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José Cernicharo - One of the best experts on this subject based on the ideXlab platform.
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The millimeter-wave spectrum and astronomical search for Ethyl mEthyl sulfide.
Astronomy & Astrophysics, 2020Co-Authors: Carlos Cabezas, C. Bermúdez, Belén Tercero, José CernicharoAbstract:Context Sulfur-containing molecules constitute only 8% of the molecules observed in the interstellar medium (ISM), in spite of the fact that sulfur has been shown to be an abundant element in the ISM. In order to understand the chemical behavior of the ISM and specific cases like the missing sulfur reservoir, a detailed chemical molecular composition in the ISM must be mapped out. Aims Our goal is to investigate the rotational spectrum of Ethyl mEthyl sulfide, CH3CH2SCH3, which ms to be a potential candidate for observation in the ISM since the simpler analogs, CH3SH and CH3CH2SH, have already been detected. Rotational spectrum of Ethyl mEthyl sulfide has been observed before, but its experimental rotational parameters are not precise enough to allow its detection in the ISM. Methods The rotational spectrum of Ethyl mEthyl sulfide in the frequency range 72-116.5 GHz was measured using a broadband millimeter-wave spectrometer based on radio astronomy receivers with fast Fourier transform backends. The spectral searches and identification of the vibrational excited states of Ethyl mEthyl sulfide was supported by high-level ab initio calculations on the harmonic and anharmonic force fields. Results The rotational spectra for the trans and gauche conformers of Ethyl mEthyl sulfide was analyzed, and a total of 172 and 259 rotational transitions were observed for each one, respectively. The observation of A - E internal rotation splittings allowed the experimental determination of the V3 hindered internal rotation barrier height for both trans and gauche species. In addition, the vibrational excited states, resulting from the lowest frequency vibrational mode ν30 were identified for both conformers. The new experimental rotational parameters were employed to search for Ethyl mEthyl sulfide in the warm and cold molecular clouds Orion KL, Sgr B2(N), B1-b and TMC-1, using the spectral surveys captured by IRAM 30 m at 3 mm and 2 mm. Conclusions
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Searching for Trans Ethyl MEthyl Ether in Orion KL
Astronomy and Astrophysics - A&A, 2015Co-Authors: Belén Tercero, José Cernicharo, A., López, N. Brouillet, L., Kolesniková, R. A., Motiyenko, L., Margulès, J. L., Alonso, J.-c., GuilleminAbstract:We report on the tentative detection of trans Ethyl mEthyl ether (tEME), t-CHCHOCH, through the identification of a large number of rotational lines from each one of the spin states of the molecule towards Orion KL. We also search for gauche-trans-n-propanol, Gt-n-CHCHCHOH, an isomer of tEME in the same source. We have identified lines of both species in the IRAM 30 m line survey and in the ALMA Science Verification data. We have obtained ALMA maps to establish the spatial distribution of these species. Whereas tEME mainly arises from the compact ridge component of Orion, Gt-n-propanol appears at the emission peak of ethanol (south hot core). The derived column densities of these species at the location of their emission peaks are ≤(4.0 ± 0.8) × 10 cm and ≤(1.0 ± 0.2)× 10 cm for tEME and Gt-n-propanol, respectively. The rotational temperature is ~100 K for both molecules. We also provide maps of CHOCOH, CHCHOCOH, CHOCH, CHOH, and CHCHOH to compare the distribution of these organic saturated O-bearing species containing mEthyl and Ethyl groups in this region. Abundance ratios of related species and upper limits to the abundances of non-detected ethers are provided. We derive an abundance ratio (CHOCH)/(tEME) ≥ 150 in the compact ridge of Orion.
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discovery of mEthyl acetate and gauche Ethyl formate in orion
The Astrophysical Journal, 2013Co-Authors: Belén Tercero, José Cernicharo, A., López, I Kleiner, Ha Vinh Lam Nguyen, G Munoz M CaroAbstract:We report on the discovery of mEthyl acetate, CH3COOCH3, through the detection of a large number of rotational lines from each one of the spin states of the molecule: AA species (A1 or A2), EA species (E1), AE species (E2), and EE species (E3 or E4). We also report, for the first time in space, the detection of the gauche conformer of Ethyl formate, CH3CH2OCOH, in the same source. The trans conformer is also detected for the first time outside the Galactic center source SgrB2. From the derived velocity of the emission of mEthyl acetate, we conclude that it arises mainly from the compact ridge region with a total column density of (4.2 ± 0.5) × 1015 cm–2. The derived rotational temperature is 150 K. The column density for each conformer of Ethyl formate, trans and gauche, is (4.5 ± 1.0) × 1014 cm–2. Their abundance ratio indicates a kinetic temperature of 135 K for the emitting gas and suggests that gas-phase reactions could participate efficiently in the formation of both conformers in addition to cold ice mantle reactions on the surface of dust grains.
