3,3'-Dichlorobenzidine Dihydrochloride
This dihydrochloride salt is how 3,3'-dichlorobenzidine actually moves through commerce — the free-base diamine is unstable and difficult to handle directly, so pigment plants buy the stabilised salt and liberate the reactive diamine in-process, immediately before it is diazotized and coupled into a diarylide pigment.
Chelora Chemicals supplies 3,3'-dichlorobenzidine dihydrochloride to diarylide (benzidine yellow and orange) pigment producers worldwide, in UN-approved packing, with a batch COA and GHS safety data sheet on every consignment, and treats its carcinogen classification as the defining fact of the product.
Product identity
- CAS Number
- 612-83-9
- IUPAC name
- 4-(4-Amino-3-chlorophenyl)-2-chloroaniline dihydrochloride
- Molecular formula
- C₁₂H₁₀Cl₂N₂·2HCl
- Molecular weight
- ≈ 326.02 g/mol
- EC / EINECS
- 210-323-0
- UN Number
- 3077 · Class 9
- Free base CAS
- 91-94-1 (3,3'-DCB)
- HS Code
- 2921 59*
* Confirm the exact HS heading with your customs broker, and note that several jurisdictions impose additional import controls on benzidine-class amines independent of the standard tariff classification.
What 3,3'-Dichlorobenzidine Dihydrochloride is used for
3,3'-Dichlorobenzidine dihydrochloride is a white to light-gray or tan crystalline solid, insoluble in water, that exists specifically to make the free-base diamine (3,3'-dichlorobenzidine, CAS 91-94-1) commercially handleable. The free amine itself is a gray to purple crystalline powder that is awkward to store and ship at scale; the hydrochloride salt is the stable, tradeable form.
Its essentially exclusive commercial use is as the diazo precursor in diarylide pigment manufacture — the Benzidine Yellow and Benzidine Orange pigment families (Pigment Yellow 12/13/14/17, Pigment Orange 13/34 and related Colour Index numbers) that dominate yellow and orange shades in printing inks, flexible packaging, textile printing and plastics masterbatch. The free base is liberated from the salt in a controlled reaction step, then bis-diazotized and double-coupled to build the diarylide pigment structure.
Where it sits in the benzidine-pigment family
- 3,3'-Dichlorobenzidine dihydrochloride (this product) the stabilised salt form used for transport and storage; liberates the reactive diamine in-process.
- 3,3'-Dichlorobenzidine (free base, CAS 91-94-1) the actual diazo precursor, generated from the salt immediately before diazotization — not typically stocked or shipped independently.
- Diarylide Yellow / Orange pigments the finished Colour Index pigments (PY12, PY13, PY14, PY17, PO13, PO34 and others) made by coupling the diazotized diamine with acetoacetanilide derivatives.
- Fast Bordeaux GP Base a different diazo-component chemistry entirely, used in azoic ice-color dyeing rather than pigment manufacture. See that page.
This material is sold strictly for declared, controlled industrial pigment-manufacturing use — state your end-use and intended handling protocol on every enquiry. See the full dye and pigment intermediate range.
Appearance and handling character
The material ships as a white to light-gray or pale tan crystalline solid, commercial samples sometimes showing color from trace oxidation, insoluble in water and giving a mildly acidic aqueous suspension. It is classified as a known or anticipated human carcinogen, structurally closely related to benzidine itself, and is absorbed through skin, inhalation and ingestion. The safety section below is not optional reading on this product — it should be read before any handling is planned, by every person who will touch the material.
| Parameter | Typical value |
|---|---|
| Appearance | White to light-gray/tan crystalline solid |
| Assay | 98.0% min |
| Moisture | Reported per batch |
| Residual aniline / isomer impurities | Reported per batch |
| Particle size | Reported per batch, graded on request |
Important: the figures above are indicative of commercial-grade material and are offered for planning only. The batch certificate of analysis is the governing document. Assay and residual free-base content are the figures that most affect pigment shade and consistency — tell us your target and we will quote against it.
| Property | Value |
|---|---|
| Physical state | Crystalline solid or wet paste |
| Water solubility | Poorly soluble; often supplied as a wet paste |
| Free-base melting point | ≈ 132–133 °C (91-94-1) |
| Combustibility | Combustible, poorly flammable |
| Aqueous reaction | Mildly acidic suspension |
| Environmental hazard | Hazardous to the aquatic environment |
Physical constants compiled from public reference data for CAS 612-83-9 and rounded for readability. Treat them as orientation, not as a specification.
