Polyester-synthesis intermediate
Manufacturer and attributed industrial records identify terephthalic acid as a precursor for PET and PBT polyesters. [5]
01
THE ESSENTIALS
Terephthalic Acid in 30 Seconds
The 1,4, or para, arrangement is a molecular-connectivity identity. It is distinct from 1,2 phthalic acid and 1,3 isophthalic acid despite sharing their formula and molecular weight.
Terephthalic acid places two carboxyl groups opposite each other on a benzene ring. It is a polymer precursor; familiar PET bottle and fiber properties belong to the polyester made from it. [1] [3]
Safety at a glance — TCI T0166 identifies respiratory irritation and organ damage from prolonged or repeated exposure. Its reviewed European SDS additionally identifies eye irritation and possible dust explosion when powder mixes with air. Do not describe the powder as harmless because it is a PET precursor; obtain current local dust-control and handling instructions. [4] [5] [6] [14]
A condensed structural formula keeps the functional groups visible. [1]
02
GO A LITTLE DEEPER
Understanding Terephthalic Acid
THE SIMPLE EXPLANATION
The functional groups
The 1,4, or para, arrangement is a molecular-connectivity identity. It is distinct from 1,2 phthalic acid and 1,3 isophthalic acid despite sharing their formula and molecular weight. [1]
A LITTLE DEEPER
What the structure changes
Condensation with a diol incorporates terephthalate residues into polyester. Deprotonated carboxylates also serve as linker groups in coordination materials. Neither reaction leaves the finished material chemically identical to free terephthalic acid. [1] [12]
Technical detail Identity, dissociation & specification
Connectivity and neutral formula identify this acid. Positional isomers, water-containing products, salts and esters require their own specifications. Measured reference conditions, assay methods and unresolved discrepancies remain visible. [1] [2] [4] [5] [6]
Acid–base reference values describe equilibria under specified conditions. They are not a substitute for a validated formulation or an assay on the purchased lot.
03
MAKE THE CONNECTION
How Terephthalic Acid Compares
Similar names and functional groups do not mean interchangeable chemicals.
SIDE-BY-SIDE COMPARISON
Terephthalic Acid vs Isophthalic Acid
Para aromatic dicarboxylic acid
versusMeta aromatic dicarboxylic acid
Fixed comparison for this prototype. Acid selectors are disabled; additional comparisons are coming later.
| Property | Terephthalic Acid | Isophthalic Acid |
|---|---|---|
| Molecular formula | C₈H₆O₄ [1] | C₈H₆O₄ [7] |
| Molecular weight | 166.13 g/mol [1] | 166.13 g/mol [7] |
| Carbon atoms | 8 [1] | 8 [7] |
| Carboxyl groups | 2 [1] | 2 [7] |
| Structure | 1,4-C₆H₄(COOH)₂ [1] | 1,3-C₆H₄(COOH)₂ [7] |
| Chemical family | Para aromatic dicarboxylic acid [1] | Meta aromatic dicarboxylic acid [7] |
| Identity focus | Neutral free acid; water and derivatives specified separately [1] | Free acid [7] |
Chemical identities are compared here; supplier grades, concentrations, and stereochemical specifications are separate purchasing attributes. pKa values retain their stated conditions; no quantitative solubility ranking is implied.
When Might You Choose One Instead of the Other?
Choose terephthalic acid for a target specifying para terephthalate residues; choose isophthalic acid for meta residues or a validated comonomer requirement. Establish process grade, water and other aromatic-acid limits separately from a laboratory assay. [1] [3] [7]
Specified starting material
Terephthalic Acid
Match 1,4-C₆H₄(COOH)₂ and the method’s required chemical form.
Isophthalic Acid
Match 1,3-C₆H₄(COOH)₂; verify the identity before substituting a related acid.
Before choosing: match the reaction or formulation, then verify the exact form, grade, assay basis, and impurities. These contexts do not establish suitability for an industrial or regulated application.
