Toluenediamine (TDA) CAS 95-80-7

What is Toluenediamine (TDA)?

Toluenediamine sits one step upstream of a very large industry. Phosgenate it and you get toluene diisocyanate, the isocyanate behind the overwhelming majority of flexible polyurethane foam — mattresses, furniture cushioning, automotive seating, carpet underlay. Alkoxylate it instead and you get an aromatic amine-initiated polyol, the backbone of rigid polyurethane and polyisocyanurate insulation. Two divergent routes, one feedstock, and both at a scale measured in millions of tonnes a year.

Commercial TDA is not a single compound but a mixture of isomers, and the ratio is part of the specification rather than an impurity profile. The dinitrotoluene from which it is made nitrates predominantly to the 2,4- and 2,6-positions, and the resulting diamine is sold at roughly 80:20 or 65:35 in those two. The ratio carries right through to the finished isocyanate — TDI 80/20 and TDI 65/35 are both standard commercial grades — and it matters downstream because the 2,6-isomer's two amine groups are symmetrically placed and sterically similar, while the 2,4-isomer has one much more reactive position than the other. That asymmetry gives foam formulators a reactivity profile they can control, and it is why the ratio is specified rather than optimised to a single value.

The ortho isomers — 2,3- and 3,4-TDA — are present in small quantities and are generally undesirable: they behave differently in phosgenation and can contribute colour and by-products. Their level, along with residual nitro and amino-nitro compounds from incomplete hydrogenation, is what separates a TDI-grade material from an ordinary one. Phosgenation is unforgiving of impurities, so purity requirements here are set by the downstream process rather than by the diamine's own stability.

TDA carries a carcinogen classification, is prohibited in cosmetic products, and is restricted as a releasable aromatic amine in textile and leather articles under several regulatory regimes. In practice almost all of it is consumed as an isolated intermediate inside integrated chemical plants, which is both why the volumes are enormous and why the substance is largely invisible outside them. Chelora supplies TDA on that basis — to industrial users with the handling infrastructure and regulatory position in place, against a written end-use declaration.

What TDI and polyol producers specify

• Controlled isomer ratio 80:20 or 65:35 held to a tight band, because the ratio passes straight through to the isocyanate grade and the foam's reactivity profile.
• Low ortho isomers 2,3- and 3,4-TDA controlled, since they phosgenate differently and contribute colour and by-products.
• Low residual nitro compounds Incomplete hydrogenation leaves nitro and amino-nitro species that are a liability in phosgenation. Monitored on every batch.
• Low water Phosgene and water are an expensive combination. Moisture is controlled at the point of fill and protected in transit.
• Colour control Aromatic diamines darken readily; colour is reported because it tracks oxidative and thermal history.
• Molten logistics that work Heated isotanks and tankers with temperature records, so material arrives liquid, nitrogen-blanketed and ready to charge.

How TDA is Manufactured

TDA is made by hydrogenating dinitrotoluene. The isomer distribution is set in the nitration step that precedes it and is carried through essentially unchanged, which is why the ratio is a feedstock property rather than something adjusted at the diamine stage.

• Nitration of toluene Toluene is nitrated to dinitrotoluene. The methyl group directs substitution so that the 2,4- and 2,6-isomers dominate, in the ratio that will define the final product grade.
• Catalytic hydrogenation Dinitrotoluene is hydrogenated over a supported metal catalyst, converting both nitro groups to primary amines. The reaction is strongly exothermic and heat removal governs the plant design.
• Catalyst separation and dehydration Catalyst is recovered and the water of reaction removed. Residual water is a direct liability in downstream phosgenation, so this step is taken further than the diamine itself requires.
• Purification Distillation removes light ends, ortho isomals, residual nitro and amino-nitro species and high boilers. TDI-grade purity is set by phosgenation tolerance rather than by the diamine's own requirements.
• Molten filling or solidification Product is filled molten into heated tanks for integrated isocyanate users, or flaked and bagged for polyol and specialty consumers.