Chi-min Shu - One of the best experts on this subject based on the ideXlab platform.
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Effects of acetone on mEthyl Ethyl ketone peroxide runaway reaction.
Journal of Hazardous Materials, 2007Co-Authors: Yan-fu Lin, J.m. Tseng, Chi-min ShuAbstract:Abstract Runaway reactions by mEthyl Ethyl ketone peroxide (MEKPO) are an important issue in Asia, due to its unstable structure and extensive heat release during upset situations. This study employed differential scanning calorimetry (DSC) to draw the experimental data for MEKPO 31 mass% and with acetone 99 mass% on three types of heating rate of 2, 4, and 10 °C/min; the kinetic and safety parameters were then evaluated via curve fitting. Through the reproducible tests in each condition, the results show that acetone is not a contaminant, because it could increase the activation energy ( E a ) and onset temperature ( T o ) when combined with MEKPO, which differs from the hazard information of the material safety data sheet (MSDS).
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Thermal hazard evaluation for mEthyl Ethyl ketone peroxide mixedwith inorganic acids
Journal of Thermal Analysis and Calorimetry, 2006Co-Authors: J.m. Tseng, R. H. Chang, Jao-jia Horng, M. K. Chang, Chi-min ShuAbstract:MEthyl Ethyl ketone peroxide (MEKPO) possesses complex structures which have caused many incidents involving fires or explosions by mixing with incompatible substances, external fires, and others. In this study, reactivities or incompatibilities of MEKPO with inorganic acids (HCl, HNO3, H3PO4 and H2SO4) were assessed by differential scanning calorimetry (DSC) and vent sizing package 2 (VSP2). Parameters obtained by the above-mentioned devices could be readily employed to discuss the runaway reaction, such as onset temperature (T0), heat of reaction (ΔHd), time to maximum rate (TMR), maximum self heat rate (dT/dt)max, adiabatic temperature rise (ΔTad), maximum pressure of decomposition (Pmax) and so on.
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Thermal Hazard Analysis of MEthyl Ethyl Ketone Peroxide
Industrial & Engineering Chemistry Research, 2003Co-Authors: Po-yin Yeh, Chi-min Shu, Yih-shing DuhAbstract:In the past 4 decades in Japan and Taiwan, many thermal explosions have been caused by mEthyl Ethyl ketone peroxide (MEKPO) subjected to external heating including fire. Thermograms of commercialized MEKPO dimers were first screened by differential scanning calorimetry (DSC) to determine the heat of decomposition and exothermic onset temperature. Thermal runaway phenomena were then thoroughly investigated using Vent Sizing Package2. Instead of the normal one-reaction peak for the MEKPO dimer seen in the adiabatic calorimeter, two distinct exothermic peaks occurred in the DSC thermograms near 110 and 170 °C, indicative of series reactions. The onset temperature of the MEKPO monomer was determined to be about 40 °C, showing it to be extremely reactive under storage or process conditions. Thermokinetic and related data were obtained that can be used for hazard analysis to prevent thermal explosions in both the monomer and the dimer.
Belén Tercero - One of the best experts on this subject based on the ideXlab platform.
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The millimeter-wave spectrum and astronomical search for Ethyl mEthyl sulfide.