04
FROM STRUCTURE TO APPLICATION
What Is Terephthalic Acid Used For?
Polyester-synthesis intermediate
Manufacturer and attributed industrial records identify terephthalic acid as a precursor for PET and PBT polyesters. Packaging, fiber and device performance belongs to the finished polymer. [5]
Coordination-material intermediate
Sigma documents terephthalic acid as a linker precursor for metal-organic frameworks. Performance claims for a particular framework are not direct properties of the unreacted acid. [5]
06
SOURCE WITH CONTEXT
Terephthalic Acid Suppliers
Compare specific products and package options. Listings are not ranked recommendations.
3 suppliers · 3 products · 7 package listingsLatest supplier check: October 3, 2026
Package sizes stay grouped under the supplier product. Assay methods, product forms, and regional markets remain visible. Laboratory GC, titration and method-unspecified products are not automatically purified terephthalic acid qualified for an industrial polymer line. Wako 95% capillary GC differs from the 98–99% entries. Confirm para identity and process-specific impurities.
Scroll horizontally if needed. Supplier and package identity stay visible.
| Supplier | Product / Grade | Purity / Assay | Package Size | Public Price | Normalized Price | Documentation | Last Checked | Action |
|---|---|---|---|---|---|---|---|---|
| TCI AmericaTerephthalic Acid | Named grade not statedT0166 · 25 g | GC: minimum 99.0% Neutralization titration: minimum 99.0% | 25 g | $17.00USD · US public price | Not comparedGrades, assay bases, or forms differ | Document notes: TCI America
| View Product: TCI America, T0166 · 25 g (opens new tab) | |
| Named grade not statedT0166 · 500 g | GC: minimum 99.0% Neutralization titration: minimum 99.0% | 500 g | $23.00USD · US public price | Not comparedGrades, assay bases, or forms differ | View Product: TCI America, T0166 · 500 g (opens new tab) | |||
| Sigma-AldrichTerephthalic Acid | Named grade not stated185361-5GList prices shown; web-only promotional prices were USD 31.70 / 38.33 / 42.67 respectively. No bulk purified-terephthalic-acid process grade inferred. | 98%; method not stated | 5 g | $37.30USD · US public list price | Not comparedGrades, assay bases, or forms differ | Document notes: Sigma-Aldrich
| View Product: Sigma-Aldrich, 185361-5G (opens new tab) | |
| Named grade not stated185361-100GList prices shown; web-only promotional prices were USD 31.70 / 38.33 / 42.67 respectively. No bulk purified-terephthalic-acid process grade inferred. | 98%; method not stated | 100 g | $45.10USD · US public list price | Not comparedGrades, assay bases, or forms differ | View Product: Sigma-Aldrich, 185361-100G (opens new tab) | |||
| Named grade not stated185361-500GList prices shown; web-only promotional prices were USD 31.70 / 38.33 / 42.67 respectively. No bulk purified-terephthalic-acid process grade inferred. | 98%; method not stated | 500 g | $50.20USD · US public list price | Not comparedGrades, assay bases, or forms differ | View Product: Sigma-Aldrich, 185361-500G (opens new tab) | |||
| FUJIFILM WakoTerephthalic Acid | Wako 1st Grade208-08162Research / further manufacturing; confirm US availability separately from Japan stock. | 95.0+% (Capillary GC) | 25 g | $27.00USD · US catalog list price | Not comparedGrades, assay bases, or forms differ | Document notes: FUJIFILM Wako
| View Product: FUJIFILM Wako, 208-08162 (opens new tab) | |
| Wako 1st Grade202-08165Research / further manufacturing; confirm US availability separately from Japan stock. | 95.0+% (Capillary GC) | 500 g | $48.00USD · US catalog list price | Not comparedGrades, assay bases, or forms differ | View Product: FUJIFILM Wako, 202-08165 (opens new tab) |
TCI America
Terephthalic Acid
Neutralization titration: minimum 99.0%
Named grade not stated
25 g
T0166 · 25 g- Public price
- $17.00USD · US public price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
500 g
T0166 · 500 g- Public price
- $23.00USD · US public price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
Documentation
Document notes: TCI America
- A product-specific certificate retrieval option was visible; no lot certificate was reviewed. Open the product page and use its certificate section.
