Phase-change-material research
Sigma documents stearic acid as the core of nanoencapsulated phase-change materials. [5]
01
THE ESSENTIALS
Stearic Acid in 30 Seconds
C18:0 has 18 carbons, no C=C bonds and one COOH group. The neutral molecular identity is achiral and differs from stearate salts.
Stearic acid is the saturated C18 free acid. Commercial materials sold under the name can have different fatty-acid compositions; the assay method is essential to understanding a listing. [1] [3]
Safety at a glance — Sigma identifies combustible-solid storage for its stearic powder/flakes. Dust/contact and heated-material exposure require exact-product controls. An empty product-page GHS field is not proof of harmlessness; obtain the local SDS before handling, including any melting or thermal experiment. [4] [5] [6]
A condensed structural formula keeps the functional groups visible. [1]
02
GO A LITTLE DEEPER
Understanding Stearic Acid
THE SIMPLE EXPLANATION
The functional groups
C18:0 has 18 carbons, no C=C bonds and one COOH group. The neutral molecular identity is achiral and differs from stearate salts. [1]
A LITTLE DEEPER
What the structure changes
A stearate salt is formed by neutralization, while stearate esters form through esterification. Titration reports acid equivalents and can remain high in a mixture of fatty acids. A C18-specific chromatographic specification is a different measure. [1] [12]
Technical detail Identity, dissociation & specification
The molecular identity specifies carbon count and double-bond geometry. A salt, ester, oil blend or oxidation product is separately identified. Overall assay, acid equivalents, isomer composition and package measurement basis remain separate specifications. [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 Stearic Acid Compares
Similar names and functional groups do not mean interchangeable chemicals.
SIDE-BY-SIDE COMPARISON
Stearic Acid vs Palmitic Acid
C18 saturated straight-chain fatty acid
versusC16 saturated straight-chain fatty acid
Fixed comparison for this prototype. Acid selectors are disabled; additional comparisons are coming later.
| Property | Stearic Acid | Palmitic Acid |
|---|---|---|
| Molecular formula | C₁₈H₃₆O₂ [1] | C₁₆H₃₂O₂ [7] |
| Molecular weight | 284.5 g/mol [1] | 256.42 g/mol [7] |
| Carbon atoms | 18 [1] | 16 [7] |
| Carboxyl groups | 1 [1] | 1 [7] |
| Structure | CH₃–(CH₂)₁₆–COOH [1] | CH₃–(CH₂)₁₄–COOH [7] |
| Chemical family | C18 saturated straight-chain fatty acid [1] | C16 saturated straight-chain fatty acid [7] |
| Identity focus | Saturated free acid; composition limits separate [1] | Saturated free acid; composition limits separate [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 a stearic product when the method calls for C18:0 or a validated commercial composition; choose palmitic acid for a C16 target. If the application needs a metal stearate, source and qualify that salt rather than substituting free acid. [1] [3] [7]
Specified starting material
Stearic Acid
Match CH₃–(CH₂)₁₆–COOH and the method’s required chemical form.
Palmitic Acid
Match CH₃–(CH₂)₁₄–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 Stearic Acid Used For?
Phase-change-material research
Sigma documents stearic acid as the core of nanoencapsulated phase-change materials. This verifies a direct research-material role; finished encapsulation, cycling and thermal performance require separate validation. [5]
Stearate and ester synthesis intermediate
Manufacturer and attributed industrial records identify methyl-stearate and metal-stearate preparation. Soap, lubricant and other derivative performance belongs to the formed material. [3]
06
SOURCE WITH CONTEXT
Stearic Acid Suppliers
Compare specific products and package options. Listings are not ranked recommendations.
3 suppliers · 3 products · 8 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 S0163 specifies 98% titration but only 95% GC; Wako Guaranteed Reagent specifies 95% C18 GC area/area; Sigma’s 95% method is unstated. Guaranteed Reagent is not a pharmaceutical grade. Wako’s 20 kg price is unverified and remains inquiry-only.