Where our customers put this intermediate to work
This is effectively a single-purpose intermediate. Every application below is a variation on the diarylide pigment chain.
Diarylide Yellow pigment manufacture
Bis-diazotization of the liberated diamine and double coupling with acetoacetanilide derivatives gives Pigment Yellow 12, 13, 14 and 17, the dominant diarylide yellow pigments.
- Printing ink and packaging pigments
- Colour-critical specification required
- See our pigment intermediate range
Diarylide Orange pigment manufacture
The same diazotization and coupling chemistry, with different coupling components, gives Pigment Orange 13 and Pigment Orange 34.
- Printing ink and plastics masterbatch pigments
- Colour-critical specification required
- Technical desk review of your route
Plastics masterbatch colourants
Diarylide pigments made from this intermediate are widely used in polyolefin and other plastics masterbatch colouring.
- Masterbatch-grade pigment manufacture
- End-use declaration required
- Custom synthesis quantities available
Textile printing pigments
Diarylide yellow and orange pigments are used in textile printing pastes where their brightness and cost profile suit the application.
- Textile pigment manufacture
- Technical support for your route
- Full impurity profile on request
Curing agent for isocyanate-terminated resins
A documented but smaller-scale industrial use, separate from pigment chemistry, as a curing agent for certain solid urethane plastics.
- Specialty resin-curing applications
- End-use declaration required
- Ask our technical desk
Contract & scheduled supply
Pigment plants consume this intermediate on a scheduled, controlled basis under strict access protocols. We hold inventory and release it against your production calendar.
- Annual contracts with scheduled call-off
- Price held across the contract period
- Second source held in reserve
How we supply 3,3'-Dichlorobenzidine Dihydrochloride
Chelora Chemicals is a supplier and sourcing partner, not a manufacturer. On an intermediate whose entire value chain runs through a carcinogen classification, owning no plant means we can route your order to the producer whose containment, worker-exposure controls and documentation actually meet your site's import standard — not just whichever captive unit has stock.
We place your order with whichever qualified producer best matches your assay, your specification, your price point and your delivery window.
We keep a second qualified source on this line. When a plant goes down for maintenance, your order switches source rather than stalling.
- Assay and residual-impurity content confirmed before we quote. 98% min is the commercial standard — we state the exact figure on the COA, since isomer and residual-amine impurities carry into pigment shade.
- Carcinogen classification stated unambiguously, every time. Known or anticipated human carcinogen — we never soften this, and we confirm your site's controlled-substance handling protocol before the first drum moves.
- Batch COA shared before dispatch. You approve assay, moisture and particle size against your own spec while the material is still in our warehouse.
- End-use declaration required on every order. We only supply this material for declared industrial pigment-manufacturing use with appropriate engineering controls in place.
- Pre-shipment samples for qualification. New account or new source, your laboratory runs a trial before the full quantity ever moves.
- Export machinery handled in-house. UN 3077 classification, approved packing, labelling, freight booking and customs paperwork are ours to manage, alongside any destination-specific controlled-substance import permit.
Packed the way your plant receives it
Pack format drives your landed cost and your handling effort. Tell us how the material will be charged at your end and we will quote the format that suits your operation.
Lined fibre drums / bags
UN-approved lined packs for Class 9 environmentally-hazardous solids, sealed to prevent dust escape during transit and storage.
Bulk bag (FIBC) / container
Bulk packaging for established, qualified pigment-plant accounts with the containment infrastructure to receive it safely.
Trial / sample quantities
Small, DG-compliant containers dispatched only to qualified industrial accounts for process-development qualification.
