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1,4-Benzenedicarbonyl dichloride is a symmetrical aromatic diacid chloride used primarily as a high-reactivity monomer for advanced polymers.
1,4-Benzenedicarbonyl dichloride provides two para-oriented acyl chloride groups that form amide or ester bonds rapidly while releasing hydrogen chloride.
1,4-Benzenedicarbonyl dichloride is particularly important in aramid fibres, rigid-rod polyamides, specialty polyesters, membrane layers and high-performance engineering materials.
CHEMICAL IDENTITY AND COMMON NAMES
1,4-Benzenedicarbonyl dichloride is the diacid chloride derived from terephthalic acid.
The para arrangement of the two carbonyl chloride groups creates a rigid, linear and geometrically symmetrical monomer.
The principal commercial name for 1,4-Benzenedicarbonyl dichloride is terephthaloyl chloride.
The abbreviation TPC is widely used in polymerization and materials-development work.
Common Name: Terephthaloyl chloride
Common Abbreviations: TPC and TCL
Chemical Family: Aromatic dicarbonyl chlorides
Functional Groups: Two acyl chloride groups
Chemical Functionality: Two reactive acyl chloride groups per molecule
Synonyms: Terephthaloyl chloride, Terephthaloyl dichloride, Terephthalic acid dichloride, Terephthalic acid chloride, Terephthalic dichloride, Terephthalyl chloride, Terephthalyl dichloride, Benzene-1,4-dicarbonyl chloride, Benzene-1,4-dicarbonyl dichloride, 1,4-Bis(chlorocarbonyl)benzene, para-Bis(chlorocarbonyl)benzene, 1,4-Dichloroformylbenzene, 4-(Chlorocarbonyl)benzoyl chloride, p-Phthaloyl chloride, p-Phthaloyl dichloride, p-Phthalyl dichloride, p-Phenylenedicarbonyl dichloride, para-Benzenedicarbonyl dichloride, TPC and TCL
TECHNICAL IDENTIFICATION
CAS Number: 100-20-9
EC Number: 202-829-5
Molecular Formula: C8H4Cl2O2
Molecular Weight: 203.02 g/mol
IUPAC Name: Benzene-1,4-dicarbonyl chloride
Exact Mass: 201.9588
Acyl Chloride Equivalent Weight: 101.51 g/eq
Theoretical Total Chlorine Content: Approximately 34.93%
InChIKey: LXEJRKJRKIFVNY-UHFFFAOYSA-N
Canonical SMILES: O=C(Cl)c1ccc(C(=O)Cl)cc1
MDL Number: MFCD00000693
PHYSICAL AND REACTIVE PROFILE
Appearance: White to almost white crystalline powder, crystals, flakes or chips
Physical State: Solid
Odour: Sharp, irritating acid-chloride odour
Melting Point: Approximately 79–84 °C
Boiling Point: Approximately 265–266 °C
Density: Approximately 1.34 g/cm³
Vapour Pressure: Approximately 0.02 mmHg at 25 °C
Vapour Density: Approximately 7 relative to air
Water Behaviour: Reacts rapidly with water
Hydrolysis Products: Terephthalic acid and hydrogen chloride
Solubility in Dry Toluene: Soluble
Solubility in Dry Ether: Soluble
Solubility in Alcohols: Reacts through ester formation
Moisture Sensitivity: Highly moisture sensitive
Acid-Base Behaviour in Water: Hydrolysis produces a strongly acidic mixture
Combustibility: Combustible when exposed to sufficient heat
Thermal Decomposition: Hydrogen chloride, carbon oxides and other irritating chlorinated fumes may form during fire
A reported alcohol solubility value does not describe simple physical dissolution because 1,4-Benzenedicarbonyl dichloride reacts chemically with alcohols.
Dry, non-nucleophilic solvents are therefore selected when the acyl chloride functionality must remain intact.
FUNCTIONALITY, STOICHIOMETRY AND HYDROGEN CHLORIDE GENERATION
Each molecule of 1,4-Benzenedicarbonyl dichloride contains two independently reactive acyl chloride groups.
Complete reaction with a diamine, diol or water generates two moles of hydrogen chloride for every mole of 1,4-Benzenedicarbonyl dichloride consumed.
