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.

Gold(I) salts are found to mediate the decarboxylation of a variety of aromatic and heteroaromatic carboxylic acids at significatively lower temperatures (as low as 60 °C) than the currently used copper(I) (180–190 °C) and silver(I) (80–140 °C) systems. In contrast to silver(I)- and copper(I)-mediated decarboxylations, the resulting aryl-gold(I) complexes are stable towards protodemetallation and can be readily isolated.