Para Nitrophenol
A high-volume nitrophenol intermediate supplied by Chelora Chemicals — the key precursor to paracetamol (acetaminophen) and p-aminophenol chemistry, a working pH indicator, and a standard chromogenic substrate for enzyme assays — exported from Indonesia with full batch documentation on every shipment.
What Para Nitrophenol is, and why buyers source it
A working overview of the compound's chemistry, its central role as the gateway to paracetamol manufacture, and the grades Chelora Chemicals keeps in regular supply.
Para Nitrophenol (4-nitrophenol, PNP) is a phenol bearing a nitro group para to the hydroxyl. The nitro group withdraws electron density strongly by both resonance and induction, which makes the phenolic hydroxyl considerably more acidic than phenol itself (its conjugate base, the para-nitrophenolate ion, is a stable, intensely yellow chromophore) and leaves the ring deactivated toward further electrophilic substitution. This combination — an acidic, strongly coloured phenolate and a deactivated ring — is exactly what makes the molecule useful as both a chemical intermediate and an analytical reagent.
At room temperature it is a colourless to pale yellow crystalline solid that darkens slightly on exposure to light and air. It is moderately soluble in water (more so as the sodium salt) and freely soluble in common organic solvents, and is handled as a solid oxidising hazard with standard dust-control precautions.
Where it fits in the synthesis chain
Para Nitrophenol's largest-volume use by far is as the intermediate en route to paracetamol (acetaminophen): catalytic reduction of the nitro group gives 4-aminophenol, which is then O-acetylated to the finished analgesic. The same reduction step also supplies 4-aminophenol for phenetidine and related fungicide and dye-intermediate chemistry. Independently of this reduction chemistry, the compound and its sodium salt are used directly as a classical acid-base pH indicator, and as the chromogenic group in substrates such as para-nitrophenyl phosphate and para-nitrophenyl glycosides used to assay alkaline phosphatase and glycosidase activity by absorbance at around 405 nm.
Grades we supply
Chelora Chemicals offers Para Nitrophenol in technical grade (≈99% assay) for standard pharmaceutical-intermediate and dye-chemistry buyers, and high-purity grade (99.5%+) for analytical-reagent and enzyme-assay-substrate applications where colour and trace-metal content matter. Both grades are supplied with a batch-wise certificate of analysis.
How Para Nitrophenol is made
An overview of the production route for orientation purposes. Our manufacturing partners' own process parameters and in-process controls are proprietary and are not disclosed beyond what is needed to interpret the certificate of analysis.
Para Nitrophenol is manufactured industrially by two established routes. The first is direct nitration of phenol with dilute nitric acid at or near room temperature, which gives a mixture of 2-nitrophenol and 4-nitrophenol; the two isomers are separated by exploiting their very different volatility and solubility (ortho-nitrophenol is appreciably more volatile and can be removed by steam distillation), and the para isomer is recrystallised to the required purity. The second, and industrially more common, route is alkaline hydrolysis of para-nitrochlorobenzene (PNCB) under pressure with aqueous sodium hydroxide, which displaces chloride and gives sodium para-nitrophenolate directly; acidification then precipitates the free phenol.
After either route, the crude product is purified by recrystallisation or vacuum distillation, dried, and milled or flaked to the grade required before packing.
Why the PNCB hydrolysis route is favoured at scale
Hydrolysing para-nitrochlorobenzene avoids the isomer-separation burden of direct phenol nitration and gives a cleaner, more consistent product stream at production scale, which is why most merchant-grade para-nitrophenol used in paracetamol manufacture today traces back to this route rather than to phenol nitration.
Industries and processes that use it
Para Nitrophenol is consumed overwhelmingly by pharmaceutical-intermediate manufacture, with secondary demand from analytical-reagent and dye-intermediate chemistry. The fields below account for most of the demand we see through our export desk.
Paracetamol (Acetaminophen) Intermediate
Catalytic reduction gives 4-aminophenol, which is O-acetylated to paracetamol — the single largest end use of this product worldwide.
Phenetidine & Dye-Intermediate Chemistry
The same 4-aminophenol reduction product feeds phenetidine (acetophenetidine) and related dye- and fungicide-intermediate synthesis.
pH Indicator
The compound and its sodium salt are used as a classical acid-base indicator, colourless below roughly pH 5.4 and yellow above roughly pH 7.5.
Enzyme-Assay Chromogenic Substrate
Para-nitrophenyl phosphate and para-nitrophenyl glycoside derivatives are standard substrates for assaying alkaline phosphatase and glycosidase activity by absorbance near 405 nm.
How the molecule is typically carried forward
The nitro group's reducibility and the phenol's acidity govern almost all of this molecule's further reaction chemistry. Reaction classes below account for most of the ways Para Nitrophenol is converted into a finished intermediate or reagent.
