Para Toluidine
A high-purity aromatic amine, supplied as 4-methylaniline for diazotization into azo dyes and pigments and for fine chemical intermediate manufacture.
What is Para Toluidine?
Para Toluidine, formally 4-methylaniline, is a white to pale brown crystalline solid with an amino group at C-1 and a methyl group directly opposite at C-4. It melts a little above 40°C, so flake will soften in a warm store, and it darkens gradually on exposure to air and light.
With the methyl group sitting well away from the amine, nothing hinders the reaction centre: the amine diazotizes cleanly and couples to a predictable end point. The methyl group still earns its place further along, lifting the shade and improving fastness in the finished dye or pigment, which is why the para isomer is chosen wherever a clean, reproducible strike matters more than the crystal effects the ortho isomer brings.
At Chelora Dyes, PT is crystallised and controlled to a high setting point with isomer content held to a tight limit, and packed sealed to hold colour through storage and transit.
- Appearance
- White to pale brown
- Odour
- Amine-like
- Solubility
- Alcohol, dilute acid
- Function
- Diazo component
- Grade
- Technical / distilled
Aniline ring with a para methyl substituent
- Molecular formulaC7H9N
- Molecular weight107.15 g/mol
- IUPAC name4-Methylaniline
- Functional groupsPrimary aromatic amine, methyl
- CAS number106-49-0
Technical product information
Standard specification for Chelora Dyes' technical grade Para Toluidine. Custom-grade and molten bulk specifications are available on request.
| Chemical name | Para Toluidine |
|---|---|
| Synonyms | 4-Methylaniline, p-Toluidine, PT, 4-Aminotoluene |
| CAS number | 106-49-0 |
| Molecular formula | C7H9N |
| Molecular weight | 107.15 g/mol |
| Assay (purity) | ≥ 99.5% |
| Appearance | White to pale brown crystalline flakes; darkens on exposure |
| Melting range | 43–45°C |
| Setting point | ≥ 43.0°C |
| Boiling point | Approx. 200°C |
| Ortho + meta isomers | ≤ 0.3% |
| Moisture content | ≤ 0.2% |
| Solubility | Slightly soluble in water; soluble in alcohol, ether and dilute acid |
| Packaging | 25 kg / 50 kg lined bags or drums; heated ISO tanks for molten supply |
| Shelf life | 12 months in sealed original packaging |
Applications of Para Toluidine
Azo pigments
Diazotized and coupled to build golden yellow through red pigments for inks, coatings and plastics.
Azo and direct dyes
Serves as a diazo component in textile and leather dye chemistry where a clean strike is essential.
Pigment intermediates
Feeds intermediates used in masterbatch, dispersion and printing ink formulation.
Agrochemical intermediates
Used as a starting material where a para-methyl aniline core is required in crop protection chemistry.
Rubber and specialty chemicals
Applied in accelerator, antioxidant and other specialty chemical syntheses.
Laboratory reagents
Supplied as a reagent for derivatisation and analytical test methods.
Why choose Chelora Dyes
Consistent purity
Assay controlled at ≥99.5% with setting point and isomer content verified before dispatch.
Full documentation
COA, SDS, and regulatory data supplied with every shipment.
Protective packing
Sealed lined packaging with nitrogen blanketing available to hold colour.
Technical support
Diazotization, handling, and compliance guidance from our chemistry team.
Storage and guidelines
- Store in tightly sealed original packaging in a cool, dry, well-ventilated store.
- Keep below 30°C where possible — flake softens and fuses as it nears its melting range.
- Keep in the dark; light and air both drive discolouration.
- Melt drums whole in a controlled hot box; never apply direct or localised heat.
- Segregate from oxidising agents, acids and acid chlorides.
- Contain all spillage — the product is very toxic to aquatic life and must not reach drains.
Handling precautions
Para Toluidine is toxic by inhalation, ingestion and skin absorption, and repeated or uncontrolled exposure can cause methaemoglobinaemia. It is also a skin sensitiser and carries a suspected carcinogen classification in some jurisdictions.
It is very toxic to aquatic organisms, so spillage must be contained rather than washed away.
Prevent all skin contact. Use chemically resistant gloves, chemical splash goggles and protective clothing, control dust at weighing and charging, and provide local exhaust ventilation at every open transfer point. Molten material adds a thermal burn risk.
Refer to the current Safety Data Sheet for exposure limits, spill containment, disposal and first-aid measures before any handling operation.
Frequently asked questions
What is Para Toluidine used for?
It is diazotized and coupled as a diazo component for azo dyes and pigments across the golden yellow to red band, and it serves as a building block in agrochemical, pharmaceutical and rubber chemical manufacture. It is also used as a laboratory reagent.
How is it different from ortho toluidine?
Both carry an amine and a methyl group, but the para isomer has them opposite rather than adjacent. That gives a solid rather than a liquid, an unhindered amine that diazotizes cleanly, and a different shade and crystal behaviour in the coupled pigment. The two isomers are also classified differently for health hazards, so they are not interchangeable in a risk assessment.
Why has the material darkened?
Aromatic amines oxidise slowly on contact with air and light, and the oxidation products are deeply coloured. A shift from white towards pale brown is normal and does not by itself indicate loss of assay. Keep drums sealed, cool and dark, and nitrogen blanket part-used containers.
It has softened or fused in the drum. Is it still usable?
The product melts at around 44°C, so flake will soften or fuse in a hot warehouse. This does not affect assay. Store below 30°C where possible, and re-melt the whole drum under controlled heating rather than applying localised heat.
Is Para Toluidine soluble in water?
Only slightly. It dissolves sparingly in water but freely in alcohol, ether and dilute mineral acid, and the acid solution is the normal starting point for diazotization.
What purity do you supply?
Standard grade is supplied at a minimum assay of 99.5%, with a controlled setting point and isomer content and moisture held to tight limits. Higher assay and low-colour grades can be manufactured to order.
What packaging sizes are available?
25 kg and 50 kg lined bags or drums for flake material, nitrogen blanketed on request, and heated ISO tanks for molten bulk supply.
How should it be stored, and for how long?
In sealed original packaging in a cool, dry, dark and ventilated store away from heat, oxidising agents and acids. Shelf life is 12 months from manufacture when storage conditions are maintained.
Is it hazardous to handle?
Yes. It is toxic by inhalation, ingestion and skin absorption, can cause methaemoglobinaemia, is a skin sensitiser and is very toxic to aquatic life. It also carries a suspected carcinogen classification in some jurisdictions. Prevent skin contact and review the current Safety Data Sheet before any handling operation.
