Substituent effects on the relative rates and free energies of ortho-lithiation reactions: families of fluorobenzenes as the substrates - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue ARKIVOC - Online Journal of Organic Chemistry Année : 2015

Substituent effects on the relative rates and free energies of ortho-lithiation reactions: families of fluorobenzenes as the substrates

F Mongin
C Curty
  • Fonction : Auteur
E Marzi
  • Fonction : Auteur
M Schlosser
  • Fonction : Auteur

Résumé

2-, 3- and 4-substituted fluorobenzenes and 5-substituted 1,3-difluorobenzenes were metalated with sec-butyllithium (LIS) and with lithium 2,2,6,6-tetramethylpiperidide (LiTMP) under irreversible conditions in order to determine the rates of reaction relative to the unsubstituted parent compounds (fluorobenzene and 1,3- difluorobenzene). In addition, the pairs of resulting aryllithiums were subjected to acid-base equilibration to furnish the thermodynamic stabilities (or: basicities) of these species again relative to the parent compounds. Not surprisingly, the effect diminishes with the distance of a given substituent to the lithiation center (ortho > meta > para) and it reaches its maximum at the ground state equilibration of the organometallic intermediate whereas it fades away at transition states, in particular reactant-like ones. Fluorine, the most powerful activator in the entire series if located at an ortho position, increases the rates of LIS- and LiTMP-promoted metalations by respectively 2 and 3 powers of ten, but by 7 to 8 powers of ten the aryllithium equilibrium stability.

Domaines

Chimie organique
Fichier principal
Vignette du fichier
substituent-effects-on-the-relative-rates-and-free-energies.pdf (154.76 Ko) Télécharger le fichier
Origine : Fichiers éditeurs autorisés sur une archive ouverte

Dates et versions

hal-02304104 , version 1 (15-12-2023)

Identifiants

Citer

F Mongin, C Curty, E Marzi, Frédéric Leroux, M Schlosser. Substituent effects on the relative rates and free energies of ortho-lithiation reactions: families of fluorobenzenes as the substrates. ARKIVOC - Online Journal of Organic Chemistry, 2015, 4, pp.48-65. ⟨10.3998/ark.5550190.p008.926⟩. ⟨hal-02304104⟩
40 Consultations
6 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More