4,4′-Methylenebis(2-chloroaniline) · MbOCA · DACPM · Prills, pastilles and molten supply
MOCA is the chlorinated cousin of MDA and the curative that built the cast polyurethane elastomer industry. Two chlorine atoms sitting ortho to the amino groups pull electron density off the nitrogens, slowing the reaction with isocyanate just enough to give a workable pot life — long enough to mix, degas and pour a large roller, short enough to demould the same shift. The result is an elastomer with load-bearing capacity, tear strength and dynamic performance that few alternatives match. It is also a category 1B carcinogen on the REACH Authorisation List, supplied only against a confirmed end use. Chelora Amines supplies MOCA as prills, pastilles and molten, with a batch-wise COA and SDS on every dispatch.
156.14 + 12.10 + 70.90 + 28.01 = 267.15 g/mol
MOCA — properly 4,4′-methylenebis(2-chloroaniline), and written MBOCA or MbOCA depending on who is writing — is a chlorinated aromatic diamine. Structurally it is 4,4′-MDA with a chlorine atom added to each ring in the position next to the amino group. It is a tan to light brown solid supplied as prills, pastilles or flakes, melting at about 100–110 °C and handled molten in production.
Its single large application is the curing of isocyanate-terminated polyurethane prepolymers to make cast elastomers. Those two ortho chlorines are the whole point: an unsubstituted aromatic diamine reacts with a TDI prepolymer far too fast to pour, while MOCA gives a workable several-minute pot life at mixing temperature and still demoulds within the hour. The elastomers that result carry load, resist tearing and survive repeated flexing better than almost anything else a casting house can make.
MOCA carries a serious health classification. It is a category 1B carcinogen, classified by IARC as carcinogenic to humans with the bladder as the target organ, and it is listed on the REACH Candidate List and Authorisation List. Several jurisdictions require biological monitoring of urine for exposed workers. It is supplied here for industrial use under closed handling, with end-use and regulatory checks before an order is accepted.
| Chemical name | 4,4′-Methylenebis(2-chloroaniline) |
| Common synonyms | MOCA, MBOCA, MbOCA, DACPM, methylene bis-orthochloroaniline, bis-amine curative |
| CAS number | 101-14-4 |
| EC / EINECS number | 202-918-9 |
| HS / HSN code | 2921 59 (other aromatic polyamines; HSN 2921 59 on Indian invoices) |
| Molecular formula | C₁₃H₁₂Cl₂N₂ ((H₂N·ClC₆H₃)₂CH₂) |
| Molecular weight | 267.15 g/mol |
| Appearance | Tan to light brown prills, pastilles or flakes; amber liquid when molten |
| Odour | Faint amine-like odour |
| Melting point | About 100–110 °C |
| Boiling point | About 379 °C at atmospheric pressure |
| Density | About 1.44 g/cm³ at 20 °C |
| Solubility in water | Very low — about 0.01 g/L; soluble in acetone, esters and chlorinated solvents |
| Amine equivalent weight | 133.6 (one per amino group; AHEW about 66.8 on four active hydrogens) |
| Melt handling temperature | Typically 110–120 °C, degassed under vacuum |
| Flash point | About 230 °C (closed cup) |
| UN number | UN 2811, Toxic solid, organic, n.o.s. (4,4′-methylenebis(2-chloroaniline)), Class 6.1, Packing Group III |
| Regulatory status | CLP Carc. 1B; IARC Group 1; REACH Candidate List (SVHC) and Annex XIV authorisation list |
Figures are typical values for the technical grade. The values for the material you order are stated on its Certificate of Analysis and Safety Data Sheet.
Everything MOCA does commercially follows from one fact: the chlorine atoms make the amino groups less nucleophilic, so every reaction is slower and more controllable than it would be with an unsubstituted diamine.
Each amino group adds across an isocyanate group to give a substituted urea. Two amines per molecule means MOCA links prepolymer chains and builds the hard-segment network that carries load in the finished elastomer.
R–NCO + H₂N–Ar → R–NH–CO–NH–ArThe ortho chlorines withdraw electron density and sterically crowd the nitrogen. The reaction with isocyanate is slowed by roughly an order of magnitude against an unsubstituted diamine — the difference between a pourable mix and a solid lump.
slower k than MDA or MPDADosing follows the prepolymer's free NCO content. At full theory, parts of MOCA per hundred parts of prepolymer are about 3.18 times the %NCO; most shops run 90–95% of theory to tune hardness and cure.
phr ≈ 3.18 × %NCO × 0.95Melted at 110–120 °C and vacuum-degassed before use. Supercooling is common, so remelt cycles and hold times are controlled to keep the curative clear and free of crystals at the mixhead.
melt 110–120 °C, degas under vacuumMoisture in the prepolymer or the curative competes for isocyanate and generates carbon dioxide, giving voids. Both components are kept dry and degassed, which is why moisture appears on every MOCA specification.
