Phenolic-assay calibration
Sigma documents gallic acid as a calibration standard for extractable phenolics and Folin–Ciocalteu tannin-content measurements. [5]
01
THE ESSENTIALS
Gallic Acid in 30 Seconds
OH groups occupy ring positions 3, 4 and 5. The neutral free acid is achiral; its formula excludes any crystal water. Three phenolic OH groups do not mean three COOH groups.
Gallic acid has three phenolic hydroxyl groups and one carboxyl group. Free-acid, moisture-containing and fixed-hydrate products need separate descriptions before assay or price comparison. [1] [3]
Safety at a glance — Sigma G7384 identifies skin/eye and respiratory irritation. TCI specifies air/light sensitivity and hygroscopicity for its moisture-containing product. Control dust and follow exact-product storage instructions; antioxidant research and biological occurrence do not establish therapeutic safety of the reagent. [4] [5] [6]
A condensed structural formula keeps the functional groups visible. [1]
02
GO A LITTLE DEEPER
Understanding Gallic Acid
THE SIMPLE EXPLANATION
The functional groups
OH groups occupy ring positions 3, 4 and 5. The neutral free acid is achiral; its formula excludes any crystal water. Three phenolic OH groups do not mean three COOH groups. [1]
A LITTLE DEEPER
What the structure changes
Phenolic oxidation and carboxyl esterification are distinct reactivities. Gallate esters and tannin-bound galloyl groups are derivatives; their antioxidant or material performance is not automatically a use of raw gallic acid. A drying-basis titration also differs from chromatographic composition. [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 Gallic Acid Compares
Similar names and functional groups do not mean interchangeable chemicals.
SIDE-BY-SIDE COMPARISON
Gallic Acid vs 4-Hydroxybenzoic Acid
Polyhydroxy phenolic monocarboxylic acid
versusPara phenolic monocarboxylic acid
Fixed comparison for this prototype. Acid selectors are disabled; additional comparisons are coming later.
| Property | Gallic Acid | 4-Hydroxybenzoic Acid |
|---|---|---|
| Molecular formula | C₇H₆O₅ [1] | C₇H₆O₃ [7] |
| Molecular weight | 170.12 g/mol [1] | 138.12 g/mol [7] |
| Carbon atoms | 7 [1] | 7 [7] |
| Carboxyl groups | 1 [1] | 1 [7] |
| Structure | 3,4,5-(HO)₃–C₆H₂–COOH [1] | 4-HO–C₆H₄–COOH [7] |
| Chemical family | Polyhydroxy phenolic monocarboxylic acid [1] | Para phenolic monocarboxylic acid [7] |
| Identity focus | Neutral free acid; water and derivatives specified separately [1] | Neutral free acid; water and derivatives specified separately [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 gallic acid for a specified galloyl precursor or phenolic assay calibration; choose the para monohydroxy acid for that target. Define water, hydration identity, assay basis and oxidation-related impurity limits before comparing products. [1] [3] [7]
Specified starting material
Gallic Acid
Match 3,4,5-(HO)₃–C₆H₂–COOH and the method’s required chemical form.
4-Hydroxybenzoic Acid
Match 4-HO–C₆H₄–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 Gallic Acid Used For?
Phenolic-assay calibration
Sigma documents gallic acid as a calibration standard for extractable phenolics and Folin–Ciocalteu tannin-content measurements. This verifies a direct analytical context; method response and reference-material qualification remain separate. [5]
Gallate synthesis intermediate
Attributed industrial references identify synthesis of propyl, octyl and dodecyl gallates from gallic acid. Antioxidant uses of these esters belong to derivatives, not automatically the free acid. [3]
06
SOURCE WITH CONTEXT
Gallic Acid Suppliers
Compare specific products and package options. Listings are not ranked recommendations.
3 suppliers · 3 products · 10 package listingsLatest supplier check: October 3, 2026
Package sizes stay grouped under the supplier product. Assay methods, product forms, and regional markets remain visible. TCI G0011 now labels the free acid and treats moisture as impurity, with up to 10% drying loss and titration after drying. Sigma titration spans 97.5–102.5%. Santa Cruz’s SAMPLE UHPLC result is not a current lot certificate. Fixed monohydrate CAS 5995-86-8 / 188.13 g/mol is excluded from this price table.