One kilogram of fully reacted 1,4-Benzenedicarbonyl dichloride theoretically generates approximately 0.359 kg of hydrogen chloride.
This hydrogen-chloride load directly influences base demand, corrosion control, ventilation and off-gas scrubber capacity.
The acyl chloride equivalent weight of 101.51 g/eq is used when calculating functional-group balance.
Polymerization calculations must compare acyl chloride equivalents rather than relying only on the gross mass of each monomer.
Small stoichiometric errors have a disproportionately large effect on step-growth polymer molecular weight.
An ideal one-percent functional-group imbalance can limit the attainable number-average degree of polymerization to approximately 199 even before conversion losses and impurities are considered.
HYDROLYSIS AND CHAIN-TERMINATION RISK
Water attacks 1,4-Benzenedicarbonyl dichloride rapidly and converts acyl chloride groups into carboxylic acid groups.
Partial hydrolysis forms 4-(chlorocarbonyl)benzoic acid, while complete hydrolysis produces terephthalic acid.
Partial hydrolysis converts a bifunctional monomer into a material with only one remaining acyl chloride group.
This monofunctional species terminates growing polymer chains and lowers attainable molecular weight.
Complete hydrolysis removes both reactive acyl chloride groups and creates insoluble or poorly soluble terephthalic acid contamination.
Hydrolysed material can increase turbidity, block filters and create deposits in polymerization equipment.
Moisture exposure can occur through raw materials, humid air, wet solvent, inadequately dried vessels or permeable packaging.
Closed transfer and dry inert-gas protection are consequently central requirements rather than optional storage refinements.
PRODUCTION AND PURIFICATION
Industrial production of 1,4-Benzenedicarbonyl dichloride can use the reaction of terephthalic acid with phosgene in the presence of a catalytic amide complex.
This route supports continuous or batch production of high-purity polymer-grade material.
Another production route reacts terephthalic acid with thionyl chloride in a dry organic medium.
The resulting crude material is separated from excess chlorinating agent, reaction gases, catalyst and solvent.
Alternative manufacturing chemistry can use chlorinated aromatic intermediates or other chlorinating reagents.
The selected route influences residual catalyst, chloride profile, colour-forming impurities and purification demand.
Vacuum distillation, crystallization and controlled solidification can provide high-purity flakes or crystals.
All finishing operations require dry equipment and protection from atmospheric humidity.
Colour-forming impurities can originate from incompletely oxidized substances present in the terephthalic-acid feedstock.
Formylbenzoyl and dichlorotoluoyl derivatives are particularly important because small concentrations can affect high-performance polymer colour.
POLYMER-GRADE PURITY AND MOLECULAR-WEIGHT CONTROL
Gas-chromatographic purity alone does not fully describe the suitability of 1,4-Benzenedicarbonyl dichloride for demanding polycondensation.
Active acyl chloride content, water, free acid, solution clarity and monofunctional impurities are equally important.
A batch can show a high chromatographic assay while containing enough hydrolysed functionality to reduce polymer molecular weight.
Active-chloride titration therefore provides information that complements chromatographic purity.
Low colour is important for natural-coloured fibres, films and engineering polymers.
Solution turbidity is also significant because insoluble hydrolysis products can indicate moisture damage or incomplete purification.
Polymer-grade procurement requires close control of sampling conditions.
Opening a container in humid air can change the sample before the analysis is completed.
APPLICATIONS AND INDUSTRIES
Para-aramid fibres and rigid-rod polyamides
1,4-Benzenedicarbonyl dichloride reacts with para-phenylenediamine to form poly-para-phenylene terephthalamide.
The para-oriented aromatic structure produces a highly linear and rigid polymer backbone.
Strong intermolecular hydrogen bonding between amide groups supports high tensile strength, stiffness and thermal resistance.
The resulting aramid materials are used in protective textiles, reinforcement fibres, ropes, cables, friction materials and advanced composites.
Low-temperature solution polycondensation is commonly performed in a dry polar aprotic medium.
The rapidly increasing molecular weight and viscosity make mixing, heat removal and monomer distribution critical process variables.
Meta-oriented heat-resistant aramids
1,4-Benzenedicarbonyl dichloride reacts with meta-phenylenediamine to produce a less linear aromatic polyamide.
The resulting chain geometry provides a different balance of processability, thermal resistance and mechanical performance.