Astronomy & Astrophysics, 2020Co-Authors: Carlos Cabezas, C. Bermúdez, Belén Tercero, José CernicharoAbstract:Context Sulfur-containing molecules constitute only 8% of the molecules observed in the interstellar medium (ISM), in spite of the fact that sulfur has been shown to be an abundant element in the ISM. In order to understand the chemical behavior of the ISM and specific cases like the missing sulfur reservoir, a detailed chemical molecular composition in the ISM must be mapped out. Aims Our goal is to investigate the rotational spectrum of Ethyl mEthyl sulfide, CH3CH2SCH3, which ms to be a potential candidate for observation in the ISM since the simpler analogs, CH3SH and CH3CH2SH, have already been detected. Rotational spectrum of Ethyl mEthyl sulfide has been observed before, but its experimental rotational parameters are not precise enough to allow its detection in the ISM. Methods The rotational spectrum of Ethyl mEthyl sulfide in the frequency range 72-116.5 GHz was measured using a broadband millimeter-wave spectrometer based on radio astronomy receivers with fast Fourier transform backends. The spectral searches and identification of the vibrational excited states of Ethyl mEthyl sulfide was supported by high-level ab initio calculations on the harmonic and anharmonic force fields. Results The rotational spectra for the trans and gauche conformers of Ethyl mEthyl sulfide was analyzed, and a total of 172 and 259 rotational transitions were observed for each one, respectively. The observation of A - E internal rotation splittings allowed the experimental determination of the V3 hindered internal rotation barrier height for both trans and gauche species. In addition, the vibrational excited states, resulting from the lowest frequency vibrational mode ν30 were identified for both conformers. The new experimental rotational parameters were employed to search for Ethyl mEthyl sulfide in the warm and cold molecular clouds Orion KL, Sgr B2(N), B1-b and TMC-1, using the spectral surveys captured by IRAM 30 m at 3 mm and 2 mm. Conclusions
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Searching for Trans Ethyl MEthyl Ether in Orion KL
Astronomy and Astrophysics - A&A, 2015Co-Authors: Belén Tercero, José Cernicharo, A., López, N. Brouillet, L., Kolesniková, R. A., Motiyenko, L., Margulès, J. L., Alonso, J.-c., GuilleminAbstract:We report on the tentative detection of trans Ethyl mEthyl ether (tEME), t-CHCHOCH, through the identification of a large number of rotational lines from each one of the spin states of the molecule towards Orion KL. We also search for gauche-trans-n-propanol, Gt-n-CHCHCHOH, an isomer of tEME in the same source. We have identified lines of both species in the IRAM 30 m line survey and in the ALMA Science Verification data. We have obtained ALMA maps to establish the spatial distribution of these species. Whereas tEME mainly arises from the compact ridge component of Orion, Gt-n-propanol appears at the emission peak of ethanol (south hot core). The derived column densities of these species at the location of their emission peaks are ≤(4.0 ± 0.8) × 10 cm and ≤(1.0 ± 0.2)× 10 cm for tEME and Gt-n-propanol, respectively. The rotational temperature is ~100 K for both molecules. We also provide maps of CHOCOH, CHCHOCOH, CHOCH, CHOH, and CHCHOH to compare the distribution of these organic saturated O-bearing species containing mEthyl and Ethyl groups in this region. Abundance ratios of related species and upper limits to the abundances of non-detected ethers are provided. We derive an abundance ratio (CHOCH)/(tEME) ≥ 150 in the compact ridge of Orion.
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discovery of mEthyl acetate and gauche Ethyl formate in orion
The Astrophysical Journal, 2013Co-Authors: Belén Tercero, José Cernicharo, A., López, I Kleiner, Ha Vinh Lam Nguyen, G Munoz M CaroAbstract:We report on the discovery of mEthyl acetate, CH3COOCH3, through the detection of a large number of rotational lines from each one of the spin states of the molecule: AA species (A1 or A2), EA species (E1), AE species (E2), and EE species (E3 or E4). We also report, for the first time in space, the detection of the gauche conformer of Ethyl formate, CH3CH2OCOH, in the same source. The trans conformer is also detected for the first time outside the Galactic center source SgrB2. From the derived velocity of the emission of mEthyl acetate, we conclude that it arises mainly from the compact ridge region with a total column density of (4.2 ± 0.5) × 1015 cm–2. The derived rotational temperature is 150 K. The column density for each conformer of Ethyl formate, trans and gauche, is (4.5 ± 1.0) × 1014 cm–2. Their abundance ratio indicates a kinetic temperature of 135 K for the emitting gas and suggests that gas-phase reactions could participate efficiently in the formation of both conformers in addition to cold ice mantle reactions on the surface of dust grains.
Saurabh S Soni - One of the best experts on this subject based on the ideXlab platform.