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 AmericaGallic Acid | Named grade not statedG0011 · 25 gCurrent CAS 149-91-7 free-acid label; manufacturer treats moisture as impurity, drying loss maximum 10%. Some older labels used hydrate identity. Request water and dry-basis assay; no fixed hydration inferred. | HPLC: minimum 98.0 area% Neutralization titration: minimum 98.0% after drying | 25 g | $31.00USD · US public price | Not comparedGrades, assay bases, or forms differ | Document notes: TCI America
| View Product: TCI America, G0011 · 25 g (opens new tab) | |
| Named grade not statedG0011 · 100 gCurrent CAS 149-91-7 free-acid label; manufacturer treats moisture as impurity, drying loss maximum 10%. Some older labels used hydrate identity. Request water and dry-basis assay; no fixed hydration inferred. | HPLC: minimum 98.0 area% Neutralization titration: minimum 98.0% after drying | 100 g | $61.00USD · US public price | Not comparedGrades, assay bases, or forms differ | View Product: TCI America, G0011 · 100 g (opens new tab) | |||
| Named grade not statedG0011 · 500 gCurrent CAS 149-91-7 free-acid label; manufacturer treats moisture as impurity, drying loss maximum 10%. Some older labels used hydrate identity. Request water and dry-basis assay; no fixed hydration inferred. | HPLC: minimum 98.0 area% Neutralization titration: minimum 98.0% after drying | 500 g | $119.00USD · US public price | Not comparedGrades, assay bases, or forms differ | View Product: TCI America, G0011 · 500 g (opens new tab) | |||
| Sigma-AldrichGallic Acid | Suitable for UV spectrophotometry / general useG7384-100GFree-acid identity. 1 kg list price shown; promotional USD 404.25 was also displayed. Titration above 100% is not chromatographic purity. | 97.5–102.5% (titration) | 100 g | $125.00USD · US public list price | Not comparedGrades, assay bases, or forms differ | Document notes: Sigma-Aldrich
| View Product: Sigma-Aldrich, G7384-100G (opens new tab) | |
| Suitable for UV spectrophotometry / general useG7384-250GFree-acid identity. 1 kg list price shown; promotional USD 404.25 was also displayed. Titration above 100% is not chromatographic purity. | 97.5–102.5% (titration) | 250 g | $204.00USD · US public list price | Not comparedGrades, assay bases, or forms differ | View Product: Sigma-Aldrich, G7384-250G (opens new tab) | |||
| Suitable for UV spectrophotometry / general useG7384-1KGFree-acid identity. 1 kg list price shown; promotional USD 404.25 was also displayed. Titration above 100% is not chromatographic purity. | 97.5–102.5% (titration) | 1 kg | $539.00USD · US public list price | Not comparedGrades, assay bases, or forms differ | View Product: Sigma-Aldrich, G7384-1KG (opens new tab) | |||
| Santa Cruz BiotechnologyGallic Acid | Research use only; named grade not statedsc-205704SAMPLE COA is not the supplied lot. Its >99.5% result is not promoted as product purity. Predicted boiling point, density and pKa on this page are excluded from experimental property fields. | Minimum 98%; page sample COA specifies UHPLC; current lot method/results unreviewed | 10 g | $56.00USD · US public price | Not comparedGrades, assay bases, or forms differ | Document notes: Santa Cruz Biotechnology
| View Product: Santa Cruz Biotechnology, sc-205704 (opens new tab) | |
| Research use only; named grade not statedsc-205704ASAMPLE COA is not the supplied lot. Its >99.5% result is not promoted as product purity. Predicted boiling point, density and pKa on this page are excluded from experimental property fields. | Minimum 98%; page sample COA specifies UHPLC; current lot method/results unreviewed | 100 g | $87.00USD · US public price | Not comparedGrades, assay bases, or forms differ | View Product: Santa Cruz Biotechnology, sc-205704A (opens new tab) | |||
