2907.29 - Other:

This category, HTS 2907.29, encompasses a diverse group of polyphenols and phenol-alcohols that do not fall under the more specifically defined sibling categories within the 2907.2 series. It serves as a residual classification for compounds characterized by the presence of multiple hydroxyl (-OH) groups attached to an aromatic ring system, or those with both phenolic hydroxyl groups and alcoholic hydroxyl groups. These substances are integral to various chemical processes and industries, often serving as intermediates, antioxidants, or components in the synthesis of more complex materials.

Distinguishing this category from its siblings is crucial. HTS 2907.21.00.00 exclusively covers resorcinol and its salts, while 2907.22 addresses hydroquinone (quinol) and its salts. Similarly, 2907.23.00.00 is dedicated to 4,4'-isopropylidenediphenol (Bisphenol A) and its salts. Therefore, HTS 2907.29 is intended for polyphenols and phenol-alcohols *other than* these explicitly enumerated compounds. Classification here relies on the absence of specific identifying features that would place a substance into one of the more precise subheadings.

The subcategories within 2907.29 further refine the classification of these "other" polyphenols and phenol-alcohols. For example, phenol-alcohols, like those that contain both a phenolic hydroxyl and an alcoholic hydroxyl group on the same molecule, are itemized separately. Similarly, specific, well-known polyphenols such as pyrogallic acid and 4,4'-biphenol are provided with their own distinct classifications. The presence of tert-butylhydroquinone also warrants a separate subheading due to its common use as an antioxidant. The final subheading, 2907.29.90.00, acts as a further residual for any remaining polyphenols and phenol-alcohols that do not fit into the more specific sub-subheadings but still meet the criteria of HTS 2907.29.