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excess molar volumes excess isentropic compressibilities excess viscosities relative permittivity and molar polarization deviations for mEthyl acetate Ethyl acetate butyl acetate isoamyl acetate mEthyl propionate Ethyl propionate Ethyl butyrate methy
Journal of Molecular Liquids, 2013Co-Authors: N V Sastry, Sunil R Patel, Saurabh S SoniAbstract:Abstract Experimental densities, dynamic viscosities, speeds of sound and relative permittivities for ten binary mixtures of mEthyl acetate +, Ethyl acetate +, butyl acetate +, isoamyl acetate +, mEthyl propionate +, Ethyl propionate +, Ethyl butyrate +, mEthyl methacrylate +, Ethyl methacrylate +, and butyl methacrylate + cyclohexane at T = 298.15 and 303.15 K have been measured. Applicability of Grunberg–Nissan, McAllister and Auslander equations was tested for correlating viscosity of mixtures. The suitability of free length and collision factor theories, and Nomoto and Junjie equations for predicting the speeds of sound in binary mixtures have been explored. Excess molar volumes, excess isentropic compressibilities, excess viscosities, relative permittivity and molar polarization deviations have been calculated and their compositional variation has been mathematically expressed by Redlich–Kister equation. The analysis of excess and deviation functions has been done to ascertain the predominant type of interactions in the bulk state of mixtures.
J.m. Tseng - One of the best experts on this subject based on the ideXlab platform.
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Effects of acetone on mEthyl Ethyl ketone peroxide runaway reaction.
Journal of Hazardous Materials, 2007Co-Authors: Yan-fu Lin, J.m. Tseng, Chi-min ShuAbstract:Abstract Runaway reactions by mEthyl Ethyl ketone peroxide (MEKPO) are an important issue in Asia, due to its unstable structure and extensive heat release during upset situations. This study employed differential scanning calorimetry (DSC) to draw the experimental data for MEKPO 31 mass% and with acetone 99 mass% on three types of heating rate of 2, 4, and 10 °C/min; the kinetic and safety parameters were then evaluated via curve fitting. Through the reproducible tests in each condition, the results show that acetone is not a contaminant, because it could increase the activation energy ( E a ) and onset temperature ( T o ) when combined with MEKPO, which differs from the hazard information of the material safety data sheet (MSDS).
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Thermal hazard evaluation for mEthyl Ethyl ketone peroxide mixedwith inorganic acids
Journal of Thermal Analysis and Calorimetry, 2006Co-Authors: J.m. Tseng, R. H. Chang, Jao-jia Horng, M. K. Chang, Chi-min ShuAbstract:MEthyl Ethyl ketone peroxide (MEKPO) possesses complex structures which have caused many incidents involving fires or explosions by mixing with incompatible substances, external fires, and others. In this study, reactivities or incompatibilities of MEKPO with inorganic acids (HCl, HNO3, H3PO4 and H2SO4) were assessed by differential scanning calorimetry (DSC) and vent sizing package 2 (VSP2). Parameters obtained by the above-mentioned devices could be readily employed to discuss the runaway reaction, such as onset temperature (T0), heat of reaction (ΔHd), time to maximum rate (TMR), maximum self heat rate (dT/dt)max, adiabatic temperature rise (ΔTad), maximum pressure of decomposition (Pmax) and so on.
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Thermal hazard simulations for mEthyl Ethyl ketone peroxide induced by contaminants
Korean Journal of Chemical Engineering, 2005Co-Authors: J.m. Tseng, Yi-chun YuAbstract:Historically, mEthyl Ethyl ketone peroxide (MEKPO), a universal hardener in the rubber industries, has caused many serious explosions and fires in Taiwan, Japan, Korea, and China. This study used certain thermal analytical methods to thoroughly explore both why MEKPO led to these accidents and what happened during the upset conditions. Potential process contaminants, such as H_2SO_4, KOH, and Fe_2O_3, were deliberately selected to mix with MEKPO in various concentrations. Differential scanning calorimetry (DSC) was employed to calculate the thermokinetic parameters. Kinetic evaluation was also implemented by means of the methods and software developed by Chem-Inform St. Petersburg, Ltd. The results indicate that MEKPO is highly hazardous when mixed with any of the above-mentioned contaminants. Fire and explosion hazards can be effectively lessened if safety parameters and thermokinetic parameters are properly imbedded into manufacturing processes.
