N-Phenylaniline · Anilinobenzene · Flakes, crystals and molten supply
Diphenylamine is a secondary aromatic amine — two benzene rings sharing a single nitrogen. Flanked by two electron-withdrawing rings, that nitrogen is a very poor base but an excellent hydrogen donor: it gives up its N–H hydrogen to peroxy radicals and stops oxidation chains before they propagate. Almost everything DPA is used for follows from that one property — antioxidants for rubber and lubricating oils, antiozonants for tyre compounds, stabilisers for nitrocellulose, and scald control on stored apples and pears. Chelora Amines supplies DPA worldwide in flake, crystal and molten form, with a batch-wise COA and SDS on every dispatch.
144.13 + 11.08 + 14.01 = 169.22 g/mol
Diphenylamine, also called N-phenylaniline or anilinobenzene, is a secondary aromatic amine made of two phenyl rings bonded to a single nitrogen. It is a white to light amber crystalline solid with a faintly floral odour, melting at 52–54 °C — low enough that it is routinely handled molten in bulk, and low enough that flake product needs a cool store in a hot climate.
Chemically, DPA is defined by what its nitrogen will not do and what its N–H will. Two conjugated rings strip electron density from the nitrogen, leaving a very weak base that will not form stable salts with ordinary acids. The same conjugation stabilises the aminyl radical formed when the N–H hydrogen is abstracted, so DPA readily donates that hydrogen to a peroxy radical and halts an oxidation chain. That is the mechanism behind every aminic antioxidant on the market.
Very little DPA is used as DPA. Most of it is alkylated, aminated or condensed into a derivative — octylated and styrenated diphenylamines for lubricants, 4-aminodiphenylamine on the way to the 6PPD antiozonants used in tyres, and acetone–diphenylamine condensates for general rubber work. Its two direct uses are nitrocellulose stabilisation and, where it remains registered, post-harvest scald control on apples and pears.
| Chemical name | Diphenylamine (N-phenylaniline) |
| Common synonyms | DPA, N-phenylaniline, anilinobenzene, N-phenylbenzenamine, big-dipper crystals |
| CAS number | 122-39-4 |
| EC / EINECS number | 204-539-4 |
| HS / HSN code | 2921 44 (diphenylamine and its derivatives; HSN 2921 44 on Indian invoices) |
| Molecular formula | C₁₂H₁₁N ((C₆H₅)₂NH) |
| Molecular weight | 169.22 g/mol |
| Appearance | White to light amber crystalline flakes or crystals; darkens in light |
| Odour | Characteristic faint floral odour |
| Melting point | 52–54 °C |
| Boiling point | About 302 °C at atmospheric pressure |
| Density | About 1.16 g/cm³ at 20 °C |
| Solubility in water | About 0.3 g/L at 20 °C — practically insoluble; soluble in alcohol, ether, benzene and acetone |
| Basicity | pKa of the conjugate acid about 0.8 — a very weak base |
| Flash point | About 153 °C (closed cup) |
| Autoignition temperature | About 630 °C |
| UN number | UN 3077, Environmentally hazardous substance, solid, n.o.s. (diphenylamine), Class 9, Packing Group III |
Figures are typical values for the technical grade. Laboratory grade values may differ. All values for the material you order are stated on its Certificate of Analysis and Safety Data Sheet.
One N–H group and two activated rings. The N–H hydrogen is what makes DPA an antioxidant; the ring positions are what make it an intermediate.
The core function. DPA donates its N–H hydrogen to a peroxy radical, terminating the oxidation chain and leaving a resonance-stabilised aminyl radical that does not propagate.
ROO• + Ph₂NH → ROOH + Ph₂N•Friedel–Crafts alkylation with diisobutylene or styrene gives octylated and styrenated diphenylamines — liquid or low-melting aminic antioxidants that disperse easily in oils and polymers.
Ph₂NH + alkene → alkylated DPA4-Aminodiphenylamine is reductively alkylated with methyl isobutyl ketone to give 6PPD, and with acetone to give IPPD — the p-phenylenediamine antiozonants used in tyre compounds.
4-ADPA + MIBK + H₂ → 6PPDDPA scavenges the nitrogen oxides released as nitrocellulose slowly decomposes, preventing an autocatalytic loop. The classical stabiliser role, still specified in propellant formulations.
Ph₂NH + NOₓ → nitroso / nitro DPAAcid-catalysed condensation with acetone gives acetone–diphenylamine condensate, a long-established general-purpose antioxidant for rubber, latex and adhesives.
