4-Sulfo-1,8-Naphthalic Anhydride from Mexico
4-Sulfo-1,8-naphthalic anhydride is a sulfonated aromatic polycarboxylic anhydride used in fluorescent brighteners and dye intermediates. Explicitly listed in HTS 2917.39.04.00 covering sulfonated derivatives per Chapter notes. Chemically defined compound with sulfo group directly characterized.
Duty Rate — Mexico → United States
16.5%
Rate breakdown
9903.05.5510%Except for products described in headings 9903.05.85–9903.05.92 and 9903.05.94, articles the product of Mexico, as provided for in U.S. note 52 to this subchapter
Import Tips
• Verify CAS 81-46-9 registration; confirm sulfo group content via FTIR spectroscopy
• Hazard Class 8 corrosive labeling required (UN 3261); segregation from amines mandatory
• Dye industry end-use certificates prevent reclassification as coloring matter (Chapter 32 exclusion)