| Research use only; named grade not statedsc-205704BSAMPLE COA is not the supplied lot. Its >99.5% result is not promoted as product purity. Predicted boiling point, density and pKa on this page are excluded from experimental property fields. | Minimum 98%; page sample COA specifies UHPLC; current lot method/results unreviewed | 500 g | $245.00USD · US public price | Not comparedGrades, assay bases, or forms differ | View Product: Santa Cruz Biotechnology, sc-205704B (opens new tab) | |||
| Research use only; named grade not statedsc-205704CSAMPLE COA is not the supplied lot. Its >99.5% result is not promoted as product purity. Predicted boiling point, density and pKa on this page are excluded from experimental property fields. | Minimum 98%; page sample COA specifies UHPLC; current lot method/results unreviewed | 5 kg | $2,100.00USD · US public price | Not comparedGrades, assay bases, or forms differ | View Product: Santa Cruz Biotechnology, sc-205704C (opens new tab) |
TCI America
Gallic Acid
Neutralization titration: minimum 98.0% after drying
Named grade not stated
Current CAS 149-91-7 free-acid label; manufacturer treats moisture as impurity, drying loss maximum 10%. Some older labels used hydrate identity. Request water and dry-basis assay; no fixed hydration inferred.
25 g
G0011 · 25 g- Public price
- $31.00USD · US public price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
100 g
G0011 · 100 g- Public price
- $61.00USD · US public price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
500 g
G0011 · 500 g- Public price
- $119.00USD · 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
Gallic Acid
Suitable for UV spectrophotometry / general use
Free-acid identity. 1 kg list price shown; promotional USD 404.25 was also displayed. Titration above 100% is not chromatographic purity.
100 g
G7384-100G- Public price
- $125.00USD · US public list price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
250 g
G7384-250G- Public price
- $204.00USD · US public list price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
1 kg
G7384-1KG- Public price
- $539.00USD · 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:
Santa Cruz Biotechnology
Gallic Acid
Research use only; named grade not stated
SAMPLE COA is not the supplied lot. Its >99.5% result is not promoted as product purity. Predicted boiling point, density and pKa on this page are excluded from experimental property fields.
10 g
sc-205704- Public price
- $56.00USD · US public price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
100 g
sc-205704A- Public price
- $87.00USD · US public price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
500 g
sc-205704B- Public price
- $245.00USD · US public price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
5 kg
sc-205704C- Public price
- $2,100.00USD · US public price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
Documentation
Document notes: Santa Cruz Biotechnology
- 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
Hydration / assay: CONDITION-DEPENDENT. Current TCI product treats variable moisture as impurity and uses after-drying titration; older hydrate labels and a separately defined monohydrate are not interchangeable. Thermal properties: CONFLICT UNRESOLVED. Attributed references identify stable/unstable thermal forms and sublimation near 210 °C; decomposition ranges differ from supplier 251–253 °C values. No universal clean melting point. Boiling / density / pKa: OMITTED. Supplier predicted boiling/density/pKa excluded from experimental fields. Compiled pKa lacks matched conditions; one density unit is suspect and not silently corrected.
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 Gallic 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 Gallic Acid
Selections remain only while this page is open.
09
FOR YOUR REFERENCE
Gallic Acid Technical Reference
Identity, product reference properties, and handling context.
