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Send EmailIsophthalic Acid, Benzene Dicarboxylic Acid, PIA, IPA, 121-91-5
Isophthalic Acid / Benzene-1,3-dicarboxylic Acid / PIA / IPA
CAS Number: 121-91-5
EC Number: 204-506-4
| Parameter | Information |
|---|---|
| Product Name | Isophthalic Acid |
| Abbreviation | PIA / IPA |
| Chemical Name (IUPAC) | Benzene-1,3-dicarboxylic Acid |
| Other Names | Isophthalic Acid, 1,3-Benzenedicarboxylic Acid, m-Phthalic Acid |
| CAS Number | 121-91-5 |
| EC Number (EINECS) | 204-506-4 |
| Molecular Formula | C₆H₄(CO₂H)₂ / C₈H₆O₄ |
| Molecular Weight | 166.13 g/mol |
| Chemical Class | Aromatic dicarboxylic acid |
| Appearance | White crystalline powder |
| Odor | Practically odorless |
| Physical State (20°C) | Solid (crystalline) |
Isophthalic Acid is an aromatic dicarboxylic acid with the carboxyl groups positioned at the 1,3- (meta) positions on the benzene ring. It is a versatile intermediate used primarily in the production of high-performance unsaturated polyester resins, alkyd resins, and various engineering plastics. Compared to terephthalic acid and phthalic anhydride, isophthalic acid offers superior properties such as improved chemical resistance, thermal stability, and mechanical strength.
| Type | Name |
|---|---|
| Common Names | Isophthalic Acid, PIA, IPA |
| Chemical Names | Benzene-1,3-dicarboxylic Acid, 1,3-Benzenedicarboxylic Acid, m-Phthalic Acid |
| CAS Number | 121-91-5 |
| EC Number | 204-506-4 |
| HS Code | 2917.39 |
Isophthalic acid consists of a benzene ring with two carboxyl groups (-COOH) attached at the 1 and 3 positions (meta configuration).
Structural Formula:
COOH
|
C
/ \
/ \
/ \
/ \
C C
| |
C - H C - COOH
| |
C C
\ /
\ /
\ /
\ /
C
\
COOH
Simplified Representation:
COOH
|
C₆H₄ - COOH
(1,3-configuration)
C₆H₄(CO₂H)₂ / C₈H₆O₄
166.13 g/mol
| Feature | Description |
|---|---|
| Core Structure | Benzene ring (C₆H₄) |
| Functional Groups | Two carboxyl groups (-COOH) |
| Substitution Pattern | 1,3 (meta) configuration |
| Aromatic Ring | 6-membered ring with delocalized electrons |
| Acidity | Dicarboxylic acid (two acidic protons) |
| Property | Value |
|---|---|
| Appearance | White crystalline powder |
| Odor | Practically odorless |
| Molecular Formula | C₆H₄(CO₂H)₂ / C₈H₆O₄ |
| Molecular Weight | 166.13 g/mol |
| Density | ~1.54 g/cm³ |
| Melting Point | ~345 °C |
| Boiling Point | Sublimes (decomposes before boiling) |
| Water Solubility (20°C) | Low (~0.1 g/L) |
| Solubility in Methanol | Slightly soluble |
| Solubility in Acetone | Slightly soluble |
| Solubility in Ethanol | Slightly soluble |
| Solubility in Dimethylformamide (DMF) | Soluble |
| Solubility in Dimethyl Sulfoxide (DMSO) | Soluble |
| pKa₁ (25°C) | ~3.54 |
| pKa₂ (25°C) | ~4.60 |
| Flash Point | Non-flammable (solid) |
| Autoignition Temperature | ~650 °C |
| Stability | Stable under normal storage conditions |
| Solvent | Solubility | Conditions |
|---|---|---|
| Water | Low (~0.1 g/L) | 20°C |
| Water | Slightly soluble | 100°C |
| Methanol | Slightly soluble | 25°C |
| Ethanol | Slightly soluble | 25°C |
| Acetone | Slightly soluble | 25°C |
| Dimethylformamide (DMF) | Soluble | 25°C |
| Dimethyl Sulfoxide (DMSO) | Soluble | 25°C |
| Benzene | Insoluble | 25°C |
| Toluene | Insoluble | 25°C |
| Property | Description |
|---|---|
| Chemical Character | Weakly acidic (dicarboxylic acid) |
| Stability | Stable under normal storage conditions |
| Reactivity | Reacts with alcohols to form esters; with amines to form amides |
| Esterification | Reacts with alcohols to produce isophthalate esters |
| Polycondensation | Reacts with glycols to form polyesters |
| Decomposition | Decomposes at high temperatures to CO₂ and benzene derivatives |
| Incompatible Materials | Strong oxidizers, strong bases, reducing agents |
PIA + 2 R-OH → Isophthalate Diester + 2 H₂O
PIA + HO-R-OH → Polyester + H₂O
PIA + 2 NaOH → Sodium Isophthalate + 2 H₂O
PIA + 2 R-NH₂ → Isophthalamide + 2 H₂O
Isophthalic Acid is produced primarily by the oxidation of m-xylene.
