2921.41 - Aniline and its salts:

This HTS category, 2921.41, specifically addresses **aniline and its salts**. Aniline is a fundamental aromatic amine, characterized by an amino group (-NH2) directly attached to a benzene ring. It serves as a crucial building block in the synthesis of a vast array of industrial chemicals, including dyes, pharmaceuticals, plastics, and rubber accelerators. Salts of aniline refer to compounds formed when the basic amino group of aniline reacts with an acid.

Within the broader classification of aromatic monoamines and their derivatives, 2921.41 is distinct from its siblings. For instance, 2921.42 covers aniline *derivatives*, meaning compounds where the aniline structure has been chemically modified by substituting hydrogen atoms on the amino group or the benzene ring. Similarly, categories like 2921.43 (toluidines) and 2921.45 (naphthylamines) deal with related but distinct aromatic amines, differentiated by their specific substituent groups (methyl in toluidines, naphthalene ring in naphthylamines).

The subcategories under 2921.41 provide a direct breakdown of aniline into its two primary forms for classification purposes: the free base, **aniline (2921.41.10.00)**, and its various **salts (2921.41.20.00)**. This distinction is important for customs procedures, as salts may exhibit different physical properties and handling requirements compared to the parent compound.