Solvent and substituent effects on the kinetics of thermolysis of cis-fused 1,2,4-trioxanes

Autores
Cafferata, Lázaro F. R.; Jefford, Charles W.
Año de publicación
2001
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
The kinetics of the thermal decomposition reaction of cis-6-phenyl-5,6-(2- phenylpropyliden)-3,3-pentamethylene-1,2,4-trioxacyclohexane (Ia) were investigated in benzene and methanol solutions in the temperature and concentration ranges of 353.3-413.2 K and (1.1 - 13.1)×10-3 M, respectively. First-order rate constant values were obtained for up to at least ca. 20% conversions of that cyclic peroxide. The activation parameter values for the initial unimolecular homolysis of that molecule, results supported by the effect of the addition of di-tert-butyl-p-cresol as a free radical scavenger, indicate a stepwise reaction mechanism which is in keeping with the reaction products analysis. The corresponding activation parameters for the reaction of Ia in methanol (ΔH# = 20.2 ± 0.6 kcal mol-1; ΔS# = 0.1 ± 1.6 cal mol-1K-1; ΔG# = 20.2 ± 0.6 kcal mol-1 and in benzene (ΔH# = 15.4 ± 0.2 kcal mol-1; ΔS# = -13.2 ± 0.5 cal mol-1K-1; ΔG# = 20.5 ± 0.2 kcal mol-1 solutions are compared with values obtained for cis-6-phenyl-5,6-(2-phenylpropyliden)-3,3- tetramethylene-1,2,4-trioxacyclohexane (Ib) thermolysis in the same solvents. The thermolysis kinetics of Ia are less sensitive to solvent changes compared to the behaviour already reported for the analogous reactions of Ib. Because both molecules in solution are flexible structures due to their configurations, the relatively small solvent effect found on the former trioxane reaction is attributed to the extent of the chain of methylene groups attached on C-3 of the corresponding molecular rings. Furthermore, the pertinent substituent effect on the peroxidic bond strength of those molecules in solution was evaluated.
Facultad de Ciencias Exactas
Materia
Ciencias Exactas
Química
cis-Substituted 1,2,4-trioxanes
cresol
kinetics
cyclohexane derivative
methanol
solvent and substituent effects
stepwise reaction mechanism
peroxide
scavenger
solvent
unclassified drug
chemical bond
Nivel de accesibilidad
acceso abierto
Condiciones de uso
http://creativecommons.org/licenses/by/3.0/
Repositorio
SEDICI (UNLP)
Institución
Universidad Nacional de La Plata
OAI Identificador
oai:sedici.unlp.edu.ar:10915/35056

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oai_identifier_str oai:sedici.unlp.edu.ar:10915/35056
network_acronym_str SEDICI
repository_id_str 1329
network_name_str SEDICI (UNLP)
spelling Solvent and substituent effects on the kinetics of thermolysis of cis-fused 1,2,4-trioxanesCafferata, Lázaro F. R.Jefford, Charles W.Ciencias ExactasQuímicacis-Substituted 1,2,4-trioxanescresolkineticscyclohexane derivativemethanolsolvent and substituent effectsstepwise reaction mechanismperoxidescavengersolventunclassified drugchemical bondThe kinetics of the thermal decomposition reaction of <i>cis</i>-6-phenyl-5,6-(2- phenylpropyliden)-3,3-pentamethylene-1,2,4-trioxacyclohexane <b>(Ia)</b> were investigated in benzene and methanol solutions in the temperature and concentration ranges of 353.3-413.2 K and (1.1 - 13.1)×10<SUP>-3</SUP> M, respectively. First-order rate constant values were obtained for up to at least ca. 20% conversions of that cyclic peroxide. The activation parameter values for the initial unimolecular homolysis of that molecule, results supported by the effect of the addition