| Stage | Process | Description |
|---|---|---|
| 1 | Oxidation | m-Xylene is oxidized in the liquid phase with air in the presence of a catalyst (cobalt/manganese/ bromine system) at elevated temperature and pressure. |
| 2 | Separation | The crude isophthalic acid is separated from the reaction mixture. |
| 3 | Purification | The crude product is purified by recrystallization or distillation to obtain high-purity isophthalic acid. |
| 4 | Drying | The purified product is dried to remove residual moisture. |
| 5 | Packaging | The dried product is packaged in appropriate containers. |
Overall Reaction:
m-Xylene + 3 O₂ → Isophthalic Acid + 2 H₂O
| Application | Description |
|---|---|
| Unsaturated Polyester Resins (UPR) | Provides high chemical resistance, thermal stability, and mechanical strength |
| High-Performance Polyesters | Used in corrosion-resistant applications (tanks, pipes, marine) |
| Sheet Molding Compounds (SMC) | Automotive parts, construction panels |
| Bulk Molding Compounds (BMC) | Electrical components, appliance parts |
| Application | Description |
|---|---|
| Alkyd Resins | Provides hardness, gloss, and weather resistance |
| Powder Coatings | Provides excellent weatherability and chemical resistance |
| Industrial Coatings | High-performance coatings for metal and wood |
| Automotive Coatings | Provides durability and gloss retention |
| Application | Description |
|---|---|
| Plasticizers | Isophthalate esters as non-phthalate plasticizers |
| Heat Stabilizers | Thermal stabilizer for PVC |
| Flame Retardants | Intermediate for flame retardant compounds |
| Application | Description |
|---|---|
| Polyurethanes | Rigid and flexible foams |
| Polyamide-imides | High-performance engineering plastics |
| Polybenzimidazoles | High-temperature polymers |
| Application | Description |
|---|---|
| Adhesive Formulations | Provides adhesion and durability |
| Structural Adhesives | High-strength bonding applications |
| Application | Description |
|---|---|
| Fiberglass Reinforced Plastics | Marine, automotive, construction |
| Paints and Varnishes | High-quality finishes |
| Electrical Insulation | Insulating materials |
| Printing Inks | Specialty ink formulations |
| Property | Isophthalic Acid (PIA) | Terephthalic Acid (PTA) | Phthalic Anhydride (PA) |
|---|---|---|---|
| Substitution Pattern | 1,3 (meta) | 1,4 (para) | 1,2 (ortho, anhydride) |
| Melting Point | ~345°C | ~300°C | 131.6°C |
| Solubility | Low | Very low | Hydrolyzes |
| Chemical Resistance | Excellent | Excellent | Moderate |
| Thermal Stability | Excellent | Excellent | Moderate |
| Applications | UPR, coatings, adhesives | PET, fibers, bottles | Plasticizers, UPR |
| Parameter | Value |
|---|---|
| Acute Oral Toxicity (LD50, Rat) | > 5,000 mg/kg (low toxicity) |
| Acute Dermal Toxicity (LD50, Rabbit) | > 2,000 mg/kg |
| Acute Inhalation Toxicity | Low risk; dust may cause respiratory irritation |
| Skin Irritation | Mild irritant (powder) |
| Eye Irritation | Moderate irritant (powder) |
| Skin Sensitization | Not a sensitizer |
| Mutagenicity | Negative |
| Carcinogenicity | Not classified as a carcinogen |
| Reproductive Toxicity | Not classified as a reproductive toxin |
| Target Organs | No specific target organs identified |
| Hazard Class | Category | H-Statement |
|---|---|---|
| Eye Irritation | Category 2 | H319 |
