Para Phenylenediamine PPD · CAS 106-50-3

What is Para Phenylenediamine?

Para Phenylenediamine, also known as PPD or 1,4-phenylenediamine, is a benzene ring carrying two amine groups positioned directly opposite each other, formula C₆H₈N₂. It is supplied as a white to light pink crystalline solid that darkens to purple or brown on exposure to air and light — the same oxidation behaviour that makes it useful as a dye precursor.

Its value as an intermediate comes from having two reactive amine groups on a symmetrical ring, which lets it be oxidised in situ to form coloured compounds, or used as a building block where a 1,4-diamine linkage is the structural requirement. This is distinct from the 1,2- and 1,3-phenylenediamine isomers, which oxidise and react differently.

Commercially it is produced by the catalytic hydrogenation of para-nitroaniline, reducing the nitro group to a second amine.

Handling follows standard precautions for a reactive diamine — chemical-resistant gloves and eye protection, adequate ventilation, and storage away from incompatible materials such as strong oxidisers and strong acids. PPD is a well-documented skin sensitiser, so dermal exposure control is a central part of safe handling.

Why Para Phenylenediamine specifically

• A specific 1,4-diamine geometry. The para substitution pattern gives the oxidative colour chemistry that ortho- and meta-phenylenediamine do not replicate in the same way.
• Oxidative dye precursor. The industry-standard base for permanent hair-colour and fur-dye formulations.
• Rubber & polymer building block. A starting material for rubber-antioxidant/antiozonant and polymer-colorant intermediate routes.
• Distinct from ortho- and meta-isomers. The oxidation behaviour, colour development and reactivity differ enough from 1,2- and 1,3-phenylenediamine that they are not interchangeable in most formulations.

How Para Phenylenediamine is Manufactured

Para Phenylenediamine is produced by the catalytic hydrogenation of Para Nitro Aniline, which we also supply, reducing its nitro group to a second amine.

• Hydrogenation. Para Nitro Aniline is reduced under catalytic hydrogenation conditions, converting the nitro group to an amine.
• Workup. The crude diamine is separated from catalyst and process by-products.
• Purification. The product is purified by crystallisation to the target assay and colour specification.
• Quality release and packing. Assay, melting point and colour are confirmed against specification before the batch is packed and released, typically under inert atmosphere to limit oxidation.

Typical Commercial Specification

Figures below are representative of commercial-grade Para Phenylenediamine. Tell us your downstream route and the grade you need, and we will advise on the specification to order against.

Physical & Chemical Properties

Behaviour in the process

Para Phenylenediamine's reactivity pattern is what oxidative-dye, rubber-chemical and polymer-colorant producers are buying:

• Oxidative colour chemistry. Oxidises readily in the presence of air, peroxide or coupling agents to form coloured compounds — the basis of oxidative hair and fur dyes.
• Dual amine reactivity. Both amine groups are available for acylation, alkylation or condensation chemistry in rubber-antioxidant and polymer intermediate routes.
• Oxidative sensitivity. Darkens on prolonged exposure to air and light; store and handle accordingly.

Para Phenylenediamine and Related Diamines

Choosing between phenylenediamine isomers, or between PPD and its nitro precursor, comes down to the position of the substituents and whether the target application needs the oxidative-colour chemistry specifically.

Stated plainly: an oxidative-dye formulation built around the 1,4-diamine pattern needs this specific isomer — the ortho- and meta-phenylenediamine isomers oxidise and couple differently and are not drop-in substitutes.

Industries We Supply Para Phenylenediamine To

The same diamine feeds a hair- and fur-dye formulator, a rubber-chemical producer and a polymer-colorant manufacturer. What changes is the downstream formulation chemistry and the documentation each requires.

Where Para Phenylenediamine is Used

In downstream functionalisation

Para Phenylenediamine's two amine groups are carried through oxidative coupling, alkylation or condensation chemistry to build the target dye, rubber-chemical or colorant intermediate. The 1,4-diamine geometry gives reactivity distinct from the ortho- and meta-isomers, which is often exactly why a formulation is designed around this material specifically.

Quality Control & Testing

Every lot is released against a batch-specific Certificate of Analysis, with colour reported alongside the main assay because PPD oxidises readily and colour drift directly signals ageing or storage-related purity loss.

• Para Phenylenediamine content — by GC/HPLC assay, the primary grade measure.
• Melting point — reported because it is a sensitive indicator of purity.
• Colour — reported because oxidation darkens the material over time.