of di-<i>tert</i>-butyl-<i>p</i>-cresol as a free radical scavenger, indicate a stepwise reaction mechanism which is in keeping with the reaction products analysis. The corresponding activation parameters for the reaction of <b>Ia</b> in methanol (ΔH<SUP>#</SUP> = 20.2 ± 0.6 kcal mol<SUP>-1</SUP>; ΔS<SUP>#</SUP> = 0.1 ± 1.6 cal mol<SUP>-1</SUP>K<SUP>-1</SUP>; ΔG<SUP>#</SUP> = 20.2 ± 0.6 kcal mol<SUP>-1</SUP> and in benzene (ΔH<SUP>#</SUP> = 15.4 ± 0.2 kcal mol<SUP>-1</SUP>; ΔS<SUP>#</SUP> = -13.2 ± 0.5 cal mol<SUP>-1</SUP>K<SUP>-1</SUP>; ΔG# = 20.5 ± 0.2 kcal mol<SUP>-1</SUP> solutions are compared with values obtained for cis-6-phenyl-5,6-(2-phenylpropyliden)-3,3- tetramethylene-1,2,4-trioxacyclohexane (<b>Ib</b>) thermolysis in the same solvents. The thermolysis kinetics of <b>Ia</b> are less sensitive to solvent changes compared to the behaviour already reported for the analogous reactions of <b>Ib</b>. Because both molecules in solution are flexible structures due to their configurations, the relatively small solvent effect found on the former trioxane reaction is attributed to the extent of the chain of methylene groups attached on C-3 of the corresponding molecular rings. Furthermore, the pertinent substituent effect on the peroxidic bond strength of those molecules in solution was evaluated.Facultad de Ciencias Exactas2001info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionArticulohttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdf699-709http://sedici.unlp.edu.ar/handle/10915/35056enginfo:eu-repo/semantics/altIdentifier/url/http://www.mdpi.com/1420-3049/6/8/699info:eu-repo/semantics/altIdentifier/issn/1420-3049info:eu-repo/semantics/openAccesshttp://creativecommons.org/licenses/by/3.0/Creative Commons Attribution 3.0 Unported (CC BY 3.0)reponame:SEDICI (UNLP)instname:Universidad Nacional de La Platainstacron:UNLP2025-10-15T10:49:41Zoai:sedici.unlp.edu.ar:10915/35056Institucionalhttp://sedici.unlp.edu.ar/Universidad públicaNo correspondehttp://sedici.unlp.edu.ar/oai/snrdalira@sedici.unlp.edu.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:13292025-10-15 10:49:42.243SEDICI (UNLP) - Universidad Nacional de La Platafalse
dc.title.none.fl_str_mv Solvent and substituent effects on the kinetics of thermolysis of cis-fused 1,2,4-trioxanes
title Solvent and substituent effects on the kinetics of thermolysis of cis-fused 1,2,4-trioxanes
spellingShingle Solvent and substituent effects on the kinetics of thermolysis of cis-fused 1,2,4-trioxanes
Cafferata, Lázaro F. R.
Ciencias Exactas
Química
cis-Substituted 1,2,4-trioxanes
cresol
kinetics
cyclohexane derivative
methanol
solvent and substituent effects
stepwise reaction mechanism
peroxide
scavenger
solvent
unclassified drug
chemical bond
title_short Solvent and substituent effects on the kinetics of thermolysis of cis-fused 1,2,4-trioxanes
title_full Solvent and substituent effects on the kinetics of thermolysis of cis-fused 1,2,4-trioxanes
title_fullStr Solvent and substituent effects on the kinetics of thermolysis of cis-fused 1,2,4-trioxanes
title_full_unstemmed Solvent and substituent effects on the kinetics of thermolysis of cis-fused 1,2,4-trioxanes
title_sort Solvent and substituent effects on the kinetics of thermolysis of cis-fused 1,2,4-trioxanes
dc.creator.none.fl_str_mv Cafferata, Lázaro F. R.
Jefford, Charles W.
author Cafferata, Lázaro F. R.
author_facet Cafferata, Lázaro F. R.
Jefford, Charles W.
author_role author
author2 Jefford, Charles W.
