4,4′-Diaminodiphenylmethane · DDM · DAPM · Flakes and molten supply
4,4′-Methylenedianiline is an aromatic diamine: two aniline rings joined by a methylene bridge, each carrying a primary amino group in the para position. Four reactive N–H hydrogens on a rigid aromatic backbone make it both the principal precursor to MDI and a high-performance epoxy curing agent that gives glass transition temperatures aliphatic hardeners cannot reach. It is also a substance of very high concern — a category 1B carcinogen, on the REACH Authorisation List — and is supplied only to users with the containment and controls the material requires. Chelora Amines supplies MDA in flake and molten form, with a batch-wise COA and SDS on every dispatch.
156.14 + 14.11 + 28.01 = 198.26 g/mol
4,4′-Methylenedianiline — also called 4,4′-diaminodiphenylmethane, DDM or DAPM — is a primary aromatic diamine formed by joining two aniline molecules through a methylene bridge. The amino groups sit in the para position on each ring, which is what the "4,4′" denotes and what gives the molecule its symmetry. It is a light brown to tan solid supplied as flakes, pastilles or lumps, melting at about 90 °C and handled molten by most large consumers.
Two things define it commercially. First, it is the gateway to MDI: condensing aniline with formaldehyde gives MDA and its oligomers, and converting those amine groups to isocyanate groups gives MDI and polymeric MDI — the basis of rigid polyurethane insulation foam, binders and adhesives. Second, as an isolated pure isomer it is a high-performance epoxy curing agent, delivering glass transition temperatures, chemical resistance and electrical properties that aliphatic and cycloaliphatic hardeners cannot match.
MDA carries a serious health classification. It is a category 1B carcinogen, a suspected mutagen, a skin sensitiser and a known liver toxicant, and it is listed on the REACH Candidate List and Authorisation List. It is supplied here for industrial and professional use under closed handling, with end-use and regulatory checks before an order is accepted.
| Chemical name | 4,4′-Methylenedianiline |
| Common synonyms | MDA, DDM, DAPM, 4,4′-diaminodiphenylmethane, bis(4-aminophenyl)methane, methylenedianiline |
| CAS number | 101-77-9 |
| EC / EINECS number | 202-974-4 |
| HS / HSN code | 2921 59 (other aromatic polyamines; HSN 2921 59 on Indian invoices) |
| Molecular formula | C₁₃H₁₄N₂ ((H₂NC₆H₄)₂CH₂) |
| Molecular weight | 198.26 g/mol |
| Appearance | Light brown to tan flakes, pastilles or lumps; pale yellow liquid when molten |
| Odour | Faint amine-like odour |
| Melting point | About 90–92 °C |
| Boiling point | About 398 °C at atmospheric pressure |
| Density | About 1.06 g/cm³ |
| Solubility in water | About 1 g/L at 20 °C — slightly soluble; soluble in alcohols, acetone and most polar organics |
| Amine value | About 560–570 mg KOH/g |
| Amine hydrogen equivalent weight | About 49.6 (four active hydrogens per molecule) |
| Flash point | About 221 °C (closed cup) |
| UN number | UN 2811, Toxic solid, organic, n.o.s. (4,4′-methylenedianiline), Class 6.1, Packing Group III |
| Regulatory status | CLP Carc. 1B; REACH Candidate List (SVHC) and Annex XIV authorisation list |
Figures are typical values for the technical grade. High-purity and laboratory grade values may differ. All values for the material you order are stated on its Certificate of Analysis and Safety Data Sheet.
Two primary aromatic amines on a rigid backbone. Every amine reaction is available twice over, which is what turns MDA from a reagent into a network former.
Each N–H adds across an epoxide ring, so one MDA molecule ties four epoxy chains together. The aromatic backbone keeps the resulting network stiff, giving a high glass transition temperature and strong chemical resistance.
AHEW ≈ 49.6 · 4 active HConverting the two amino groups to isocyanate groups gives MDI and, from the oligomeric MDA fraction, polymeric MDI — by volume the overwhelming industrial outlet for this chemistry.
MDA → MDI (–NH₂ → –NCO)Reaction with aromatic dianhydrides gives poly(amic acid), which is cyclised thermally to a polyimide — the chemistry behind high-temperature films, wire enamels and composite matrices.
MDA + dianhydride → polyimideUsed as an aromatic diamine chain extender in polyurethane and polyurea prepolymer systems, giving hard segments with high modulus and heat resistance.
prepolymer–NCO + H₂N–R → ureaCondensation with dicarboxylic acids or their chlorides gives aromatic polyamides and polyamide-imides used where thermal stability is the design requirement.
H₂N–R–NH₂ + diacid → polyamideHydrogenating both aromatic rings gives 4,4′-methylenebis(cyclohexylamine), the cycloaliphatic curing agent used where UV stability and low colour matter.
