The crystal structure of altrenogest has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional techniques. Altrenogest crystallizes in space group P212121 (#19) with a = 7.286 916(16), b = 10.580 333(19), c = 22.266 08(7) Å, V = 1716.671(6) Å3, and Z = 4 at 295 K. Thermal expansion between 113 and 295 K is anisotropic. An O–H⋯O hydrogen bond links the molecules into chains along the c-axis. The powder pattern has been submitted to ICDD for inclusion in the Powder Diffraction File™ (PDF®).