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 AmericaStearic Acid | Named grade not statedS0163 · 25 g98% titration headline does not establish 98% C18 composition. | GC: minimum 95.0% Neutralization titration: minimum 98.0% | 25 g | $21.00USD · US public price | Not comparedGrades, assay bases, or forms differ | Document notes: TCI America
| View Product: TCI America, S0163 · 25 g (opens new tab) | |
| Named grade not statedS0163 · 500 g98% titration headline does not establish 98% C18 composition. | GC: minimum 95.0% Neutralization titration: minimum 98.0% | 500 g | $29.00USD · US public price | Not comparedGrades, assay bases, or forms differ | View Product: TCI America, S0163 · 500 g (opens new tab) | |||
| Sigma-AldrichStearic Acid | Reagent grade175366-100G | 95%; method not stated | 100 g | $46.40USD · US public list price | Not comparedGrades, assay bases, or forms differ | Document notes: Sigma-Aldrich
| View Product: Sigma-Aldrich, 175366-100G (opens new tab) | |
| Reagent grade175366-1KG | 95%; method not stated | 1 kg | $49.80USD · US public list price | Not comparedGrades, assay bases, or forms differ | View Product: Sigma-Aldrich, 175366-1KG (opens new tab) | |||
| Reagent grade175366-5KG | 95%; method not stated | 5 kg | $139.00USD · US public list price | Not comparedGrades, assay bases, or forms differ | View Product: Sigma-Aldrich, 175366-5KG (opens new tab) | |||
| Reagent grade175366-12KG | 95%; method not stated | 12 kg | $329.00USD · US public list price | Not comparedGrades, assay bases, or forms differ | View Product: Sigma-Aldrich, 175366-12KG (opens new tab) | |||
| FUJIFILM WakoStearic Acid | Guaranteed Reagent199-10995Research / further manufacturing; Japan stock does not confirm US availability. 20 kg is inquiry-priced. GC area composition is distinct from neutralization equivalents. No compendial pharma grade inferred. | 95.0+% C18H36O2 (GC area/area) | 500 g | $26.00USD · US catalog list price | Not comparedGrades, assay bases, or forms differ | Document notes: FUJIFILM Wako
| View Product: FUJIFILM Wako, 199-10995 (opens new tab) | |
| Guaranteed Reagent195-10997Research / further manufacturing; Japan stock does not confirm US availability. 20 kg is inquiry-priced. GC area composition is distinct from neutralization equivalents. No compendial pharma grade inferred. | 95.0+% C18H36O2 (GC area/area) | 20 kg | Public price not verified | Not comparedGrades, assay bases, or forms differ | View Product: FUJIFILM Wako, 195-10997 (opens new tab) |
TCI America
Stearic Acid
Neutralization titration: minimum 98.0%
Named grade not stated
98% titration headline does not establish 98% C18 composition.
25 g
S0163 · 25 g- Public price
- $21.00USD · US public price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
500 g
S0163 · 500 g- Public price
- $29.00USD · 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
Stearic Acid
Reagent grade
100 g
175366-100G- Public price
- $46.40USD · US public list price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
1 kg
175366-1KG- Public price
- $49.80USD · US public list price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
5 kg
175366-5KG- Public price
- $139.00USD · US public list price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
12 kg
175366-12KG- Public price
- $329.00USD · 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:
FUJIFILM Wako
Stearic Acid
Guaranteed Reagent
Research / further manufacturing; Japan stock does not confirm US availability. 20 kg is inquiry-priced. GC area composition is distinct from neutralization equivalents. No compendial pharma grade inferred.
500 g
199-10995- Public price
- $26.00USD · US catalog list price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
20 kg
195-10997- Public price
- Public price not verified
- 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
Water solubility: CONFLICT UNRESOLVED. Attributed 0.568 and 0.597 mg/L at 25 °C differ modestly, but NTP 1–10 mg/mL near room temperature is far higher. Solvent/material/method cause not resolved; no numeric main limit promoted. Atmospheric thermal / density: CONFLICT UNRESOLVED. Pressure-free boiling references 361 and 371 °C differ from NTP about 383 °C at 760 mmHg; density 0.9408 g/cm³ at 20 °C differs from relative 0.86 at 20 °C. No single normal boiling or density constant chosen. pKa: OMITTED. Condition-matched measured dissociation value not verified. Assay / composition: CONDITION-DEPENDENT. 98% acid-equivalent titration and 95% C18 GC composition are separate specifications, not a purity conflict to normalize away.
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 Stearic 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 Stearic Acid
Selections remain only while this page is open.
09
FOR YOUR REFERENCE
Stearic Acid Technical Reference
Identity, product reference properties, and handling context.
