2908.99.06.00 - 4-Hydroxy-1-naphthalenesulfonic acid (1-Naphthol-4-sulfonic acid)

This HTS subcategory, 2908.99.06.00, specifically covers 4-Hydroxy-1-naphthalenesulfonic acid, also known as 1-Naphthol-4-sulfonic acid. This compound is a sulfonated derivative of naphthol, characterized by the presence of a hydroxyl group and a sulfonic acid group attached to a naphthalene ring structure. Its classification falls under the broader heading of halogenated, sulfonated, nitrated, or nitrosated derivatives of phenols or phenol-alcohols, specifically within the "other" subcategories for derivatives containing only sulfo groups, their salts, and esters.

It is important to distinguish this specific compound from its sibling entries. For instance, sibling 2908.99.03.00 enumerates a variety of other dihydroxybenzenesulfonic and naphthalenedisulfonic acids and their salts. Similarly, sibling 2908.99.09.00 focuses on 1,8-Dihydroxynaphthalene-3,6-disulfonic acid and its disodium salt. The defining characteristic of 2908.99.06.00 is the singular presence of 4-Hydroxy-1-naphthalenesulfonic acid itself, without the addition of other hydroxyl groups on the naphthalene core or as specified salts in sibling categories.

As this node represents a leaf node within the HTS structure, there are no further subcategories to introduce. The classification is definitive at this level, meaning that any product meeting the chemical identity and description of 4-Hydroxy-1-naphthalenesulfonic acid, and not specifically listed or included within a broader group in a sibling category, will be classified under 2908.99.06.00. This ensures precise tariff application for this particular chemical compound.