title: The ortho-substituent effect on the Ag-catalysed decarboxylation of benzoic acids.
abstract: A combined experimental and computational investigation on the Ag-catalysed decarboxylation of benzoic acids is reported herein. The present study demonstrates that a substituent at the ortho position exerts dual effects in the decarboxylation event. On one hand, ortho-substituted benzoic acids are inherently destabilised starting materials compared to their meta- and para-substituted counterparts. On the other hand, the presence of an ortho-electron-withdrawing group results in an additional stabilisation of the transition state. The combination of both effects results in an overall reduction of the activation energy barrier associated with the decarboxylation event. Furthermore, the Fujita-Nishioka linear free energy relationship model indicates that steric bulk of the substituent can also exert a negative effect by destabilising the transition state of decarboxylation.
authors.affiliation: School of Biological and Chemical Sciences, Queen Mary University of London, Joseph Priestley Building, Mile End Road, E1 4NS, London (UK).
authors.forename: Rachel
authors.initials: R
authors.lastname: Grainger
authors.forename: Josep
authors.initials: J
authors.lastname: Cornella
authors.forename: David C
authors.initials: DC
authors.lastname: Blakemore
authors.forename: Igor
authors.initials: I
authors.lastname: Larrosa
authors.forename: Josep M
authors.initials: JM
authors.lastname: Campanera
mesh_terms: D001565:Benzoates / Q000737:chemistry*; D002384:Catalysis; D003653:Decarboxylation; D012834:Silver / Q000737:chemistry*
chemical_list: D001565:Benzoates; D012834:Silver
keywords: catalysis; decarboxylation; density functional calculations; kinetics; linear free energy relationships