• Journal of the Korean Wood Science and Technology
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• v.34 no.5
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• pp.104-110
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• 2006

We investigated why aspen extractives are more resistant in kraft pulping than pine extractives. Residual extractives content in aspen kraft pulps were 0.5~1.1% compared with 0.1~0.2% in pine pulps. This different response arises from the different composition of extractives in wood chips. Resin acids in pine were almost completely removed in kraft pulping but those are not existence in aspen. Slower saponification of aspen steryl esters resulted from different chemical structure of aspen steryl esters. Main sterols in aspen steryl esters were 24-methyl cyclolanostenol which was highly resistant to alkaline hydrolysis with its characteristic steric hindrance. Sterols in aspen were not well removed in kraft pulping. The relative composition of sterol in aspen kraft pulps was increased with increasing pulping time. The presence of fatty acids in aspen kraft pulps is considered to unusual. Fatty acids in alkaline are supposed to be well ionized and removed well in the washing stage. Nevertheless, there were significant amount of fatty acids remaining in aspen kraft pulps.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.1
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• pp.40-45
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• 2006

Electrical insulation is one of the most important parts in a high voltage apparatus. Traditionally mineral oils and synthetic esters have been widely used as dielectric coolants for power transformers. Recently, researchers are interested in the environmentally friendly vegetable oil from the environmental viewpoint. This paper reports on the synthesis and characterization of soybean based ester oils. Two different types of soybean based transformer oils, named as methyl ester and isopropyl ester were synthesized. The synthesis of these esters was achieved by transesterification reactions between soybean oil and alcohol in the presence of catalyst. The GC and NMR spectroscopic analysis of the esters have been performed. It was observed that isopropyl ester has better thermal resistance than methyl ester by TGA. Also, two esters have a good breakdown voltage and electrical resistance.

• Applied Biological Chemistry
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• v.48 no.3
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• pp.292-295
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• 2005

Synthesis of methyl 3-methyloctanoate, a perfume component isolated from African orchid Aerangis confusa (or Aerangis kirkii) was achieved starting from itaconic acid in 9 steps. Itaconic acid is one of the cheapest organic compounds which is the fermentation product of microorganism Asp. terreus. As the key intermediate, 2-methyl-1,4-butanediol 4-acetate was obtained through the enzymatic regioselective hydrolysis of 2-methyl-1,4-butanediol diacetate with lipase. After Grignard reaction and oxidation, 3-methyloctanoic acid was obtained and converted to the various corresponding scented esters with a variety of alkyl alcohols, and the resulting fragrancy esters are expected to be utilized as the aroma additive materials in cosmetics, drinks and foods.

• KSBB Journal
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• v.28 no.6
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• pp.423-427
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• 2013

A new convenient derivatization method of ${\alpha}$-amino acid esters as nitrobenzoxadiazole (NBD) derivatives for chiral resolution was introduced and the enantiomer separation of ${\alpha}$-amino acid esters as NBD derivatives was performed by normal HPLC using chiral columns based on polysaccharide derivatives. The NBD derivatives were readily prepared by stirring NBD-Cl and ${\alpha}$-amino acid methyl ester HCl with $NaHCO_3$ in ethanol. The performance of Chiralpak IA was superior to the other chiral stationary phases for enantiomer resolution of NBD derivatives of several ${\alpha}$-amino acid methyl esters. Owing to fluorescence detection as well as strong UV absorption, it is expected that the convenient analytical method developed in this study will be very useful for enantiomer separation of ${\alpha}$-amino acid esters as NBD derivatives on polysaccharide-derived chiral columns.

• Journal of the Korean Applied Science and Technology
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• v.4 no.1
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• pp.9-18
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• 1987