Common Process Problems & Likely Causes

Packaging, Storage & Shipping

• Standard packing. HDPE bags or fibre drums, typically 25 – 200 kg net, with larger bulk formats on contract supply.
• Oxidation protection. Store under inert gas where possible and keep containers tightly sealed to limit darkening.
• Temperature control. Store in a cool, dry, well-ventilated area away from direct sun, heat and ignition sources.
• Material compatibility. Avoid contact with strong oxidisers and strong acids.
• Transport classification. Commonly shipped under UN 1673 (Phenylenediamines, solid), Class 6.1, Packing Group III — confirm the correct entry and packing group against your own current SDS before shipping.

Hazards & Safe Handling

Para Phenylenediamine is toxic if swallowed, in contact with skin or if inhaled, and is a well-documented skin and respiratory sensitiser — repeated or prolonged skin contact can trigger allergic reactions. Standard precautions for a reactive diamine and good laboratory and plant practice apply throughout handling.

• Skin and eye contact. Chemical-resistant gloves and goggles are standard practice given PPD's sensitisation potential; rinse thoroughly with water on contact.
• Inhalation. Use adequate ventilation and dust control when handling, given the material's toxicity and sensitising properties.
• PPE. Chemical-resistant gloves, safety goggles and, where dust exposure is a concern, a suitable respirator.
• Repeated exposure. Workers with known sensitisation to aromatic amines should avoid direct contact; follow your site's occupational exposure controls.

Regulatory & Compliance Notes

Para Phenylenediamine is a registered specialty diamine, and its use in cosmetic hair-dye formulations is separately regulated in most major markets (including maximum permitted concentrations). Because obligations differ by territory and use, the notes below are orientation rather than legal advice.

• GHS classification. Classified as toxic if swallowed, in contact with skin or if inhaled, and as a skin sensitiser (Signal word: Danger); the SDS carries the full hazard statements for your grade.
• REACH and chemical inventories. Registered under EU REACH and listed on major chemical inventories.
• Cosmetic-use regulation. Where PPD is destined for hair-dye formulation, confirm the permitted concentration limits and labelling requirements in your target market.
• Dangerous goods transport. Commonly shipped under UN 1673 (Phenylenediamines), Class 6.1, Packing Group III. Confirm the correct entry and packing group with your logistics/EHS team against your current SDS before shipping.
• HS code. Commonly declared under the aromatic diamine derivatives heading; confirm the exact tariff line with your customs broker for your jurisdiction.

We Supply Para Phenylenediamine Worldwide

Chelora Chemicals is a supplier and export partner, not a single-plant trader. We ship Para Phenylenediamine from India and from partner sources to customers across Asia, Europe, the Middle East, Africa, and North and South America, handling the export documentation and freight so the material arrives ready to use.

• Incoterms. EXW, FOB, CIF, CFR and DAP quoted to suit your purchasing terms and freight arrangements.
• Ports. Regular shipments through Nhava Sheva (JNPT) and Mundra, with other ports arranged as routing allows.
• Documentation. Commercial invoice, packing list, certificate of origin, COA and SDS issued as a complete set.
• Flexible volumes. From trial quantities up to repeat bulk shipments on a supply contract.

Buying Para Phenylenediamine from Chelora

We are an independent sourcing and supply partner. For this product that means settling three things at enquiry: the purity and colour grade your application needs, the packing format, and the quantity you are buying.

• Documentation on every lot. Batch-specific COA with assay, melting point and colour grade, plus the current SDS.
• Analysis before commitment. Representative analysis shared ahead of a commercial order so your lab can qualify the material.
• Quantities. Trial quantities through to larger bulk shipments on contract supply.
• Inspection. Independent third-party inspection available at loading when the contract requires it.
• Related intermediates. Para Nitro Aniline (the nitro precursor to PPD) and other dye intermediates alongside this product from one supplier.

How ordering works

• Send the enquiry. Purity, colour grade, quantity, destination port and the Incoterm you buy on.
• We quote. Price, lead time, packing format and a sample COA, normally within one working day.
• Qualify the supply. For first orders or cosmetic-grade applications, we share the analysis so your technical team can sign off before you commit.
• Confirm the order. Proforma invoice issued; payment terms agreed against the volume and the relationship.
• Ship and document. Packed, labelled and loaded with the full export document set, and tracked through to arrival.

Related Dye & Diamine Intermediates