Periodontal and Implant Science
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• v.25 no.1
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• pp.35-44
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• 1995

The purpose of present study was to evaluate the relationship between the early change of gingival condition and methyl mercaptan concentration during experimental gingivitis. Ten men(23-25 years old) whose gingiva were clinically healthy were selected. The participants have ceased to perform all forms of oral hygiene during 14 days and then did thorough plaque control for 7 days. For each subject, the methyl mercaptan concentration was measured by $B.B.Checker^{(R)}$ (Bad Breath Checker with printer, Tokuyama Soda Co.,LTD., Japan)before experiment and 1,4,7,14,21 days during experiment. Plaque index(Silness & $L\ddot{o}e$), gingival sulcus depth and sulcus bleeding index($M\ddot{u}hlemann$ & Son)score were recorded. The results were as follows. 1. Methyl mercaptan concentration increased continuously from the first day to the 14th day, decreased on the 21th day but it was still higher(P<0.001). 2. Plaque index score and sulcus bleeding index score tended to increase on the 4th day, markedly increased on the 14th day and returned to baseline level on the 21th day. 3. There was parallel relationhsip among methyl mercaptan concentration, plaque index score and sulcus bleeding index score. This result suggests that methyl mercaptan concentration increased with deterioration in gingival health, but decreased during recovery of normal health condition.

• Textile Coloration and Finishing
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• v.5 no.3
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• pp.221-228
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• 1993

Cellulose acetate and methyl cellulose were synthesized from waste cellulose in order to make waste knit on value added highly. Crystal waste cellulose by oxidation using $HIO_4$ and then acetylation was decrystallized. A degee of crystallinity was measured by X-ray diffraction and the structure was identified by FT-IR spetroscopy, respectively. Cellulose acetate was prepared from the reaction of decrystallized cellulose with acetic acid, cone-$H_{2}SO_{4}$ and acetic anhydride. Also, structure identification by FT-IR and a degree of crystallinity by X-ray diffraction were performed. DS of the synthesized cellulose acetate was 2.8 and viscosity average molecular weight was 238,000. Also, methyl cellulose was synthesized by treating cellulose acetate with NaOH and iodomethane. DS of the synthesized methyl cellulose was 3.0. Glucose unit with three hydroxy groups was all substituted by methoxyl groups. It was identified by FT-IR spectroscopy. Also, the thermal properties of the synthesized methyl cellulose were examined by DSC. It shewed two shewed melting peaks at 22$0^{\circ}C$ and 24$0^{\circ}C$ in the 2nd scan. It proved that DS=3.0 of methyl cellulose was a thermotropic liquid crystal.

• Applied Chemistry for Engineering
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• v.17 no.4
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• pp.426-431
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• 2006

Acryl and vinyl sulfone functionalized blue and orange azo dyes were prepared by the coupling reaction of 6-bromo-2-cyano-4-nitroaniline and 2,5-dimethoxy-4-(vinylsulfonyl)benzenamine with 3-acrylamido-(N,N-diethylamino)benzene and 3-methyl-(N,N-diethylamino)benzene, respectively, for the coloring of poly(methyl methacrylate) (PMMA). Allyl functionalized dye was also prepared by reacting vinyl sulfone-containing dye with allylamine. Three types of dyeing method were used: the copolymerization of reactive dye with methyl methacrylate (MMA) and dyeing by polymerization of MMA in the presence of polymeric dye and dye 2 without reactive function. The color fastness for the three PMMAs were evaluated by comparing the solubility of dye under various conditions.