3-(4-Hydroxynaphthalen-1-yl)-3-(1-hydroxynaphthalen-2-yl)isobenzofuran-1(3H)-one

3-(4-hydroxynaphthalen-1-yl)-3-(1-hydroxynaphthalen-2-yl)isobenzofuran-1(3H)-one is a previously unknown derivative of the well-known acid/base indicator naphtholphthalein. We report the synthesis and the molecular structure of the title compound, as determined by single-crystal X-ray diffraction. 1H and 13C NMR spectroscopy data, IR spectroscopy data, and mass spectrometry data are provided.