1,8-Dihydroxynaphthalene-3,6-disulfonic acid (H Acid)
Pure 1,8-Dihydroxynaphthalene-3,6-disulfonic acid, known as H Acid, is a key intermediate for azo dye synthesis. This sulfonated phenol derivative falls under HTS 2908.99.0900 due to its specific chemical structure with only sulfo groups and its disodium salt form being explicitly named in the tariff.
Import Duty Rates by Country of Origin
Alternative Classifications
This product could be classified differently depending on its characteristics or intended use.
If pre-reacted with diazonium salts to form synthetic azo dyes
Once converted to finished azo coloring matter, it moves from Chapter 29 intermediates to Chapter 32 synthetic dyes.
If imported as an aqueous solution exceeding 30% concentration for transport
Mixtures or solutions not qualifying under Chapter 29 note (e) fall into mixtures of Chapters 28-38.
If lacking the specific naphthalene structure or additional substituents beyond sulfo groups
Other sulfonated cyclic alcohols without the exact 1,8-dihydroxy-3,6-disulfo configuration classify under different oxygen-function headings.
Not sure which classification is right?
The Tariff Assistant works through the GRI rules on your specific product to reach the right HTS code — and can price the duty on it in the same conversation.
Import Tips & Compliance
• Provide detailed chemical analysis certificates confirming purity and structure match to avoid misclassification
• Ensure SDS (Safety Data Sheets) comply with HAZMAT regulations for sulfonated organic acids
• Verify import licenses for dye precursors if destined for textile or pigment manufacturing
Related Products under HTS 2908.99.09.00
H Acid 98% Technical Grade Powder
Technical grade 1,8-Dihydroxynaphthalene-3,6-disulfonic acid at 98% purity with minimal impurities, packaged for industrial dye production. Classified under HTS 2908.99.0900 as the specific sulfonated derivative meeting chapter purity requirements.
Gamma Acid (1,8-Dihydroxynaphthalene-3,6-disulfonic acid isomer)
Gamma Acid, a positional isomer of H Acid also classified as 1,8-Dihydroxynaphthalene-3,6-disulfonic acid per tariff specificity. Used interchangeably in reactive dye manufacturing under the same HTS 2908.99.0900 provision.
Disodium 1,8-Dihydroxynaphthalene-3,6-disulfonate (H Salt)
The disodium salt form of 1,8-Dihydroxynaphthalene-3,6-disulfonic acid, commonly called H Salt, used in water-soluble dye coupling. HTS 2908.99.0900 explicitly includes this salt as a halogenated/sulfonated phenol derivative containing only sulfo groups.