Abstract Isobaric charge-exchange reactions induced by beams of 112 Sn have been investigated at the GSI facility using the fragment separator FRS. The high-resolving power of this spectrometer makes it possible to obtain the isobaric charge-exchange cross sections with an uncertainty of 3.5% and to separate quasi-elastic and inelastic contributions in the missing-energy spectra, in which the inelastic component is associated to the in-medium excitation of baryonic resonances such as the Δ resonance. We report on the results obtained for the ( p,n ) channel excited by using different targets that cover a large range in neutron excess. In addition, we also compare the missing-energy spectra with an intranuclear cascade model coupled to a de-excitation code to investigate the in-medium effects in the production of baryonic resonances.