Polymer intermediates
Used in unsaturated polyester and alkyd-related chemistry. [3]
01
THE ESSENTIALS
Fumaric Acid in 30 Seconds
The molecule has two carboxyl groups and a double bond in the middle. “Trans” means the carboxyl groups lie on opposite sides of that double bond.
Fumaric acid is a four-carbon diacid with a trans carbon–carbon double bond. That unsaturation distinguishes it from succinic acid and from its cis isomer, maleic acid. [1] [3]
Safety at a glance — The listed Sigma fumaric-acid product 800269 (US listing) is classified as causing serious eye irritation (H319). This is not a serious-eye-damage classification; confirm the classification of the exact product being handled. [4]
A condensed structural formula keeps the functional groups visible. [1]
02
GO A LITTLE DEEPER
Understanding Fumaric Acid
THE SIMPLE EXPLANATION
The functional groups
The molecule has two carboxyl groups and a double bond in the middle. “Trans” means the carboxyl groups lie on opposite sides of that double bond. [1]
A LITTLE DEEPER
What the structure changes
The E configuration is part of fumaric acid’s identity. Maleic acid has the cis arrangement and is a separate substance. Fumarate salts also differ from the free acid sold here. [1] [4] [5] [6]
Technical detail Identity, dissociation & specification
The compiled pKa values are 3.03 and 4.54 at 25 °C. A different reference gives 3.03 and 4.44 at 18 °C. The source and temperature differences are retained; temperature alone has not been established as the cause of the difference. [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 Fumaric Acid Compares
Similar names and functional groups do not mean interchangeable chemicals.
SIDE-BY-SIDE COMPARISON
Fumaric Acid vs Succinic Acid
Unsaturated dicarboxylic acid
versusDicarboxylic acid
Fixed comparison for this prototype. Acid selectors are disabled; additional comparisons are coming later.
| Property | Fumaric Acid | Succinic Acid |
|---|---|---|
| Molecular formula | C₄H₄O₄ [1] | C₄H₆O₄ [7] |
| Molecular weight | 116.07 g/mol [1] | 118.09 g/mol [7] |
| Carbon atoms | 4 [1] | 4 [7] |
| Carboxyl groups | 2 [1] | 2 [7] |
| Structure | HOOC–CH=CH–COOH · E (trans) [1] | HOOC–CH₂–CH₂–COOH [7] |
| Chemical family | Unsaturated dicarboxylic acid [1] | Dicarboxylic acid [7] |
| Identity focus | Solid [1] | Solid [7] |
| pKa context | 3.03 / 4.54 (25 °C) [2] | 4.207 / 5.635 (25 °C) [11] |
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 fumaric acid when the procedure requires the trans unsaturated diacid. Choose succinic acid for the saturated four-carbon framework. For biological work, distinguish fumarate and succinate salts from the free acids. [1] [3] [7]
Specified starting material
Fumaric Acid
Match HOOC–CH=CH–COOH · E (trans) and the method’s required chemical form.
Succinic Acid
Match HOOC–CH₂–CH₂–COOH; 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 Fumaric Acid Used For?
Polymer intermediates
Used in unsaturated polyester and alkyd-related chemistry. The resulting resin is a derivative with its own specification. [3]
Acidulant formulations
Fumaric acid is used in food formulation contexts. Solubility, process conditions, and the applicable grade must be validated. For the US uses covered by 21 CFR 172.350, fumaric acid must contain at least 99.5% by weight on an anhydrous basis and meet the other applicable requirements. The laboratory products shown are not demonstrated to meet that requirement solely from their displayed minimum assays; this does not establish that a particular lot fails. [3] [14]
Biological context
Fumarate participates in cellular metabolism. That biological role does not establish a particular experimental use for purchased free fumaric acid; free acid and salts must be distinguished. [12]
06
SOURCE WITH CONTEXT
Fumaric 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. Confirm fumaric E/trans identity rather than maleic cis form or a fumarate salt.
