2-{3-Cyano-4-[2-(4-diethylamino-2-hy­droxyphenyl)ethenyl]-5,5-dimethyl-2,5-dihydrofuran-2-ylidene}malononitrile acetone 0.25-solvate

In the title compound, C₂₂H₂₂N₄O₂·0.25C₃H₆O, the disordered acetone mol­ecule lies with partial occupancy about the 2 axis. The mol­ecule of the malononitrile derivative is essentially planar excluding the methyl groups, with the largest deviation from the mean plane through the non-H atoms being 0.1955 (13) Å. Two rotamers with different orientations of the benzene ring are observed in the ratio of 0.919 (2):0.081 (2), and as a result the OH group is disordered over two sets of sites. In the crystal, the mol­ecules form ribbons along (101) utilizing a strong O—H...N(cyano) hydrogen bond. Inter­leaving of the nearly planar ribbons is provided by the twofold disordered acetone molecule through C—H...O inter­actions.