Atmospheric chemistry of ethyl propionate

Ethyl propionate is a model for fatty acid ethyl esters used as first-generation biodiesel. The atmospheric chemistry of ethyl propionate was investigated at 980 mbar total pressure. Relative rate measurements in 980 mbar N(2) at 293 ± 0.5 K were used to determine rate constants of k(C(2)H(5)C(O)OC(2)H(5) + Cl) = (3.11 ± 0.35) × 10(-11), k(CH(3)CHClC(O)OC(2)H(5) + Cl) = (7.43 ± 0.83) × 10(-12), and k(C(2)H(5)C(O)OC(2)H(5) + OH) = (2.14 ± 0.21) × 10(-12) cm(3) molecule(-1) s(-1). At 273-313 K, a negative Arrhenius activation energy of -3 kJ mol(-1) is observed.. The chlorine atom-initiated oxidation of ethyl propionate in 980 mbar N(2) gave the following products (stoichiometric yields): ClCH(2)CH(2)C(O)OC(2)H(5) (0.204 ± 0.031), CH(3)CHClC(O)OC(2)H(5) (0.251 ± 0.040), and C(2)H(5)C(O)OCHClCH(3) (0.481 ± 0.088). The chlorine atom-initiated oxidation of ethyl propionate in 980 mbar of N(2)/O(2) (with and without NO(x)) gave the following products: ethyl pyruvate (CH(3)C(O)C(O)OC(2)H(5)), propionic acid (C(2)H(5)C(O)OH), formaldehyde (HCHO), and, in the presence of NO(x), PAN (CH(3)C(O)OONO(2)). The lack of acetaldehyde as a product suggests that the CH(3)CH(O)C(O)OC(2)H(5) radical favors isomerization over decomposition. From the observed product yields, we conclude that H-abstraction by chlorine atoms from ethyl propionate occurs 20.4 ± 3.1%, 25.1 ± 4.0%, and 48.1 ± 8.8% from the CH(3)-, -CH(2)-, and -OCH(2)- groups, respectively. The rate constant and branching ratios for the reaction between ethyl propionate and the OH radical were investigated theoretically using quantum mechanical calculations and transition state theory. The stationary points along the reaction path were optimized using the CCSD(T)-F12/VDZ-F12//BH&HLYP/aug-cc-pVTZ level of theory; this model showed that OH radicals abstract hydrogen atoms primarily from the -OCH(2)- group (80%).     

Thermodynamic properties of organic oxygen compounds XLIV. Vapour heat capacities and enthalpies of vaporization of methyl acetate,ethyl acetate,and propyl acetate

Measured values of the vapour heat capacities of methyl, ethyl, and propyl acetates are reported for the temperature range 335 to 450 K and at pressures from 25 kPa to atmospheric. Experimental values of the enthalpies of vaporization at these pressures and calculated values of the second virial coefficients are also given.     

Thermophysical properties of biodiesel and related systems: Low-pressure vapour–liquid equilibrium of methyl/ethyl Jatropha curcas biodiesel

Biodiesel production from non-edible oils has been considered in recent years due to their economic, politics and environmental aspects. Vapour–liquid equilibrium data for the pseudo-binary and pseudo-ternary systems involving fatty acid methyl/ethyl esters from Jatropha curcas oil were determined over the pressure range from (6.7 to 66.7) kPa in an Othmer-type ebulliometer. All systems presented non-ideal behaviour and positive deviations from Raoult’s law. It was observed that the addition of up to 10 wt.% of alcohol (methanol or ethanol) promoted a significant decrease in the boiling point temperatures for the evaluated systems. The UNIQUAC model was used to correlate the experimental values, with good agreement between experiment and model results.     

Isomer-specific fuel destruction pathways in rich flames of methyl acetate and ethyl formate and consequences for the combustion chemistry of esters

The influences of fuel-specific destruction pathways on flame chemistry are determined for two isomeric ester fuels, methyl acetate, CH3(CO)OCH3, and ethyl formate, H(CO)OC2H5, used as model representatives for biodiesel compounds, and their potential for forming air pollutants is addressed. Measurements are presented of major and intermediate species mole fractions in premixed, laminar flat flames using molecular-beam sampling and isomer-selective VUV-photoionization mass spectrometry. The observed intermediate species concentrations depend crucially on decomposition of the different radicals formed initially from the fuels. The methyl acetate structure leads to preferential formation of formaldehyde, while the ethyl formate isomer favors the production of acetaldehyde. Ethyl formate also yields higher concentrations of the C2 species (C2H2 and C2H4) and C4 species (C4H2 and C4H4). Benzene concentrations, while larger for ethyl formate, are at least an order of magnitude smaller for both flames than seen for simple hydrocarbon fuels (ethylene, ethane, propene, and propane).     

