Analytical reagents
Used in analytical chemistry, including standardized solutions for specified titration methods. [3]
01
THE ESSENTIALS
Oxalic Acid in 30 Seconds
There is no CH₂ spacer between the acidic groups. Both carbon atoms belong to carboxyl groups.
Oxalic acid is the smallest carbon-chain dicarboxylic acid: its two carboxyl carbons are directly joined. Buying it also requires a choice between anhydrous solid, hydrate, and standardized solution. [1] [3]
Safety at a glance — The listed anhydrous Sigma product 816144 (US listing) is harmful if swallowed or in contact with skin and causes serious eye damage (H302/H312/H318). Cleaning and processing uses require controlled handling. Do not transfer the solid product’s exact classification to a dilute standard solution. [4]
A condensed structural formula keeps the functional groups visible. [1]
Metal and textile processing
Oxalic acid is used in cleaning and processing applications. [3]
Oxalate intermediates
A precursor for specified oxalate compounds. [3]
Commercial availability
The supplier section separates package size, assay, grade, and market context for three named products. [4] [5] [6]
02
GO A LITTLE DEEPER
Understanding Oxalic Acid
THE SIMPLE EXPLANATION
The functional groups
There is no CH₂ spacer between the acidic groups. Both carbon atoms belong to carboxyl groups. [1]
A LITTLE DEEPER
What the structure changes
Anhydrous oxalic acid and oxalic acid dihydrate are different mass-based materials. A volumetric standard solution is a third kind of product, with concentration expressed as solution strength rather than solid purity. [1] [4] [5] [6]
Technical detail Identity, dissociation & specification
The anhydrous identity is CAS 144-62-7. The dihydrate has CAS 6153-56-6. The linked Thermo standard is 0.1 N, with a stated strength of 0.0998–0.1002 N at 20 °C; this is not 99.98% solid purity. Normality depends on the reaction basis. [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 Oxalic Acid Compares
Similar names and functional groups do not mean interchangeable chemicals.
SIDE-BY-SIDE COMPARISON
Oxalic Acid vs Malonic Acid
Dicarboxylic acid
versusDicarboxylic acid
Fixed comparison for this prototype. Acid selectors are disabled; additional comparisons are coming later.
| Property | Oxalic Acid | Malonic Acid |
|---|---|---|
| Molecular formula | C₂H₂O₄ [1] | C₃H₄O₄ [7] |
| Molecular weight | 90.03 g/mol [1] | 104.06 g/mol [7] |
| Carbon atoms | 2 [1] | 3 [7] |
| Carboxyl groups | 2 [1] | 2 [7] |
| Structure | HOOC–COOH [1] | HOOC–CH₂–COOH [7] |
| Chemical family | Dicarboxylic acid [1] | Dicarboxylic acid [7] |
| Identity focus | Solid · anhydrous identity [1] | Solid [7] |
| pKa context | 1.27 / 4.266 (25 °C, water, zero ionic strength) [2] | ≈2.8 / 5.7 (water, 25 °C; rounded compiled reference) [10] |
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 a verified volumetric standard when the analytical method specifies that solution strength. Choose the correct solid hydration state for a mass-based synthesis. Do not replace either with malonic acid merely because both have two carboxyl groups. [1] [3] [7]
Specified starting material
Oxalic Acid
Match HOOC–COOH and the method’s required chemical form.
Malonic Acid
Match HOOC–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 Oxalic Acid Used For?
Analytical reagents
Used in analytical chemistry, including standardized solutions for specified titration methods. Solution strength and temperature matter. [3]
Metal and textile processing
Oxalic acid is used in cleaning and processing applications. These uses require controlled industrial procedures and the applicable SDS. [3]
Oxalate intermediates
A precursor for specified oxalate compounds. Oxalate salts and esters must be distinguished from the free acid. [3]
06
SOURCE WITH CONTEXT
Oxalic Acid Suppliers
Compare specific products and package options. Listings are not ranked recommendations.
3 suppliers · 3 products · 5 package listingsLatest supplier check: October 3, 2026
Package sizes stay grouped under the supplier product. Assay methods, product forms, and regional markets remain visible. Specify anhydrous or dihydrate; for a solution, state normality, temperature, and method.