MDA + 6 H₂ → PACMBoth amino groups diazotise and couple, giving bis-azo dyes and pigment intermediates — a smaller but long-established outlet.
2 × ArNH₂ → bis-diazoniumReacts with mineral and organic acids to give water-soluble salts, used in some analytical and process applications and as a route to handling MDA in solution.
MDA + 2 HCl → dihydrochlorideHandling note — read before ordering. MDA is a category 1B carcinogen and a liver toxicant, absorbed through skin as well as inhaled as dust or vapour. It should be charged in a closed system or from a melt, never as loose dust in an open workshop. Molten handling lines must be traced above about 100 °C, and both flake and molten material darken on exposure to air and light. Do not accept an MDA process design that relies on operator PPE alone — engineering containment comes first.
Discuss your processMDA is made by the acid-catalysed condensation of aniline with formaldehyde. The reaction gives a mixture of isomers and higher oligomers; whether that mixture is separated or kept intact depends on whether the destination is an epoxy hardener or an MDI plant.
Excess aniline and aqueous formaldehyde are specified, with aniline quality controlling the colour of the finished product.
Aniline and formaldehyde combine under acid catalysis to give an intermediate that rearranges to the diaminodiphenylmethane skeleton.
The acid catalyst is neutralised and the organic phase separated and washed, with excess aniline recovered and recycled.
Vacuum distillation and crystallisation isolate the 4,4′-isomer from the 2,4′ and 2,2′ isomers and the higher oligomers, giving purity above 99%.
Molten product is flaked or pastillated under nitrogen and bagged in a contained plant, or loaded hot into heated tankers for molten delivery.
Isolated 4,4′-MDA at 99% and above is what an epoxy, polyimide or polyurea formulator needs: a defined molecular weight, a known amine hydrogen equivalent weight and a predictable cure. Polymeric MDA — the uncut reaction mixture containing the 2,4′ isomer and a tail of three-ring and four-ring oligomers — is not a formulation product at all; it goes straight into MDI manufacture, where the oligomer distribution determines the functionality of the resulting polymeric MDI. If you are formulating rather than converting, specify the 4,4′-isomer content and the 2,4′ limit explicitly, because the isomer ratio shifts both the mix ratio and the cure profile.
MDA darkens steadily on exposure to air and light, moving from light tan towards brown. The change is a surface oxidation and does not affect amine value in any meaningful way, but it carries into the colour of cured epoxy systems, so colour-sensitive users should specify a Gardner limit and order against their draw-down. In sealed, opaque packaging stored cool and dry, flake MDA normally holds specification for twenty-four months from manufacture. Molten storage should be nitrogen-blanketed and not held hot for extended periods — prolonged hot storage both darkens the product and increases vapour exposure risk.
The right grade depends on whether you are formulating with a defined diamine or converting a mixture. Isomer purity, amine value and colour are the three parameters that decide it.
Isolated 4,4′-isomer in flake or pastille form for epoxy curing agents, polyimides, polyureas and specialty synthesis.
Same specification, delivered hot in heated road or ISO tankers for continuous consumers with contained melt receipt.
Highest purity for analytical, research and reference use, supplied in small sealed packs with full batch documentation.
| Parameter | Test method | Typical specification |
|---|---|---|
| Appearance | Visual | Light brown to tan flakes or pastilles |
| Purity, 4,4′-isomer | GC | ≥ 99.0% w/w |
| 2,4′-isomer | GC | ≤ 0.8% w/w |
| Free aniline | GC | ≤ 0.1% w/w |
| Melting range | Capillary | 89 – 92 °C |
| Amine value | Potentiometric titration | 560 – 570 mg KOH/g |
| Colour, molten (Gardner) | Gardner | ≤ 8 |
| Moisture | Karl Fischer | ≤ 0.2% w/w |
| Ash | 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 isomer or colour limit, say so at enquiry stage.
Two quite different worlds use MDA: the bulk polyurethane chain that converts it onwards into MDI, and the high-performance resin world that uses the pure isomer as a curing agent.
The dominant outlet by volume. MDA and its oligomers are converted to MDI, which goes into rigid insulation foam, wood binders, flexible foam, adhesives and elastomers.
The classical high-Tg hardener for filament-wound pressure vessels, aerospace and tooling laminates, electrical laminates and chemically resistant linings.
Condensed with aromatic dianhydrides to give polyimides used as magnet wire enamel, high-temperature films, adhesives and composite matrices.
An aromatic chain extender and curative for prepolymer systems, producing hard segments with high modulus, heat resistance and dynamic performance.
Used where a cured matrix must hold its properties above 150 °C — aerospace structures, pressure vessels, high-temperature tooling and electrical insulation.
An intermediate for aromatic Schiff bases, inhibitor packages and a small number of rubber processing chemicals.
