Buying m-Tolidine: What Matters
m-Tolidine (CAS 84-67-3) is a specialty aromatic diamine supplied in modest volumes for polyimide and epoxy applications. Buying it well means getting the identity right, agreeing a purity specification, choosing the right form, and securing the documentation that a benzidine-type aromatic diamine requires.
For the chemistry and applications behind these points, see our main article on m-Tolidine (CAS 84-67-3).
Step 1: Confirm the Identity
Because “tolidine” is used loosely, identity is the first and most important check.
| Substance | CAS | Distinguishing feature |
|---|---|---|
| m-Tolidine | 84-67-3 | 2,2′-dimethyl (ortho to the ring–ring bond) |
| o-Tolidine | 119-93-7 | 3,3′-dimethyl |
| Benzidine | 92-87-5 | No methyl groups |
Always specify the CAS number and require the supplier to confirm it.
Step 2: Agree the Purity Specification
| Parameter | Why it matters | Typical value |
|---|---|---|
| Assay | Defines the useful content and the polymer stoichiometry | 98–99%+ depending on grade |
| Melting point | Sharp mp near 105–106 °C indicates a clean product | 105–106 °C |
| Isomeric purity | Related isomers and mono-amines affect polymerisation | Per agreed limits |
| Colour | White to off-white; discolouration means oxidation | White to off-white |
| Moisture | Affects weighing and storage | Low, kept dry |
Step 3: Choose the Form
Because the free base is difficult to isolate, m-Tolidine may be supplied as the free base or as a salt (dihydrochloride or sulfate), depending on the application. Confirm which form your process needs, and its assay.
Step 4: Secure the Documentation
- SDS covering the irritant and aromatic-amine hazards.
- Per-batch COA reporting assay, melting point and colour.
- Regulatory statements confirming the status in your market and for your end use.
Supplier Checklist
- Identity. CAS 84-67-3 and the 2,2′-isomer confirmed.
- Assay and isomeric purity. Agreed specifications met batch to batch.
- Form. Free base or salt, as your process requires.
- Colour and moisture. Within specification, indicating good storage.
- Documentation. SDS, per-batch COA and regulatory statements.
- Handling. Packaging and containment suited to a hazardous aromatic diamine.
Common Buying Mistakes
- Buying “tolidine” without a CAS. You may receive the wrong isomer.
- Assuming the form is the free base. Some uses require a salt; confirm.
- Ignoring isomeric purity. Related isomers can spoil a polymerisation.
- Skipping documentation. Benzidine-type diamines need full SDS/COA and regulatory confirmation.
- Poor storage. Aromatic diamines discolour on oxidation; keep them sealed, dark and dry.
How PolyBlueChem Can Help
PolyBlueChem can supply m-Tolidine (CAS 84-67-3) as a specialty intermediate, with the documentation appropriate to your application. To request current specifications, a COA or a quotation, contact the PolyBlueChem team.
Frequently Asked Questions
What should I look for when buying m-Tolidine?
Confirm the CAS number (84-67-3), agree the assay and isomeric purity, choose the correct form, and secure the SDS, COA and regulatory statements.
How do I make sure I am not sent o-Tolidine?
Specify CAS 84-67-3 on the order and require the supplier to confirm it on the certificate of analysis.
Is m-Tolidine supplied as the free base or a salt?
Both are possible; because the free base is hard to isolate, some uses take a salt. Confirm the form and assay your process needs.
What documents should come with a shipment?
At minimum an SDS and a per-batch COA, plus any regulatory statements required for your market.
How should m-Tolidine be stored?
Sealed, dark and dry, away from oxidising agents, to prevent oxidation and discolouration.