Identification Names, formula & identifiers
- Principal CAS
- 149-91-7
- Identity focus
- Neutral free acid; water and derivatives specified separately
- Formula
- C₇H₆O₅
- Molecular weight
- 170.12 g/mol
- IUPAC name
- 3,4,5-trihydroxybenzoic acid
- Connectivity SMILES
- C1=C(C=C(C(=C1O)O)O)C(=O)O
- Identity SMILES
- C1=C(C=C(C(=C1O)O)O)C(=O)O
- InChI
- InChI=1S/C7H6O5/c8-4-1-3(7(11)12)2-5(9)6(4)10/h1-2,8-10H,(H,11,12)
- PubChem CID
- 370
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. High-temperature references include decomposition and sublimation; water content and thermal form need qualification. [13] [4] [5]
- Thermal reference
- Sigma G7384: 251 °C (decomposition); TCI: 253 °C (decomposition) [5]
- Water-solubility reference
- TCI: 11.9 g/L at 25 °C; consistent with the attributed AQUASOL compilation, method unstated [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]
Hydration / assay: CONDITION-DEPENDENT. Current TCI product treats variable moisture as impurity and uses after-drying titration; older hydrate labels and a separately defined monohydrate are not interchangeable. Thermal properties: CONFLICT UNRESOLVED. Attributed references identify stable/unstable thermal forms and sublimation near 210 °C; decomposition ranges differ from supplier 251–253 °C values. No universal clean melting point. Boiling / density / pKa: OMITTED. Supplier predicted boiling/density/pKa excluded from experimental fields. Compiled pKa lacks matched conditions; one density unit is suspect and not silently corrected.
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
Sigma G7384 identifies skin/eye and respiratory irritation. TCI specifies air/light sensitivity and hygroscopicity for its moisture-containing product. Control dust and follow exact-product storage instructions; antioxidant research and biological occurrence do not establish therapeutic safety of the reagent. [4] [5] [6]
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
Gallic Acid FAQ
What distinguishes Gallic Acid?
OH groups occupy ring positions 3, 4 and 5. The neutral free acid is achiral; its formula excludes any crystal water. Three phenolic OH groups do not mean three COOH groups. [1]
How does it differ from 4-Hydroxybenzoic Acid?
4-Hydroxybenzoic acid has one phenolic hydroxyl, while gallic acid has three. Their phenolic patterns and oxidation contexts differ. Both have one carboxyl group, so hydroxyl count cannot be used as a total acid-equivalent specification. [7]
What must a buyer specify?
TCI G0011 now labels the free acid and treats moisture as impurity, with up to 10% drying loss and titration after drying. Sigma titration spans 97.5–102.5%. Santa Cruz’s SAMPLE UHPLC result is not a current lot certificate. Fixed monohydrate CAS 5995-86-8 / 188.13 g/mol is excluded from this price table. [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?
Hydration / assay: CONDITION-DEPENDENT. Current TCI product treats variable moisture as impurity and uses after-drying titration; older hydrate labels and a separately defined monohydrate are not interchangeable. Thermal properties: CONFLICT UNRESOLVED. Attributed references identify stable/unstable thermal forms and sublimation near 210 °C; decomposition ranges differ from supplier 251–253 °C values. No universal clean melting point. Boiling / density / pKa: OMITTED. Supplier predicted boiling/density/pKa excluded from experimental fields. Compiled pKa lacks matched conditions; one density unit is suspect and not silently corrected.
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.
- Santa Cruz Biotechnology · 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.
- 4-Hydroxybenzoic Acid · identity (opens new tab)
Primary structural comparison. Practical interpretation does not establish suitability.
- 3-Hydroxybenzoic Acid · identity (opens new tab)
Related identity and structural relationship.
- Salicylic Acid · identity (opens new tab)
Related identity and structural relationship.
- Gluconic Acid · identity (opens new tab)
Related identity and structural relationship.
- 4-Hydroxybenzoic 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.
- Wako · separately defined gallic-acid monohydrate (opens new tab)
Different CAS 5995-86-8, water-containing formula and MW 188.13 verified; excluded from free-acid pricing.
Review limits
Hydration / assay: CONDITION-DEPENDENT. Current TCI product treats variable moisture as impurity and uses after-drying titration; older hydrate labels and a separately defined monohydrate are not interchangeable. Thermal properties: CONFLICT UNRESOLVED. Attributed references identify stable/unstable thermal forms and sublimation near 210 °C; decomposition ranges differ from supplier 251–253 °C values. No universal clean melting point. Boiling / density / pKa: OMITTED. Supplier predicted boiling/density/pKa excluded from experimental fields. Compiled pKa lacks matched conditions; one density unit is suspect and not silently corrected.
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.