Identification Names, formula & identifiers
- Principal CAS
- 57-11-4
- Identity focus
- Saturated free acid; composition limits separate
- Formula
- C₁₈H₃₆O₂
- Molecular weight
- 284.5 g/mol
- IUPAC name
- octadecanoic acid
- Connectivity SMILES
- CCCCCCCCCCCCCCCCCC(=O)O
- Identity SMILES
- CCCCCCCCCCCCCCCCCC(=O)O
- InChI
- InChI=1S/C18H36O2/c1-2-3-4-5-6-7-8-9-10-11-12-13-14-15-16-17-18(19)20/h2-17H2,1H3,(H,19,20)
- PubChem CID
- 5281
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; displayed product melting ranges do not establish the composition or phase behavior of every commercial stearic blend. [13] [4] [5]
- Melting specification
- TCI S0163: 68–71 °C; Wako reference 68–71 °C; Sigma literature range 67–72 °C [4]
- Reduced-pressure boiling reference
- TCI S0163: 240 °C at 16 mmHg [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]
Water solubility: CONFLICT UNRESOLVED. Attributed 0.568 and 0.597 mg/L at 25 °C differ modestly, but NTP 1–10 mg/mL near room temperature is far higher. Solvent/material/method cause not resolved; no numeric main limit promoted. Atmospheric thermal / density: CONFLICT UNRESOLVED. Pressure-free boiling references 361 and 371 °C differ from NTP about 383 °C at 760 mmHg; density 0.9408 g/cm³ at 20 °C differs from relative 0.86 at 20 °C. No single normal boiling or density constant chosen. pKa: OMITTED. Condition-matched measured dissociation value not verified. Assay / composition: CONDITION-DEPENDENT. 98% acid-equivalent titration and 95% C18 GC composition are separate specifications, not a purity conflict to normalize away.
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 identifies combustible-solid storage for its stearic powder/flakes. Dust/contact and heated-material exposure require exact-product controls. An empty product-page GHS field is not proof of harmlessness; obtain the local SDS before handling, including any melting or thermal experiment. [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
Stearic Acid FAQ
What distinguishes Stearic Acid?
C18:0 has 18 carbons, no C=C bonds and one COOH group. The neutral molecular identity is achiral and differs from stearate salts. [1]
How does it differ from Palmitic Acid?
Palmitic acid is C16:0 and stearic acid is C18:0. A stearic product containing other fatty acids is not identical to high-composition C18 material even when total acid assay is high. Process and formulation requirements must specify composition. [7]
What must a buyer specify?
TCI S0163 specifies 98% titration but only 95% GC; Wako Guaranteed Reagent specifies 95% C18 GC area/area; Sigma’s 95% method is unstated. Guaranteed Reagent is not a pharmaceutical grade. Wako’s 20 kg price is unverified and remains inquiry-only. [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?
Water solubility: CONFLICT UNRESOLVED. Attributed 0.568 and 0.597 mg/L at 25 °C differ modestly, but NTP 1–10 mg/mL near room temperature is far higher. Solvent/material/method cause not resolved; no numeric main limit promoted. Atmospheric thermal / density: CONFLICT UNRESOLVED. Pressure-free boiling references 361 and 371 °C differ from NTP about 383 °C at 760 mmHg; density 0.9408 g/cm³ at 20 °C differs from relative 0.86 at 20 °C. No single normal boiling or density constant chosen. pKa: OMITTED. Condition-matched measured dissociation value not verified. Assay / composition: CONDITION-DEPENDENT. 98% acid-equivalent titration and 95% C18 GC composition are separate specifications, not a purity conflict to normalize away.
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.
- Palmitic Acid · identity (opens new tab)
Primary structural comparison. Practical interpretation does not establish suitability.
- Myristic Acid · identity (opens new tab)
Related identity and structural relationship.
- Oleic Acid · identity (opens new tab)
Related identity and structural relationship.
- Linoleic Acid · identity (opens new tab)
Related identity and structural relationship.
- Palmitic 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 conditions reviewed; derivative contamination and unresolved discrepancies excluded from unqualified constants.
Review limits
Water solubility: CONFLICT UNRESOLVED. Attributed 0.568 and 0.597 mg/L at 25 °C differ modestly, but NTP 1–10 mg/mL near room temperature is far higher. Solvent/material/method cause not resolved; no numeric main limit promoted. Atmospheric thermal / density: CONFLICT UNRESOLVED. Pressure-free boiling references 361 and 371 °C differ from NTP about 383 °C at 760 mmHg; density 0.9408 g/cm³ at 20 °C differs from relative 0.86 at 20 °C. No single normal boiling or density constant chosen. pKa: OMITTED. Condition-matched measured dissociation value not verified. Assay / composition: CONDITION-DEPENDENT. 98% acid-equivalent titration and 95% C18 GC composition are separate specifications, not a purity conflict to normalize away.
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.