Aza-Morita-Baylis-Hillman reaction of ethyl (arylimino)acetate with methyl vinyl ketone and ethyl vinyl ketone

Aza-Morita-Baylis-Hillman (aza-MBH) reaction of ethyl (arylimino)acetate with methyl vinyl ketone and ethyl vinyl ketone has been investigated. We found that aza-MBH adducts 1 could be formed in the presence of DABCO (30 mol %) and the corresponding adducts 2 could be obtained in the presence of PPh₃ (30 mol %) in moderate to good yields in acetonitrile under mild conditions, respectively.     

1,3-Migration of hydrogen in radical telomerization of allyl acetate with methyl propionate

Conclusions The telomerization of allyl acetate with methyl propionate is accompanied by rearrangement of the CH₃CO₂CH₂CHCH₂CH(CH₃)CO₂CH₃ radical with 1,3-migration of the hydrogen atom.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1670–1673, July, 1981.     

Rheology and MT-DSC studies of the flow properties of ethyl and methyl babassu biodiesel and blends

The synthesis of pigments from the system Ce_1−x O₂–M _x O (M = Cu, Co) was achieved via a polymeric precursors method, Pechini method. Differential scanning calorimetry (DSC) and thermogravimetry (TG) techniques were used to accurately characterize the distinct thermal events occurring during synthesis. The TG and DSC results revealed a series of decomposition temperatures due to different exothermal events, which were identified as H₂O elimination, organic compounds degradation, and phase formation. X-Ray diffraction patterns show the presence of pure cubic CeO₂ phase for the samples with low Cu and Co loading. A decrease of the specific surface area with increasing copper and cobalt content was observed. The UV–visible diffuse reflectance technique was employed to study the optical properties in the 200–800 nm range. Colorimetric coordinates L*, a*, b* were calculated for the pigment powders. The powders presented a variety of colors from yellow for pure CeO₂, to brown for the ones loaded with copper and gray for the ones with cobalt.     

Structure of proton disolvates formed in the acid hydrolysis of ethyl formate and methyl acetate

By the density functional method (B3LYP/6-31++G(d,p)) optimal structures of proton hetero and homo disolvates involving water molecules, ethyl formate, methyl acetate and products of their hydrolysis are calculated. The data on the structure of these ions and the strength of their H bonds are analyzed together with the results of a similar calculation previously performed for methyl formate. It is shown that in proton solvation by two molecules present in the solution during the hydrolysis of ethyl formate, methyl acetate, and methyl formate stable (X…H…X)⁺ or (X…H…Y)⁺ particles form. Structural and energy parameters of their O…H…O bridges obey the same regularities and are mainly determined by a difference in the proton affinity of X and Y molecules. Calculation results are compared to the data of a number of experimental studies of the acid hydrolysis of esters.     

Gas phase ion chemistry of methyl acetate,methyl propanoate and their enolic tautomers. An experimental approach

From a combination of isotopic substitution, time-resolved measurements and sequential collision experiments, it was proposed that whereas ionized methyl acetate prior to fragmentation rearranges largely into \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_3 \mathop {\rm C}\limits^ + ({\rm OH}){\rm O}\mathop {\rm C}\limits^{\rm .} {\rm H}_2 $\end{document}, in contrast, methyl propanoate molecular ions isomerize into \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^. {\rm H}_2 {\rm CH}_2 \mathop {\rm C}\limits^ + ({\rm OH}){\rm OCH}_3 $\end{document}. Metastably fragmenting methyl acetate molecular ions are known predominantly to form H₂?OH together with \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_3 - \mathop {\rm C}\limits^ + = {\rm O} $\end{document}, whereas ionized methyl propanoate largely yields H₃CO˙ together with \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_3 {\rm CH}_2 - \mathop {\rm C}\limits^ + = {\rm O} $\end{document}. The observations were explained in terms of the participation of different distonic molecular ions. The enol form of ionized methyl acetate generates substantially more H₃CO˙ in admixture with H₂?OH than the keto tautomer. This is ascribed to the rearrangement of the enol ion to the keto form being partially rate determining, which results in a wider range of internal energies among metastably fragmenting enol ions. Extensive ab initio calculations at a high level of theory would be required to establish detailed reaction mechanisms.     

