Para Nitro Phenol
A high-purity nitrophenol supplied as the precursor to p-aminophenol and as an intermediate for agrochemical, dye, and pharmaceutical manufacture.
What is Para Nitro Phenol?
Para Nitro Phenol — PNP, or 4-nitrophenol — is a pale yellow crystalline solid produced by hydrolysing para nitrochlorobenzene or by nitrating phenol and separating the isomers.
The nitro group makes the phenolic hydroxyl markedly more acidic than in phenol itself, so PNP dissolves readily in dilute alkali as the intensely yellow phenolate. Reducing the nitro group gives p-aminophenol, the direct precursor to paracetamol, which accounts for a large share of world demand.
At Chelora Chemicals, PNP is crystallised and refined with isomer content, melting range, and moisture held to specification, so that reduction and etherification steps downstream run to consistent yield.
- Appearance
- Pale yellow crystalline solid
- Odour
- Faint, characteristic
- Solubility
- Slightly soluble in water; soluble in alcohol and dilute alkali
- Function
- Chemical intermediate
- Grade
- Technical
Formula diagram
Phenol with a nitro group in the para position
- Molecular formulaC6H5NO3
- Molecular weight139.11 g/mol
- IUPAC name4-Nitrophenol
- Functional groupsPhenol, nitro
- CAS number100-02-7
Technical product information
Standard specification for Chelora Chemicals' technical grade Para Nitro Phenol. Custom-grade and bulk specifications are available on request.
| Chemical name | Para Nitro Phenol |
|---|---|
| Synonyms | PNP, 4-Nitrophenol, p-Nitrophenol |
| CAS number | 100-02-7 |
| Molecular formula | C6H5NO3 |
| Molecular weight | 139.11 g/mol |
| Assay (purity) | ≥ 99.0% |
| Appearance | Pale yellow crystalline solid |
| Melting point | 112–114°C |
| Boiling point | 279°C |
| Isomer content | ≤ 0.5% |
| Moisture | ≤ 0.5% |
| Packaging | 25 kg bags, 500 kg jumbo bags |
| Shelf life | 24 months from date of manufacture |
Applications of Para Nitro Phenol
p-Aminophenol route
Reduced to p-aminophenol, the direct precursor to paracetamol and related analgesics.
Agrochemical intermediates
Used in the manufacture of organophosphate and related crop-protection actives where registered.
Dye intermediates
Feeds nitrophenol-based colour intermediate chemistry.
Leather & specialty chemicals
Applied in leather treatment and specialty formulation.
pH indicators & reagents
Used as an analytical indicator and enzyme substrate precursor.
Fine chemicals
Applied where an acidic, activated phenol is required in synthesis.
Why choose Chelora Chemicals
Every batch of Para Nitro Phenol is manufactured, tested, and documented to a standard that formulators and process chemists can build on with confidence — from first sample to full production volume.
Consistent purity
Assay controlled at ≥99% with isomer content and melting range verified before dispatch.
Full documentation
COA, SDS, and regulatory data supplied with every shipment.
Flexible volumes
From 25 kg bags to 500 kg jumbo bags and full container loads.
Technical support
Process, handling, and compliance guidance from our chemistry team.
Storage and guidelines
- 01Store in tightly closed original packaging in a cool, dry, well-ventilated store.
- 02Keep away from heat, ignition sources, and direct sunlight.
- 03Segregate from strong oxidising agents, strong bases, and reducing agents.
- 04Keep bags palletised and dry; control dust and re-seal opened packaging promptly.
- 05Store away from food, feed, and drinking water in a locked or access-controlled area.
- 06Prevent release to drains, surface water, and soil; the product is toxic to aquatic life.
Handling precautions
PNP is toxic if swallowed, in contact with skin, or if inhaled, and causes damage to organs through prolonged exposure. It is for industrial use by trained personnel only.
It is readily absorbed through intact skin and causes methaemoglobin formation, reducing the blood's oxygen-carrying capacity. Chemical-resistant gloves, coveralls, and eye protection are required.
Control dust during bag emptying, sieving, and charging, and use local exhaust ventilation at all transfer points.
Nitrophenols can decompose exothermically if overheated. Drying and heated processing require temperature control and a documented thermal assessment.
The product stains skin and surfaces yellow; treat discolouration as evidence of contact and wash immediately.
Refer to the full Safety Data Sheet for exposure limits, medical surveillance, spill response, and first-aid measures before use.
Frequently asked questions
What is Para Nitro Phenol used for?
Its largest outlet is reduction to p-aminophenol for paracetamol manufacture. It also serves agrochemical, dye, and leather chemical routes, and is used as an analytical indicator.
How is PNP manufactured?
Either by hydrolysing para nitrochlorobenzene under alkaline conditions, or by nitrating phenol and separating the ortho and para isomers. The PNCB route generally gives better isomer purity.
Why is it more acidic than phenol?
The para nitro group withdraws electron density and stabilises the phenolate anion formed when the hydroxyl proton is lost. That is why PNP dissolves readily in dilute caustic and gives an intensely yellow solution.
Why does the alkaline solution turn bright yellow?
The phenolate anion absorbs strongly in the visible region in a way the neutral molecule does not. This colour change is also why PNP works as a pH indicator.
What is the relationship with paracetamol?
Reducing PNP gives p-aminophenol, which is acetylated to paracetamol. It is one of the more direct routes from a bulk nitroaromatic to a high-volume pharmaceutical.
Is it soluble in water?
Slightly in neutral water, and freely in dilute alkali as the phenolate salt. Alkaline dissolution is the usual route into further chemistry.
How does it differ from 2,5-dichlorophenol?
Both are activated phenols, but PNP is activated by a nitro group and 25DCP by chlorines. PNP is the pharmaceutical and agrochemical feedstock; 25DCP serves narrower specialty routes.
What purity do you supply?
Standard technical grade is supplied at a minimum assay of 99% with isomer content at or below 0.5% and moisture at or below 0.5%. Tighter specifications can be produced to order.
What packaging sizes are available?
25 kg bags and 500 kg jumbo bags, with full container loads for bulk users.
Is PNP hazardous?
Yes. It is toxic by several routes, skin-absorbable, harmful to organs on repeated exposure, and toxic to aquatic life. Dust control, PPE, and thermal controls all apply.
Do you provide a Certificate of Analysis?
Yes. Every batch is dispatched with a Certificate of Analysis and Safety Data Sheet covering assay, isomer content, melting range, moisture, and appearance.