Incoterms to suit you
Quoted on the Incoterm your purchasing team works to, with DG and controlled-substance documentation filed before the booking is made.
Campaign despatch
We hold contracted tonnage and release it against your pigment plant's production calendar under agreed access controls.
A classified carcinogen — controls are not optional
3,3'-Dichlorobenzidine and its salts are classified as known or anticipated human carcinogens, structurally related to benzidine. The material is a skin sensitizer, hepatotoxin and bladder/liver carcinogen in animal studies, and is very toxic to aquatic life. The summary below is orientation only — the safety data sheet supplied with your consignment is the authoritative document.
Classified hazards
H350May cause cancer.H341Suspected of causing genetic defects.H312Harmful in contact with skin.H317May cause an allergic skin reaction.H410Very toxic to aquatic life with long lasting effects.
Hazard statements reflect classifications commonly published for CAS 612-83-9 and its free base (91-94-1). NIOSH and other occupational-health authorities identify the bladder and liver as target organs based on animal carcinogenicity data, and classify this compound alongside benzidine itself as an occupational carcinogen requiring the strictest available engineering controls. Always read the SDS issued with your specific batch.
Spill & emergency orientation
Plan your response before the pallet arrives. Sections 4, 5 and 6 of the SDS are the authoritative instructions and should be posted at the point of use.
- Contain, do not hose to drain. H410 applies, and this material must never reach a watercourse — collect mechanically, avoid raising dust, and dispose of as regulated hazardous waste by a licensed carrier.
- Treat every spill as a carcinogen-containment event. Not a routine cleanup — follow your site's designated carcinogen spill procedure, with full PPE, before any cleanup begins.
- Assume skin and respiratory exposure on any uncontrolled release. Remove contaminated clothing immediately, wash exposed skin thoroughly, and seek medical evaluation even for apparently minor contact.
- Restrict area access immediately. Only personnel trained and equipped for carcinogen handling should enter the affected area.
- Log and investigate every incident. Given the carcinogen classification, your occupational-health programme should treat any exposure incident, however minor, as reportable.
Storage
- Dedicated, access-controlled carcinogen storage. Segregated from general chemical stock, with entry logged and restricted to trained personnel only.
- Cool, dry, sealed original packing. Combustible but poorly flammable — keep away from ignition sources as routine practice, not because it is a fire-reactive risk.
- Segregate from strong oxidizing agents and reducing agents. Reacts as a weak acid and can react vigorously with strong oxidizers, generating flammable gas with strong reducers.
- No fixed shelf life under correct storage. Re-assay before use after extended storage to confirm assay and impurity profile remain within specification.
- Container integrity checks on a defined schedule. Given the carcinogen classification, routine visual inspection for pack damage or dust escape is a control measure, not a formality.
Handling & PPE
- Engineering controls first, always. Closed transfer, local exhaust ventilation and containment design are the primary controls — PPE is the last line, never the only line.
- Full carcinogen-handling PPE. Respiratory protection, chemical-resistant coveralls, gloves and eye protection for any operation that can generate dust or direct contact.
- Mandatory health surveillance for all handlers. Given the carcinogen classification, your occupational health provider must define and maintain an exposure-monitoring and surveillance programme.
- Dedicated, decontaminated equipment. Tools and vessels used for this material should not be shared with other processes without full decontamination.
- Never discharge to drain or watercourse under any circumstance. H410 and the environmental-hazard classification both apply — contain and dispose of as regulated hazardous waste.
Transport
3,3'-Dichlorobenzidine dihydrochloride moves as regulated cargo under UN 3077, Class 9, Packing Group III (Environmentally hazardous substance, solid, n.o.s.). We classify each consignment, apply UN-approved packaging and labelling, and file the dangerous-goods declaration before the booking is made — several destinations additionally require a controlled-substance import permit for benzidine-class amines, which we confirm before quoting. Ask us for the current DG and import paperwork when you plan the shipment.