R–NCO + H₂O → R–NH₂ + CO₂Used occasionally as an epoxy hardener where a long open time is wanted. With four active hydrogens and an AHEW of about 66.8, the mix ratio is higher than MDA and the cure noticeably slower.
AHEW ≈ 66.8 · 4 active HReacts with mineral and organic acids to give salts. The chlorines make MOCA a markedly weaker base than MDA, so salt formation needs stronger acid and is less useful as a handling route.
MOCA + 2 HCl → dihydrochlorideLike all aromatic amines MOCA darkens on exposure to air and light. Colour has little effect on cure but carries into pale-pigmented parts, so packs are kept sealed and melt is not held hot longer than needed.
air + light → darkeningA process question, not just a purchase. MOCA performance depends as much on melt discipline, mix ratio and mould temperature as on the curative itself. Tell us your prepolymer type and free NCO, target hardness and part size, and we will match the grade and form to the way your shop actually runs.
Discuss your processMOCA is made the same way as MDA, but starting from o-chloroaniline instead of aniline. The chlorine is already on the ring before the molecule is assembled — it is not added afterwards.
o-Chloroaniline and aqueous formaldehyde are specified. Feedstock purity controls both the isomer profile and the colour of the finished curative.
o-Chloroaniline and formaldehyde combine under acid catalysis, and the intermediate rearranges to the methylene-bridged diamine skeleton.
The acid catalyst is neutralised, the organic phase separated and washed, and excess o-chloroaniline recovered for recycle.
Distillation and crystallisation remove isomers, residual o-chloroaniline and higher oligomers, bringing the assay above 99%.
Molten product is prilled or pastillated in a contained plant and bagged, or loaded hot into heated vessels for molten delivery.
Prills and pastilles melt faster and more evenly than coarse flake or lump, which shortens the time the curative spends hot and reduces both colour pickup and the chance of a crystal reaching the mixhead. Free-flowing prills also charge more cleanly into a melt pot, which is an exposure-control advantage as much as a convenience. Molten delivery removes the melting step entirely and suits continuous casting operations with a heated receiving vessel and metered dosing — the arrangement that keeps operators furthest from the material. Flake and lump remain available for shops running small batches, but if you are specifying for a new line, start with prills.
Residual o-chloroaniline is the impurity that matters most. It is volatile, which means it contributes disproportionately to vapour exposure when the curative is melted, and it is monofunctional, which means it caps a growing chain instead of extending it and quietly costs you crosslink density. A good technical grade holds it to 0.3% or below, and shops running pale or thin-section parts often ask for tighter. Residual moisture is the other number to watch: water competes for isocyanate and gives carbon dioxide, and the resulting voids will not polish out of a roller face.
Assay, free o-chloroaniline and moisture are the three numbers that decide whether a batch runs cleanly. The form you take decides how your operators handle it.
Free-flowing prills or pastilles for cast polyurethane elastomers — the working grade for rollers, wheels, screens and liners.
Tighter colour and impurity limits for light-pigmented and thin-section castings where discolouration shows on the finished part.
Same specification delivered hot in heated vessels for continuous casters with contained melt receipt and metered dosing.
| Parameter | Test method | Typical specification |
|---|---|---|
| Appearance | Visual | Tan to light brown prills or pastilles |
| Assay | GC | ≥ 99.0% w/w |
| Free o-chloroaniline | GC | ≤ 0.3% w/w |
| Melting range | Capillary | 99 – 110 °C |
| Amine equivalent weight | Titration | 133 – 137 |
| Moisture | Karl Fischer | ≤ 0.2% w/w |
| Colour, molten (Gardner) | Gardner | ≤ 10 |
| Ash | Gravimetric | ≤ 0.1% w/w |
| Insolubles | Filtration | Substantially free |
Indicative specification for planning. The controlling document is the Certificate of Analysis issued for your batch. If your parts need a tighter colour or free-amine limit, say so at enquiry stage.
Almost all of it goes into one place — cast polyurethane elastomers — but that one place covers a remarkable spread of industries.
Print, paper, steel, textile and film-converting rollers, where the coating has to carry nip load, resist abrasion and hold a ground finish shift after shift.
