9-O-Butyl-berberrubinium bromide.

In the title compound, C(23)H(24)NO(4) (+)·Br(-), the butyl chain is disordered between two conformations; the occupancies refined to 0.735 (7) and 0.265 (7). The dihedral angle between the naphthalene ring system and the phenyl ring is 11.6 (2)°. In the crystal structure, the cations are packed via π-π inter-actions into stacks propagating in the [010] direction. Weak inter-molecular C-H⋯O and C-H⋯Br hydrogen bonds contribute further to the crystal packing stability.