Homogeneous, unimolecular gas‐phase elimination kinetics of ethyl esters of glyoxylic, 2‐oxo‐propanoic, and 3‐methyl‐2‐oxo‐butanoic acids

Reyes, A.; Domínguez, Rosa M.; Tosta, María; Herize, Armando; Chuchani, Gabriel

doi:10.1002/kin.20240

Cited by 5 publications

(4 citation statements)

References 15 publications

(26 reference statements)

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“…The elimination kinetics of ethyl esters of 2-oxocarboxylic acids with nitrogen attached at the acid side, that is, ethyl oxamate and ethyl oxanilinate, suggests that the first step of the reaction is a decarbonylation process by migration of the amino substituent. Similarly, the gas-phase decomposition of ethyl glyoxylate was shown to undergo a parallel and consecutive homogeneous elimination as described in reaction , where step 2 is also thought to comprise a decarbonylation followed by H migration. …”

Section: Introductionmentioning

confidence: 99%

Joint Experimental and DFT Study of the Gas-Phase Unimolecular Elimination Kinetic of Methyl Trifluoropyruvate

et al. 2010

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The elimination kinetics of methyl trifluoropyruvate in the gas phase was determined in a static system, where the reaction vessel was always deactivated with allyl bromide, and in the presence of at least a 3-fold excess of the free-radical chain inhibitor toluene. The working temperature range was 388.5-430.1 degrees C, and the pressure range was 38.6-65.8 Torr. The reaction was found to be homogeneous and unimolecular and to obey a first-order rate law. The products of the reaction are methyl trifluoroacetate and CO gas. The Arrhenius equation of this elimination was found to be as follows: log k(1) (s(-1)) = (12.48 +/- 0.32) - (204.2 +/- 4.2) kJ mol(-1)(2.303RT)(-1) (r = 0.9994). The theoretical calculation of the kinetic and thermodynamic parameters and the mechanism of this reaction were carried out at the B3LYP/6-31G(d,p), B3LYP/6-31++G(d,p), MPW1PW91/6-31G(d,p), MPW1PW91/6-31++G(d,p), PBEPBE/6-31G(d,p), and PBEPBE/6-31G++(d,p) levels of theory. The theoretical study showed that the preferred reaction channel is a 1,2-migration of OCH(3) involving a three-membered cyclic transition state in the rate-determining step.

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Section: Introductionmentioning

confidence: 99%

Joint Experimental and DFT Study of the Gas-Phase Unimolecular Elimination Kinetic of Methyl Trifluoropyruvate

et al. 2010

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“…However, the absence of the β‐hydrogen, that is, the replacement of ethyl group by a methyl group in carboxylic esters has rarely shown abstraction of α‐H of the CH 3 group. In association with this fact, the work on the gas‐phase elimination of methyl benzoylformate described in reaction appeared to be give an interesting and different result when compared with the reported papers showing no abstraction of the α‐H in the CH 3 group.…”

Section: Introductionmentioning

confidence: 94%

“…Further investigation related to the gas‐phase elimination of esters of 2‐oxo‐acids [reactions and ] containing electron‐withdrawing substituents (Cl, NH 2 and NHPh) was to change it to electron‐releasing groups, i.e. methyl (ethyl‐2‐oxo‐propionate) and isopropyl (3‐methyl‐2‐oxo‐butyrate) . The thermal decomposition of these substrates underwent as in ethyl carboxylic acids through a concerted six‐membered cyclic transition state mechanism, producing the corresponding 2‐oxo‐acid and ethylene.…”

Section: Introductionmentioning

confidence: 99%

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Homogeneous and unimolecular gas‐phase thermal decomposition kinetics of methyl benzoylformate: experimental and theoretical study

Monascal

Maldonado

Mora

et al. 2014

J of Physical Organic Chem

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The kinetics of the gas‐phase thermal decomposition of the α‐ketoester methyl benzoylformate was carried out in a static system with reaction vessel deactivated with allyl bromide, and in the presence of the free radical inhibitor propene. The rate coefficients were determined over the temperature range of 440–481 °C and pressures from 32 to 80 Torr. The reaction was found to be homogenous, unimolecular and obey a first‐order rate law. The products are methyl benzoate and CO. The temperature dependence of the rate coefficient gives the following Arrhenius parameters: log10 k (s−1) = 13.56 ± 0.31 and Ea (kJ mol−1) = 232.6 ± 4.4. Theoretical calculations of the kinetic and thermodynamic parameters are in good agreement with the experimental values using PBE1PBE/6‐311++g(d,p). A theoretical Arrhenius plot was constructed at this level of theory, and the good agreement with the experimental Arrhenius plot suggests that this model of transition state may describe reasonably the elimination process. These results suggest a concerted non‐synchronous semi‐polar three‐membered cyclic transition state type of mechanism. The most advanced coordinate is the bond breaking Cδ+‐‐‐δ‐OCH3 with an evolution of 66.7%, implying this as the limiting factor of the elimination process. Copyright © 2014 John Wiley & Sons, Ltd.

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Kinetics of the gas‐phase homogeneous unimolecular elimination of selected ethyl esters of 2‐oxo‐carboxylic acids

Reyes

Domínguez

Tosta

et al. 2010

J of Physical Organic Chem

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The gas‐phase elimination kinetics of selected ethyl esters of 2‐oxo‐carboxylic acid have been studied over the temperature range of 270–415 °C and pressures of 37–114 Torr. The reactions are homogeneous, unimolecular, and follow a first‐order rate law in a seasoned static reaction vessel, with an added free radical suppressor toluene. The observed overall and partial rate coefficients are expressed by the following Arrhenius equations: Ethyl oxalyl chloride log koverall (s−1) = (13.22 ± 0.45) − (179.4 ± 4.9) kJ mol−1 (2.303 RT)−1 Ethyl piperidineglyoxylate log k(CO2) (s−1) = (12.00 ± 0.30) − (191.2 ± 3.9) kJ mol−1 (2.303 RT)−1 log k(CO) (s−1) = (12.60 ± 0.09) − (210.7 ± 1.2) kJ mol−1 (2.303 RT)−1 log kt(overall) (s−1) = (12.22 ± 0.26) − (193.4 ± 3.4) kJ mol−1 (2.303 RT)−1 Ethyl benzoyl formate log k(CO2) (s−1) = (12.89 ± 0.72) − (203.8 ± 9.0) kJ mol−1 (2.303 RT)−1 log k(CO) (s−1) = (13.39 ± 0.31) − (213.3 ± 3.9) kJ mol−1 (2.303 RT)−1 log kt(overall) (s−1) = (13.24 ± 0.60) − (205.8 ± 7.6) kJ mol−1 (2.303 RT)−1 The kinetic and thermodynamic parameters of these reactions, together with those reported in the literature, lead to consider three different mechanistic pathways of elimination. Copyright © 2010 John Wiley & Sons, Ltd.

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Homogeneous, unimolecular gas‐phase elimination kinetics of ethyl esters of glyoxylic, 2‐oxo‐propanoic, and 3‐methyl‐2‐oxo‐butanoic acids

Cited by 5 publications

References 15 publications

Joint Experimental and DFT Study of the Gas-Phase Unimolecular Elimination Kinetic of Methyl Trifluoropyruvate

Joint Experimental and DFT Study of the Gas-Phase Unimolecular Elimination Kinetic of Methyl Trifluoropyruvate

Homogeneous and unimolecular gas‐phase thermal decomposition kinetics of methyl benzoylformate: experimental and theoretical study

Kinetics of the gas‐phase homogeneous unimolecular elimination of selected ethyl esters of 2‐oxo‐carboxylic acids

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