2930.90.49.50 - Other

This HTS category, 2930.90.49.50, encompasses organo-sulfur compounds that are classified as "other" under the broader heading of "other" carboxylic acids. It serves as a residual category for substances that meet the definition of organo-sulfur compounds and possess carboxylic acid functionalities but do not fall into the more specifically defined subcategories of thioglycolic acid or other mercaptocarboxylic acids. These are typically complex organic molecules where a sulfur atom is bonded to carbon, and a carboxyl group (-COOH) is also present, but the specific arrangement or complexity prevents them from being categorized elsewhere.

The distinction from sibling categories is crucial for accurate classification. Unlike 2930.90.49.10, which specifically covers thioglycolic acid (also known as mercaptoacetic acid), and 2930.90.49.20, which pertains to a broader range of mercaptocarboxylic acids, this subcategory is for compounds that are organo-sulfur compounds with carboxylic acid groups that do not fit those more defined descriptions. This often includes compounds with sulfur bridges, more complex sulfur-containing functional groups, or carboxylic acids where the sulfur is present but not as a mercapto (-SH) group directly attached to the carbon chain of the acid.

As this is a leaf node within the HTS, there are no further subcategories. Therefore, classification into 2930.90.49.50 relies on a thorough examination of the chemical structure and properties of the imported substance. Importers and customs brokers must ensure that the compound is definitively an organo-sulfur compound and possesses a carboxylic acid group, while also confirming it does not meet the specific criteria for the preceding, more narrowly defined categories within 2930.90.49. This often involves consulting chemical analyses and referencing CAS (Chemical Abstracts Service) numbers or scientific nomenclature to ensure proper duty assessment.