Ph₂NH + (CH₃)₂CO → condensateReaction with nitrous acid gives N-nitrosodiphenylamine, formerly a standard vulcanisation retarder, and the basis of the classical nitrite and nitrate spot test.
Ph₂NH + HNO₂ → Ph₂N–NO + H₂OIn strong sulfuric acid DPA oxidises to an intensely coloured violet-blue species. That reaction is the basis of the classical nitrate test and of DPA's use as a redox indicator in iron(II) titrations.
deep blue on oxidationAt high temperature over a catalyst, DPA cyclises with loss of hydrogen to carbazole — an intermediate for dyes, pigments and electroactive polymers.
Ph₂NH → carbazole + H₂Process notes. DPA darkens on exposure to light and air through surface oxidation; keep flake product in closed, opaque bags and keep molten material under nitrogen. Molten handling lines should be traced and held above about 60 °C to avoid solidification in dead legs. DPA is toxic by ingestion and skin contact and is very toxic to aquatic life — bunding and drain protection are essential wherever it is stored or melted. Avoid contact with strong oxidising agents.
Discuss your processCommercial DPA is made by the thermal deamination of aniline: two aniline molecules condense over an acidic catalyst, giving diphenylamine and ammonia, which is recovered and recycled.
Aniline of 99.5% or better is specified, with controls on colour and residual nitrobenzene that carry into the product.
Aniline is passed over an acidic catalyst at elevated temperature; two molecules combine with loss of ammonia to form diphenylamine.
The ammonia released is scrubbed and recovered. Unconverted aniline is separated and returned to the reactor feed.
Vacuum distillation and crystallisation remove residual aniline, triphenylamine and carbazole, bringing purity above 99%.
Molten product is flaked on a chilled belt and bagged, or loaded hot into heated tankers for customers who take it molten.
Flake is the default: easy to store, easy to weigh out, and suitable for batch addition into rubber, resin and lubricant formulations. Molten supply in heated road or ISO tankers suits continuous consumers — typically alkylation plants and antioxidant producers — because it removes a melting step, eliminates dust exposure and allows metered dosing. The trade-off is infrastructure: a heated receiving tank, traced lines held above about 60 °C, and a nitrogen blanket to protect colour. Tell us your consumption rate at enquiry stage and we will advise which form actually costs you less.
Two specification points carry most of the commercial weight. Residual aniline matters because it is more toxic and more volatile than DPA and can cause odour and compliance problems downstream; the technical grade holds it below about 0.3%. Colour matters because DPA darkens on light exposure, and alkylated derivatives inherit that colour. In closed, opaque packaging stored cool and dry, flake DPA normally holds specification for twenty-four months from manufacture. Molten storage should be kept under nitrogen and not held hot for extended periods.
The right grade depends on whether residual aniline and colour carry through into your finished product, and on whether you can take molten material.
The standard grade in flake or crystal form for rubber chemicals, lubricant antioxidants, resin stabilisers and intermediate synthesis.
Same specification, delivered hot in heated road or ISO tankers for continuous consumers with a melt-receiving tank.
Highest purity for analytical use, including redox indicator and nitrate spot-test work. Packed in amber bottles.
| Parameter | Test method | Typical specification |
|---|---|---|
| Appearance | Visual | White to light amber flakes or crystals |
| Purity (diphenylamine) | GC | ≥ 99.0% w/w |
| Solidification point | Crystallising point | ≥ 52.0 °C |
| Free aniline | GC | ≤ 0.3% w/w |
| Colour, molten (APHA) | APHA / Hazen | ≤ 100 |
| Moisture | Karl Fischer | ≤ 0.2% w/w |
| Ash | Gravimetric | ≤ 0.05% w/w |
| Insoluble matter in methanol | Gravimetric | ≤ 0.05% w/w |
Indicative specification for planning. The controlling document is the Certificate of Analysis issued for your batch. If your process needs a tighter free-aniline or colour limit, say so at enquiry stage.
DPA is an anti-ageing chemical. Rubber, lubricating oil, propellant and stored fruit all have the same problem — slow oxidation — and DPA chemistry is the answer in all four.
The largest outlet. Through 4-aminodiphenylamine, DPA feeds the 6PPD and IPPD antiozonants that protect tyre sidewalls, and directly gives the acetone–DPA condensates used across technical rubber goods.
Octylated and styrenated diphenylamines are the standard aminic antioxidants in engine oils, turbine and hydraulic fluids, greases and compressor oils — effective at temperatures where phenolics have faded.
