Alkylation of nitroarenes via VicariousNucleophilicSubstitution (VNS) was tested experimentally and modelled with DFT calculations. Mechanistic studies reveal intrinsic differences between reactions of archetypal carbanion precursor PhSO2CH2Cl, and alkyl phenyl sulfones, in which benzenesulfinate acts as a leaving group. Accordingly, for the latter precursors steric hindrance develops at the β-elimination