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 |
|---|---|---|---|---|---|---|---|---|
| Sigma-AldrichFumaric Acid | For synthesis8002690100 | ≥99.0% (acidimetric) | 100 g | $48.80USD · US public price | Not comparedGrades, assay bases, or forms differ | Document notes: Sigma-Aldrich
| View Product: Sigma-Aldrich, 8002690100 (opens new tab) | |
| For synthesis8002691000 | ≥99.0% (acidimetric) | 1 kg | $69.90USD · US public price | Not comparedGrades, assay bases, or forms differ | View Product: Sigma-Aldrich, 8002691000 (opens new tab) | |||
| For synthesis8002699050 | ≥99.0% (acidimetric) | 50 kg | $923.00USD · US public price | Not comparedGrades, assay bases, or forms differ | View Product: Sigma-Aldrich, 8002699050 (opens new tab) | |||
| TCIFumaric Acid | Check supplierF0067Catalog headline >99.0% (GC)(T); separate specification minima are shown. | ≥99.0% — GC specification ≥99.0% — neutralization titration specification | 25 g | $20.00USD · US public price | Not comparedGrades, assay bases, or forms differ | Document notes: TCI
| View Product: TCI, F0067 (opens new tab) | |
| Check supplierF0067Catalog headline >99.0% (GC)(T); separate specification minima are shown. | ≥99.0% — GC specification ≥99.0% — neutralization titration specification | 500 g | $25.00USD · US public price | Not comparedGrades, assay bases, or forms differ | View Product: TCI, F0067 (opens new tab) | |||
| FUJIFILM WakoFumaric Acid | Wako Special Grade069-00652 | ≥98.0% (titration) | 25 g | $21.00USD · US list price | Not comparedGrades, assay bases, or forms differ | Document notes: FUJIFILM Wako
| View Product: FUJIFILM Wako, 069-00652 (opens new tab) | |
| Wako Special Grade063-00655 | ≥98.0% (titration) | 500 g | $25.00USD · US list price | Not comparedGrades, assay bases, or forms differ | View Product: FUJIFILM Wako, 063-00655 (opens new tab) |
Sigma-Aldrich
Fumaric Acid
For synthesis
100 g
8002690100- Public price
- $48.80USD · US public price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
1 kg
8002691000- Public price
- $69.90USD · US public price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
50 kg
8002699050- Public price
- $923.00USD · US public 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:
TCI
Fumaric Acid
≥99.0% — neutralization titration specification
Check supplier
Catalog headline >99.0% (GC)(T); separate specification minima are shown.
25 g
F0067- Public price
- $20.00USD · US public price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
500 g
F0067- Public price
- $25.00USD · US public price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
Documentation
Document notes: TCI
- 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
Fumaric Acid
Wako Special Grade
25 g
069-00652- Public price
- $21.00USD · US list price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
500 g
063-00655- Public price
- $25.00USD · US 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
Compiled pKa references and supplier solubility entries are not fully comparable. Use stated conditions and confirm a suitable experimental reference for quantitative work. A 50 kg package is listed, but current availability and bulk terms are unverified.
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 Fumaric 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 Fumaric Acid
Selections remain only while this page is open.
09
FOR YOUR REFERENCE
Fumaric Acid Technical Reference
Identity, product reference properties, and handling context.
Identification Names, formula & identifiers
- Principal CAS
- 110-17-8
- Identity focus
- Solid
- Formula
- C₄H₄O₄
- Molecular weight
- 116.07 g/mol
- IUPAC name
- (E)-but-2-enedioic acid
- Connectivity SMILES
- C(=CC(=O)O)C(=O)O
- PubChem CID
- 444972
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
Thermal behavior is reported around 287 °C with decomposition; the observed range depends on measurement method (PubChem compiled references). TCI reports water solubility 6.3 g/L at 25 °C. Sigma lists 4.9 g/L with incompletely specified conditions. The discrepancy is unresolved; temperature alone has not been shown to explain it. [13] [5] [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
Reference pKa: 3.03 / 4.54 (25 °C). [2]
Compiled pKa references and supplier solubility entries are not fully comparable. Use stated conditions and confirm a suitable experimental reference for quantitative work. A 50 kg package is listed, but current availability and bulk terms are unverified.