Bis-diazotisation and coupling give bis-azo dyes and pigment intermediates — a long-established if smaller outlet.
A standard aromatic diamine in polymer chemistry research, cure kinetics studies and as an analytical reference material under laboratory containment.
From roof insulation panels to aerospace laminates — the value chain downstream of 4,4′-MDA.
| Derivative | Made by | End use |
|---|---|---|
| MDI and polymeric MDI | Conversion of the amino groups to isocyanate groups | Rigid and flexible polyurethane foam, binders, adhesives, elastomers |
| MDA-cured epoxy networks | Stoichiometric cure of epoxy resin at AHEW ≈ 49.6 | Aerospace laminates, filament-wound vessels, tooling, electrical laminates |
| PACM — 4,4′-methylenebis(cyclohexylamine) | Hydrogenation of both aromatic rings | Light-stable cycloaliphatic epoxy curing agent |
| H₁₂MDI | Conversion of PACM to the diisocyanate | Aliphatic isocyanate for weatherable coatings and elastomers |
| Polyimide and polyamide-imide resins | Condensation with aromatic dianhydrides | Magnet wire enamel, high-temperature films, composite matrices |
| MOCA-type elastomer curatives | Ring chlorination of the MDA backbone | Cast polyurethane elastomer curing agents |
| Bis-azo dyes and pigment intermediates | Diazotisation of both amino groups and coupling | Dyes and organic pigments |
Every container carries the Chelora Amines label with product name, grade, net weight, batch number, manufacturing date, UN number and hazard pictograms, including the health hazard pictogram. Packs are sealed under nitrogen and designed to be opened once.
PE-lined, heat-sealed bags of flake or pastille product, or lined fibre drums where a rigid pack suits your charging arrangement. Palletised and shrink-wrapped.
Lined FIBCs with a discharge spout for contained charging into a melt tank, keeping dust exposure to a minimum.
Heated road and ISO tankers at above 100 °C for continuous consumers; 100 g to 1 kg sealed containers for laboratory use under containment.
Pack choice for MDA is an exposure-control decision, not just a logistics one. Tell us how the material will be charged — manual addition, bulk-bag discharge or molten transfer — and we will recommend the pack that keeps your operators furthest from the dust. Export consignments are packed in UN-specification packaging with full dangerous goods documentation and shipped FOB, CIF or CFR through Nhava Sheva and Mundra.
Plan my supplyMDA may cause cancer, is suspected of causing genetic defects, may cause damage to the liver through prolonged or repeated exposure, may cause an allergic skin reaction, and is harmful if swallowed or inhaled. It is absorbed through intact skin. Several jurisdictions impose substance-specific occupational standards with exposure limits, medical surveillance and regulated-area requirements. The notes below are a summary for planning only — always work to the Safety Data Sheet, your own site risk assessment and the substance-specific regulations that apply where you operate.
Regulatory status. MDA is on the REACH Candidate List as a substance of very high concern and on Annex XIV, the Authorisation List, which means its use in the EU requires an authorisation or an applicable exemption. Several other jurisdictions apply substance-specific occupational standards with exposure limits, regulated areas and medical surveillance. We ask every buyer to confirm the end use and the regulatory basis for it before an order is accepted — not as a formality, but because the obligations sit with the user and we would rather establish them at enquiry stage than at the plant gate.
Confirm compliance| Parameter | Specification | Result |
|---|---|---|
| Appearance | Light brown to tan flakes | Complies |
| Purity, 4,4′-isomer (GC) | ≥ 99.0% | Complies |
| 2,4′-isomer | ≤ 0.8% | Complies |
| Melting range | 89 – 92 °C | Complies |
| Amine value | 560 – 570 mg KOH/g | Complies |
| Moisture (KF) | ≤ 0.2% | Complies |
MDA is checked before dispatch. Each consignment leaves with the paperwork your QC, EHS, stores and accounts teams need on day one — including the amine value and isomer figures that set your mix ratio.
Five steps for a first order of MDA. The end-use and regulatory check in step two is specific to this product.
Grade, quantity, flake or molten, isomer and colour limits, how the material will be charged, and your delivery location.
We confirm the intended use, the destination's regulatory position and — for EU destinations — the authorisation or exemption you are relying on.
We quote, then the batch is tested — isomer purity, amine value, melting range and moisture — and the COA and SDS are prepared.
Sealed, labelled packs move under dangerous goods documentation, or a heated tanker is loaded for molten delivery.
Material reaches your gate and repeat dispatches are scheduled to your usage, keeping stored quantities on site to a minimum.
Buyers who order MDA usually source these from the same list. See the full product range for the complete picture.
Short answers to what purchase, lab, EHS and plant teams ask us most. Anything else, ask us directly.
Send the grade, form, quantity, pack size, intended end use 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.