Catalytic Reduction
Hydrogenation or chemical reduction of the nitro group gives 4-aminophenol, the direct precursor to paracetamol and to phenetidine-based dye and fungicide intermediates.
O-Alkylation / Esterification
The acidic phenolic hydroxyl is readily alkylated or esterified, the basis for preparing chromogenic esters such as para-nitrophenyl phosphate used in enzyme assays.
Salt Formation
Neutralisation with sodium hydroxide gives the intensely yellow sodium para-nitrophenolate, the form generally used as a pH indicator and in some formulated products.
Etherification
Williamson-type etherification of the phenolate with alkyl halides gives para-nitrophenyl ethers, used as intermediates in agrochemical and fine-chemical synthesis.
Para Nitrophenol against related phenolic and nitroaromatic intermediates we supply
Buyers sourcing para-nitrophenol often need a related phenolic or nitroaromatic building block for an upstream or downstream step. A quick reference to what else is on our regular supply list.
| Product | CAS Number | Category | Notes |
|---|---|---|---|
| Para Nitrophenol | 100-02-7 | Nitrophenol | The product on this page — the paracetamol-chain nitrophenol intermediate in our range. |
| Para Nitro Chloro Benzene | 100-00-5 | Chloronitrobenzene | The chlorinated precursor whose alkaline hydrolysis is an industrial route to this product — see its product page. |
| 2,5-Dichloro Phenol | 583-78-8 | Chlorophenol | A related chlorinated phenol elsewhere in our range — see its product page. |
| Anisole | 100-66-3 | Aromatic ether | The methylated analogue of phenol, and a related oxygenated aromatic building block — see its product page. |
Exact physical constants and purity specifications are confirmed per batch on the certificate of analysis — treat the notes above as a sourcing guide, not a specification sheet, for products other than Para Nitrophenol.
Safety classification at a glance
Based on GHS classification as commonly listed for this substance. This is a summary for orientation only — always work from the current safety data sheet supplied with your specific batch.
Harmful if swallowed.
Harmful in contact with skin.
Harmful if inhaled.
May cause damage to organs through prolonged or repeated exposure.
Harmful to aquatic life.
Impervious gloves, dust-tight goggles and a suitable dust mask or respirator are the baseline for routine handling.
Handle as a fine crystalline solid with local exhaust ventilation to limit airborne dust and inhalation exposure.
Warning — GHS07 harmful and GHS09 environmental-hazard pictograms apply.
This compound is harmful if swallowed, in contact with skin or if inhaled, may cause organ damage on prolonged or repeated exposure, and is harmful to aquatic life. It must be handled with impervious gloves, dust-tight goggles and suitable respiratory protection in a well-ventilated area, and kept out of drains and waterways. Full first-aid, storage, spill and PPE guidance is in the MSDS issued with every shipment, and should be read in full before this material is handled.
Keeping it on spec between delivery and use
General storage guidance for this grade. Site-specific storage rules, segregation requirements and re-test intervals should follow your own EHS procedures and the MSDS issued with your batch.
Store in a cool, dry, dark, well-ventilated area, in tightly closed original packaging, segregated from strong oxidizing agents and strong bases. If a batch is held past its retest date, re-check assay, melting point and colour before use.
How it ships from Indonesia
Standard packing and export terms for this product. Confirm exact figures against your order — they vary slightly by destination and quantity.
What travels with every batch
Specification is agreed before the purchase order, not discovered on arrival. Every shipment of Para Nitrophenol leaves with a documented, checkable paper trail.
Certificate of Analysis
Batch-wise assay (by HPLC), melting point and colour, issued against the agreed specification so your QC team can check it, not just file it.
Safety Data Sheet
GHS-format SDS in English covering hazard classification, handling, storage, first-aid and spill response for the exact grade shipped.
Technical Data Sheet
Reference physical and chemical properties, recommended storage and typical applications, for internal circulation to your process or R&D teams.
Certificate of Origin
Confirms Indonesian origin for customs clearance and any preferential-duty claim at your destination port.
Dangerous Goods Declaration
UN packing group, classification and shipper's declaration prepared ahead of loading so documentation never holds up customs.
Third-Party Inspection
Independent pre-shipment inspection and re-sampling can be arranged on request, at your cost, for buyers who require it as a matter of policy.
Frequently asked questions
What buyers most often ask our sales desk about this grade.
01What is Para Nitrophenol used for?+
02What is the CAS number of Para Nitrophenol?+
03How is Para Nitrophenol made?+
04What purity grades does Chelora Chemicals supply?+
05Is Para Nitrophenol hazardous?+
06Why does the nitro group make this phenol so much more acidic?+
07What packing options are available?+
08How long does delivery take?+
09Can I get a sample before placing a bulk order?+
10Do you supply the chlorinated precursor as well?+
Need Para Nitrophenol on spec, on time?
Send us your required purity, quantity, packing preference and destination port. Our desk quotes most enquiries within one working day.