The title compound, C9H14N+·C7H7SO3 −, contains a 2-ethyl-6-methyl­anilinium cation and a 4-methyl­benzene­sulfonic anion. The cations are anchored between the anions through N—H⋯O hydrogen bonds. Electrostatic and van der Waals inter­actions, as well as hydrogen bonds, maintain the structural cohesion.

In the crystal structure of the title compound, C10H8BrN, the dihedral angle between the two six-membered rings of the quinoline system is 0.49 (16)°. The mol­ecules are packed in a face-to-face arrangement fashion, with a centroid–centroid distance of 3.76 Å between the benzene and pyridine rings of adjacent mol­ecules. No hydrogen bonding is found in the crystal structure.

In the title compound, C13H14Cl2O, the carbonyl and ethenyl groups are coplanar with the aromatic ring. There are four molecules in the asymmetric unit and all atoms in the molecule lie on mirror planes. The mol­ecules are packed in an offset face-to-face arrangement showing π–π stacking inter­actions involving the benzene rings [centroid–centroid distance = 3.564 (2) Å].

In the title compound, C10H8ClN, the crystal packing shows π–π stacking between the heterocyclic ring and the aromatic ring, with a centroid–centroid distance of 3.819 Å. The crystal studied was a racemic twin, the ratio of the twin components being 0.65 (7):0.35 (7).

In the title compound, C13H15ClO, the carbonyl and ethenyl groups are not coplanar with benzene ring system, forming dihedral angles of 35.37 (5) and 36.27 (11)°, respectively. The mol­ecules are packed in an offset face-to-face arrangement showing π–π stacking inter­actions involving the benzene rings [centroid–centroid distance = 3.586 (4) Å].