Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
Solvent and substituent effects on the kinetics of thermolysis of cis-fused 1,2,4-trioxanes
Autore:
Cafferata, LFR; Jefford, CW;
Indirizzi:
Natl Univ La Plata, Fac Ciencias Exactas, Lab LADECOR, RA-1900 La Plata, Argentina Natl Univ La Plata La Plata Argentina RA-1900 A-1900 La Plata, Argentina Univ Geneva, Chim Organ Lab, CH-1211 Geneva 4, Switzerland Univ Geneva Geneva Switzerland 4 rgan Lab, CH-1211 Geneva 4, Switzerland
Titolo Testata:
MOLECULES
fascicolo: 8, volume: 6, anno: 2001,
pagine: 699 - 709
SICI:
1420-3049(200108)6:8<699:SASEOT>2.0.ZU;2-6
Fonte:
ISI
Lingua:
ENG
Soggetto:
THERMAL-DECOMPOSITION REACTION; ACETONE CYCLIC DIPEROXIDE; BENZENE SOLUTION; MECHANISM;
Keywords:
cis-substituted 1,2,4-trioxanes; kinetics; stepwise reaction mechanism; solvent and substituent effects;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
12
Recensione:
Indirizzi per estratti:
Indirizzo: Cafferata, LFR Natl Univ La Plata, Fac Ciencias Exactas, Lab LADECOR, Calle 47 Esq 115, RA-1900 La Plata, Argentina Natl Univ La Plata Calle 47 Esq 115 La Plata Argentina RA-1900
Citazione:
L.F.R. Cafferata e C.W. Jefford, "Solvent and substituent effects on the kinetics of thermolysis of cis-fused 1,2,4-trioxanes", MOLECULES, 6(8), 2001, pp. 699-709

Abstract

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) x 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 la in methanol (DeltaH(#) = 20.2 +/- 0.6 kcal mol(-1); DeltaS(#) = 0.1 +/- 1.6 cal mot(-1) K-1; DeltaG(#) = 20.2 +/- 0.6 kcal mol(-1)) and in benzene (AW = 15.4 +/- 0.2 kcal mol(-1); DeltaS(#) = -13.2 +/- 0.5 cal mol(-1) K-1; DeltaG(#) = 20.5 +/- 0.2 kcal mol(-1)) solutions are compared withvalues 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 la are less sensitive to solvent changes compared to thebehaviour already reported for the analogous reactions of Ib. Because bothmolecules in solution arc 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.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 08/07/20 alle ore 07:00:26