Forklift and pallet-truck tyres, trolley and conveyor wheels, scaffold castors — parts that take static load without flat-spotting.
Screen panels, hydrocyclone liners, chute and pipe linings, flotation components — wear parts that outlast rubber and steel in abrasive slurry.
Hydraulic seals, suspension bushes, wear rings and vibration mounts where high modulus and low compression set are the design requirement.
Pigs, swab cups, packer elements and stripper rubbers that have to survive pressure, abrasion and hydrocarbon contact.
Cast scrapers, skirting, timing belt profiles, drive and pinch components for bulk handling and food-adjacent conveying lines.
Occasional use as a slow aromatic epoxy hardener where a long open time matters more than cure speed, and in some adhesive and potting systems.
A standard curative in elastomer formulation work, cure kinetics studies and as an analytical reference material under laboratory containment.
Most casting houses evaluate a shortlist. Here is how MOCA compares with the curatives buyers usually put beside it.
| Curative | Character | Where it is chosen |
|---|---|---|
| MOCA (CAS 101-14-4) | Solid, melted before use; moderate pot life; benchmark mechanical properties | The reference curative for TDI prepolymer casting across rollers, wheels and wear parts |
| DMTDA — dimethylthiotoluenediamine | Liquid at room temperature; no melt pot needed | Shops wanting to remove a melting step and a solid handling exposure |
| DETDA — diethyltoluenediamine | Liquid, very fast; usually blended | RIM, spray polyurea and fast-demould systems rather than open casting |
| MCDEA | Solid; long pot life, lighter colour | Pale and thick-section parts where working time is the constraint |
| HQEE — hydroquinone bis(2-hydroxyethyl) ether | Diol rather than diamine; slower, ester-type hard segment | High-temperature and dynamic parts where a diol hard segment performs better |
| 1,4-Butanediol | Liquid diol; simple and cheap | MDI prepolymer systems and general-purpose parts without MOCA-level mechanicals |
| 4,4′-MDA | Unchlorinated analogue; far too fast for open casting | Epoxy curing, polyimides and conversion to MDI rather than elastomer casting |
A curative change is never a drop-in. Mix ratio, melt temperature, pot life, demould time and post-cure all move together, and the mechanical properties of the finished part move with them. If you are evaluating a switch away from MOCA — whether for regulatory, exposure or supply reasons — plan a proper trial programme rather than a substitution on paper.
Talk through the optionsEvery 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 and designed to be opened once.
PE-lined, heat-sealed bags of prills or pastilles, or lined cartons where a rigid pack suits your melt-pot charging. Palletised and shrink-wrapped.
Lined fibre or steel drums and lined FIBCs with a discharge spout, for contained charging into a melt vessel with minimal dust.
Molten delivery at 110–120 °C for continuous casters; 500 g to 1 kg sealed containers for laboratory and trial use under containment.
Pack choice for MOCA is an exposure-control decision, not just a logistics one. Tell us how the curative will be charged — manual addition to a melt pot, bulk-bag discharge or molten transfer — and we will recommend the pack that keeps your operators furthest from the material. 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 supplyMOCA may cause cancer, is harmful if swallowed, and is absorbed through intact skin — skin is in practice the dominant exposure route in a casting shop. Several jurisdictions impose substance-specific occupational standards, and a number require biological monitoring of workers' urine. 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. MOCA 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. Other jurisdictions apply substance-specific occupational standards, and several operate mandatory or strongly recommended urinary biological monitoring programmes for exposed workers. 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 | Tan to light brown prills | Complies |
| Assay (GC) | ≥ 99.0% | Complies |
| Free o-chloroaniline | ≤ 0.3% | Complies |
| Melting range | 99 – 110 °C | Complies |
| Amine equivalent weight | 133 – 137 | Complies |
| Moisture (KF) | ≤ 0.2% | Complies |
MOCA is checked before dispatch. Each consignment leaves with the paperwork your QC, EHS, stores and accounts teams need on day one — including the equivalent weight figure that sets your mix ratio.
Five steps for a first order of MOCA. The end-use and regulatory check in step two is specific to this product.
Grade, form, quantity, your prepolymer type and free NCO, target hardness, how the curative 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 — assay, free o-chloroaniline, equivalent weight, melting range and moisture — and the COA and SDS are prepared.
Sealed, labelled packs move under dangerous goods documentation, or a heated vessel 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 MOCA usually source these from the same list. See the full product range for the complete picture.
Short answers to what purchase, lab, EHS and production 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.