Typical Commercial Specification

Typical TDI-grade specification for 80:20 material. Verify against your current COA before relying on these figures, and tell us if your phosgenation or alkoxylation process needs anything tighter.

Physical & Chemical Properties

Reactivity in practice

TDA behaves as a reactive primary aromatic diamine. Its two principal industrial reactions define the two markets it serves, and its sensitivity to air and moisture defines how it has to be stored.

• Phosgenation to TDI Both amine groups convert to isocyanate, giving toluene diisocyanate. The reaction is intolerant of water and of nitro-containing impurities, which is what drives the purity specification.
• Alkoxylation to aromatic polyols Reaction with propylene or ethylene oxide gives amine-initiated polyols used in rigid insulation foam, where the aromatic ring contributes rigidity and fire performance.
• Oxidises and darkens readily Aromatic diamines are air-sensitive. Nitrogen blanketing in storage and transport is standard, not optional, if colour specifications are to be met.
• Reacts with acids to form salts Soluble amine salts form readily; relevant to spill neutralisation and effluent handling.
• Diazotisation chemistry The basis of its historic dye use and of the analytical methods used to detect it as a releasable amine in textile testing.
• Attacks copper and brass Use stainless steel or lined equipment for melt tanks, lines and instrumentation.

TDA Compared With Related Aromatic Amines

These three aromatic amines are grouped together here for a reason that has nothing to do with their chemistry: all carry a carcinogen classification, and for all three the regulatory position rather than the technical specification usually decides whether a given use is possible in a given market. Understanding where each one stands is a prerequisite to buying it.

Stated plainly: the technical question of which curative or feedstock performs best is often settled long before the regulatory one, and it is the regulatory answer that determines whether you can proceed. For MDA and TDA, a very large majority of global volume is consumed as an isolated intermediate within integrated isocyanate plants, where different obligations apply from those on a free-standing industrial use. For MOCA, the position in Europe is specific and restrictive. Establish where your use sits before anything else.

Industries We Supply TDA To

TDA's industrial reach is enormous but entirely indirect. Almost nobody outside an isocyanate or polyol plant handles the diamine itself; the industries below consume what is made from it.

Where TDA is Used

Two applications account for nearly all consumption, and a long tail of specialty uses accounts for the rest.

Isomer ratio and what it does downstream

In the 2,4-isomer the two amine groups sit in chemically distinct environments: one is considerably more reactive than the other. In the 2,6-isomer they are symmetric and similarly hindered. Carried through to TDI, this gives formulators a two-speed reactivity profile — the fast position builds molecular weight early, the slower one completes the network — and the 2,4 : 2,6 ratio is the dial that sets how pronounced that difference is. TDI 80/20 is the general-purpose flexible foam grade; 65/35 gives a different balance used in particular slabstock and moulded systems. Specify the ratio you need rather than accepting whatever is available, because it is not an interchangeable parameter.

Purity requirements set by phosgenation

The diamine itself is reasonably robust; the process that follows is not. Water consumes phosgene and generates hydrogen chloride and carbon dioxide. Residual nitro and amino-nitro compounds from incomplete hydrogenation give coloured and high-boiling by-products that foul equipment. Ortho isomers phosgenate to isocyanates with different reactivity that end up as off-specification material. This is why TDI-grade TDA is specified far tighter than a diamine of that structure would otherwise need, and why we report residual nitro content in ppm rather than as a pass/fail.

Molten handling and logistics

TDA melts near 99 °C as the pure 2,4-isomer and somewhat lower as a mixture, so commercial movement is in heated isotanks and tankers held molten under nitrogen, with temperature records available on arrival. Nitrogen blanketing is what keeps colour inside specification; air exposure at temperature darkens the material quickly and the change is not reversible. Hold temperatures at the lower end of the workable range, keep residence short, and use stainless or lined surfaces throughout — copper and brass are ruled out. Where molten logistics are not practical, flaked and bagged material is available, accepting the melting step at the customer's end.