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-AldrichOxalic Acid | For synthesis · anhydrous8161440050 | ≥99% (manganometric) | 50 g | $69.80USD · US public price | Not comparedGrades, assay bases, or forms differ | Document notes: Sigma-Aldrich
| View Product: Sigma-Aldrich, 8161440050 (opens new tab) | |
| For synthesis · anhydrous8161440250 | ≥99% (manganometric) | 250 g | $215.00USD · US public price | Not comparedGrades, assay bases, or forms differ | View Product: Sigma-Aldrich, 8161440250 (opens new tab) | |||
| Thermo Scientific ChemicalsOxalic Acid | Volumetric standard · solution1242800100.1 N standard solution; promotional price shown through December 28, 2026. Not comparable with neat solid. | 0.0998–0.1002 N at 20 °C | 1 L · plastic bottle | $46.65USD · US public promotional price | Not comparedGrades, assay bases, or forms differ | COACheck supplierSDSCheck supplierCOOCheck supplier Document notes: Thermo Scientific Chemicals
| View Product: Thermo Scientific Chemicals, 124280010 (opens new tab) | |
| FUJIFILM WakoOxalic Acid | Wako Special Grade · anhydrous156-00452 | ≥98.0% (titration) | 25 g | $31.00USD · US list price | Not comparedGrades, assay bases, or forms differ | Document notes: FUJIFILM Wako
| View Product: FUJIFILM Wako, 156-00452 (opens new tab) | |
| Wako Special Grade · anhydrous150-00455 | ≥98.0% (titration) | 500 g | $46.00USD · US list price | Not comparedGrades, assay bases, or forms differ | View Product: FUJIFILM Wako, 150-00455 (opens new tab) |
Sigma-Aldrich
Oxalic Acid
For synthesis · anhydrous
50 g
8161440050- Public price
- $69.80USD · US public price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
250 g
8161440250- Public price
- $215.00USD · 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:
Thermo Scientific Chemicals
Oxalic Acid
Volumetric standard · solution
0.1 N standard solution; promotional price shown through December 28, 2026. Not comparable with neat solid.
1 L · plastic bottle
124280010- Public price
- $46.65USD · US public promotional price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
Documentation
COACheck supplierSDSCheck supplierCOOCheck supplier
Document notes: Thermo Scientific Chemicals
- COA availability was not verified.
- 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
Oxalic Acid
Wako Special Grade · anhydrous
25 g
156-00452- Public price
- $31.00USD · US list price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
500 g
150-00455- Public price
- $46.00USD · 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
Sigma’s dihydrate synonym conflicts with its principal anhydrous title, CAS, formula and molecular weight. This is a supplier metadata inconsistency, not evidence that the supplied material is hydrated. Confirm actual form on the lot COA. The standard-solution price is not normalized.
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 Oxalic 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 Oxalic Acid
Selections remain only while this page is open.
09
FOR YOUR REFERENCE
Oxalic Acid Technical Reference
Identity, product reference properties, and handling context.
Identification Names, formula & identifiers
- Principal CAS
- 144-62-7
- Identity focus
- Solid · anhydrous identity
- Formula
- C₂H₂O₄
- Molecular weight
- 90.03 g/mol
- IUPAC name
- oxalic acid
- Connectivity SMILES
- C(=O)(C(=O)O)O
- PubChem CID
- 971
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
Sigma’s anhydrous product 816144 lists melting/decomposition at 189 °C and water solubility 108 g/L without a displayed temperature or full measurement basis. The solubility entry is supplier-specific, not a universal saturation value. These properties do not describe the Thermo standard solution. [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: 1.27 / 4.266 (25 °C, water, zero ionic strength). [2]
Sigma’s dihydrate synonym conflicts with its principal anhydrous title, CAS, formula and molecular weight. This is a supplier metadata inconsistency, not evidence that the supplied material is hydrated. Confirm actual form on the lot COA. The standard-solution price is not normalized.
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 anhydrous Sigma product 816144 (US listing) is harmful if swallowed or in contact with skin and causes serious eye damage (H302/H312/H318). Cleaning and processing uses require controlled handling. Do not transfer the solid product’s exact classification to a dilute standard solution. [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
Oxalic Acid FAQ
What distinguishes Oxalic Acid?
There is no CH₂ spacer between the acidic groups. Both carbon atoms belong to carboxyl groups. [1]
How does it differ from Malonic Acid?
Malonic acid inserts one CH₂ between the carboxyl groups. Oxalic acid has no intervening carbon and a different acid–base profile. A solid diacid and a standardized solution also solve different purchasing problems. [7]
What must a buyer specify?
Specify anhydrous or dihydrate; for a solution, state normality, temperature, and method. [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?
Sigma’s dihydrate synonym conflicts with its principal anhydrous title, CAS, formula and molecular weight. This is a supplier metadata inconsistency, not evidence that the supplied material is hydrated. Confirm actual form on the lot COA. The standard-solution price is not normalized.
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.
- NIST · Oxalic acid aqueous ionization (opens new tab)
Goldberg, Kishore and Lennen (2002), table 7.50: evaluated aqueous pKa at 25 °C and zero ionic strength.
- 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.
- Thermo Scientific Chemicals · 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.
- Malonic Acid · identity (opens new tab)
Primary comparison identity. Explanations of structural differences are editorial interpretation of verified identities.
- Succinic 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.
- Malonic 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.
Review limits
Sigma’s dihydrate synonym conflicts with its principal anhydrous title, CAS, formula and molecular weight. This is a supplier metadata inconsistency, not evidence that the supplied material is hydrated. Confirm actual form on the lot COA. The standard-solution price is not normalized.
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.