• Journal of the Korean Applied Science and Technology
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• v.26 no.2
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• pp.213-223
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• 2009

Conventional additives were added to a newly synthesized base oil to create synthetic lubricants. Commercial polyol ester prepared in this laboratory were obtained as esterification of 1,1,1-trimethylol propane and respectively. This newly synthesized base oil had a variable chemical structure that could achieved the following properties; oxidation or thermal stability, low temperature fluidity, and higher flash points. When compared with commercial mineral lubricants, the synthetic lubricants show superior thermal and oxidation stability, and anti-wear properties.

• Journal of the Korean Chemical Society
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• v.13 no.3
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• pp.233-240
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• 1969

The synthesis is described of new pepsin substrates of benzyloxycarbonyl-glycyl-L-tyrosyl-L-phenylalanyl-glycine ethyl ester and benzyloxycarbonyl-glycyl-L-tyrosyl-L-phenylalanyl-glycine for studies on the specificity of pepsin, and thin layer chromatographic examination of the peptides prepared showed the new substrates are homogeneous and also, same examination of the incubation mixtures showed that two synthetic substrates are cleaved by pepsin at the L-tyrosyl-L-phenylalanyl bond and hydrolysis of these substrates by pepsin is achieved without transpeptidation. It is found that synthetic peptides are moderately soluble with the amount of the substrate up to a concentration of 0.7 mM in aqueous sodium citrate buffers (0.04 M) in the pH range 1.8-4.0, thus obviating the necessity for the adding of an organic solvent in the assay mixture. The kinetic parameters for synthetic substrates are tabulated in the following table. The data in the table indicate that the susceptibility of synthetic peptides to peptic hydrolysis are relatively large and the change of the carboxyl-terminal group of synthetic substrate from glycine ethyl ester to glycine causes a small decrease in the susceptibility of the L-tyrosyl-L-phenylalanyl bond.

• YAKHAK HOEJI
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• v.28 no.1
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• pp.17-20
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• 1984

Synthetic procedures to synthesize fenbufen-acetaminophen ester were searched by acid chloride method, DCC method and mixed acid anhydride method. The compound was synthesized by DCC method and mixed acid anhydride method but could not be synthesized by acid chloride method. Its anti-inflammatory activity was superior to acetaminophen and similar to fenbufen.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.4
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• pp.1367-1372
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• 2010

Copoly(ether-ether-ester)s having flexible side chain were synthesized by polycondensation. Intrinsic viscosities of polymers were between 0.42 and 0.78dl/g in tetrachloroethane. The polymer structures were investigated by $^1H$-NMR and FT-IR, and thermal and liquid crystalline properties of polymers were measured by DSC, TGA, POM and XRD. As results of investigations, synthetic copolymers exhibited lower melting temperature than homopolymers. When the biphenylene units contents in copolymer were more than 60 mol %, nematic mesophase was observed, and the mesophase of synthetic polymers was dependent upon biphenylene content.

• 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.

• Korean Journal of Environmental Agriculture
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• v.16 no.3
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• pp.269-273
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• 1997

This research aims at developing a new plant growth inhibitors related to abscisic acid by means of esterification of (S)-(+)-ABA with p-hydroxy methyl cinnamate and umbelliferone, and testing its biological activity on growth of rice seedlings. The over-all yield of ABA-methyl cinnamate(AC) and ABA-umbelliferone(AC) ester compounds were 83% and 78%, respectively. The growth inhibition activity of these synthetic compounds were shown about 3 to 10 times(AC) and 10 to 30 times(AU) higher than (S)-(+)-ABA.

