# United States tariff line 2921.59.20.00: 4,4'-Diamino-2,2'-stilbenedisulfonic acid

> In the United States tariff, line 2921.59.20.00 covers aromatic polyamines and their derivatives; salts thereof, 4,4'-Diamino-2,2'-stilbenedisulfonic acid. The general (MFN) duty rate is 6.5%. It falls under HS subheading 2921.59 in heading 29.21 (chapter 29).

Source: https://border.bot/countries/united-states/hs-codes/2921592000
Last updated: 9 October 2026

[Countries](https://border.bot/countries) / [United States](https://border.bot/countries/united-states) / [Chapter 29](https://border.bot/countries/united-states/hs-codes/29) / [2921.59](https://border.bot/countries/united-states/hs-codes/292159) / [2921.59.20.00](https://border.bot/countries/united-states/hs-codes/2921592000)

## Key facts

- Tariff line: 2921.59.20.00
- Covers: Aromatic polyamines and their derivatives; salts thereof, 4,4'-Diamino-2,2'-stilbenedisulfonic acid
- Duty (MFN): 6.5%
- Preferential rates: From free (17 programmes or origins)
- Additional duties: None recorded
- Restrictions: None recorded
- Tariff: [United States](https://border.bot/countries/united-states)
- HS subheading: [2921.59](https://border.bot/hs-codes/292159)

## What this line covers

In the United States tariff, line 2921.59.20.00 covers aromatic polyamines and their derivatives; salts thereof, 4,4'-Diamino-2,2'-stilbenedisulfonic acid.

Its legal text is “4,4'-Diamino-2,2'-stilbenedisulfonic acid”, read under “Aromatic polyamines and their derivatives; salts thereof” and “Other”.

Products commonly classified here include 4,4'-Diamino-2,2'-stilbenedisulfonic acid (CAS No. 81-11-8) (border.bot’s search keywords, not legal text).

## How it is structured

It falls under HS subheading 2921.59 in heading 29.21 (chapter 29). The first six digits are the Harmonized System code; the 4 digits after them are added by the United States tariff.

- Chapter 29: Organic chemicals
- Heading 29.21: Amine-function compounds
- Subheading 2921.59: Aromatic polyamines and their derivatives; salts thereof
- Within the subheading: Other
- Line 2921.59.20.00: 4,4'-Diamino-2,2'-stilbenedisulfonic acid

## Duty

The general (MFN) duty rate is 6.5%.

Duty-free entry applies to goods that qualify under 16 programmes, and to goods from a group of origins (origin group A).

- Free: a group of origins (origin group A) (A)
- Free: United States-Australia Free Trade Agreement (AU)
- Free: United States-Bahrain Free Trade Agreement Implementation Act (BH)
- Free: United States-Chile Free Trade Agreement (CL)
- Free: United States-Colombia Trade Promotion Agreement Implementation Act (CO)
- Free: African Growth and Opportunity Act (D)
- Free: Caribbean Basin Economic Recovery Act (E)
- Free: United States-Israel Free Trade Area (IL)
- Free: United States-Jordan Free Trade Area Implementation Act (JO)
- Free: United States-Korea Free Trade Agreement Implementation Act (KR)
- Free: United States-Morocco Free Trade Agreement Implementation Act (MA)
- Free: United States-Oman Free Trade Agreement Implementation Act (OM)
- Free: Dominican Republic-Central America-United States Free Trade Agreement (P)
- Free: United States-Panama Trade Promotion Agreement Implementation Act (PA)
- Free: United States-Peru Trade Promotion Agreement Implementation Act (PE)
- Free: United States-Mexico-Canada Agreement (S)
- Free: United States-Singapore Free Trade Agreement (SG)

## In other countries

No other national tariff on border.bot has live lines under 2921.59 yet.

