Ortho Toluidine
A distilled aromatic amine, supplied as 2-methylaniline for diazotization into azo dyes and pigments and for agrochemical intermediate manufacture.
What is Ortho Toluidine?
Ortho Toluidine, formally 2-methylaniline, is a colourless to pale yellow oily liquid carrying an amino group at C-1 and a methyl group on the neighbouring carbon. Fresh material is almost water-white; it reddens steadily on contact with air and light.
The amine is what the chemistry runs on. Dissolved in dilute acid and diazotized, it becomes a diazonium salt that couples onto naphthols and acetoacetanilides, and the methyl group sitting beside the reaction centre is what pushes the finished shade into the warm reds of the toluidine pigment family and tightens the crystal packing that gives those pigments their fastness.
At Chelora Dyes, OT is distilled to tight isomer and moisture limits and packed under nitrogen, so the material arrives light in colour and the diazotization downstream runs to a clean, reproducible end point.
- Appearance
- Pale yellow liquid
- Odour
- Amine-like
- Solubility
- Slight in water
- Function
- Diazo component
- Grade
- Technical / distilled
Aniline ring with an ortho methyl substituent
- Molecular formulaC7H9N
- Molecular weight107.15 g/mol
- IUPAC name2-Methylaniline
- Functional groupsPrimary aromatic amine, methyl
- CAS number95-53-4
Technical product information
Standard specification for Chelora Dyes' distilled grade Ortho Toluidine. Custom-grade and bulk specifications are available on request.
| Chemical name | Ortho Toluidine |
|---|---|
| Synonyms | 2-Methylaniline, o-Toluidine, OT, 2-Aminotoluene |
| CAS number | 95-53-4 |
| Molecular formula | C7H9N |
| Molecular weight | 107.15 g/mol |
| Assay (purity) | ≥ 99.5% |
| Appearance | Colourless to pale yellow liquid; darkens on exposure |
| Freezing point | Approx. −15°C |
| Boiling point | 200–202°C |
| Density | Approx. 1.008 g/cm³ at 20°C |
| Refractive index | Approx. 1.572 at 20°C |
| Moisture content | ≤ 0.2% |
| Solubility | Slightly soluble in water; miscible with alcohol and ether; soluble in dilute acid |
| Packaging | 200 kg lined MS drums, ISO tanks; nitrogen blanketed on request |
| Shelf life | 12 months in sealed original packaging |
Applications of Ortho Toluidine
Toluidine red pigments
Diazotized and coupled onto naphthols to build the warm red pigment range used in printing inks and coatings.
Azo and direct dyes
Serves as a diazo component in textile dye chemistry where shade consistency and fastness are critical.
Pigment dispersions
Feeds pigment intermediates used in masterbatch, coatings and ink formulation.
Agrochemical intermediates
A core amine in chloroacetanilide herbicide manufacture and related crop protection chemistry.
Rubber chemicals
Used in accelerator and antioxidant synthesis alongside other specialty chemical routes.
Fine chemical intermediates
Supplies a methyl-substituted aniline core for condensation and heterocycle chemistry.
Why choose Chelora Dyes
Consistent purity
Assay controlled at ≥99.5% with isomer content and colour verified before dispatch.
Full documentation
COA, SDS, and regulatory data supplied with every shipment.
Protective packing
Sealed lined drums 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 drums in a cool, dry, well-ventilated store.
- Keep in the dark — light and air both drive discolouration.
- Re-blanket part-used drums with nitrogen and re-seal them promptly.
- Segregate from strong oxidising agents, acids and acid chlorides.
- Bond and earth containers during any transfer or decanting operation.
- Bund the storage area and keep spillage out of drains and surface water.
Handling precautions
Ortho Toluidine is classified by IARC in Group 1 as carcinogenic to humans, with the urinary bladder as the target organ. Exposure must be controlled to the lowest reasonably practicable level.
It is also toxic and readily absorbed through intact skin, and repeated or uncontrolled exposure can cause methaemoglobinaemia.
Handle in closed systems. Use chemically resistant gloves, chemical splash goggles, protective clothing and local exhaust ventilation at every open transfer or sampling point, and prevent all skin contact.
Refer to the current Safety Data Sheet, and to any applicable occupational exposure limits and health surveillance requirements, before any handling operation.
Frequently asked questions
What is Ortho Toluidine used for?
It is diazotized and coupled to build azo dyes and pigments, particularly the warm red toluidine pigment family used in printing inks and coatings. It is also a starting material for chloroacetanilide herbicides, rubber chemicals and a range of fine chemical intermediates.
How is it different from para toluidine?
Both isomers carry an amine and a methyl group, but the ortho isomer has them adjacent while the para isomer has them opposite. The ortho grade is a liquid at room temperature and the para grade a solid, and the position of the methyl group relative to the diazonium centre changes both the shade and the crystal behaviour of the coupled pigment.
Why has the liquid turned red or brown?
Aromatic amines oxidise slowly on contact with air and light, and the oxidation products are deeply coloured. Some darkening is normal and does not by itself mean assay has been lost. Keep drums sealed, cool and dark, and use nitrogen blanketing on part-used containers.
Is Ortho Toluidine soluble in water?
Only slightly. It dissolves sparingly in water but mixes freely with alcohol, ether and most organic solvents, and it dissolves readily in dilute mineral acid as the amine salt, which is how diazotization is normally set up.
What purity do you supply?
Standard distilled grade is supplied at a minimum assay of 99.5%, with isomer content and moisture held within tight limits. Higher assay and low-colour grades can be manufactured to order.
What packaging sizes are available?
200 kg lined mild steel drums, nitrogen blanketed on request, with bulk supply available in ISO tanks and road tankers.
How should it be stored, and for how long?
In sealed original drums in a cool, dry, dark and ventilated store away from oxidising agents and acids. Shelf life is 12 months from manufacture when storage conditions are maintained, and older material should be checked for colour and assay before use.
Is it hazardous to handle?
Yes, and it deserves particular care. It is toxic, readily absorbed through intact skin, can cause methaemoglobinaemia, and is classified by IARC in Group 1 as carcinogenic to humans, with the bladder as the target organ. Handle in closed systems, prevent all skin contact, and follow the current Safety Data Sheet and any applicable occupational health surveillance requirements.
Do you provide a Certificate of Analysis?
Yes. Each batch ships with a Certificate of Analysis and Safety Data Sheet covering assay, isomer content, moisture, colour and density.