• Tribology and Lubricants
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• v.36 no.3
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• pp.139-146
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• 2020

Global warming has led to an increase in demand of eco-friendly vehicles, such as electric cars, for reducing greenhouse gas emissions, and especially, regulating carbon dioxide generation. In addition, electric vehicles are equipped with an electric drive-type hermetic scroll compressor and a refrigerant, which exhibit current and future trends of using environmentally friendly refrigerants, including R-1234yf. In this study, polyol ester-based refrigeration oils are prepared via condensation esterification of polyol and fatty acids. The oils can be combined with R-1234yf refrigerant for applications in air conditioning and cooling systems of electric vehicles. The structure of synthetic polyol esters is confirmed via ¹H-NMR and FT-IR spectrum analysis, and the composition of the polyol ester is analyzed via gas chromatogram analysis. Furthermore, kinematic viscosity, viscosity index, total acid value, pour point, and color are analyzed as fundamental physical properties of the synthetic polyol esters. The compatibility and chemical stability of the synthetic polyol ester combined with the R-1234yf refrigerant are obtained via high temperature and high pressure oil-resistant refrigerant tests. The changes in the oil color and catalyst activity are observed before and after the experiment to determine whether it is suitable as a refrigerator oil.

• Journal of the Korean Applied Science and Technology
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• v.31 no.1
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• pp.7-13
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• 2014

A cationic ester type surfactant, namely N-2-hydroxy-3-(2-hydroxyacetoxy) proply-N,N-dimethyldodecylaminium chloride(HPDA) was synthesized and confirmed by FT-IR and $^1H$-NMR spectroscopy. Surface tensions on the diluted aqueous solutions of the synthetic compounds were measured and evaluated critical micelle concentration. Surface tension was 33~34 dyne/cm in the range of $10^{-3}{\sim}10^{-2}mol/L$ and critical micelle concentration(c.m.c) value was $8.5{\times}10^{-3}mol/L$ by surface tension method. Emulsifying properties of the synthetic surfactant(HPDA) and Sodium lauryl sulfate (SLS), tetradecyl trimethyl ammonium bromide (TTAB) was tested. As a results, synthetic glycolic acid ester type compounds(HPDA) has been confirmed as a good emulsifier. The foaming power and stability of synthesized ester type surfactant was measured by Ross-Miles method.

• Tribology and Lubricants
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• v.38 no.2
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• pp.41-52
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• 2022

Mineral electrical insulating oil, which is widely used in transformers, exhibits excellent cooling performance and transformer efficiency. However, given that it is composed of petroleum-based components, it is weak in terms of biodegradability. This causes environmental problems in case of leakage and a low flash point, which is a factor that would cause great damage in the event of a fire in a substation. In this context, the use of eco-friendly electric insulating oil composed of bio-based vegetable oil and synthetic ester, which has excellent biodegradability and flame retardancy performance, has recently been expanded to the field of electric power, and various research and development (R&D) studies are in progress. According to different research results, vegetable oil and synthetic ester manufacturing technology, thermal stability, oxidation stability, property change, and quality control, which are characteristics of eco-friendly electrical insulating oils, are major factors affecting the maintenance of insulating oil properties. In addition, power companies have established and operated quality control standards according to the use of eco-friendly electrical insulating oil as they expand the exploitatoin of renewable energy in electricity production. In particular, deterioration and oxidation characteristics were jointly identified in R&D as an important influencing factor according to the content of saturated and unsaturated fatty acids present in vegetable oils and synthetic esters in power transformer applications.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1989.06a
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• pp.1-21
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• 1989

합성윤활유(synthetic lubricant)라 함음 현재까지도 계속되고 있는 광유(mineral oil)전성시대의 광유에 대응되는 말로써 광유계 윤활유로 부터 얻기 어려운 높은 점도지수, 낮은 저온 유동성 등의 특성을 얻기 위해 유기합성 방법에 의해 인위적으로 제조한 윤활유의 총칭이며 작용기의 종류, 합성방법, 등에 따라 다양하게 분류된다. 합성윤활유의 종류에는 합성방법에 따라 폴리머형(P형), 비포리머형(N형)으로 대별되는데, 폴리머형 합성유에는 Poly-butene, $Poly\alpha$-olefin, Polyalkylenglycol, Silicon oil, Chlorofluorocarbon, Perfluoroalkyl polyether등이 있으며, 비폴리머형 합성유에는 Alkylbenzene, Dibasicacidester, Polyolester, Silicate-ester Polyphenylether, Complex ester등이 포함된다. 전자의 경우에는 중합반응 조건을 조절하므로써 여러점도 등급의 합성유들을 얻을 수 있는 반면 후자의 경우에는 분자량이 크지 않으므로 저점도의 것만 얻어지는 것이 특징이다.