Cyclopentadecanone.

In the crystal structure, the title compound (exaltone), C(15)H(28)O, exhibits no disorder, and the 15-membered ring exists in the quinquangular [13353] C(1) symmetry conformation. The crystal exhibits nonmerohedral twinning by twofold rotation about [100], but adjustment of the temperature to 90 K causes the [101] distance to equal the c axial length, allowing the twinning to be treated as pseudo-merohedral. The literature description of the structure as disordered orthorhombic with halved a-axis length is corrected.