Added to nitrocellulose-based formulations to scavenge nitrogen oxides released during slow decomposition, preventing an autocatalytic cycle and extending safe storage life.
Where it holds a current registration, DPA is applied as a post-harvest treatment on apples and pears to prevent superficial scald during long cold storage. Registration status varies by market.
A building block for carbazole, acridine and triarylmethane chemistry, and for a range of intermediates used in dyes, pigments and electroactive materials.
Used in polyurethane, polyamide and adhesive systems where thermal and oxidative ageing has to be controlled, and as a modifier in phenolic resin formulations.
The classical redox indicator for iron(II) titrations and the reagent behind the diphenylamine spot test for nitrates and nitrites in soil, water and forensic work.
An intermediate in a number of veterinary actives and specialty fine chemicals, and a standard starting material in heterocyclic synthesis research.
From tyre sidewalls to turbine oil — the value chain downstream of DPA.
| Derivative | Made by | End use |
|---|---|---|
| Octylated diphenylamine (ODPA) | Alkylation with diisobutylene | Lubricant, grease and rubber antioxidant |
| Styrenated diphenylamine (SDPA) | Alkylation with styrene | Rubber, latex and adhesive antioxidant |
| 4-Aminodiphenylamine (4-ADPA) | Amination of the ring | Precursor to 6PPD and IPPD antiozonants |
| 6PPD and IPPD | Reductive alkylation of 4-ADPA | Tyre and technical rubber antiozonants |
| N-Nitrosodiphenylamine | Nitrosation | Vulcanisation retarder, analytical standard |
| Acetone–diphenylamine condensate | Acid-catalysed condensation with acetone | General-purpose rubber and latex antioxidant |
| Carbazole | High-temperature catalytic cyclisation | Dyes, pigments and electroactive polymers |
Every container carries the Chelora Amines label with product name, grade, net weight, batch number, manufacturing date, UN number and hazard pictograms. Bags are lined and heat-sealed to keep moisture and light out.
PE-lined, heat-sealed multiwall paper or woven bags of flake product, palletised and shrink-wrapped. The standard pack for batch consumers.
Lined FIBCs with discharge spout for high-volume flake users with bulk-bag handling. Keeps dust exposure low during charging.
Heated road and ISO tankers for continuous consumers; 100 g to 5 kg amber containers for laboratory and analytical use.
Because DPA melts at 52–54 °C, storage temperature is a real consideration in hot climates — bagged flake can soften and cake on a warehouse floor in summer. Tell us your storage conditions and consumption rate at enquiry stage and we will recommend the pack and, if it suits you better, molten delivery instead. Export consignments are packed in UN-specification packaging and shipped FOB, CIF or CFR through Nhava Sheva and Mundra.
Plan my supplyDiphenylamine is toxic if swallowed and toxic in contact with skin, may cause damage to organs through prolonged or repeated exposure, and is very toxic to aquatic life with long-lasting effects. Dust from flake handling and vapour from molten material are both exposure routes. The notes below are a summary for planning only — always work to the Safety Data Sheet supplied with your consignment and your own site risk assessment.
| Parameter | Specification | Result |
|---|---|---|
| Appearance | White to light amber flakes | Complies |
| Purity (GC) | ≥ 99.0% | Complies |
| Solidification point | ≥ 52.0 °C | Complies |
| Free aniline | ≤ 0.3% | Complies |
| Moisture (KF) | ≤ 0.2% | Complies |
| Ash | ≤ 0.05% | Complies |
Diphenylamine is checked before dispatch. Each consignment leaves with the paperwork your QC, stores and accounts teams need on day one — including the solidification point and free-aniline figures that matter downstream.
Five steps for a first order of diphenylamine.
Grade, quantity, flake or molten, pack size, free-aniline or colour limit, and your delivery location.
We confirm form and pack for your application and quote, usually within 24 hours.
The batch is tested — purity, solidification point, free aniline and moisture — and the COA, SDS and invoice details are prepared.
Bags are palletised and wrapped, or a heated tanker is loaded for molten delivery, with full transport documentation.
Material reaches your gate and repeat dispatches are scheduled to your usage and your storage temperature.
Buyers who order DPA usually source these from the same list. See the full product range for the complete picture.
Short answers to what purchase, lab and plant teams ask us most. Anything else, ask us directly.
Send the grade, form, quantity, pack size and your delivery address or destination port. We come back with a price, the documents that go with the batch and a dispatch or shipping plan, usually within 24 hours.