- A current regional SDS was not verified in this pass.
- Origin-document availability was not verified. Country of origin is unverified and is not inferred.
Last checked:
Sigma-Aldrich
Terephthalic Acid
Named grade not stated
List prices shown; web-only promotional prices were USD 31.70 / 38.33 / 42.67 respectively. No bulk purified-terephthalic-acid process grade inferred.
5 g
185361-5G- Public price
- $37.30USD · US public list price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
100 g
185361-100G- Public price
- $45.10USD · US public list price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
500 g
185361-500G- Public price
- $50.20USD · US public list price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
Documentation
Document notes: Sigma-Aldrich
- A product-specific certificate retrieval option was visible; no lot certificate was reviewed. Open the product page and use its certificate section.
- A current regional SDS was not verified in this pass.
- Origin-document availability was not verified. Country of origin is unverified and is not inferred.
Last checked:
FUJIFILM Wako
Terephthalic Acid
Wako 1st Grade
Research / further manufacturing; confirm US availability separately from Japan stock.
25 g
208-08162- Public price
- $27.00USD · US catalog list price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
500 g
202-08165- Public price
- $48.00USD · US catalog list price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
Documentation
Document notes: FUJIFILM Wako
- A product-specific certificate retrieval option was visible; no lot certificate was reviewed. Open the product page and use its certificate section.
- A current regional SDS was not verified in this pass.
- Origin-document availability was not verified. Country of origin is unverified and is not inferred.
Last checked:
Documentation evidence
COA = Certificate of Analysis · SDS = Safety Data Sheet · COO = Certificate of Origin.
Lookup means a retrieval option was visible, not that a lot certificate was reviewed. Check supplier means availability or the applicable document was not verified.
Prices may vary by quantity, account, contract, geography, and availability. These products have different grades, assay bases, or forms; no normalized comparison is shown. Foreign-market prices are reference listings only. No currency conversion, mass-to-volume conversion, or ranking is applied. Confirm equivalent specifications and a current quote before comparison. [4] [5] [6]
Verification limits & placement policy
Thermal behavior: CONFLICT RESOLVED. The 427 °C reference is explicitly sealed-tube; NTP reports sublimation without melting under its stated context. No ordinary boiling or open-vessel melting constant promoted. Density: CONFLICT UNRESOLVED. Sigma gives 1.58 g/cm³ at 25 °C while Kirk-Othmer gives specific gravity 1.522 at 25 °C. Material/method cause not established; main numeric density omitted. Water solubility: CONDITION-DEPENDENT. 15 mg/L at 20 °C and about 17 mg/L at 25 °C remain source-specific; NaOH dissolution is a different ionization context. pKa: OMITTED. Compiled pair at 25 °C lacks a fully established solvent/method/ionic-strength context.
Only the displayed identity, specification, packages, public prices and stated documentation evidence were reviewed. Current stock, lead times, shipping eligibility, contract pricing, lot certificates, and regulatory suitability are unverified.
There are no paid placements. Future paid listings will show “Sponsored” in both views; payment will not determine chemistry interpretation or imply a ranking.
07
PLAN A LARGER ORDER
Need Terephthalic Acid in Bulk?
Turn your requirements into a clear supplier brief.
Bulk RFQ feature — coming soon. Prototype form: submissions are not currently sent to suppliers. Use sample details to prepare an on-screen brief.
Prepare a bulk request Prototype form
08
A BUYER’S CHECKLIST
Before You Buy Terephthalic Acid
Selections remain only while this page is open.
09
FOR YOUR REFERENCE
Terephthalic Acid Technical Reference
Identity, product reference properties, and handling context.
