[Cd(μ₂-N,O-p-NH₂C₆H₄SO₃)₂(H₂O)₂]_n (1) is a layered coordination compound. The solid–vapor reactions between crystalline 1 and a series of volatile amines were investigated and the corresponding amine adducts were characterized by EA, TGA, PXRD and IR. Among them, the C₂H₅NH₂ and C₃H₇NH₂ adducts, namely [Cd(C₂H₅NH₂)₄(H₂O)₂](H₂NC₆H₄SO₃)₂ (3) and [Cd(C₃H₇NH₂)₄(O-p-H₂NC₆H₄SO₃)₂]·C₃H₇NH₂ (4), grew into single crystals in situ from the solid–vapor reaction processes and their crystal structures were characterized. In both cases, 4 mol equiv. of amine molecules coordinate to Cd(II) via replacing the N,O-p-NH₂C₆H₄SO₃ ligands or coordinated water molecules. The single-phase product suggests that the solid–vapor reaction between the metal sulfonate and volatile alkylamines could be used as a green process to synthesize monoamine-coordinated Cd(II) complexes without any solvent and routine separation. Finally, the substitution reaction is reversible at room conditions and selective for primary alkylamines.