Thiel, A. published the artcileBicolored phthaleins, Application of 3,3-Bis(4-hydroxynaphthalen-1-yl)isobenzofuran-1(3H)-one, the publication is Z. physik. Chem. (1931), 352-6, database is CAplus.
The phthaleins of the series homologous to phenolphthalein have been assumed to show but one color change. α-Naphtholphthalein on very careful purification lost its pink to brownish color and was obtained colorless. In alc. the color changes are from colorless to orange-yellow and then by way of green to blue. This is difficult to observe in water because of the limited solubility of the free phthalein. p-Xylenolphthalein and thymolphthalein show similar color changes including the colorless stage in alc. The 1st change is from the colorless phthalein to that of the primary quinoid anions, and the 2nd change is from this color to the deep color of the secondary meriquinoid anions.
Z. physik. Chem. published new progress about 596-01-0. 596-01-0 belongs to benzofurans, auxiliary class Benzofuran,Naphthalene,Alcohol,Ester, name is 3,3-Bis(4-hydroxynaphthalen-1-yl)isobenzofuran-1(3H)-one, and the molecular formula is C11H21BF4N2O2, Application of 3,3-Bis(4-hydroxynaphthalen-1-yl)isobenzofuran-1(3H)-one.
Referemce:
https://en.wikipedia.org/wiki/Benzofuran,
Benzofuran | C8H6O – PubChem