2918.29.20.00 - Gentisic acid; and Hydroxycinnamic acid and its salts

This HTS category, 2918.29.20.00, encompasses specific carboxylic acids with a phenolic hydroxyl group and additional oxygen functionalities, excluding those with other oxygen functions or specifically enumerated elsewhere. The primary components classified here are Gentisic acid (2,5-dihydroxybenzoic acid) and Hydroxycinnamic acid, along with their corresponding salts. These compounds are characterized by the presence of both a carboxylic acid group and at least one hydroxyl group attached to an aromatic ring, differentiating them from simpler hydroxybenzoic acids or naphthoic acids.

The distinction from sibling categories is crucial for accurate classification. For instance, while sibling 2918.29.04.00 includes various cresotic acids, certain hydroxybenzoic acid salts like calcium salt, and naphthoic acid derivatives, this code specifically targets Gentisic acid and Hydroxycinnamic acid. Similarly, it is separate from entries for other hydroxybenzoic acids such as m-hydroxybenzoic acid (2918.29.08.00) and p-hydroxybenzoic acid (2918.29.22.00), which possess a single hydroxyl group on the benzene ring. The exclusion of "other oxygen function" in the parent level also guides the classification away from more complex molecules.

As this HTS code represents a leaf node, there are no further subdivisions. Therefore, classification within 2918.29.20.00 relies on confirming the presence of Gentisic acid or Hydroxycinnamic acid and their salts, adhering strictly to the chemical structure and the established nomenclature of the Harmonized Tariff Schedule. The inclusion of salts signifies that their ionic forms are also captured under this heading.