- [The Harmonized System text for 2921.59](https://border.bot/hs-codes/292159)

## Other lines under 2921.59

- [2921.59.04.00](https://border.bot/countries/united-states/hs-codes/2921590400) 1,8-Diaminonaphthalene (1,8-Naphthalenediamine)
- [2921.59.08.00](https://border.bot/countries/united-states/hs-codes/2921590800) 5-Amino-2-(p-aminoanilino) benzenesulfonic acid; 4,4'-Diamino-3-biphenylsulfonic acid (3-Benzidinesulfonic acid); 3,3'-Dimethylbenzidine (o-Tolidine); 3,3'-Dimethylbenzidine hydrochloride; Ethyl-(2-dimethylaminoethyl) aniline;N-Ethyl-N,N'-dimethyl-N'-phenylethylene- diamine; and 4,4'-Methylenebis(2-chloroaniline)
- [2921.59.17.00](https://border.bot/countries/united-states/hs-codes/2921591700) 4,4'-Benzidine-2,2'-disulfonic acid; 1,4-Diaminobenzene-2-sulfonic acid; 4,4'-Methylene bis ((3-chloro-2,6-diethylaniline); 4,4'-Methylene bis(2,6-diethylaniline); 4,4'-Methylene bis (2,6-diisopropylaniline);m-Xylene diamine; and 3,3'-Diaminobenzidine (tetraaminobiphenyl)
- [2921.59.30.00](https://border.bot/countries/united-states/hs-codes/2921593000) 4,4'-Methylenedianiline
- [2921.59.40.00](https://border.bot/countries/united-states/hs-codes/2921594000) Products described in additional U.S. note 3 to section VI
- [2921.59.80.10](https://border.bot/countries/united-states/hs-codes/2921598010) 3,3'-Dichlorobenzidine dihydrochloride
- [2921.59.80.90](https://border.bot/countries/united-states/hs-codes/2921598090) Other

- Previous line: [2921.59.17.00](https://border.bot/countries/united-states/hs-codes/2921591700) 4,4'-Benzidine-2,2'-disulfonic acid; 1,4-Diaminobenzene-2-sulfonic acid; 4,4'-Methylene bis ((3-chloro-2,6-diethylaniline); 4,4'-Methylene bis(2,6-diethylaniline); 4,4'-Methylene bis (2,6-diisopropylaniline);m-Xylene diamine; and 3,3'-Diaminobenzidine (tetraaminobiphenyl)
- Next line: [2921.59.30.00](https://border.bot/countries/united-states/hs-codes/2921593000) 4,4'-Methylenedianiline

## Frequently asked questions

### What does tariff line 2921.59.20.00 cover in the United States tariff?

In the United States tariff, line 2921.59.20.00 covers aromatic polyamines and their derivatives; salts thereof, 4,4'-Diamino-2,2'-stilbenedisulfonic acid.

### What is the general (MFN) duty on 2921.59.20.00 in the United States?

The general (MFN) duty rate is 6.5%.

### Which preferential rates apply to 2921.59.20.00?

Duty-free entry applies to goods that qualify under 16 programmes: the United States-Australia Free Trade Agreement, the United States-Bahrain Free Trade Agreement Implementation Act, the United States-Chile Free Trade Agreement, the United States-Colombia Trade Promotion Agreement Implementation Act, African Growth and Opportunity Act, Caribbean Basin Economic Recovery Act, the United States-Israel Free Trade Area, the United States-Jordan Free Trade Area Implementation Act, the United States-Korea Free Trade Agreement Implementation Act, the United States-Morocco Free Trade Agreement Implementation Act, the United States-Oman Free Trade Agreement Implementation Act, the Dominican Republic-Central America-United States Free Trade Agreement, the United States-Panama Trade Promotion Agreement Implementation Act, the United States-Peru Trade Promotion Agreement Implementation Act, the United States-Mexico-Canada Agreement and the United States-Singapore Free Trade Agreement, and to goods from a group of origins (origin group A).

## Sources and updates

The tariff lines for the United States come from border.bot release 1 (edition 2026HTSRev21), read from the publisher’s files, and have been live since 9 October 2026.

The duty rates for the United States come from border.bot release 1 (edition 2026HTSRev21), read from the publisher’s files, and have been live since 9 October 2026.

The trade programmes for the United States come from border.bot release 1 (edition 2026HTSRev21), read from the publisher’s files, and have been live since 9 October 2026.

This page was last updated on 9 October 2026.

Guidance from published tariff data, not a binding ruling. For a decision customs must follow, apply to the destination’s customs authority for a binding tariff ruling.

Official source files:

- https://hts.usitc.gov/reststop/exportList?from=0000000000&to=9999999999&format=CSV&styles=false

Machine-readable: https://border.bot/countries/united-states/hs-codes/2921592000.json