2904.10 - Derivatives containing only sulfo groups, their salts and ethyl esters:

This category encompasses organic chemical compounds derived from hydrocarbons where sulfo groups (-SO₃H) are the sole functional group, along with their corresponding salts and ethyl ester derivatives. These substances are characterized by the presence of sulfur in their oxidation state, forming sulfonic acids or their related compounds. Examples include various sulfonic acids and their salts used as intermediates in the synthesis of dyes, pharmaceuticals, and surfactants.

It is crucial to distinguish this category from its sibling, HTS 2904.20, which covers derivatives containing only nitro (-NO₂) or nitroso (-NO) groups. While both are sulfonated, nitrated, or nitrosated derivatives of hydrocarbons, the presence of sulfo groups exclusively defines the scope of 2904.10, whereas 2904.20 focuses on nitrogen-containing functional groups. Furthermore, the broader context of HTS Chapter 29, particularly Section II concerning alcohols and their derivatives, serves as a reminder that while some derivatives within 2904 might share structural similarities, the defining functional groups dictate their precise classification.

The subcategories within 2904.10 provide further refinement based on the specific chemical structure and application of these sulfonated compounds. These subdivisions allow for the precise classification of individual sulfonic acids, their salts, and specific derivatives like sulfonyl chlorides, catering to the granular needs of trade and customs. The existence of an "Other" category acknowledges the vast array of sulfonated derivatives that may not fit into more specific pre-defined entries, ensuring comprehensive coverage within this HTS classification.