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
The listed Sigma fumaric-acid product 800269 (US listing) is classified as causing serious eye irritation (H319). This is not a serious-eye-damage classification; confirm the classification of the exact product being handled. [4]
Hazard classifications can vary by concentration, formulation, 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
Fumaric Acid FAQ
What distinguishes Fumaric Acid?
The molecule has two carboxyl groups and a double bond in the middle. “Trans” means the carboxyl groups lie on opposite sides of that double bond. [1]
How does it differ from Succinic Acid?
Succinic acid has a saturated CH₂–CH₂ segment; fumaric acid has a trans CH=CH segment. The double bond introduces reaction and polymer possibilities absent from the saturated structure. [7]
What must a buyer specify?
Confirm fumaric E/trans identity rather than maleic cis form or a fumarate salt. [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?
Compiled pKa references and supplier solubility entries are not fully comparable. Use stated conditions and confirm a suitable experimental reference for quantitative work. A 50 kg package is listed, but current availability and bulk terms are unverified.
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)
Official PUG REST identity record: formula, molecular weight, IUPAC name, and connectivity SMILES.
- PubChem · Fumaric Acid dissociation references (opens new tab)
Fumaric Acid compiled dissociation values; stated temperature and medium are retained. Unspecified conditions are not inferred.
- PubChem · applications (opens new tab)
Compiled application references; uses of derivatives are distinguished from direct use of the acid.
- Sigma-Aldrich · commercial product (opens new tab)
Direct product listing checked October 3, 2026. Product-specific grade, assay, package, public price and documentation retrieval evidence. Product-page safety information applies to the identified product and regional listing, not every grade or jurisdiction.
- TCI · commercial product (opens new tab)
Direct product listing checked October 3, 2026. Product-specific grade, assay, package, public price and documentation retrieval evidence. Product-page safety information applies to the identified product and regional listing, not every grade or jurisdiction.
- FUJIFILM Wako · commercial product (opens new tab)
Direct product listing checked October 3, 2026. Product-specific grade, assay, package, public price and documentation retrieval evidence. Product-page safety information applies to the identified product and regional listing, not every grade or jurisdiction.
- Succinic Acid · identity (opens new tab)
Primary comparison identity. Explanations of structural differences are editorial interpretation of verified identities.
- Malic Acid · identity (opens new tab)
Related chemical identity; relevance is based on structure or the stated application relationship.
- Citric Acid · identity (opens new tab)
Related chemical identity; relevance is based on structure or the stated application relationship.
- Adipic Acid · identity (opens new tab)
Related chemical identity; relevance is based on structure or the stated application relationship.
- Succinic Acid · acid–base reference (opens new tab)
The primary comparison’s pKa source; reference conditions are preserved.
- OpenStax · Citric acid cycle (opens new tab)
Succinate and fumarate in the citric acid cycle; salts/ions are distinguished from purchased free acids.
- PubChem · fumaric acid thermal properties (opens new tab)
Compiled thermal observations include decomposition and measurement-dependent ranges, rather than a clean equilibrium melting point.
- eCFR · 21 CFR 172.350 (opens new tab)
US food-use conditions include at least 99.5% fumaric acid by weight on an anhydrous basis; a laboratory listing alone does not establish compliance.
Review limits
Compiled pKa references and supplier solubility entries are not fully comparable. Use stated conditions and confirm a suitable experimental reference for quantitative work. A 50 kg package is listed, but current availability and bulk terms are unverified.
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.