These aramid materials are used in heat-resistant papers, electrical insulation, filtration media and protective textile structures.
Polymer colour and inherent viscosity depend strongly on monomer purity and moisture exclusion.
Copolyaramids and tailored fibre polymers
1,4-Benzenedicarbonyl dichloride can be polymerized with mixtures of aromatic diamines to modify solubility, toughness, compressive behaviour and processability.
Diamine selection changes chain rigidity, hydrogen bonding, liquid-crystalline behaviour and spinning performance.
Copolymer design can reduce the processing limitations associated with completely rigid polymer backbones.
Accurate control of the total amine-to-acyl-chloride equivalent ratio remains necessary when several diamines are combined.
Specialty aromatic polyamides
1,4-Benzenedicarbonyl dichloride forms polyamides with aliphatic, cycloaliphatic, aromatic and heterocyclic diamines.
The para-substituted terephthaloyl unit contributes rigidity and thermal stability to the resulting chain.
Functional diamines can introduce solubility, crosslinking sites, optical properties or specific intermolecular interactions.
These polymers are investigated for films, fibres, coatings, adhesives and high-temperature components.
Aromatic polyesters and polyarylates
1,4-Benzenedicarbonyl dichloride reacts with diols, bisphenols and hydroquinone derivatives to form aromatic polyester structures.
A base or hydrogen-chloride acceptor is normally required to sustain conversion and control acidity.
The rigid para-oriented aromatic unit can improve dimensional stability, modulus and heat resistance.
Monomer selection determines whether the resulting polymer behaves as an amorphous polyarylate, crystalline polyester or liquid-crystalline material.
Liquid-crystalline polymer systems
1,4-Benzenedicarbonyl dichloride provides a linear aromatic segment suitable for constructing rod-like mesogenic structures.
Polymer chains with sufficiently rigid and regular sequences can form ordered liquid-crystalline phases.
This ordering supports orientation during fibre or film processing.
Comonomers are selected to balance molecular alignment with melt or solution processability.
Interfacial polymerization and membrane layers
1,4-Benzenedicarbonyl dichloride can be dissolved in a dry organic phase and reacted with an aqueous diamine at a liquid-liquid interface.
A thin polyamide layer forms rapidly where the two reactants meet.
The bifunctional linear structure produces a different network architecture from trifunctional acyl chloride crosslinkers.
This distinction allows membrane developers to tune layer thickness, chain packing, solvent resistance, permeability and selectivity.
Applications include nanofiltration, organic-solvent-resistant membranes and selective barrier layers.
Acyl chloride concentration, amine functionality, contact time and hydrolysis rate determine the final membrane morphology.
Advanced engineering-polymer intermediates
1,4-Benzenedicarbonyl dichloride participates in controlled aromatic acylation reactions with aromatic ethers.
Lewis-acid-assisted reactions can produce rigid aromatic diketone intermediates for advanced polyaryl ether and ketone-containing materials.
These reactions require substantially unhydrolysed 1,4-Benzenedicarbonyl dichloride with high solution clarity.
Terephthalic-acid particles and hydrolysis-derived turbidity can interfere with catalyst complexes, filtration and product colour.
Surface modification and macromolecular coupling
1,4-Benzenedicarbonyl dichloride can couple amine- or hydroxyl-functional molecules through stable amide or ester bonds.
Difunctionality allows chain extension, surface crosslinking or attachment of two molecular components.
Applications include functional polymer beads, coated fibres, crosslinked films and modified macromolecules.
Reaction density must be controlled because excessive acylation can cause brittleness, insolubility or uncontrolled gel formation.
Porous and network materials
1,4-Benzenedicarbonyl dichloride can connect multifunctional amines or alcohols into porous organic networks.
The rigid para-oriented linker helps define spacing and structural regularity between functional nodes.
These materials are investigated for adsorption, separation, catalysis supports and molecular-recognition systems.
Pore structure depends on monomer geometry, solvent, concentration, reaction rate and crosslinking functionality.
Fine chemical synthesis
1,4-Benzenedicarbonyl dichloride serves as a bifunctional acylating reagent for terephthalamides, terephthalate esters and hydrazide derivatives.
Sequential reaction conditions can produce symmetrical products or selectively substituted unsymmetrical intermediates.