Quality Control & Testing

Every lot is released against a batch-specific Certificate of Analysis. The methods behind the numbers are standard across the industry, and we are happy to share them or to work to your own in-house test protocol.

• Isomer distribution by GC 2,4-, 2,6- and ortho isomers quantified on every batch. The measured split is reported, not the nominal grade.
• Total assay by GC Confirms purity against the TDI-grade specification.
• Residual nitro compounds Measured in ppm by GC or HPLC. The hydrogenation completeness check that phosgenation depends on.
• Water by Karl Fischer Controlled at fill and protected in transit, because water and phosgene are an expensive combination.
• Colour on the melt Reported in APHA. Tracks oxidative and thermal history through storage and shipment.
• Iron and ash Trace metals catalyse darkening and can affect downstream catalysis. Held low and reported.
• Melting range Confirms identity and consistency of the isomer mixture.
• Retained samples and temperature records Held against every batch and every molten movement, so a downstream problem can be traced or ruled out.

Common Process Problems & Likely Causes

Problems attributed to TDA usually come down to isomer ratio, moisture, residual nitro content or thermal history in transit. The sequence below is how we work through them.

Packaging, Storage & Shipping

• Heated isotanks Molten TDA under nitrogen with temperature logging, the standard mode for integrated isocyanate plants.
• Heated road and rail tankers For regional delivery to plants with molten receipt facilities.
• Drums Solid flake or cast material for smaller polyol and specialty users.
• Lined bags Flaked material in moisture-barrier liners where volumes do not justify molten logistics.
• Storage Molten under nitrogen at the lowest workable temperature, or solid in sealed packaging in a cool, dry, dark place away from oxidising agents.
• Materials of construction Stainless steel or suitably lined vessels and lines. No copper, brass or bronze anywhere in the system.

Hazards & Safe Handling

TDA is classified as a carcinogen, is harmful by several routes and is absorbed through skin. The controls below reflect how the substance is handled in the integrated industrial settings where it is actually used. Always work from the current Safety Data Sheet and your own national occupational exposure requirements.

• Carcinogen classification. This substance carries a carcinogen classification in major regulatory systems. That is the governing fact in any risk assessment and it should shape plant design, exposure control, worker selection and health surveillance — not sit as a line on a label. Exposure should be reduced to as low as reasonably practicable rather than merely kept below a limit value.
• Closed handling. Open handling of a carcinogen-classified powder is difficult to justify where a closed or enclosed alternative exists. Bulk bags with enclosed discharge, pre-weighed sachets that go into the reactor unopened, and melt-and-pump systems are the normal approaches.
• Health surveillance and biological monitoring. Most jurisdictions require health surveillance for workers exposed to carcinogen-classified aromatic amines. For some, biological monitoring of the substance or its metabolites in urine is established practice and gives a far better picture of real uptake than air sampling alone.
• Skin absorption. Aromatic amines are commonly absorbed through intact skin, which means air monitoring can look acceptable while uptake continues. Glove selection with a verified breakthrough time, and procedures that treat any skin contact as a reportable event, matter more than ventilation alone.
• PPE. Chemical-resistant gloves of a verified material, eye protection, protective clothing that is removed and laundered on site, and respiratory protection appropriate to a carcinogen-classified dust or vapour.
• Hot and molten material. Melting raises vapour and mist exposure substantially and adds thermal burn risk. Treat heated handling as a distinct operation with its own assessment and controls.
• Environment. Harmful or toxic to aquatic life. Do not allow to enter drains, surface water or groundwater. Dispose through a licensed chemical waste contractor, and treat contaminated PPE and packaging as hazardous waste.
• First aid. Remove from exposure, remove contaminated clothing, wash skin thoroughly with soap and water, flush eyes for at least 15 minutes, and seek medical attention with the SDS to hand. Record any exposure incident — it may be relevant to long-term health surveillance.

