Methyl p-hydroxybenzoate (CAS 99-76-3) — Balsamic Base Note Fragrance Ingredient
Methyl p-hydroxybenzoate
CAS 99-76-3
What Is Methyl p-hydroxybenzoate?
Methyl p-hydroxybenzoate is a synthetic preservative commonly found in cosmetics, pharmaceuticals, and some food products. It prevents microbial growth, extending shelf life. While effective at low concentrations, some individuals may experience mild skin sensitivity to this ingredient.
Safety Profile
USE WITH AWARENESSWhat Does Methyl p-hydroxybenzoate Smell Like?
Methyl p-hydroxybenzoate presents a faint phenolic character with subtle medicinal undertones. The aroma is clean but slightly antiseptic, reminiscent of hospital corridors with a whisper of wintergreen. At higher concentrations, it develops a sharper, almost plastic-like edge that dominates its profile.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used as part of antimicrobial systems in functional fragrances where shelf stability is paramount, typically at 0.1-0.3% concentrations.
2D Molecular Structure
SMILES: COC(=O)C1=CC=C(O)C=C1
Chemistry, Properties & Perfumer Guide
The Chemistry
Methyl p-hydroxybenzoate belongs to the paraben class of compounds, synthesized through esterification of p-hydroxybenzoic acid with methanol. These compounds disrupt microbial cell membranes by interfering with transport processes. The methyl ester variant offers optimal balance between antimicrobial efficacy and solubility in cosmetic formulations.
Physical & Chemical Properties
| Melting Point | 125-128 °C |
|---|---|
| Solubility | 1g/400ml water, soluble in ethanol |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Cosmetics | 0.1-0.3% | Up to 0.8% | Preservative system component |
| Pharmaceuticals | 0.05-0.25% | Regulated | Multi-purpose preservative |
Classic Accords
Tip: Combine with other preservatives like phenoxyethanol for broader spectrum efficacy.
Alternatives & Comparisons
Preferred for sensitive skin formulations, offers comparable preservation with lower sensitization potential.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not restricted by IFRA when used as preservative within cosmetic guidelines.
GHS Classification
RIFM Assessment
RIFM considers safe at current use levels based on 2019 assessment.
Sustainability
Synthesized from petrochemical feedstocks with moderate environmental impact. Biodegradability studies show partial breakdown in aquatic systems. Some concerns about potential endocrine disruption have led to reduced usage in certain markets.
Explore Methyl p-hydroxybenzoate
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References
- Soni MG et al. (2005). Safety assessment of esters of p-hydroxybenzoic acid (parabens). Food Chem Toxicol. PMID 15664878
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorIngredient Data Sheet
CAS 99-76-3Physical Properties
| Molecular Weight | 152.15 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 2🔬 PubChem |
| Boiling Point | 270.5 °C🔬 EPA CompTox |
| Vapor Pressure | 0.0002 mmHg @ 25°C📊 OPERA |
| log Kp (skin permeability) | -2.208💻 Calculated |
| SMILES | COC(=O)C1=CC=C(C=C1)O🔬 PubChem |
Volatility & Performance
| Fragrance Note | Base💻 Calculated |
| Volatility Class | Very slow💻 Calculated |
| Persistence Score | 5.5 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | balsamicwoody• leffingwell |
| Functional Groups | esterphenoletheraromatic💻 RDKit |
| Methyl p-hydroxybenzoate is odorless or has a faint characteristic odor and a slight burning taste. Methyl p-hydroxybenzoate is more commonly known as methyl paraben and is an ester of p-hydroxybenzoic acid.📖 Fenaroli | |
Sensory Thresholds
| Odor Detection Threshold | 2.6 ppm📖 van Gemert |
Physical data: PubChem (NIH/NLM), U.S. EPA CompTox Dashboard, EPA OPERA models, RDKit. Odor & flavor: Arctander (Perfume & Flavor Chemicals), Fenaroli's Handbook of Flavor Ingredients, Leffingwell. Thresholds: van Gemert (Compilations of Odour Threshold Values). Regulatory: IFRA Standards 51st, FEMA GRAS. Trade names: Surburg (Common Fragrance & Flavor Materials). All data compiled and cross-referenced for perfumertools.com.
Physicochemical Properties
DTXSID: DTXSID4022529
Physical Properties
| Molecular Weight | 152.149 g/mol🔬 EPA CompTox |
| Density | 1.38 g/cm^3🔬 EPA CTX |
| Boiling Point | 286.8 °C🔬 EPA CTX |
| Melting Point | 133.401 °C🔬 EPA CTX |
| Flash Point | 114.723 °C📊 OPERA |
| Refractive Index | 1.547 Dimensionless📊 OPERA |
| Molar Volume | 125.756 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 7.789 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | 2.051 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 2.006 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 8.57 Log10 unitless🔬 EPA CTX |
| Water Solubility | 0.017 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0 mmHg🔬 EPA CTX |
| Viscosity | 7.024 cP📊 OPERA |
| Surface Tension | 42.271 dyn/cm📊 OPERA |
| Thermal Conductivity | 149.879 mW/(m*K)📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 46.53 Ų💻 Computed |
| H-Bond Donors | 1 count💻 Computed |
| H-Bond Acceptors | 3 count💻 Computed |
| Rotatable Bonds | 1 count💻 Computed |
| Aromatic Rings | 1 count💻 Computed |
| Molar Refractivity | 39.908 cm^3/mol📊 OPERA |
| Polarizability | 15.821 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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