Para-Dichlorobenzene 1,4-Dichlorobenzene · p-DCB · CAS 106-46-7

What is Para-Dichlorobenzene?

Para-Dichlorobenzene (1,4-dichlorobenzene) is a benzene ring carrying two chlorine atoms in the opposite, 1,4-para arrangement, formula C₆H₄Cl₂. At room temperature it is a white crystalline solid with a strong, characteristic odour, melting around 53 °C and subliming readily — it is one of three dichlorobenzene isomers alongside the ortho- (1,2-) and meta- (1,3-) forms.

It is best known to the public as the active ingredient in moth-repellent crystals and toilet/urinal deodorant blocks, where its tendency to sublime at room temperature is exactly what makes it work. Industrially, it is the principal monomer for polyphenylene sulfide (PPS), a high-performance engineering plastic, and it also serves as a dye and agrochemical intermediate.

Commercially it is produced as one of the co-products of benzene chlorination, separated from the ortho- and meta-dichlorobenzene isomers by fractional distillation or crystallisation given their differing physical properties — para- is the highest-melting and most readily crystallised of the three.

Handling follows standard precautions for a chlorinated aromatic solid — chemical-resistant gloves and eye protection, adequate ventilation (the material sublimes, so vapour can build up even from solid storage), and storage away from incompatible materials.

Why Para-Dichlorobenzene specifically

• The PPS resin monomer. Para-dichlorobenzene is the standard feedstock for polyphenylene sulfide, a heat- and chemical-resistant engineering plastic used in automotive, electrical and industrial components.
• Sublimes at room temperature. This physical property, not shared equally by the ortho- and meta-isomers, is what makes it effective as a moth repellent and in deodorant/air-care blocks.
• Dye and agrochemical intermediate. Used in selected dye-intermediate synthesis and as a component in some insecticide/fungicide formulations.
• Distinct from the ortho- and meta-isomers. The 1,4-substitution pattern gives different physical behaviour and reactivity from 1,2-dichlorobenzene (a liquid solvent) and 1,3-dichlorobenzene (a dye/agrochemical intermediate) — the three are not interchangeable.

How Para-Dichlorobenzene is Manufactured

Para-Dichlorobenzene is produced as one of several co-products from the chlorination of benzene, so supply tracks installed chlorination capacity rather than a dedicated feedstock stream.

• Chlorination. Controlled chlorination of benzene gives a mixture of dichlorinated products — predominantly the ortho- and para-isomers, with meta- present only as a minor by-product.
• Isomer separation. The ortho- and para-dichlorobenzene isomers are separated from each other by fractional distillation, and the para-isomer is further purified by crystallisation, taking advantage of its comparatively high melting point.
• Purification. The para- fraction is refined to the target purity level — food/consumer-block grade and PPS-polymer grade call for different impurity tolerances.
• Quality release and packing. Assay, melting point and isomer purity are confirmed against specification before the batch is packed and released.

Typical Commercial Specification

Figures below are representative of commercial-grade Para-Dichlorobenzene. Tell us whether you need consumer-block grade or PPS-polymer grade, and we will advise on the specification to order against.

Physical & Chemical Properties

Behaviour in the process

Para-Dichlorobenzene's physical and chemical behaviour is what both its consumer-product and industrial-chemical customers are buying:

• Sublimation. Gradual, steady conversion from solid to vapour at room temperature is the mechanism behind moth-repellent crystals and deodorant/air-care blocks.
• Nucleophilic aromatic substitution. The carbon-chlorine bonds react with sodium sulfide under polymerisation conditions to build polyphenylene sulfide (PPS) resin.
• Thermal stability. Stable under normal storage conditions; classified as combustible given its flash point, so should be kept from ignition sources.
• Low water solubility. Behaves as a typical chlorinated-aromatic solid, practically insoluble in water.

Para-Dichlorobenzene and Related Chlorobenzenes

Choosing between the dichlorobenzene isomers — and against the trichlorobenzenes — comes down to which substitution pattern and physical form the target application needs.

Stated plainly: if your process is built around PPS polymerisation or a moth-repellent/deodorant-block formulation, you need the para-isomer specifically — the ortho- and meta-isomers have different physical form and reactivity and are not drop-in substitutes.

Industries We Supply Para-Dichlorobenzene To

The same material feeds a household-products manufacturer and an engineering-resin producer. What changes is the grade, the isomer-purity tolerance and the documentation each requires.

Where Para-Dichlorobenzene is Used

Two very different buyers, one material

A household-products formulator cares about a consistent sublimation rate, odour and block hardness; a PPS-resin producer cares about isomer purity and trace-impurity control because it affects polymer molecular weight and colour. We ask which of these your order is for so we can recommend the right grade.

Quality Control & Testing

Every lot is released against a batch-specific Certificate of Analysis, with isomer purity reported alongside the main assay because ortho-dichlorobenzene carryover affects sublimation behaviour in consumer blocks and reaction selectivity in PPS and dye synthesis.

