Para Nitrophenol
A hydroxylated nitrobenzene supplied as 4-nitrophenol (PNP), a coupling component and precursor used across dye, pharmaceutical and agrochemical intermediate synthesis.
What is Para Nitrophenol?
Para Nitrophenol, abbreviated PNP, is a colourless to pale yellow crystalline solid consisting of a benzene ring carrying a hydroxyl group at C-1 and a nitro group at C-4.
The phenolic hydroxyl makes PNP a useful coupling component in azo dye chemistry and a precursor to para-aminophenol, the key intermediate behind paracetamol (acetaminophen); it is also widely used as a pH indicator and as an intermediate in agrochemical synthesis.
At Chelora Dyes, PNP is crystallised and dried to a controlled assay and colour so downstream reduction, coupling and esterification reactions run cleanly and reproducibly batch to batch.
- Appearance
- Colourless to pale yellow crystalline solid
- Odour
- Faint, phenolic
- Solubility
- Moderately soluble in water; soluble in ethanol and ether
- Function
- Coupling component
- Grade
- Technical / dye intermediate
Benzene ring with para hydroxyl and nitro groups
- Molecular formulaC6H5NO3
- Molecular weight139.11 g/mol
- IUPAC name4-Nitrophenol
- Functional groupsHydroxyl, nitro
- CAS number100-02-7
Technical product information
Standard specification for Chelora Dyes' technical grade Para Nitrophenol. Custom-grade and bulk specifications are available on request.
| Chemical name | Para Nitrophenol |
|---|---|
| Synonyms | PNP, 4-Nitrophenol, p-Nitrophenol, 4-Hydroxynitrobenzene |
| CAS number | 100-02-7 |
| Molecular formula | C6H5NO3 |
| Molecular weight | 139.11 g/mol |
| Assay (purity) | ≥ 99% |
| Appearance | Colourless to pale yellow crystalline solid |
| Melting point | 110–114°C |
| Moisture content | ≤ 0.3% |
| Solubility | Moderately soluble in water (~16 g/L at 25°C); soluble in ethanol and ether |
| Packaging | 25 kg bags as standard, with drum packaging on request |
| Shelf life | 24 months in sealed original packaging |
Applications of Para Nitrophenol
Azo dye coupling component
Used as a coupling component in azo dye and pigment synthesis.
Paracetamol intermediate
Reduced to para-aminophenol, the key precursor to paracetamol (acetaminophen).
pH indicator
Used as an analytical reagent and pH indicator (transition range pH 5.4-7.5).
Agrochemical intermediates
Applied as an intermediate and known metabolite marker in pesticide chemistry.
Rubber and leather chemicals
Used as an intermediate in rubber chemical and leather processing applications.
Corrosion inhibitor intermediates
Applied as a starting material in select corrosion inhibitor synthesis.
Why choose Chelora Dyes
Consistent purity
Assay controlled at ≥ 99% with moisture and melting range verified before dispatch.
Full documentation
COA, SDS, and regulatory data supplied with every shipment.
Flexible volumes
From 25 kg bags to bulk drum quantities.
Technical support
Process, coupling, and compliance guidance from our chemistry team.
Storage and guidelines
- Store in tightly sealed original packaging in a dry environment.
- Keep in a cool, well-ventilated area away from direct sunlight and heat.
- Protect from moisture pickup and prolonged air exposure.
- Segregate from strong oxidising agents and strong bases.
- Use compatible containers: lined HDPE bags or drums.
- Re-seal packaging promptly after use to preserve colour and assay specification.
Handling precautions
Para Nitrophenol is harmful if swallowed, inhaled or absorbed through skin, and prolonged or repeated exposure may cause organ damage.
Use dust control measures, chemically resistant gloves, and eye protection during weighing, charging, and any bulk handling operation.
Provide local exhaust ventilation where dust generation is likely, and keep away from strong oxidisers and strong bases.
Refer to the full Safety Data Sheet for exposure limits, spill containment, disposal, and first-aid measures before use.
Frequently asked questions
What is Para Nitrophenol used for?
PNP is mainly used as a coupling component in azo dye synthesis, as a precursor to para-aminophenol for paracetamol manufacture, and as a pH indicator and agrochemical intermediate.
Why does the hydroxyl group matter?
The phenolic hydroxyl provides a reactive site for coupling, esterification and reduction, and together with the para-nitro group gives PNP its characteristic acidity (pKa ~7.15) and colour-change behaviour.
Is Para Nitrophenol soluble in water?
It is moderately soluble in water, with solubility increasing at higher temperatures, and dissolves readily in ethanol and ether.
What purity do you supply?
Standard technical grade is supplied at a minimum assay of 99%, with moisture content held within tight limits.
What packaging sizes are available?
25 kg bags as standard, with drum packaging available on request for larger volumes.
How should it be stored, and for how long?
In sealed original packaging in a cool, dry, ventilated store, away from oxidisers, strong bases and ignition sources. Shelf life is 24 months from manufacture when storage conditions are maintained.
Is it hazardous to handle?
It is harmful if swallowed, inhaled or absorbed through skin, so it should be handled with PPE, dust control and adequate ventilation. Review the Safety Data Sheet before any handling operation.
Do you provide a Certificate of Analysis?
Yes. Each batch ships with a Certificate of Analysis and Safety Data Sheet covering assay, moisture and appearance.