Zeng, Yunhang et al. published their research in Journal of the American Leather Chemists Association in 2016 | CAS: 3326-34-9

5-Amino-3′,6′-dihydroxy-3H-spiro[isobenzofuran-1,9′-xanthen]-3-one (cas: 3326-34-9) belongs to benzofurans derivatives. Benzofurans are compounds with a planar structure having 10 pi electrons that include the lone pair on oxygen atom, which makes it more susceptible to electrophilic attack. Substituted benzofurans find applications such as fluorescent sensors, oxidants, in drug discovery, and in another field of chemistry and agriculture.HPLC of Formula: 3326-34-9

Visualization and quantification of penetration/mass transfer of acrylic resin retanning agent in leather using fluorescent tracing technique was written by Zeng, Yunhang;Song, Ying;Li, Jing;Zhang, Wenhua;Shi, Bi. And the article was included in Journal of the American Leather Chemists Association in 2016.HPLC of Formula: 3326-34-9 This article mentions the following:

Acrylic resin is a widely used retanning agent in leather processing, and its retanning effectiveness is closely related to its penetration depth and filling parts in leather. But acrylic resin in leather cannot be visualized or quantified, and thus its application mainly depends on tanner’s experience. In this study, 5-aminofluorescein-labeled poly(acrylic acid) (AF-PAA), as a model of fluorescent acrylic resins, was synthesized using a phase-transfer reaction and then purified using Sephadex gel filtration. AF-PAA was applied to retanning process and could be well visualized and quantified in retanned leathers using fluorescence microscopy and Image J software. Looser collagen fibers, increasing amount of acrylic resin or retanning together with some anionic retanning agents could enhance penetration/mass transfer of acrylic resin in leather. The fluorescent tracing technique is useful to investigate the mass transfer and reaction mechanism of acrylic resin in leather processing. In the experiment, the researchers used many compounds, for example, 5-Amino-3′,6′-dihydroxy-3H-spiro[isobenzofuran-1,9′-xanthen]-3-one (cas: 3326-34-9HPLC of Formula: 3326-34-9).

5-Amino-3′,6′-dihydroxy-3H-spiro[isobenzofuran-1,9′-xanthen]-3-one (cas: 3326-34-9) belongs to benzofurans derivatives. Benzofurans are compounds with a planar structure having 10 pi electrons that include the lone pair on oxygen atom, which makes it more susceptible to electrophilic attack. Substituted benzofurans find applications such as fluorescent sensors, oxidants, in drug discovery, and in another field of chemistry and agriculture.HPLC of Formula: 3326-34-9

Referemce:
Benzofuran – Wikipedia,
Benzofuran | C8H6O – PubChem