1,3-Bis(3-tert-butyl-2-hy-droxy-5-meth-oxy-benz-yl)hexa-hydro-pyrimidin-5-ol monohydrate.

The asymmetric unit of the title compound, C28H42N2O5·H2O, consists of one half of the organic mol-ecule and one half-mol-ecule of water, both of which are located on a mirror plane which passes through the central C atoms and the hydroxyl group of the heterocyclic system. The hydroxyl group at the central ring is disordered over two equally occupied positions. The six-membered ring adopts a chair conformation, and the 2-hy-droxy-benzyl substituents occupy the sterically preferred equatorial positions. The aromatic rings make dihedral angles of 75.57 (9)° with the mean plane of the heterocyclic ring. The dihedral angle between the two aromatic rings is 19.18 (10)°. The mol-ecular structure features two intra-molecular phenolic O-H⋯N hydrogen bonds with graph-set motif S(6). In the crystal, mol-ecules are connected via O-H⋯O hydrogen bonds into zigzag chains running along the a-axis direction.