| Skin Irritation | Category 2 | H315 |
| Specific Target Organ Toxicity - SE | Category 3 | H335 |
Signal Word: WARNING
Hazard Pictograms: GHS07 (Exclamation Mark)
Hazard Statements (H-Codes):
| Code | Statement |
|---|---|
| H315 | Causes skin irritation. |
| H319 | Causes serious eye irritation. |
| H335 | May cause respiratory irritation. |
| Code | Statement |
|---|---|
| P261 | Avoid breathing dust. |
| P264 | Wash hands thoroughly after handling. |
| P271 | Use only outdoors or in a well-ventilated area. |
| P280 | Wear protective gloves/protective clothing/eye protection/face protection. |
| P302+P352 | IF ON SKIN: Wash with plenty of soap and water. |
| P305+P351+P338 | IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses if present. |
| P337+P313 | If eye irritation persists: Get medical advice/attention. |
| P501 | Dispose of contents/container in accordance with local regulations. |
| Route of Exposure | Action to Be Taken |
|---|---|
| Inhalation | Move to fresh air. If respiratory irritation persists, seek medical attention. |
| Skin Contact | Wash with plenty of soap and water. Remove contaminated clothing. If irritation persists, consult a physician. |
| Eye Contact | Rinse thoroughly with plenty of water for at least 15 minutes. Remove contact lenses. If irritation persists, seek medical attention. |
| Ingestion | Rinse mouth with water. Drink plenty of water. Do not induce vomiting. If large amount is swallowed, seek medical attention. |
| General Note | If symptoms persist, always consult a healthcare facility. |
| Parameter | Information |
|---|---|
| Fire Hazard | Combustible organic solid; may burn at high temperatures. |
| Hazards During Fire | Thermal decomposition produces carbon monoxide and carbon dioxide. |
| Suitable Extinguishing Media | Water spray, CO₂, dry chemical powder, alcohol-resistant foam. |
| Special Protective Equipment | Self-contained breathing apparatus (SCBA), full protective clothing. |
| Parameter | Information |
|---|---|
| Personal Protection | Dust mask, protective goggles, gloves, coverall. |
| Ventilation | Increase ventilation; use local exhaust in confined spaces. |
| Containment | Cover spilled area to prevent dust dispersion. |
| Cleaning Methods | Collect dry using vacuum or careful sweeping. Avoid washing with water. |
| Environmental Precautions | Prevent entry into drains, sewers, and water bodies. |
| Waste Disposal | Dispose of in accordance with local regulations. |
| Parameter | Information |
|---|---|
| Storage Conditions | Store in a cool, dry, and well-ventilated area at room temperature (15-25°C). |
| Container Requirements | Keep tightly closed in original packaging. Protect from moisture. |
| Materials to Avoid | Strong oxidizers, strong bases, reducing agents. |
| Shelf Life | 24 months (under proper storage conditions). |
| Stability Note | Stable; protect from moisture to prevent caking. |
| Packaging Options | 25 kg bags, 500 kg big-bags, 1000 kg palletized. |
| Packaging Type | Quantity | Material |
|---|---|---|
| Kraft Bag + PE Liner | 25 kg | Paper / Polyethylene |
| Plastic Drum | 25 kg | HDPE |
| Fiber Drum | 25 kg | Cardboard / Plastic |
| Big-Bag | 500 – 1000 kg | Polypropylene |
| Parameter | Information |
|---|---|
| UN Number | Not applicable (not classified as dangerous goods) |
| Hazard Class | Not classified as hazardous for transport |
