Buch, Kurt published the artcileColor and acid characteristics of α-naphtholphthalein, Recommanded Product: 3,3-Bis(4-hydroxynaphthalen-1-yl)isobenzofuran-1(3H)-one, the publication is Suomen Kemistiseuran Tiedonantoja (1934), 6-17, database is CAplus.
Spectrophotometric measurements were made in alk., acid and borax buffer solutions on α-naphtholphthalein prepared according to Sörensen and Palitsch (C. A. 4, 1956). In 0.1% HCl it was nearly colorless at 0.007 g./l. The secondary ion shows absorption for wave length 649 μ, and both primary and secondary ions for 496 μ. The relative concentrations can be calculated from the extinction coefficients for these wave lengths. In this way the secondary dissociation constant is found to be 0.99 × 10-8, and the primary 5.5 × 10-6.
Suomen Kemistiseuran Tiedonantoja 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 C28H18O4, Recommanded Product: 3,3-Bis(4-hydroxynaphthalen-1-yl)isobenzofuran-1(3H)-one.
Referemce:
https://en.wikipedia.org/wiki/Benzofuran,
Benzofuran | C8H6O – PubChem