Termólisis de Clorooxoacetato de Etilo en Fase Gas: Comparación con Oxoacetato de Etilo y Detalles del Sistema Estático para el Estudio Cinético / Gas Phase Ethyl ChlorooxoacetateThermolysis: Comparison with Ethyl Oxoacetate and Static System Details for Kinetic Study

• Andreína Alexandra Reyes Yanes Universidad Nacional Mayor de San Marcos, Facultad de Química e Ingeniería Química, Departamento Académico de Fisicoquímica, Ciudad Universitaria- Pabellón B- Calle Germán Amezaga Nº 375, Lima 15081, Perú. http://orcid.org/0000-0003-4603-2318

Abstract

Resumen

La ventaja de los estudios cinéticos en fase gas es que el coeficiente de velocidad no es afectado por superficies, catalizadores ni disolventes que interactúen con el sustrato. La termólisis en fase gas de los ésteres derivados del ácido oxálico ha sido poco estudiada.En esta investigación se realizó el estudio cinético de la descomposición térmica de clorooxoacetato de etilo entre 543–593 K y 76–209 mbar, utilizando un sistema estático de vacío cuyo funcionamiento se describeampliamente. Mediciones de presión total y análisis cromatográfico de productos indicanreaccionesconsecutivas de orden uno, unimoleculares y homogéneas, de decarbonilación del sustrato seguida de la eliminación de etileno, a diferencia de la termólisis de oxoacetato de etilo, que procede por vías paralelas de decarboxilación y decarbonilación.La ecuación de Arrhenius para la reacción estudiada entre 543,2 – 593,1 Kresultó serlog k₁ = (13,22 ± 0,45)–(179,4 ± 4,9) kJ mol^–1 (2,303RT)^–1, y el coeficiente de velocidad a 623 K significativamente mayor que para la decarbonilación del oxoacetato de etilo sugiere que el sustituyente cloro tendría mayor disposición que el hidrógeno de migrar al carbonilo adyacente, formando un estado de transición con enlaces más rígidos.

Abstract

The advantage offered by kinetic studies in the gas phase is that the velocity coefficient is not affected by surfaces, catalysts or solvents that interact with the substrate. So far, gas phase thermolysis of esters derived from oxalic acid have been scarcely studied.In this investigation, the kinetic study of the thermal decomposition of ethyl chlorooxoacetate between 543–593 K and 76–209 mbar was carried out, using a static vacuum system whose operation are widely described.Total pressure measurements and chromatographic products analysis indicates consecutive first orderreactions, unimolecular and homogeneous forsubstrate decarbonylation, followed by ethylene elimination, unlike the ethyl oxoacetatethermolysis, which proceeds by parallel decarboxylation and decarbonylation pathways.Arrhenius equation for the reaction studied between 543.2 – 593.1 K was found to be log k₁ = (13.22 ± 0.45)–(179.4 ± 4.9) kJ mol^–1(2.303RT)^–1 and velocity coefficient at 623 K significantly larger than for the decarbonylation of ethyl oxoacetate, suggesting that chlorine substituent would have a greater tendency than hydrogen to migrate to the adjacent carbonyl, forming more rigid bonds transition state.

 

https://doi.org/10.22209/rt.v43n3a01

References

Chuchani G., Martin I. y Avila I.: “Effect of substituents in the gas- phase elimination kinetics of β- substituted ethyl acetates”. Int. J. Chem.Kinet., Vol 11, Nº6 (1979) 561-567. https://doi.org/10.1002/kin.550110602

AlAwadi N.A., Kaul K. yElDusouqui O.M.: “Kinetics and mechanism of thermal gas- phase elimination of αsubstituted carboxylic acids: role of relative basicity of α- substituents and acidity of incipient proton”. J. Phys. Org. Chem., Vol13, Nº 9 (2000)499-504. https://doi.org/10.1002/1099-1395(200009)13:9<499::AID-POC269>3.0.CO;2-0

