Para Phenylenediamine
A high-purity aromatic diamine, supplied as 1,4-phenylenediamine for hair and fur dye bases, azo and direct dyes, rubber antioxidants and aramid polymer manufacture.
What is Para Phenylenediamine?
Para Phenylenediamine, formally benzene-1,4-diamine, is a white to light purple crystalline solid carrying an amino group at C-1 and a second directly opposite at C-4. It darkens quickly in air and light, which is why it ships sealed under nitrogen.
That readiness to oxidise is not a defect — it is the working principle behind its largest use. In an oxidative hair or fur dye the colourless amine is developed on the fibre, where it oxidises and couples in place to build the deep browns and blacks that cannot be achieved by simply staining the surface. Elsewhere the same molecule serves as a diazo and coupling component in dye manufacture, as the amine behind several rubber antioxidants, and as the linear diamine monomer in aramid fibre production.
At Chelora Dyes, PPDA is crystallised and dried to a controlled melting range and low moisture, and packed nitrogen blanketed as standard, so it arrives light in colour and performs consistently batch to batch.
- Appearance
- White to light purple
- Odour
- Faint, amine-like
- Solubility
- Water, alcohol, acid
- Function
- Diazo / coupling
- Grade
- Technical / dye base
Benzene ring with two opposed amino groups
- Molecular formulaC6H8N2
- Molecular weight108.14 g/mol
- IUPAC nameBenzene-1,4-diamine
- Functional groupsTwo primary aromatic amines
- CAS number106-50-3
Technical product information
Standard specification for Chelora Dyes' technical grade Para Phenylenediamine. Low-colour and high-assay grades are available on request.
| Chemical name | Para Phenylenediamine |
|---|---|
| Synonyms | 1,4-Phenylenediamine, p-Phenylenediamine, PPDA, PPD, 1,4-Diaminobenzene |
| CAS number | 106-50-3 |
| Molecular formula | C6H8N2 |
| Molecular weight | 108.14 g/mol |
| Assay (purity) | ≥ 99.0% |
| Appearance | White to light purple crystalline flakes; darkens on exposure |
| Melting range | 138–141°C |
| Boiling point | Approx. 267°C |
| Moisture content | ≤ 0.5% |
| Ash content | ≤ 0.1% |
| Solubility | Soluble in water, alcohol, ether and dilute acid |
| Packaging | 25 kg / 50 kg lined fibre or HDPE drums, nitrogen blanketed |
| Shelf life | 12 months in sealed original packaging |
Applications of Para Phenylenediamine
Hair and fur dye bases
The primary intermediate in oxidative dye systems, developed on the fibre for deep brown and black shades.
Azo and direct dyes
Serves as a diazo and coupling component in textile and leather dye manufacture.
Rubber antioxidants
The amine behind several antioxidant and antiozonant grades used in tyre and technical rubber.
Aramid polymers
The linear diamine monomer used with aromatic diacid chlorides in high-strength fibre production.
Photographic developers
Applied in developer chemistry and related redox formulations at smaller volumes.
Fine chemical intermediates
Supplies a para-diamine core for polymer, condensation and heterocycle chemistry.
Why choose Chelora Dyes
Consistent purity
Assay controlled at ≥99% with melting range and colour verified before dispatch.
Full documentation
COA, SDS, and regulatory data supplied with every shipment.
Protective packing
Sealed lined drums, nitrogen blanketed as standard to limit oxidation.
Technical support
Formulation, storage, and compliance guidance from our chemistry team.
Storage and guidelines
- Store in sealed, nitrogen blanketed original packaging in a cool, dry store.
- Keep in the dark — light and air both drive rapid discolouration.
- Re-blanket and re-seal part-used drums immediately after charging.
- Segregate from oxidising agents, acids and acid chlorides.
- Use lined fibre, HDPE or stainless containers; avoid bare mild steel.
- Contain all spillage — the product is very toxic to aquatic life and must not reach drains.
Handling precautions
Para Phenylenediamine is a potent skin and respiratory sensitiser and one of the best-known industrial contact allergens. Once someone is sensitised even brief contact can provoke a severe reaction, so exposure must be prevented rather than merely limited.
It is also toxic if swallowed or inhaled and very toxic to aquatic organisms.
Control dust at every weighing and charging point, use chemically resistant gloves, chemical splash goggles, protective clothing and respiratory protection where dust may be generated, and provide local exhaust ventilation.
Use in cosmetic products is regulated in most markets, with concentration limits and mandatory finished-product warnings. Confirm current requirements for each market of sale, and refer to the full Safety Data Sheet before any handling operation.
Frequently asked questions
What is Para Phenylenediamine used for?
It is the primary base of oxidative hair and fur dyes, where it is developed on the fibre to give deep browns and blacks. It is also a diazo and coupling component in azo and direct dye manufacture, the amine behind several rubber antioxidants and antiozonants, and the diamine monomer used in aramid fibre production.
How does it differ from meta and ortho phenylenediamine?
All three carry two amino groups, but only in the para isomer do they sit directly opposite each other. That symmetry gives the linear structure needed for aramid polymers and the oxidation behaviour that oxidative hair dyes rely on, while the ortho isomer dominates benzimidazole chemistry and the meta isomer is used mainly as a dye coupler.
Why does the material darken so quickly?
It oxidises readily in air and light, and the coloured oxidation products are precisely what makes it useful as a dye base. A shift from white towards purple or brown in storage is normal and does not by itself indicate loss of assay, but drums should be kept sealed, cool, dark and nitrogen blanketed.
Is Para Phenylenediamine soluble in water?
Yes, appreciably, and freely in alcohol, ether and acetone. It also dissolves in dilute acid as the amine salt, which is the usual form for diazotization.
What purity do you supply?
Standard grade is supplied at a minimum assay of 99%, with a controlled melting range and moisture and ash held to tight limits. Higher assay and low-colour grades can be manufactured to order for cosmetic and polymer applications.
Are there regulatory restrictions on cosmetic use?
Yes. Use in hair dye products is regulated in most markets, with limits on maximum concentration and mandatory warning statements on the finished product. Anyone formulating for cosmetic use should confirm the current requirements in each market of sale before proceeding.
What packaging sizes are available?
25 kg and 50 kg lined fibre or HDPE drums, nitrogen blanketed as standard, with larger volumes available on a scheduled supply basis.
How should it be stored, and for how long?
In sealed, nitrogen blanketed original packaging 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 re-assayed before use.
Is it hazardous to handle?
Yes. It is a potent skin and respiratory sensitiser and one of the better-known industrial contact allergens, so contact must be prevented rather than merely limited. It is also toxic if swallowed or inhaled and very toxic to aquatic life. Control dust, use full personal protective equipment and review the current Safety Data Sheet before any handling operation.