What travels with every consignment
A chemical shipment is only as good as the file that travels with it. Verifying what the source plant sends is precisely the work you are buying from a supplier.
Certificate of Analysis
Batch-specific assay, moisture, residual-amine and isomer content — checked against your purchase specification before release.
GHS Safety Data Sheet
Full 16-section SDS in GHS format covering carcinogen hazard classification, exposure controls, handling, storage, spill response and disposal, issued in the language your destination requires.
Dangerous Goods Declaration
UN 3077, Class 9 declaration prepared and filed before the container is booked, with correctly marked and labelled packaging.
Controlled-substance import documentation
Benzidine-class amine import permits and declarations prepared for destinations that require them, confirmed before quoting.
Third-party inspection
SGS, Intertek or Bureau Veritas sampling and inspection arranged on request before loading, giving you independent verification of what actually ships.
Retained & pre-shipment samples
Pre-shipment samples carry the same COA as the commercial lot, so what your laboratory qualifies is exactly what arrives.
A stabilised salt, carrying a reactive diamine to the reactor
The dihydrochloride salt exists purely as a stable, shippable form of the free diamine, which is liberated and used immediately before diazotization. The routes below are the general industrial pattern, not a process disclosure.
Liberate the free diamine
3,3'-Dichlorobenzidine dihydrochloride is treated with base to release the free-base diamine (CAS 91-94-1) immediately before use.
Bis-diazotize both amine groups
Both amine groups on the biphenyl backbone are converted to diazonium salts in a controlled, low-temperature step.
Double-couple to the pigment structure
The bis-diazonium salt couples with two equivalents of an acetoacetanilide-type coupling component to build the diarylide pigment molecule.
Isolate and finish the pigment
The crude diarylide pigment is isolated, conditioned and finished to the particle size and strength required for ink, plastics or textile use.
Why impurity profile carries through to pigment shade and regulatory status
On a controlled-substance intermediate, purity is both a technical and a compliance question:
- Residual free amine affects downstream handling risk. The salt form is chosen specifically because the free amine is harder to handle — its presence in the salt itself is tracked and limited.
- Isomer impurities shift pigment shade. As with other benzidine-based intermediates, an isomeric contaminant couples to a different hue, visible immediately in a colour-critical application.
- Regulatory status tracks purity and form. Many jurisdictions regulate this compound class specifically, and documentation must match the exact salt form and purity being imported.
- Moisture and particle size affect handling safety. A free-flowing, well-characterised solid is easier to handle within a closed system than a variable, caked or fine-dust-prone lot.
That is why we quote against your written specification and end-use declaration rather than a generic listing, and why the batch COA and compliance documentation are shared for approval before dispatch.
| Material | Downstream / use |
|---|---|
| 3,3'-Dichlorobenzidine dihydrochloride CAS 612-83-9 — this product | Diarylide Yellow/Orange pigment precursor |
| 3,3'-Dichlorobenzidine (free base) CAS 91-94-1 | Liberated in-process immediately before diazotization |
| Benzidine CAS 92-87-5 | The parent compound; heavily restricted, largely superseded |
| Fast Bordeaux GP Base CAS 96-96-8 | Unrelated azoic diazo chemistry for ice-color dyeing |
We supply across this intermediate family — see the full intermediate range. Send the CAS number and we will confirm the correct material before quoting.
What actually moves the price of this product
Knowing what drives the quote helps you time a purchase and read whether an offer is realistic.
Regulatory and handling cost dominate price.
Carcinogen-classified intermediates carry containment, monitoring and documentation costs that sit inside the delivered price far more than for an ordinary dye intermediate.
- Fewer qualified producers globally
- Documentation and permitting lead time varies by destination
- We check this before quoting, not after
Benzidine-class feedstock restriction.
Production of this compound class is concentrated among a small number of producers with the specific regulatory approvals to manufacture it.
- Limited global producer base
- Ask us about producer qualification status
- Long-term contracts secure allocation
Freight and import-permit lead time.
Class 9 environmentally-hazardous cargo combined with controlled-substance import rules means freight booking and customs clearance both need longer lead time than for a standard dye intermediate.
