Sorensen, S. P. L. published the artcileA New Indicator, α-Naphtholphthalein, with Color Change near the Neutral Point, Name: 3,3-Bis(4-hydroxynaphthalen-1-yl)isobenzofuran-1(3H)-one, the publication is Biochemische Zeitschrift (1910), 381-6, database is CAplus.
The substance is made by the method of Grabowski (Ber., 4, 725). It shows a good color change at an H ion concentrate of 10-7.26 to 10-8.68. Proteins interfere with the end reaction.
Biochemische Zeitschrift 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 C15H14N2, Name: 3,3-Bis(4-hydroxynaphthalen-1-yl)isobenzofuran-1(3H)-one.
Referemce:
https://en.wikipedia.org/wiki/Benzofuran,
Benzofuran | C8H6O – PubChem