2921.45.20.00 - 3-Amino-2,7-naphthalenedisulfonic acid; 4-Amino-1-naphthalenesulfonic acid, sodium salt; 5-Amino-1-naphthalenesulfonic acid (Laurent's acid); 8-Amino-2-naphthalenesulfonic acid and its salts; 7-Amino-1,3,6-naphthalenetrisulfonic acid; 8-Anilino-1-naphthalenesulfonic acid (Phenyl Peri acid) and its salts; andN-Ethyl-1-naphthylamine

This HTS category encompasses specific amino derivatives of naphthalene, particularly disulfonic and trisulfonic acids, along with certain aniline derivatives and related salts. It is crucial to note that the substances classified here are defined by their precise chemical structures and functional groups. Examples include 3-Amino-2,7-naphthalenedisulfonic acid, 4-Amino-1-naphthalenesulfonic acid (as its sodium salt), Laurent's acid (5-Amino-1-naphthalenesulfonic acid), 8-Amino-2-naphthalenesulfonic acid and its salts, 7-Amino-1,3,6-naphthalenetrisulfonic acid, Phenyl Peri acid (8-Anilino-1-naphthalenesulfonic acid) and its salts, and N-Ethyl-1-naphthylamine. These compounds are primarily used as intermediates in the synthesis of dyes and pigments.

The distinction between this category and its sibling, 2921.45.10.00, lies in the specific isomeric and substituted naphthalene sulfonic acids and amines listed. For instance, while sibling 2921.45.10.00 includes 7-Amino-1,3-naphthalenedisulfonic acid and N-Phenyl-2-naphthylamine, this category features distinct positional isomers and differently substituted compounds such as 7-Amino-1,3,6-naphthalenetrisulfonic acid and N-Ethyl-1-naphthylamine. Similarly, it differentiates from 2921.45.25.00, which covers mixtures of specific amino-naphthalenesulfonic acids and o-Naphthionic acid.

As this node is a leaf node, it has no further subcategories within the HTS. Therefore, classification under 2921.45.20.00 is determined by whether a specific chemical compound precisely matches one of the listed descriptions. Any substance not explicitly enumerated within this heading, but falling under the broader scope of aromatic monoamines and their derivatives at the preceding levels, would be classified under the residual "Other" category at the appropriate level.