The effects of procedures for preparation of fatty acid methyl esters for gas chromatography were investigated. A quantitative comparison of four procedures for the preparation of the fatty acid methyl esters from Korean sesame seed lipids which can be representative of fatty acid ranges of Korean vegetable oils has been made. The procedures employed were $BF_3$-methanol, HCI-methanol, sodium methoxide-methanol, and tetramethylammonium hydroxide-methanol. Twelve fatty acids ranged from 14:0 to 24:0 were identified in the lipids from Korean white and black sesame seeds. All four procedures gave similar results for the fatty acids, 16:0, 18:0, 18:1, 18:2, and 18:3 present in the range of $1{\sim}44%$ but only in the HCI-methanol procedure, the fatty acids, 16:1, 20:0, 22:0, 24:0 present in the range of $0.02{\sim}1%$ showed the lowest values. When using tetramethylammonium hydroxide-methanol procedure for determination of total fatty acid composition from white and black sesame seed lipids, unsaponifiable matters including sesamol, sesamolin and sesamin present in the seed lipids are not removed from the resulting reaction mixture. Thus the transesterification mixture is used without further treatment for injection into the gas chromatography. However, the gas chromatographic analysis of the transesterification mixture showed that the unsaponifiable matters had no effect on the fatty acid composition of the seed lipids. From the results, it appears that the $BF_3$-methanol, sodium methoxide-methanol and tetramethylammonium hydroxide-methanol procedures can be used to prepare fatty acid methyl esters from Korean vegetable oils. Among the methods, the tetramethylammonium hydroxide-methanol procedure, which give total fatty acid composition, glyceride fatty acid composition and composition of free fatty acids present, appears to be a simple, convenient and quantitative procedure and applicable to samples containing broad ranges of fatty acids.

• 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.26 no.1
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• pp.49-57
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• 1982

Transesterification reactions were carried out with myo-inositol and five fatty acid methyl esters such as methyl laurate, methyl myristate, methyl palmitate, methyl stearate and methyl oleate in the dimethylsulfoxide solvent. Their products were separated by both thin layer chromatography and column chromatography, and myo-inositol monoesters were quantitatively separated by counter current distribution. We measured their surface tension, foaming power and emulsifying power, determined critical micelle concentrations by the color method, and evaluated their hydrophilic-lipophilic balance. The results show that myo-inositol monoesters exhibit surface activites.

• Korean Journal of Food Science and Technology
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• v.32 no.5
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• pp.1035-1042
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• 2000

Volatile compounds of kochujang prepared with meju and koji were analyzed by using a purge and trap method during fermentation and identified with GC-MSD. Thirteen alcohols, seventeen esters, seven acids, six aldehydes and nine others were identified. Twenty four volatile flavor detected immediately after making kochujang including 7 alcohols and 9 esters. Six volatile flavor compounds including 1 alcohol and 3 esters were more found after 30 day of fermentation and increased to forty nine of volatile compounds after 150 days. Six alcohols such as ethanol, 3-methyl-butanol, 2-methyl-1-propanol, 1-butanol and nine esters such as ethyl acetate, ethyl butyrate, ethyl caproate, ethyl carpylate and seven others were commonly found through the fermentation period. Peak area (%) of 1-butanol was the highest one among the volatile flavor compounds after 30 day of fermentation and ethanol showed the highest peak area after 60-90 day and 150 day of fermentation, and 3-methyl-1-butanol showed the highest peak area after 120 day of fermentation, 2-Methyl-1-propanol, ethyl butyrate, ethyl acetate, acetaldehyde, ethoxyethene, ethenone, methylbenzene were detected in the kochujang during the fermentation.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.1
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• pp.115-121
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• 2012

This study was performed to assess the possibility of application of sewage sludge which is the side-product from domestic sewage treatment plant to the materials for biodiesels by investigating the yields and composition of the lipids and fatty acid methyl esters(FAMEs) from soxhlet extraction and in-situ transesterification. As the results, yields of in-situ transesterification were higher than soxhlet extraction. In comparison by sewage sludge type, yields of sewage sludge mixed nightsoil or livestock were higher than a single sewage sludge. And maximum yield showed up to 14 wt%. Fatty acid composition of extracted lipids and synthesized FAMEs consists of palmitic acid(C16:0), palmitoleic acid(C16:1), stearic acid(C18:0), oleic acid(C18:1), and linoleic acid(C18:2).

• Journal of the Korean Applied Science and Technology
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• v.20 no.3
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• pp.251-258
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• 2003

Biodiesel as methyl esters derived from vegetable oils has considerable advantages in terms of environmental protetion. In the present work, methyl esters were produced from soybean oil by lipase-catalyzed transesterification. To reduce inactivation of commercial immobilized lipases emulsified two-step process was developed using the stepwise addition of methanol with 4:1 molar ratio at 4h intervals. Also with immobilized lipase from Candida antarctica(Novozym 435) high conversion of 98.5 percent was possible at $45^{\circ}C$ of reaction temperature with 4:1 of methanol-to-oil molar ratio and 1%(v/v) methyl glucoside oleic polyester as an emulsifier in the presence of cosolvent.