2921.42.21.00 - Metanilic acid

This HTS classification, specifically 2921.42.21.00, encompasses metanilic acid. Metanilic acid, also known as 3-aminobenzenesulfonic acid, is an aromatic amine characterized by both an amino group and a sulfonic acid group attached to a benzene ring in a meta (1,3) orientation. It is a derivative of aniline and finds significant use as an intermediate in the synthesis of dyes, pharmaceuticals, and other organic chemicals. Its distinct chemical structure, with the meta positioning of its functional groups, is the primary defining characteristic for its classification.

Within the broader category of aniline derivatives and their salts (2921.42), metanilic acid is distinguished from its sibling categories by the specific arrangement of its functional groups and the absence of additional substituents or modifications. For instance, while 2921.42.18.00 lists several other aniline derivatives, including orthanilic acid (where the sulfonic acid group is in the ortho position), metanilic acid’s meta positioning is key. Similarly, it differs from compounds like sulfanilic acid (2921.42.22.00), which features a para-oriented sulfonic acid group.

As a leaf node, HTS code 2921.42.21.00 does not have further subcategories. This means that any substance fitting the definition of metanilic acid, regardless of its purity or specific salt form (unless explicitly provided for elsewhere), would be classified under this code. The classification relies on the fundamental chemical structure of metanilic acid, distinguishing it from other aniline derivatives based on substituent positions.