• Para-Dichlorobenzene content — by GC assay, the primary grade measure.
• Melting point — a fast purity and identity check.
• Isomer purity — ortho- and meta-dichlorobenzene carryover, reported because it affects downstream chemistry and product performance.
• Moisture content — measured because moisture can affect downstream reaction yield and block quality.

Common Process Problems & Likely Causes

Packaging, Storage & Shipping

• Standard packing. Fibre drums or HDPE bags, typically 25 – 200 kg net, with larger bulk formats on contract supply.
• Sealed containers. Because the material sublimes at room temperature, poorly sealed packaging leads to product loss and odour escape during storage and transport — containers are sealed accordingly.
• Temperature control. Store in a cool, dry, well-ventilated area away from direct sun, heat and ignition sources; the material is combustible given its flash point.
• Material compatibility. Avoid contact with strong oxidisers.
• Transport classification. Widely published as UN 3077, Class 9, Packing Group III ("Environmentally Hazardous Substance, Solid, N.O.S."), though classification can still vary by transport mode and jurisdiction — confirm against your own current SDS before finalising shipping documents.

Hazards & Safe Handling

Para-Dichlorobenzene is harmful if swallowed, causes serious eye irritation, is suspected of causing cancer, and is very toxic to aquatic life with long-lasting effects. Standard precautions for a chlorinated aromatic solid and good laboratory and plant practice apply throughout handling.

• Skin and eye contact. Chemical-resistant gloves and goggles are standard practice for chlorinated aromatics; rinse thoroughly with water on contact.
• Inhalation. The material sublimes readily, so vapour can accumulate in poorly ventilated storage or handling areas even without visible dust — ensure adequate ventilation.
• PPE. Chemical-resistant gloves, safety goggles and, where dust or vapour builds up, a suitable respirator.
• Environment. Very toxic to aquatic organisms with long-lasting effects; avoid uncontrolled release to water and follow local effluent rules.

Regulatory & Compliance Notes

Para-Dichlorobenzene is a long-established, widely registered industrial and consumer-product chemical. Because obligations differ by territory and use, the notes below are orientation rather than legal advice.

• GHS classification. Classified as harmful if swallowed, causing serious eye irritation, suspected of causing cancer, and very toxic to aquatic life with long-lasting effects (GHS07/GHS08/GHS09, Signal word: Warning; IARC Group 2B — possibly carcinogenic to humans). The SDS carries the full hazard statements for your grade.
• REACH and chemical inventories. Registered under EU REACH (Index No. 602-035-00-2) and listed on major chemical inventories worldwide.
• Consumer/retail use. Because of its carcinogenicity classification, some markets apply additional restrictions or labelling requirements to consumer-facing products containing Para-Dichlorobenzene (moth repellents, deodorant blocks). Confirm current rules for your target market before shipping finished consumer goods into it.
• Dangerous goods transport. Consistently documented as UN 3077, Class 9, Packing Group III — confirm the exact requirements for your transport mode and lane with your logistics/EHS team against your current SDS before shipping.
• HS code. Internationally classified under HS heading 2903.61 (chlorobenzene, ortho-dichlorobenzene and para-dichlorobenzene); confirm the exact national tariff subheading with your customs broker, as these differ by country.

We Supply Para-Dichlorobenzene Across All Seven Continents

Chelora Chemicals is a supplier and export partner, not a single-plant trader. We ship Para-Dichlorobenzene from India and from partner sources to customers across every inhabited continent, handling the export documentation 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 ports arranged as routing allows.
• Documentation. Commercial invoice, packing list, certificate of origin, COA and SDS issued as a complete set.
• Flexible volumes. From trial quantities up to repeat bulk shipments on a supply contract.

Buying Para-Dichlorobenzene from Chelora

We are an independent sourcing and supply partner. For this product that means settling three things at enquiry: whether you need consumer-block grade or PPS-polymer grade, the packing format, and the quantity you are buying — and confirming transport classification with you before the first shipment.

• Documentation on every lot. Batch-specific COA with assay and isomer breakdown, plus the current SDS.
• Analysis before commitment. Representative analysis shared ahead of a commercial order so your lab can qualify the material.
• Quantities. Trial quantities through to larger bulk shipments on contract supply.
• Inspection. Independent third-party inspection available at loading when the contract requires it.
• Related chlorinated benzenes. Other dichloro- and trichlorobenzene isomers alongside this product from one supplier.

How ordering works

• Send the enquiry. Grade (consumer-block or PPS-polymer), quantity, destination port and the Incoterm you buy on.
• We quote. Price, lead time, packing format and a sample COA, normally within one working day.
• Qualify the supply. For first orders or PPS/dye-grade applications, we share the analysis so your technical team can sign off before you commit.
• Confirm transport classification. We work with you and your logistics team to confirm the UN number and transport class for your lane.
• Confirm the order. Proforma invoice issued; payment terms agreed against the volume and the relationship.
• Ship and document. Packed, labelled and loaded with the full export document set, and tracked through to arrival.

Related Dichlorobenzene & Trichlorobenzene Intermediates