Homologation of methyl acetate to ethyl acetate with ruthenium catalysts: Part II. effect and role of lewis and protonic acids as promoters

Upon the addition of Lewis and protonic acids, promoters to ruthenium carbonyl iodide catalysts ([Ru(CO)₃I₃]⁻), important effects are observed on the activity and selectivity of the hydrogenation, carbonylation and homologation reactions of methyl acetate.The improvement in selectivity to the valuable products acetic acid and ethyl acetate, and the decrease of the formation of hydrocarbons are related to the acceleration by Lewis acids of the alkyl migration-carbonyl insertion step of the process.The effect on the kinetics is related to the formation and maintenance in the catalytic solution of the hydrido species, HRu(CO)₃I₃, and to the availability of I⁻ involved in the activation of the substrates.     

Intercalation of multiply solvated hexafluorophospate anion into graphite electrode from mixtures of methyl acetate,ethyl methyl and ethylene carbonates

Graphite is a universal host material for ion intercalation.Li+-graphite intercalation compounds (GICs) have been successfully utilized as the anode material in...     

Catalytic combustion of ethyl acetate over CeMnO_x and CeMnZrO_x compounds synthesized by coprecipitation method

Ce0.6Mn0.4O2 catalysts with different sources of manganese and Ce0.6-xZrxMn0.4O2 mixed oxide catalysts were prepared by coprecipitation method and were characterized by N2 adsorption-desorption,TPR,XRD,and XPS techniques.The activities of the prepared catalysts for ethyl acetate combustion,and the effects of calcination temperature and space velocity on catalytic activity were investigated.The results showed that partial replacement of Mn(NO3)2 with KMnO4 as sources of manganese could improve activities of catalysts.Ce0.45Zr0.15Mn0.4O2 catalyst exhibited the best catalytic activity and high thermal stability,e.g.,T90 could be still below 210℃ even if space velocity was up to 20000h-1.     

Simultaneous determination of odorous volatile organic compounds with gas chromatography and a thermal desorber: A case study on methyl ethyl ketone, methyl isobutyl ketone, butyl acetate, toluene, and xylene

In this study, a series of experiments were conducted to examine the feasibility of the gas chromatographic approach for the quantification of several odorous volatile organic compounds (VOCs) in environmental samples which included methyl ethyl ketone, isobutyl alcohol, methyl isobutyl ketone, and butyl acetate plus benzene, toluene, and xylene (namely, BTX). The gaseous working standards (WS) of seven compounds were initially calibrated at varying concentration ranges by direct injection (DI) into GC injector. The detection properties of these compounds were then tested with a thermal desorber (TD). The relative sensitivities of three aromatic VOCs differed greatly between DI and TD methods. In contrast, four polar VOCs tend to consistently exhibit relative enhancement in response factors with increasing molecular mass (an exception of butyl acetate), regardless of method. The TD-based analysis was reliable enough to detect all target VOCs below their odor threshold values with their detection limit (DL) values. This TD method, when tested against a number of environmental samples collected from several industrial facilities, confirmed the presence of these odorous VOCs at a wide concentration range.     

Telomerization of propylene with methyl propionate

Conclusions The principal products of the telomerization of propylene with methyl propionate are telomers with the structure , where n=1–4.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2534–2537, November, 1973.     

Oxidation of methyl and ethyl butanoates

This paper describes an experimental and modeling study of the oxidation of methyl and ethyl butanoates in a shock tube. The ignition delays of these two esters mixed with oxygen and argon for equivalence ratios from 0.25 to 2 and ester concentrations of 0.5% and 1% were measured behind a reflected shock wave for temperatures from 1250 to 2000 K and pressures around 8 atm. To extend the range of studied temperatures in the case of methyl butanoate, two sets of measurements were also made in a jet‐stirred reactor at 800 and 850 K, at atmospheric pressure, at residence times varying between 1.5 and 9 s and for equivalence ratios of 0.5 and 1. Detailed mechanisms for the combustion of methyl and ethyl butanoates have been automatically generated using a version of EXGAS software improved to take into account these oxygenated reactants. These mechanisms have been validated through comparison of simulated and experimental results in both types of reactor. The main reaction pathways have been derived from reaction flux and sensitivity analyses performed at different temperatures. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 226–252, 2010     

Stereoselection in the condensation between ethyl propionate and aldehydes

Ethyl propionate can be converted stereoselectively into geometrical isomers of O-ethyl-O-trimethylsilylmethylketene acetal ($\text{5}$). The E-isomer of $\text{5}$ condenses with aldehydes by titanium tetrachloride to give stereoselectively the threo isomers of ethyl 2-methyl-3-hydroxy carboxylates.