• Clean Technology
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• v.14 no.2
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• pp.144-151
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• 2008

Life cycle assessment was carried out to evaluate the environmental values of dimethylas a diesel alternative fuel with the assumption of dimethyl ether production from natural gas via synthesis gas. The whole life cycles from raw material acquisitions to the final usages of diesel and dimethyl ether were involved in the assessment. Inventory analysis showed that the most significant environmental impacts came from resource depletions and air emissions. Impact assessment revealed that dimethyl ether was environmentally better in the aspect of human health and ecosystem quality but worse in resource depletions compared with diesel fuel. Suggestions for environmental improvement of dimethyl ether as a diesel alternative fuel were prepared based on the assessment results.

• Applied Biological Chemistry
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• v.37 no.5
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• pp.402-408
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• 1994

For the examination of the role of monocerin(1) on the biological activity, (8S, 9S, 11R)-(-)-monocerin(20) and (9S, 11R)-(+)-fusarentin 4, 5-dimethyl ether(19) were synthesized by a condensation of the benzylic anion of ethyl 2, 3, 4-trimethoxy-6-methylbenzoate(16) with modifyed (R)-ethyl 3-hydroxyhexanoate (9). In a key step, bioreduction with active dried baker's yeast in organic solvent system was employed to get a chiral aldehyde 12. Their phytotoxic activities were tested on rice seedlings and lettuce seeds.

• Journal of the Korean Electrochemical Society
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• v.9 no.2
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• pp.89-94
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• 2006

Nafion/poly(ether(amino sulfone)) acid-base blend polymer electrolyte membranes were prepared and their proton conductivity and dimethyl ether permeability were investigated. Characteristics of direct dimethyl ether fuel cell (DDMEFC) performance using prepared blend membrane were studied. The increase of amine groups in the base polymer in composite membranes resulted in the decrease in dimethyl ether permeability. The proton conductivity of the blend membranes gradually increased as increasing temperature. The conductivity of Nafion/PEAS-0.6 (85:15) blend membranes was measured to be $1.42\times10^{-2}S/cm\;at\;120^{\circ}C$ which was higher than that of the recast Nafion. The performance of direct dimethyl ether fuel cell (DDMEFC) using the Nafion/PEAS blend membranes was higher than that using $Nafion^(R)115$ membrane. Enhanced performance of direct dimethyl ether fuel cells using Nafion/PEAS blend membrane was explained by reducing dimethyl ether (DME) crossover through the electrolyte membrane and maintenance of the proton conductivity at high temperature.

• Bulletin of the Korean Chemical Society
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• v.23 no.8
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• pp.1103-1105
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• 2002

H-ZSM-5 and γ-alumina were treated with formaldehyde and sodium carbonate. The treatment increased the amounts of weak acid sites, removing strong acid sites. The maximum temperature of weak acid sites in their ammonia TPD spectra shifted in the direction of high temperature. The modified H-ZSM-5 and g-alumina were mixed with the methanol synthesis catalyst to perform dimethyl ether synthesis from syn-gas. The modified catalysts showed better selectivity to dimethyl ether, minimizing the reforming reaction to carbon dioxide. The maximum yield of 53.3% to dimethyl ether was achieved under the reaction conditions of 54.4 atm, 523 K, and the feed rate of 4500 Lhr-1 .gcat-1.

• Natural Product Sciences
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• v.4 no.4
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• pp.215-220
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• 1998

A new flavonol $3,5-di-O-KSO_3$:kaempferol 7,4'-dimethyl ether $3,5-O-KSO_3$, was isolated and identified from the flowers of Tamarix amplexicaulis. The known compounds quercetin $3-mono-O-KSO_3$, kaempferol 4'-methyl ether $3-mono-O-KSO_3$, kaempferol 7,4'-dimethyl ether $3-O-KSO_3$, quercetin 7,4'-dimethyl ether $3-mono-O-KSO_3$, kaempferol 3-O-glucuronide and quercetin 3-O-glucuronide were also separated and identified. Structures were established by conventional methods, including electrophoretic analysis, and confirmed by negative FAB-MS, $^1H-\;and\;^{13}C-NMR$.

• Natural Product Sciences
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• v.4 no.4
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• pp.245-252
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• 1998

The unique sulphated phenolics, gallic acid 3-methyl ether 5-potassium sulphate, isoferulic acid 3-potassium sulphate, and ellagic acid 4,4'-dimethyl ether 3-potassium sulphate have been isolated from the flowers of Tamarix amplexicaulis Ehrenb. (Tamaricaceae). The hitherto unknown natural phenolic acid, gallic acid 3-methyl ether, together with the known phenolic, gallic acid, gallic acid 4-methyl ether, isoferulic acid, ferulic acid, ellagic acid, and ellagic acid 4,4'-dimethyl ether have been also separated and characterized. The structures were established by conventional methods, including electrophoretic analysis and confirmed by ESI-MS, $^1H-\;and\;^{13}C-NMR$.

• 한국연소학회:학술대회논문집
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• 2013.06a
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• pp.103-105
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• 2013

Spherically expanding flames are used to measure flame speeds, which are derived the corresponding laminar flame speeds at zero stretch. Dimethyl Ether-Air mixtures at high pressure are studied over an extensive range of equivalence ratios. The classical shadowgraph technique is used to detect the reaction zone. In analytical methodology the optimization process using least mean squares is performed to extract the laminar flame speeds. Laminar flame speeds are compared with results reported in the literature.

• Bulletin of the Korean Chemical Society
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• v.11 no.1
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• pp.58-59
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• 1990

A method is described for the selective functionalization of calix[4]arene at the para positions of the phenyl rings. The diametrically substituted calix[4]arene dimethyl ether 3, obtained from the treatment of calix[4]arene 2 with methyl iodide in the presence of $K_2CO_3$, is converted to the diacetyloxy calix[4]arene dimethyl ether 4. This compound undergoes Fries rearrangement to yield the diametrically p-diacetylcalix[4]arene dimethyl ether 5 in 68% yield.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.211-214
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• 2012

A short reaction mechanism was developed in order to predict the flame phenomena in premixed Dimethyl Ether-Air flame with the methods of SEM-CM(Simulation Error Minimization Connectivity Method), sensitivity analysis, and the rate of production analysis. It consisted of 31 species including nitrogen as inert gas and 177 elementary reactions. The flame structures obtained using a detailed reaction mechanism and the short reaction mechanism were compared with various equivalence ratios and pressure, and the results were in good agreement. Therefore, the short reaction mechanism would be used to aim at studying the development of a reduced reaction mechanism.

• Tribology and Lubricants
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• v.29 no.2
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• pp.117-123
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• 2013

Dimethyl ether (DME) has a high cetane number that is suitable for diesel fuel. DME does not contain sulfur or nitrogen, and is an oxygenated fuel so it produces no particulate matter when combusted and is environmentally friendly. DME fuel for diesel engines show excellent material properties such as a lower volumetric heating value, lower boiling point, lower lubricity, and stronger solvent effect than light oil. This study experimentally examined a lubricity improver (LI) for dimethyl ether. A diesel LI based on biodiesel and fatty acid methyl ester was tested among DME LI candidates. The long-term storage stability and physical properties of the optimum LI for DME were determined.