Fine-chemical work often uses an organic base to capture hydrogen chloride.
Temperature and addition rate are controlled to limit side reactions and preserve sensitive functional groups.
GRADE SELECTION ACCORDING TO END USE
Aramid-grade 1,4-Benzenedicarbonyl dichloride requires high active functionality, very low moisture, low free terephthalic acid and tightly controlled colour.
Polymer trials can connect incoming monomer quality with inherent viscosity, dope appearance and final fibre colour.
Membrane-grade 1,4-Benzenedicarbonyl dichloride emphasizes organic-phase solubility, solution clarity and low particulate content.
Fine particles or hydrolysis products can produce defects in micrometre- or nanometre-scale selective layers.
Engineering-polymer grade 1,4-Benzenedicarbonyl dichloride requires low turbidity and controlled colour-forming impurities.
Lewis-acid-catalysed aromatic acylation can be particularly sensitive to water and insoluble material.
Synthesis-grade 1,4-Benzenedicarbonyl dichloride is commonly supplied at approximately 98–99% purity.
This grade supports laboratory acylation, monomer screening and general organic synthesis.
Reagent-grade 1,4-Benzenedicarbonyl dichloride can include structural confirmation and chromatographic purity data.
Analytical work may additionally require water, melting range and active-chloride results.
PROCESS DESIGN FOR ACYL CHLORIDE REACTIONS
Reaction vessels, feed lines, solvents and comonomers must be dry before 1,4-Benzenedicarbonyl dichloride is charged.
A dry nitrogen or argon atmosphere limits hydrolysis during transfer and reaction.
Low-temperature polycondensation commonly begins around 0–15 °C to manage the rapid reaction and heat release.
Temperature can be adjusted after initial addition according to conversion, viscosity and polymer-solubility behaviour.
1,4-Benzenedicarbonyl dichloride is often introduced as a dry solid or as a freshly prepared solution in an inert solvent.
Complete dissolution and rapid distribution help prevent local stoichiometric imbalance.
Reaction mixtures can change from low-viscosity liquids to highly viscous polymer dopes within a short period.
Mixer torque, feed position, reactor geometry and heat-transfer area therefore influence molecular-weight distribution.
Hydrogen chloride must be removed, neutralized or incorporated into a controlled salt system.
Unmanaged hydrogen chloride can protonate diamines, slow polymerization and corrode equipment.
Interfacial polymerization deliberately brings an organic solution of 1,4-Benzenedicarbonyl dichloride into contact with an aqueous amine phase.
Hydrolysis competes with polymer formation, so phase contact time and acyl chloride concentration require precise control.
Alcoholysis and aminolysis are strongly exothermic at high concentration.
Controlled addition, cooling and suitable hydrogen-chloride capture prevent runaway temperature and localized overreaction.
QUALITY CONTROL AND IMPURITY CONSEQUENCES
Assay Methods: Gas chromatography, liquid chromatography or validated titration
Active Acyl Chloride: Argentometric or equivalent functional-group titration
Identity: Infrared spectroscopy, nuclear magnetic resonance spectroscopy or chromatographic comparison
Water Content: Karl Fischer analysis
Appearance: White to almost white flakes, crystals or powder
Melting Range: Commonly 79–84 °C
Solution Quality: Clarity, colour and turbidity in a specified dry solvent
Free Acid: Terephthalic acid and partially hydrolysed acid chloride
Residual Components: Solvents, chlorinating agents, catalyst residues and process-related aromatic impurities
Particulate Control: Insoluble matter or filtered solution residue
Colour Control: Solid colour and solution colour
Elemental Control: Iron and other process-relevant metals when required
Water analysis must be interpreted together with active acyl chloride and free-acid results.
A dried but previously hydrolysed batch can show low current water while still containing chain-terminating acid groups.
Solution turbidity is particularly useful for detecting fine terephthalic-acid contamination.
A clear initial solution can also be monitored over time to identify delayed precipitation from partially hydrolysed material.
Polymer-grade release testing can include a standardized small-scale polycondensation.
Polymer viscosity, colour, clarity and filtration behaviour provide direct evidence of monomer performance.
SAFETY AND HYDROLYTIC HAZARD
1,4-Benzenedicarbonyl dichloride is corrosive and toxic by inhalation.
