Ortho Toluidine

Ortho Toluidine carries a methyl group on the ring position beside the amino group. We state this plainly and early rather than in a hazard section buried at the bottom of the page: this substance is classified by IARC as Group 1, carcinogenic to humans — the most severe classification carried by any product in our range, and more severe than the Category 1B entries elsewhere on this site. The evidence is epidemiological, from bladder cancer in rubber-chemical and dye-industry workers, and it carries a harmonised EU Category 1B carcinogen classification, H350, under Annex VI to CLP.

We supply it because it remains a legitimate, regulated industrial intermediate with real downstream demand, not because the hazard is in doubt. Physically it is a colourless liquid when fresh, darkening to reddish-brown on exposure to air and light. It is only slightly soluble in water and dissolves in common organic solvents. Its boiling point of 200–202 °C and flash point of 85 °C sit close to its meta and para relatives, which is unsurprising given how similar the three isomers are structurally — the hazard profile is where they diverge sharply.

Where it fits in the synthesis chain

Ortho Toluidine is used as an intermediate for rubber-industry accelerators and antidegradants, for dye and pigment manufacture, and — via 6-ethyl-o-toluidine — for the chloroacetanilide herbicides metolachlor and acetochlor. Its historical dominance in dye manufacture has declined over recent decades, driven by cost competition from producers in China and India rather than by a formal phase-out; current demand through our desk is weighted towards rubber chemicals and agrochemical intermediate use.

Grades we supply

Chelora Chemicals offers Ortho Toluidine in technical grade (99%) and high-purity grade (99.5%+), both with a batch-wise certificate of analysis. Given its carcinogen classification, every order for this product is accompanied by the classification documentation and handling guidance appropriate to a Category 1B substance, and we will discuss your intended use, occupational controls and destination-country import rules at the enquiry stage as a matter of course.

Ortho Toluidine is made by nitrating toluene under conditions selective for the ortho position, separating 2-nitrotoluene from the accompanying para and minor meta isomers by distillation, and then reducing the nitro group — by catalytic hydrogenation or an equivalent chemical reduction — to the amine.

The nitration step does not give a single isomer cleanly; toluene nitration produces a mixture dominated by ortho and para nitrotoluene with a small meta fraction, and the three nitro isomers are physically similar enough that the separation, not the reduction, is the demanding part of the process.

After reduction the crude amine is washed and distilled to remove residual nitro compound, isomeric carryover and catalyst metal before packing. Because this product is regulated as a carcinogen, process containment and worker exposure control at the reduction and finishing stages are a significant part of what a compliant manufacturing site has to manage — detail that sits with our manufacturing partners rather than with the buyer.

Why the isomer separation, not the chemistry, is the hard part

All three toluidine isomers come from reducing the corresponding nitrotoluene, and all three nitrotoluenes come from the same toluene nitration step in different proportions. The separation of ortho from para nitrotoluene before reduction is what fixes isomer purity, and it is set upstream of the chemistry described above — a mixed or poorly separated nitrotoluene feed carries isomeric toluidine contamination all the way through to the finished product, which matters acutely here given how differently the three isomers are regulated.