Salicylic Acid (CAS 69-72-7) — Green Heart Note Fragrance Ingredient
Salicylic Acid
CAS 69-72-7
What Is Salicylic Acid?
Salicylic acid is a common ingredient in acne treatments, wart removers, and some anti-dandruff shampoos. While odorless in pure form, its derivatives create wintergreen-like aromas in fragrances. This molecule bridges skincare and perfumery, appearing in both functional products and artistic compositions.
Safety Profile
USE WITH AWARENESSWhat Does Salicylic Acid Smell Like?
Pure salicylic acid is odorless, but its methyl ester (methyl salicylate) delivers the crisp, medicinal sweetness of wintergreen. In perfumery, salicylates contribute a clean, sharp character – like crushed aspirin tablets meeting fresh snow. They add brightness to fougères and chypres, cutting through heavier bases with clinical precision. The effect is cooling and slightly antiseptic, evoking hospital corridors or alpine forests after rain.
Scent Profile
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Uses methyl salicylate to sharpen its lavender-citrus opening, creating a bracing medicinal effect that contrasts with vanilla base notes.
Salicylate derivatives enhance the aquatic freshness, mimicking the crispness of ocean spray without literal marine notes.
Relies on salicylates to cut through its heavy fougère base, adding a barbershop antiseptic cleanness.
Salicylate nuances amplify the dew-on-grass effect, creating crystalline freshness in the violet leaf accord.
2D Molecular Structure
SMILES: OC(=O)C1=C(O)C=CC=C1
Chemistry, Properties & Perfumer Guide
The Chemistry
A beta-hydroxy acid (BHA) with a benzene ring substituted by both carboxyl and hydroxyl groups. Naturally occurs in willow bark (Salix spp.) but is typically synthesized from phenol via Kolbe-Schmitt carboxylation. The ortho-positioning of functional groups creates intramolecular hydrogen bonding, reducing volatility compared to meta- or para-isomers. Salicylate esters like methyl salicylate are more fragrant due to increased volatility.
Physical & Chemical Properties
| Boiling Point | 211 °C at 20 mmHg |
|---|---|
| Melting Point | 157 °C |
| Flash Point | 157 °C (closed cup) |
| Density | 1.44 g/cm³ |
| Vapor Pressure | 0.000082 mmHg |
| Refractive Index | 1.565 at 25°C |
| Solubility | 2.24 g/L in water at 25°C |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.1-1% | Up to 2% | As methyl salicylate for freshness |
| Functional Products | 0.5-2% | Up to 3% | In anti-dandruff shampoos |
| Skincare | 0.5-2% | Up to 3% | As exfoliant in acne treatments |
Classic Accords
Tip: Use salicylates to create ‘sterile’ freshness in functional fragrances or contrast sweet bases.
Alternatives & Comparisons
The fragrant ester form providing wintergreen aroma when salicylic acid’s odorless nature is limiting.
Alternative preservative with milder odor profile when salicylic acid’s acidity is problematic.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. IFRA, REACH, EU Cosmetics Regulation standards update periodically. Consult current IFRA Standards Library before formulating. Not legal or regulatory advice.
IFRA Status
No IFRA restrictions on salicylic acid itself, though methyl salicylate is limited to 0.04% in leave-on products (IFRA 49).
GHS Classification
RIFM Assessment
RIFM considers salicylic acid safe at current cosmetic use levels based on dermal exposure risk assessment.
Sustainability
Most commercial salicylic acid is synthesized from petrochemical phenol, though some producers use biomass-derived feedstocks. Willow bark extraction remains niche due to low yields. The molecule readily biodegrades (OECD 301B) and has low aquatic toxicity (EC50 >100 mg/L).
Explore Salicylic Acid
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References
- PubChem CID 338 – Salicylic Acid PubChem
- Kolbe H. (1860). Ueber Synthese der Salicylsäure Annalen der Physik
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Mar 2026.
Report a data errorPhysicochemical Properties
DTXSID: DTXSID7026368
Physical Properties
| Molecular Weight | 138.122 g/mol🔬 EPA CompTox |
| Density | 1.428 g/cm^3🔬 EPA CTX |
| Boiling Point | 211 °C🔬 EPA CTX |
| Melting Point | 158.578 °C🔬 EPA CTX |
| Flash Point | 157.025 °C🔬 EPA CTX |
| Refractive Index | 1.616 Dimensionless📊 OPERA |
| Molar Volume | 100.393 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 2.248 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | -0.134 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | -1.193 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 7.44 Log10 unitless🔬 EPA CTX |
| Water Solubility | 0.015 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0 atm-m3/mole🔬 EPA CTX |
Transport Properties
| Vapor Pressure | 0 mmHg🔬 EPA CTX |
| Surface Tension | 64.417 dyn/cm📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 57.53 Ų💻 Computed |
| H-Bond Donors | 2 count💻 Computed |
| H-Bond Acceptors | 2 count💻 Computed |
| Rotatable Bonds | 1 count💻 Computed |
| Aromatic Rings | 1 count💻 Computed |
| Molar Refractivity | 35.064 cm^3/mol📊 OPERA |
| Polarizability | 13.901 Å^3📊 OPERA |
Data Sources:
🔬 EPA Experimental data from U.S. EPA CompTox Chemicals Dashboard & CTX APIs. 📊 OPERA Predicted using EPA's OPERA QSAR models. 💻 Computed Calculated from SMILES using RDKit.
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