Regulatory & Compliance Notes

TDA's regulatory position differs from MDA's and MOCA's in an important way: it is not generally on an authorisation list, but it carries specific prohibitions in consumer applications. The notes below are orientation, not a compliance opinion.

• Carcinogen classification TDA is classified as a Category 1B carcinogen in the EU CLP system and similarly under other GHS implementations. This triggers occupational carcinogen controls, health surveillance and exposure-record obligations at the user's site.
• Prohibited in cosmetics 2,4-Toluenediamine is on the EU cosmetics prohibited-substances list and equivalent lists elsewhere. It has no permitted use in cosmetic products, including hair dyes, in those markets.
• Restricted as a releasable amine in textiles and leather TDA is one of the aromatic amines whose release from azo colourants in textile and leather articles is restricted under REACH Annex XVII and comparable national rules, with specified detection limits and test methods.
• Isolated intermediate use Almost all TDA is consumed as an isolated intermediate inside integrated plants, converted to TDI or polyol without leaving the site. That use pattern is central to how the substance is regulated and supplied.
• Transport classification UN 1709, Toluenediamine, solid, Class 6.1, Packing Group III. Molten shipments fall additionally under elevated-temperature provisions. Confirm the current entry on the SDS before each shipment.
• End-use declaration We ask for a written statement of intended use before despatch, and we supply TDA only to industrial users with appropriate handling infrastructure. This is a condition of supply.

We Supply TDA Worldwide

Chelora Chemicals is a supplier and export partner, not a single-plant trader. We ship Toluenediamine (TDA) from India to customers across Asia, Europe, the Middle East, Africa, and North and South America, handling the export documentation, dangerous-goods paperwork 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 Indian ports arranged where it suits the routing.
• Documentation. Commercial invoice, packing list, certificate of origin, COA, SDS and dangerous-goods declaration issued as a complete set.
• Flexible volumes. A single drum for laboratory qualification, through LCL consolidations, up to repeat full loads on a supply contract.
• Supply continuity. Because we are independent of any one producer, a plant turnaround or a shipping disruption at one source does not have to become your stock-out.

Buying TDA from Chelora

TDA is a large-volume, logistics-intensive intermediate. The useful conversation covers grade, delivery mode and continuity rather than price alone.

• Specify the isomer ratio 80:20, 65:35 or something else. It is a sourcing decision set in nitration upstream, so tell us the target early rather than treating it as adjustable.
• Tell us the downstream process Phosgenation and alkoxylation impose different purity priorities. Knowing which you run lets us match grade and specification rather than quoting a generic one.
• Settle the delivery mode Heated isotank, tanker, drum or bag. Molten receipt needs tank heating, nitrogen and unloading arrangements confirmed before the first shipment.
• End-use documentation Written statement of intended use and your occupational control position, before despatch.
• Contract volumes with scheduled call-off TDA is not a product to buy spot if you are running a continuous plant. We work on contracts with agreed call-off schedules and inventory cover.
• Full batch documentation COA with measured isomer split, assay, residual nitro, water and colour, plus SDS, TDS and molten temperature records with every consignment.

How ordering works

• Send the enquiry. Product, grade or specification, quantity, destination port and the Incoterm you buy on. If you have a spec sheet, attach it — it saves a round trip.
• We quote. Price, lead time, packing and a sample COA, normally within one working day.
• Sample and qualify. For first orders or critical applications, we send a trial quantity so your lab can sign off before you commit.
• Confirm the order. Proforma invoice issued; payment terms agreed against the volume and the relationship.
• Production and QC. Material allocated and released against a batch-specific COA, with a pre-shipment sample where the application calls for it.
• Ship and document. Packed, labelled and loaded with the full export and dangerous-goods document set, and tracked through to arrival.

Related Amines & Intermediates

Other aromatic amines and the polyurethane and epoxy intermediates we supply alongside them.