| Packing Group | Not applicable |
| ADR/RID | Not regulated |
| IMDG Code | Not regulated |
| IATA (Air) | Not regulated |
| Marine Pollutant | No |
| Transport Temperature | Ambient temperature; protect from moisture. |
| Region / Authority | Status |
|---|---|
| European Union (REACH) | Registered; industrial chemical. |
| USA (TSCA) | Listed. |
| Turkey (KKDIK) | Registered under chemical registration regulations. |
| EINECS | 204-506-4 |
| FDA | Indirect food contact approved (certain grades) |
| Parameter | Information |
|---|---|
| Aquatic Toxicity | Low toxicity to aquatic organisms |
| Biodegradability | Slowly biodegradable |
| Bioaccumulation | Low potential |
| Mobility in Soil | Low to moderate |
| Waste Disposal | Incineration or disposal in accordance with local regulations |
| Name | Context |
|---|---|
| Isophthalic Acid | Common name |
| PIA | Abbreviation |
| IPA | Abbreviation |
| Benzene-1,3-dicarboxylic Acid | IUPAC name |
| 1,3-Benzenedicarboxylic Acid | Chemical name |
| m-Phthalic Acid | Chemical name |
| CAS | 121-91-5 |
| EC | 204-506-4 |
| Property | Value |
|---|---|
| CAS Number | 121-91-5 |
| EC Number | 204-506-4 |
| Molecular Formula | C₆H₄(CO₂H)₂ / C₈H₆O₄ |
| Molecular Weight | 166.13 g/mol |
| Appearance | White crystalline powder |
| Odor | Practically odorless |
| Density | ~1.54 g/cm³ |
| Melting Point | ~345 °C |
| Water Solubility (20°C) | Low (~0.1 g/L) |
| Primary Uses | Polyester resins, coatings, adhesives, engineering plastics |
| Shelf Life | 24 months |
| UN Number | Not applicable |
| GHS Signal Word | WARNING |
CRITICAL NOTICES:
Dust Hazard: Isophthalic acid is a fine powder that can form dust clouds. Avoid inhalation and dust formation. Use local exhaust ventilation.
Moisture Sensitivity: Protect from moisture to prevent caking and agglomeration.
Thermal Stability: Stable at room temperature; decomposes at high temperatures.
Incompatibility: Incompatible with strong oxidizers, strong bases, and reducing agents.
Eye and Skin Irritation: May cause irritation. Use appropriate personal protective equipment.
Quality Grades: Various grades available (standard, high-purity, polymer grade). Select appropriate grade for your application.
BEST PRACTICE RECOMMENDATIONS:
Storage: Store in a cool, dry, and well-ventilated area. Keep containers tightly closed. Protect from moisture.
Handling: Use protective gloves, goggles, and dust mask. Avoid dust formation. Ensure adequate ventilation.
Processing: In polyester resin production, use appropriate catalysts and reaction conditions.
Quality Control: Test for purity, moisture content, and color. Ensure product meets specifications.
Waste Management: Dispose of waste in accordance with local regulations. Incineration is recommended for contaminated materials.
LEGAL DISCLAIMER:
This Technical Data Sheet (TDS) is for informational purposes only and is prepared based on available technical data. The user is solely responsible for determining the suitability of the product for their specific application and for complying with all local, national, and international regulations. For complete safety, storage, handling, transport, waste, and regulatory compliance information, the official Safety Data Sheet (SDS/MSDS) provided by the manufacturer/supplier must be consulted. This document does not substitute professional advice.