2921.43.90.40 - p-Toluidine-m-sulfonic acid (CAS No. 88-44-8)

This HTS category encompasses p-Toluidine-m-sulfonic acid, a specific organic chemical identified by CAS No. 88-44-8. As an aromatic monoamine derivative, it falls under the broader classification of toluidines and their related compounds. The "other" designation at this level signifies that it is a distinct compound not specifically enumerated in other sub-classifications within the toluidine family.

Distinguishing this code from its sibling, 2921.43.90.20 (2-Chloro-p-toluidine-5-sulfonic acid), is the absence of a chlorine substituent and the differing position of the sulfonic acid group on the toluidine ring. While both are sulfonic acid derivatives of toluidine, the specific arrangement of functional groups dictates their separate HTS classification. The sibling category 2921.43.90.90 serves as a residual catch-all for any other, unlisted toluidine sulfonic acid derivatives.

As this is a leaf node within the HTS structure, there are no further subcategories to introduce. Therefore, the classification of p-Toluidine-m-sulfonic acid is precisely defined by its chemical structure and the absence of any more specific tariff lines. Classification relies on the accurate identification of this compound and its unique chemical properties.