5-Nitro-2-aminophenol (CAS 121-88-0): Properties, Uses and Applications

For Indian dye, specialty chemical, and pharma-intermediate buyers, 5-nitro-2-aminophenol is a small molecule with a surprisingly large purchasing risk: the names are similar, the isomers are easy to confuse, and the wrong CAS can change color performance or downstream synthesis results. This guide explains what CAS 121-88-0 is, where it is used, and what to check before sending an RFQ.

What Is 5-Nitro-2-aminophenol?

5-Nitro-2-aminophenol, also called 2-amino-5-nitrophenol or 2-hydroxy-4-nitroaniline, is an aromatic intermediate with amino, hydroxyl, and nitro functional groups on the same benzene ring. Its CAS number is 121-88-0, molecular formula is C6H6N2O3, and molecular weight is 154.12.

• Common synonyms: 2-amino-5-nitrophenol, 5-NAP, 2-hydroxy-4-nitroaniline.

• Typical appearance: brown, rust-brown, or orange-brown crystalline powder.

• Main commercial roles: dye intermediate, organic synthesis building block, and niche pharmaceutical research intermediate.

Key Physical and Chemical Properties

Specifications vary by supplier and grade, so the COA should always state the assay method, melting point range, moisture or loss on drying, and total impurities.

Common Synthesis Routes

Industrial routes usually protect or direct the aminophenol ring before nitration, then hydrolyze the protected intermediate to obtain 5-NAP. Literature and supplier references describe routes through benzoxazolone or 2-methylbenzoxazole, while some lab references describe direct nitration of 2-aminophenol under controlled acidic conditions.

1. Start from 2-aminophenol or a protected derivative.

2. Control nitration temperature and acid strength to favor the desired positional isomer.

3. Hydrolyze, isolate, crystallize, and dry the product.

4. Verify assay and isomer impurity by HPLC or another agreed analytical method.

Where 5-NAP Is Used

5-NAP is not AquaChem's main water-treatment product line, but it is a relevant specialty intermediate for customers who also source dye, textile, and fine-chemical raw materials. Its value comes from reactivity, not from being a finished active ingredient.

• Azo and metal complex dyes for textile, leather, ink, and resin colorants.

• Hair-colorant and toner chemistry in regulated formulations.

• Organic synthesis routes that need an aminonitrophenol building block.

• Pharmaceutical R&D where benzoxazinone or other bioactive scaffolds are being explored.

Dye and Pigment Applications

In dye chemistry, the amino group can be diazotized and coupled with suitable partners to build azo chromophores. Buyers normally care about shade consistency, metal content, residual isomers, and insoluble matter because small upstream differences can show up as shade drift in the final dye.

Pharmaceutical and Organic Synthesis Uses

For pharmaceutical synthesis, 5-NAP should be positioned carefully. It is better described as a niche building block or R&D intermediate than as a mainstream API precursor. Published references connect it with biologically active benzoxazinone derivatives and diazotization or coupling chemistry, but buyers still need to validate the exact route, impurity limits, and regulatory boundary for their own product.

Quality Specifications Buyers Should Request

Dye applications may tolerate technical grades, while pharma R&D and regulated colorant work usually require tighter impurity data.

Packaging, Safety, and Import Notes for India

Indian buyers should align packaging, HS code, and documentation before shipment. Many commercial listings use 25 kg drums or bags, but the correct package depends on grade, moisture sensitivity, and transport classification.

• Ask for the latest SDS and confirm GHS hazard statements before import.

• Check whether the quoted HS code matches your customs broker's classification.

• Confirm inner liner, drum or bag type, net weight, and palletization.

• For samples, verify whether the same analytical method will be used for bulk batches.

How to Choose a 5-NAP Supplier

A reliable supplier should be able to identify the product unambiguously, explain the grade, provide batch documents, and support logistics to India. AquaChem's core business remains water treatment chemicals, but this 5-NAP page can serve buyers who need a specialty dye or pharmaceutical intermediate from an established chemical exporter.

View AquaChem 5-Nitro-2-aminophenol specifications and request a COA

FAQ

Is 5-nitro-2-aminophenol the same as 2-amino-5-nitrophenol?

Yes. These names commonly refer to CAS 121-88-0. Always verify by CAS number because similar aminophenol isomers have different properties.

What purity should I request?

For dye manufacturing, technical or high-purity grades may be acceptable depending on the process. For pharmaceutical R&D, ask for HPLC purity, impurity profile, and batch COA.

Can it be used for water treatment?

No. It is better treated as a dye, organic synthesis, or pharmaceutical intermediate, while AquaChem's main product focus remains water treatment chemicals.

Conclusion

5-Nitro-2-aminophenol is useful because one molecule combines amino, hydroxyl, and nitro functionality, but that same chemistry also makes specification control important. Indian buyers should verify CAS 121-88-0, melting point, assay method, impurity profile, documents, and shipment details before purchase.

Request 5-NAP product details from AquaChem

Specification Review for Indian Buyers

Before approving a 5-NAP order, Indian buyers should convert the supplier's specification into an internal acceptance sheet. The sheet should separate identity tests from quality tests. Identity tests answer whether the material is truly CAS 121-88-0; quality tests answer whether the batch is suitable for the buyer's process.

A practical review starts with the product name, CAS number, molecular formula, and synonym list. Then it checks HPLC assay, melting point, moisture, insolubles, and any named isomer impurities. For dye producers, shade trial results can be more useful than a single assay number. For pharmaceutical research teams, unknown impurities and trace contaminants deserve more attention because they can affect downstream route development.

How to Discuss 5-NAP with a Supplier

A strong RFQ should not simply ask for 'best price 5-nitro-2-aminophenol.' It should state the application, expected purity, sample quantity, target bulk quantity, destination port or city, and document requirements. This gives the supplier enough context to quote the right grade and packaging instead of sending a generic offer.

• State whether the material is for dye synthesis, pharma R&D, trading inventory, or another use.

• Ask whether the quoted batch is from stock or future production.

• Request a COA format before payment, especially if your QC team needs specific tests.

• Confirm whether the supplier can support repeat supply, not just one spot shipment.

Common Mistakes to Avoid

The most common mistake is approving a quotation by synonym only. Another mistake is comparing suppliers by purity percentage without checking test method. A third mistake is ignoring logistics until after payment, when packaging, transport classification, and customs documents may already be fixed.

For this product, a cautious purchasing process is not slow bureaucracy. It protects the buyer from wrong-CAS substitutions, unexpected customs questions, and pilot batches that do not scale into stable production.