author2_role author
dc.subject.none.fl_str_mv Ciencias Exactas
Química
cis-Substituted 1,2,4-trioxanes
cresol
kinetics
cyclohexane derivative
methanol
solvent and substituent effects
stepwise reaction mechanism
peroxide
scavenger
solvent
unclassified drug
chemical bond
topic Ciencias Exactas
Química
cis-Substituted 1,2,4-trioxanes
cresol
kinetics
cyclohexane derivative
methanol
solvent and substituent effects
stepwise reaction mechanism
peroxide
scavenger
solvent
unclassified drug
chemical bond
dc.description.none.fl_txt_mv The kinetics of the thermal decomposition reaction of <i>cis</i>-6-phenyl-5,6-(2- phenylpropyliden)-3,3-pentamethylene-1,2,4-trioxacyclohexane <b>(Ia)</b> were investigated in benzene and methanol solutions in the temperature and concentration ranges of 353.3-413.2 K and (1.1 - 13.1)×10<SUP>-3</SUP> M, respectively. First-order rate constant values were obtained for up to at least ca. 20% conversions of that cyclic peroxide. The activation parameter values for the initial unimolecular homolysis of that molecule, results supported by the effect of the addition of di-<i>tert</i>-butyl-<i>p</i>-cresol as a free radical scavenger, indicate a stepwise reaction mechanism which is in keeping with the reaction products analysis. The corresponding activation parameters for the reaction of <b>Ia</b> in methanol (ΔH<SUP>#</SUP> = 20.2 ± 0.6 kcal mol<SUP>-1</SUP>; ΔS<SUP>#</SUP> = 0.1 ± 1.6 cal mol<SUP>-1</SUP>K<SUP>-1</SUP>; ΔG<SUP>#</SUP> = 20.2 ± 0.6 kcal mol<SUP>-1</SUP> and in benzene (ΔH<SUP>#</SUP> = 15.4 ± 0.2 kcal mol<SUP>-1</SUP>; ΔS<SUP>#</SUP> = -13.2 ± 0.5 cal mol<SUP>-1</SUP>K<SUP>-1</SUP>; ΔG# = 20.5 ± 0.2 kcal mol<SUP>-1</SUP> solutions are compared with values obtained for cis-6-phenyl-5,6-(2-phenylpropyliden)-3,3- tetramethylene-1,2,4-trioxacyclohexane (<b>Ib</b>) thermolysis in the same solvents. The thermolysis kinetics of <b>Ia</b> are less sensitive to solvent changes compared to the behaviour already reported for the analogous reactions of <b>Ib</b>. Because both molecules in solution are flexible structures due to their configurations, the relatively small solvent effect found on the former trioxane reaction is attributed to the extent of the chain of methylene groups attached on C-3 of the corresponding molecular rings. Furthermore, the pertinent substituent effect on the peroxidic bond strength of those molecules in solution was evaluated.
Facultad de Ciencias Exactas
description The kinetics of the thermal decomposition reaction of <i>cis</i>-6-phenyl-5,6-(2- phenylpropyliden)-3,3-pentamethylene-1,2,4-trioxacyclohexane <b>(Ia)</b> were investigated in benzene and methanol solutions in the temperature and concentration ranges of 353.3-413.2 K and (1.1 - 13.1)×10<SUP>-3</SUP> M, respectively. First-order rate constant values were obtained for up to at least ca. 20% conversions of that cyclic peroxide. The activation parameter values for the initial unimolecular homolysis of that molecule, results supported by the effect of the addition of di-<i>tert</i>-butyl-<i>p</i>-cresol as a free radical scavenger, indicate a stepwise reaction mechanism which is in keeping with the reaction products analysis. The corresponding activation parameters for the reaction of <b>Ia</b> in methanol (ΔH<SUP>#</SUP> = 20.2 ± 0.6 kcal mol<SUP>-1</SUP>; ΔS<SUP>#</SUP> = 0.1 ± 1.6 cal mol<SUP>-1</SUP>K<SUP>-1</SUP>; ΔG<SUP>#</SUP> = 20.2 ± 0.6 kcal mol<SUP>-1</SUP> and in benzene (ΔH<SUP>#</SUP> = 15.4 ± 0.2 kcal mol<SUP>-1</SUP>; ΔS<SUP>#</SUP> = -13.2 ± 0.5 cal mol<SUP>-1</SUP>K<SUP>-1</SUP>; ΔG# = 20.5 ± 0.2 kcal mol<SUP>-1</SUP> solutions are compared with values obtained for cis-6-phenyl-5,6-(2-phenylpropyliden)-3,3- tetramethylene-1,2,4-trioxacyclohexane (<b>Ib</b>) thermolysis in the same solvents. The thermolysis kinetics of <b>Ia</b> are less sensitive to solvent changes compared to the behaviour already reported for the analogous reactions of <b>Ib</b>. Because both molecules in solution are flexible structures due to their configurations, the relatively small solvent effect found on the former trioxane reaction is attributed to the extent of the chain of methylene groups attached on C-3 of the corresponding molecular rings. Furthermore, the pertinent substituent effect on the peroxidic bond strength of those molecules in solution was evaluated.
publishDate 2001
dc.date.none.fl_str_mv 2001
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
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Creative Commons Attribution 3.0 Unported (CC BY 3.0)
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