Dust, vapour and hydrogen chloride generated by hydrolysis can severely damage the respiratory tract.
Direct contact causes severe skin burns and serious eye damage.
Moisture on skin or in the eyes accelerates hydrolysis and creates hydrochloric acid at the contact site.
Water must not be applied directly to a bulk spill of 1,4-Benzenedicarbonyl dichloride.
Uncontrolled water contact can generate heat, corrosive hydrogen chloride and splashing acidic material.
Dry spill-control materials and closed recovery equipment are required for initial containment.
Controlled destruction or hydrolysis is performed only by trained personnel using cooling, ventilation and acid-gas control.
1,4-Benzenedicarbonyl dichloride can corrode metals when moisture is present.
Equipment design must account for the combined effects of acid chloride, hydrogen chloride and process solvent.
Combustion or severe heating produces hydrogen chloride, carbon oxides and irritating chlorinated decomposition products.
Firefighters require full protective equipment and independent respiratory protection.
Transport Profile: Corrosive solid with an additional toxic inhalation hazard
Signal Word: Danger
Principal Health Hazards: Toxic if inhaled and causes severe skin burns and eye damage
Metal Hazard: May be corrosive to metals in the presence of moisture
FIRST AID
Inhalation: Move the exposed person immediately to fresh air and keep the person at rest.
Obtain emergency medical attention because delayed respiratory injury is possible.
Skin Contact: Carefully remove visible dry material without spreading contamination and remove affected clothing.
Flush the skin immediately with large amounts of water for at least 15 minutes and obtain emergency medical attention.
Eye Contact: Rinse the eyes immediately with clean water for at least 15 minutes while holding the eyelids open.
Remove contact lenses when easy to do and obtain urgent specialist medical treatment.
Ingestion: Rinse the mouth and do not induce vomiting.
Obtain immediate medical assistance because severe corrosive injury can occur.
Note to Physicians: Treat exposure as combined acid-chloride and hydrochloric-acid injury.
Monitor inhalation cases for airway damage, bronchospasm and delayed pulmonary effects.
HANDLING, STORAGE AND TRANSFER
Handling: Transfer 1,4-Benzenedicarbonyl dichloride through closed, completely dry equipment under an inert atmosphere.
Prevent dust generation and exclude humid air from charging and sampling points.
Ventilation: Provide enclosed extraction at reactors, pack-opening stations and sampling locations.
Route hydrogen-chloride-containing vents to an appropriate scrubbing system.
Storage: Store 1,4-Benzenedicarbonyl dichloride in tightly sealed moisture-barrier packaging in a cool and dry area.
High-purity material benefits from inert-gas protection and storage at a controlled temperature below approximately 15 °C.
Incompatibilities: Keep 1,4-Benzenedicarbonyl dichloride away from water, humid air, alcohols, amines, strong bases and uncontrolled nucleophilic materials.
Alcohols, amines and bases are introduced only as deliberate reactants under controlled process conditions.
Sampling: Use dry sampling tools and reseal the container immediately after sample removal.
Routine open-air sampling can compromise both the remaining material and the analytical result.
PACKAGING AND PROCUREMENT CONSIDERATIONS
1,4-Benzenedicarbonyl dichloride is commonly packaged in sealed moisture-barrier bags within compatible drums.
High-purity quantities can be supplied in inert-gas-filled bottles, cans or drums.
Packaging must limit water-vapour transmission throughout transport and warehouse storage.
A damaged liner or poorly resealed drum can convert saleable polymer-grade material into partially hydrolysed material.
A procurement specification should define active acyl chloride, chromatographic assay, water, free acid, colour, melting range and solution turbidity.
Polymer applications should also state the target diamine or diol, solvent system and required final polymer performance.
The inquiry should distinguish between general synthesis grade and molecular-weight-critical polymer grade.
Required pack size, inert-gas packaging, sampling arrangement and humidity-controlled handling should be defined before shipment.
ATAMAN KIMYA SUPPLY AND CONTACT
Ataman Kimya supports the supply of 1,4-Benzenedicarbonyl dichloride for aramids, specialty polyamides, polyesters, membrane materials and fine-chemical synthesis.
Ataman Kimya can coordinate monomer grade, moisture limits, active-chloride requirements, packaging and technical documentation.
Email: info@atamankimya.com
Phone: +90 216 577 10 10