- Book well ahead of your production schedule
- We manage import-permit documentation in-house
- Compare on landed cost including permit lead time
Diarylide pigment demand trends.
End-market demand for diarylide yellow and orange pigments in printing ink and plastics shapes overall demand for this intermediate.
- We track pigment-market trends on your behalf
- Ask us what the pigment market is doing
- Contracted call-off smooths exposure
Source availability is genuinely limited.
A disruption at one of the few qualified producers has an outsized effect on this market compared with commodity dye intermediates.
- We hold a second qualified source where possible
- Qualify the alternate before you need it
- Ask us about allocation planning
| If your end use is… | Specify |
|---|---|
| Diarylide Yellow pigment manufacture | 98% min assay, tight isomer and residual-amine limits |
| Diarylide Orange pigment manufacture | 98% min assay, coupling-component-matched impurity profile |
| Resin-curing agent application | Standard commercial grade, end-use declaration required |
| Laboratory / qualification | Small DG-compliant pack, full COA, controlled-substance documentation |
Not sure which column you are in? Describe what you make from it and our technical desk will recommend the grade — including telling you when a cheaper specification would do the job just as well.
Support that goes beyond shipping the drum
What our technical desk will do
- Confirm your end use and site controls before anything else. This material is supplied only for declared industrial use with appropriate engineering and health-surveillance controls, and we confirm this at enquiry stage, not after shipment.
- Confirm assay and residual-impurity limits for your pigment shade. On a colour-critical product, isomer and residual-amine content decide batch-to-batch consistency.
- Be unambiguous about the carcinogen classification. We never soften or qualify this — stated plainly at enquiry stage so your EHS team can confirm its controls meet the requirement before ordering.
- Review import-permit requirements for your destination early. Controlled-substance documentation lead time is often the longest single item in the order timeline.
Regulatory & compliance notes
- Benzidine-class amines are specifically regulated in many jurisdictions. Beyond standard dangerous-goods rules, several countries require a controlled-substance import permit or notification for this compound class — we check this before quoting.
- Occupational exposure limits and health surveillance are commonly mandated. Confirm your site's monitoring programme meets the applicable regulatory requirement before the first delivery.
- Import controls vary by destination and change periodically. We check current destination rules before quoting, not from memory.
- Effluent and aquatic-toxicity rules are strict. H410 and the environmental-hazard classification both apply — check your discharge consent before introducing this material to site.
None of the above is legal advice — your own regulatory affairs team owns the final compliance position for your import and your workplace. What we commit to is accurate product identity data, an honest statement of the hazard classification and complete documentation to work from.
From enquiry to delivered pallet
Send the specification and end-use declaration
Product name or CAS 612-83-9, your declared pigment-manufacturing end use, assay requirement, quantity and destination port.
Receive a firm quote with compliance lead time
Pricing, lead time (including any import-permit process), packing and Incoterm confirmed in writing — our sourcing desk is staffed around the clock.
Qualify and approve
Sample dispatched to qualified accounts for process qualification. Batch COA shared for your approval before the material is released.
Ship and track
UN 3077 classification filed, controlled-substance documentation prepared where required, DG freight booked, and the consignment tracked through transit and clearance.
Others in the Chelora range
What buyers ask us about 3,3'-Dichlorobenzidine Dihydrochloride
What is 3,3'-dichlorobenzidine dihydrochloride used for?
Why is it supplied as a salt rather than the free amine?
Is this compound a carcinogen?
Does buying this require special permits?
What purity do you normally supply?
What is the minimum order quantity?
Is this a dangerous good? What paperwork comes with it?
Do you supply to any buyer, or only qualified accounts?
Do you manufacture this yourself?
Request pricing on 3,3'-Dichlorobenzidine Dihydrochloride
Send your declared end use, required assay, quantity and destination port. Because this material carries controlled-substance import requirements in several jurisdictions, our sourcing desk confirms compliance lead time alongside pricing — available 24 hours a day, 7 days a week.