2907.22 - Hydroquinone (Quinol) and its salts:

This HTS classification covers Hydroquinone (also known as Quinol) and its salts. Hydroquinone is an aromatic organic compound with the chemical formula C₆H₄(OH)₂. It is a white crystalline solid that is soluble in water and is widely used as a reducing agent and antioxidant.

This category is distinguished from its siblings, such as Resorcinol and Bisphenol A, by the specific chemical structure of Hydroquinone. While all fall under the broader group of polyphenols and phenol-alcohols, Hydroquinone is characterized by two hydroxyl groups situated opposite each other on a benzene ring. This specific isomeric arrangement differentiates it from compounds like Resorcinol (hydroxyl groups at adjacent positions) and Bisphenol A.

The subcategories for 2907.22 further refine the classification based on the intended use or purity of the Hydroquinone. "Photographic grade" specifically denotes Hydroquinone manufactured to high purity standards for use in photographic developing solutions. The "Other" subcategory encompasses all remaining forms and salts of Hydroquinone not meeting the specific requirements of the photographic grade, including industrial and laboratory grades.