Identification Names, formula & identifiers
- Principal CAS
- 100-21-0
- Identity focus
- Neutral free acid; water and derivatives specified separately
- Formula
- C₈H₆O₄
- Molecular weight
- 166.13 g/mol
- IUPAC name
- terephthalic acid
- Connectivity SMILES
- C1=CC(=CC=C1C(=O)O)C(=O)O
- Identity SMILES
- C1=CC(=CC=C1C(=O)O)C(=O)O
- InChI
- InChI=1S/C8H6O4/c9-7(10)5-1-2-6(4-3-5)8(11)12/h1-4H,(H,9,10)(H,11,12)
- PubChem CID
- 7489
Connectivity SMILES describes connectivity; it is not an independent stereochemical assignment. CAS and product-form distinctions are supported by the supplier listings. [1] [4] [5] [6]
Physical Properties Product references & conditions
Solid at 20 °C. Sublimation references and a sealed-tube melting reference describe different experimental contexts. [13] [4] [5]
- High-temperature reference
- Attributed Kirk-Othmer: 427 °C in a sealed tube; not an open-vessel ordinary melting constant [13]
- Water-solubility reference
- TCI: 15 mg/L at 20 °C; Sigma: approximately 17 mg/L at 25 °C. Methods unstated; temperatures differ. [4]
Hydrate, concentration, stereoisomer, and temperature can change the relevant specification. Product reference data are not a reviewed lot certificate.
Acid/Base Properties Verified values & missing data
A numeric pKa was not verified for the selected identity in this review; no value is inferred. [2]
Thermal behavior: CONFLICT RESOLVED. The 427 °C reference is explicitly sealed-tube; NTP reports sublimation without melting under its stated context. No ordinary boiling or open-vessel melting constant promoted. Density: CONFLICT UNRESOLVED. Sigma gives 1.58 g/cm³ at 25 °C while Kirk-Othmer gives specific gravity 1.522 at 25 °C. Material/method cause not established; main numeric density omitted. Water solubility: CONDITION-DEPENDENT. 15 mg/L at 20 °C and about 17 mg/L at 25 °C remain source-specific; NaOH dissolution is a different ionization context. pKa: OMITTED. Compiled pair at 25 °C lacks a fully established solvent/method/ionic-strength context.
Temperature, ionic strength, and the use of activities versus concentrations matter in quantitative work. These reference values are not buffer recipes.
Safety at a Glance Product-specific hazards
TCI T0166 identifies respiratory irritation and organ damage from prolonged or repeated exposure. Its reviewed European SDS additionally identifies eye irritation and possible dust explosion when powder mixes with air. Do not describe the powder as harmless because it is a PET precursor; obtain current local dust-control and handling instructions. [4] [5] [6] [14]
Hazard classifications can vary by concentration, product, supplier and jurisdiction. Review the SDS for the exact product before handling. This summary does not replace the SDS.
Supplier safety information and SDS retrieval (opens new tab)
A product-page safety classification is not verification of every regional SDS. Confirm product code, chemical form and current local document.
Review supplier documentation10
COMMON QUESTIONS
Terephthalic Acid FAQ
What distinguishes Terephthalic Acid?
The 1,4, or para, arrangement is a molecular-connectivity identity. It is distinct from 1,2 phthalic acid and 1,3 isophthalic acid despite sharing their formula and molecular weight. [1]
How does it differ from Isophthalic Acid?
The para and meta acids differ in attachment geometry, changing the repeat-unit connectivity. This does not establish a universal stiffness, melting or process-performance ranking for every finished polymer. [7]
What must a buyer specify?
Laboratory GC, titration and method-unspecified products are not automatically purified terephthalic acid qualified for an industrial polymer line. Wako 95% capillary GC differs from the 98–99% entries. Confirm para identity and process-specific impurities. [4]
Are the listed products directly price-comparable?
No. The table retains differing grades, assay bases, forms, and markets. No normalized ranking or currency conversion is applied. [5]
What reference data still need checking?