Al-Awadi S.A., Abdallah M.R., Dib H.H., Ibrahim M.R., Al-Awadi N.A. y El-Dusouqui O.M.E.:“Kinetics and mechanism of thermal gas-phase elimination of β-substituted carboxylic acids”. Tetrahedron, Vol. 61, Nº 24 (2005), 5769-5777. https://doi.org/10.1016/j.tet.2005.04.031

Silva A.M.:“A theoretical study of the pyrolysis of isopropyl acetate”. Chem. Phys.Lett., Vol. 439, Nº 1-3 (2007)8-13. https://doi.org/10.1016/j.cplett.2007.03.037

Floyd K. y Smith G.:“Structure-reactivity relationships in homogeneous gas phase reactions: thermolysis and rearrangements”.Prog. Phys. Org. Chem., Vol. 8 (2009) 75. https://10.1002/9780470171875.ch2

Moldoveanu S.C.:“The chemistry of the pyrolytic process”. In Techniques and Instrumentation in Analytical Chemistry,Amsterdam, Elsevier, Vol 28(2010) 28:7-48.https://doi.org/10.1016/S0167-9244(09)02802-9

Wu P., Chen X., Li J. y Huang Y.: “Theoretical studies on the pyrolysis of thiocarbonates”. Comput. Theor. Chem., Vol. 1030 (2014) 67-73. https://doi.org/10.1016/j.comptc.2013.12.026

Shiroudi A. yZahedi E.:“Understanding the kinetics of thermal decomposition of 2, 3-epoxy-2, 3-dimethylbutane using RRKM theory”. RSC Adv., Vol. 6, Nº 94(2016) 91882-91892.https://doi.org/10.1039/C6RA21963B

Al-Awadi N.: “Gas‐Phase Pyrolytic Reactions. Chapter 4: Structure/Reactivity Correlation” (2019)https://doi.org/10.1002/9781119010753.ch4

Laidler K.J.:“Reaction kinetics: Homogeneous gas reactions”. Vol. 1. Amsterdam,Elsevier (2013) 97-149.

Cordova T., Rotinov A. yChuchani G.:“Experimental and theoretical study of the homogeneous, unimolecular gas-phase elimination kinetics of methyl oxalyl chloride”. J. Phys. Org. Chem.Vol 17, Nº 2(2004)148-151. https://doi.org/10.1002/poc.705

Reyes Y.A.:“Estudio cinético de la termólisis del oxoacetato de etilo”. Afinidad, Vol. 74, Nº 579(2017)208-213.https://www.raco.cat/index.php/afinidad/article/view/328556

Johnson R. L. y Stimson V.R.:“The thermal decomposition of ethyl chloroformate”.Aust. J. Chem., Vol. 29, Nº 6(1976) 1389-1392.https://doi.org/10.1071/CH9761389

Benson, S.W.:“Predictability of chain reactions”. Ind. Eng. Chem., Vol. 56, Nº 1 (1964) 18-27. https://doi.org/10.1021/ie50649a004

Márquez E., Domínguez R., Tosta M. y Chuchani, G.:“Cinética y mecanismos de la eliminación homogénea en fase gaseosa unimolecular del ortoacetato de trimetilo y del ortobutirato de trimetilo”. J. Phys. Chem. A, Vol. 112, Nº 47 (2008) 12140-12142. https://doi.org/10.1021/jp8074942

Vasiliou A.G.,Piech K.M., Zhang X.,Nimlos M.R., Ahmed M., Golan A. et al.:“The products of the thermal decomposition of CH3CHO”. J. Chem. Phys., Vol. 131, Nº 1(2011)014306.https://doi.org/10.1063/1.3604005

Moreno B.M,Quach A.L.,Merves M.N. y Klein M.T.:“Discrimination between free-radical and concerted pyrolysis mechanisms”. Energy Fuels, Vol. 28, Nº 7(2014) 4256-4259.https://doi.org/10.1021/ef500055a

