Marie-Josèphe Bourgeois

Determinations cinetiques par microcalorimetrie differentielle en programmation de temperature. III. Probleme de la non correspondance entre temperatures mesurees et constantes de vitesse

Abstract Rate constants of the free radical decomposition of AIBN have been determinated in different solvents using a differential scanning microcalorimeter at several temperature programmes. They seem to depend on the heating rate; but this is explained by the existence of a difference in temperature between the studied solution and the position at which θ is measured. At low heating rate, there is agreement between real and measured temperatures and, thus, fair correspondence between rate constants and temperatures observed.

Fonctionnalisation des γ- et δ-pyronènes. Synthèse et étude de la réactivité des composés peroxydiques

Resume La photooxygenation des γ- et δ-pyronenes, realisee pour la premiere fois, conduit classiquement a un hydroperoxyde, un hydroperoxy-peroxyde, et un endoperoxyde respectivement. La reactivite de ces peroxydes est etudiee. Ils conduisent a des composes mono-, di-, voire trifonctionnels, la plupart inedits, pouvant constituer des bases de depart pour la synthese de molecules a potentialite olfactive ou therapeutique.

Epoxyesters p-menthaniques et pinaniques en milieu basique – Parfum de noix de coco

Base-Induced Reactions of p-Menthane- and Pinane-Derived Epoxyesters – Coconut Fragrance The base-induced isomerization of p-menthane- and pinane-derived epoxy esters was studied. The reaction is dependent on the structure of the terpene compound, the nature of the base, and experimental conditions. Among all the new synthesized compounds, one, 6a, emits a very strong fragrance of coconut. In the structure of this tricyclic lactone, the presence of a methyl substituent is essential.

Isomérisation d'époxypinanes fonctionnels en milieu basique

Abstract Functional pinocarveols and bifunctional spiropinanes could be prepared by basic isomerisation of 2,3-epoxypinanes bearing a function or a functional chain on the carbone 10. Preliminary results are presented, which illustrate a general synthesis of these new compounds.

Induced Decomposition of Peroxycompounds in Synthesis: Free Radical Functionalization of Crown Ethers

Free radical additions of commercial 12-crown-4, 15-crown-5 and 18-crown-6 to various unsaturated peroxyesters and peroxides allowed their functionalization: acetonyl, 2, 3-epoxypropyl, 2-oxacyclopentylmethyl, 3-oxo-2-oxacyclopentylmethyl and 3-oxo-2,4-dioxacyclopentylmethyl groups were grafted onto the heterocycle. Polyfunctionalization could be obtained by changing the ratio crown ether/peroxycompound.

Competing β-scission and hydrogen transfer to the pinanyl radical in the addition of methyl thioglycolate to β-pinene derivatives

Despite previous reports to the contrary, addition of methyl thioglycolate to β-pinene always leads to both pinane and p-menthene adducts, the proportion of the latter increasing with the reaction temperature. This is attributable to the substantially higher activation entropy for β-scission than for hydrogen transfer, while the activation enthalpy is higher for the latter reaction. Any substituent at the 3-carbon of β-pinene, trans with respect to the gem-dimethyl bridge, increases the p-menthene yield: polar effects of the mainly electron-withdrawing substituents appear to disfavour hydrogen transfer to the tertiary pinanyl radical and favour β-scission. Analysis of the temperature dependence of the pinane∶p-menthene ratio for the substituted β-pinenes indicates that variations in the activation entropy difference for the two reactions are at least as important as those of the activation enthalpy.

“One-Pot” Synthesis of Disymmetrically α,α′-Disubstituted Succinic Anhydrides Precursors

Abstract A “one-pot” synthesis for disymmetrically α,α′-disubstituted succinic anhydrides precursors is reported in the present paper. Substituents are aryl, primary or secondary alkyl groups. This reaction represents a simple and quick method with fair yields.

Kinetic Application of Differential Scanning Microcalorimetry : Thermal Decomposition of O-Isopropyl O,O-t-Butyl Percarbonate

The kinetic study of the thermal decomposition of 0-isopropyl O,O-t-butyl peroxycarbonate has been performed by Differential Scanning Microcalorimetry. The mathematical work up of the thermal curves has led to the determination of the experimental order of the induced decomposition reaction ; it fits very well with the theoretical values. The rate constant values of induced and spontaneous processes have been determined.