Thermal behavior: CONFLICT RESOLVED. The 427 °C reference is explicitly sealed-tube; NTP reports sublimation without melting under its stated context. No ordinary boiling or open-vessel melting constant promoted. Density: CONFLICT UNRESOLVED. Sigma gives 1.58 g/cm³ at 25 °C while Kirk-Othmer gives specific gravity 1.522 at 25 °C. Material/method cause not established; main numeric density omitted. Water solubility: CONDITION-DEPENDENT. 15 mg/L at 20 °C and about 17 mg/L at 25 °C remain source-specific; NaOH dissolution is a different ionization context. pKa: OMITTED. Compiled pair at 25 °C lacks a fully established solvent/method/ionic-strength context.
Can I request a bulk quote here?
The RFQ is a prototype that prepares an on-screen brief. Nothing is sent to suppliers. Confirm actual bulk terms directly with the supplier.
11
TRACE THE INFORMATION
Sources & Editorial Notes
Identity and compiled reference values are separated from supplier-specific specifications. Structural comparisons and buyer guidance are editorial interpretation. Sources were checked October 3, 2026; supplier information can change.
- PubChem · chemical identity (opens new tab)
Neutral molecular identity verified independently through PUG REST; CAS also checked on all selected supplier products.
- PubChem / HSDB · dissociation references (opens new tab)
No numeric field promoted: insufficient conditions or unresolved conflicting records.
- PubChem / HSDB · application references (opens new tab)
Attributed application records reviewed claim by claim. Free acid, intermediate, derivative and biological context are distinguished.
- TCI America · commercial product (opens new tab)
Direct product checked October 3, 2026. Identity, listed assay methods, packages, market, prices and documentation interfaces inspected. Lot certificates and stock are not verified.
- Sigma-Aldrich · commercial product (opens new tab)
Direct product checked October 3, 2026. Identity, listed assay methods, packages, market, prices and documentation interfaces inspected. Lot certificates and stock are not verified.
- FUJIFILM Wako · commercial product (opens new tab)
Direct product checked October 3, 2026. Identity, listed assay methods, packages, market, prices and documentation interfaces inspected. Lot certificates and stock are not verified.
- Isophthalic Acid · identity (opens new tab)
Primary structural comparison. Practical interpretation does not establish suitability.
- Phthalic Acid · identity (opens new tab)
Related identity and structural relationship.
- Benzoic Acid · identity (opens new tab)
Related identity and structural relationship.
- Sebacic Acid · identity (opens new tab)
Related identity and structural relationship.
- Isophthalic Acid · dissociation references (opens new tab)
Only independently reviewed values are promoted into the comparison; no condition-free acidity ranking.
- OpenStax · Carboxylic-acid structure and properties (opens new tab)
General carboxylate resonance, acidity and structural interpretation; not authority for this acid’s quantitative constants.
- PubChem / HSDB · attributed physical references (opens new tab)
Attributed references and conditions reviewed; unsupported estimates and cross-isomer data excluded.
- TCI · European T0166 SDS (opens new tab)
2018 European product SDS hazard contents reviewed; historical document, not confirmation of current US classification.
Review limits
Thermal behavior: CONFLICT RESOLVED. The 427 °C reference is explicitly sealed-tube; NTP reports sublimation without melting under its stated context. No ordinary boiling or open-vessel melting constant promoted. Density: CONFLICT UNRESOLVED. Sigma gives 1.58 g/cm³ at 25 °C while Kirk-Othmer gives specific gravity 1.522 at 25 °C. Material/method cause not established; main numeric density omitted. Water solubility: CONDITION-DEPENDENT. 15 mg/L at 20 °C and about 17 mg/L at 25 °C remain source-specific; NaOH dissolution is a different ionization context. pKa: OMITTED. Compiled pair at 25 °C lacks a fully established solvent/method/ionic-strength context.
This informational prototype is not a supplier, quotation service, or endorsement of a product’s fitness for an application. Buyers should verify the applicable specification, certification, and regulatory requirements for their intended use.