Trubetskaya A., Jensen P.A., Jensen A.D.,Glarborg P., Larsen F.H. y Andersen M.L.:“Characterization of free radicals by electron spin resonance spectroscopy in biochars from pyrolysis at high heating rates and at high temperatures”. Biomass Bioenergy, Vol. 94(2016) 117-129.https://doi.org/10.1016/j.biombioe.2016.08.020

Vahid S. y Zokaie M.: “Multichannel Gas-Phase Unimolecular Decomposition of Acetone: Theoretical Kinetic Studies”. J. Phys. Chem. A, Vol. 122, Nº 28(2018) 5895-5904.https://doi.org/10.1021/acs.jpca.8b02423

Colket M.B. ySeery D.J. (1994, January).:“Reaction mechanisms for toluene pyrolysis”. In Symposium (International) on combustion (Vol. 25, No. 1, pp. 883-891). Elsevier.https://doi.org/10.1016/S0082-0784(06)80723-X

Sivaramakrishnan R., Tranter R.S. yBrezinsky K.:“High pressure pyrolysis of toluene. 1. Experiments and modeling of toluene decomposition”.J. Phys.Chem A., Vol. 110, Nº 30 (2006)9388-9399.https://doi.org/10.1021/jp060820j

Sivaramakrishnan R., Tranter R.S. y Brezinsky K.:“High pressure pyrolysis of toluene. 2. Modeling benzyl decomposition and formation of soot precursors”. J. Phys. Chem. A, Vol. 110, Nº 30(2006) 9400-9404. https://10.1021/jp0608224

Zhang L., Cai J., Zhang T. y Qi F.:“Kinetic modeling study of toluene pyrolysis at low pressure”. Combust. Flame, Vol. 157, Nº 9(2010) 1686-1697. https://10.1016/j.combustflame.2010.04.002

Lannuzel F., Bounaceur R., Michels R., Scacchi G. yMarquaire P.M.:“An extended mechanism including high pressure conditions (700bar) for toluene pyrolysis". J. Anal. Appl.Pyrol., Vol. 87, Nº 2(2010) 236-247. https://10.1016/j.jaap.2010.01.001

Matsugi A. y Miyoshi A.:“Modeling of two- and three-ring aromatics formation in the pyrolysis of toluene”. Proc. Comb. Inst., Vol. 31, Nº 1(2013) 269-277. https://10.1016/j.proci.2012.06.032

Taylor J.E. y Milazzo T.S.: “Gasphase pyrolysis of 2,2,3,3tetramethylbutane using a wallless reactor”. Int. J. Chem. Kinet., Vol. 10, Nº 12 (1978) 1245-1257. https://doi.org/10.1002/kin.550101207

Dabbagh H.A. y Davis B.H.: “Pyrolysis of sec-butyl acetate. Is the stereospecific syn elimination a homogeneous or heterogeneous reaction?”.J. Org. Chem., Vol. 55, Nº 7(1990) 2011-2016. https://doi.org/10.1021/jo00294a011

Mascavage L.M. y Dalton D.R.: “Surface catalyzed hydrochlorination of 1,3-butadiene”. Tetrahedron Lett., Vol. 32, Nº 29 (1991) 3461-3464. https://doi.org/10.1016/0040-4039(91)80806-H

Maccoll A.:“Studies in the pyrolysis of organic bromides. Part I. The kinetics of the decomposition of allyl bromide”. J. Chem.Soc.(1955)965-973.https://doi.org/10.1039/JR9550000965

Acevedo S., Galicia L., Plaza E., Atencio R., Rodríguez A. y González E.: “Carbón activado preparado a partir de carbón mineral bituminoso activado con hidróxido de potasio”. Rev. Téc. Ing. Univ. Zulia. Vol. 39, No 2 (2016) 64-70. https://www.produccioncientificaluz.org/index.php/tecnica/article/view/21324