1-Methylnaphthalene (CAS 90-12-0) — Balsamic Base Note Fragrance Ingredient
1-Methylnaphthalene
CAS 90-12-0
What Is 1-Methylnaphthalene?
1-Methylnaphthalene is a synthetic aromatic compound primarily used in industrial applications and some niche fragrances. It’s not commonly encountered in everyday consumer products. This ingredient matters in perfumery for adding smoky, tar-like nuances to complex compositions, though its use is limited due to safety considerations.
Safety Profile
PROFESSIONAL USEWhat Does 1-Methylnaphthalene Smell Like?
1-Methylnaphthalene presents a sharp, penetrating aroma reminiscent of coal tar and creosote. The scent evolves from an initial harsh, industrial smokiness to a drier, more medicinal character. In dry-down, it leaves a persistent asphalt-like impression with subtle phenolic undertones. The odor profile lacks the sweetness of its naphthalene cousin, instead offering a raw, uncompromising petroleum edge.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used minimally to enhance the fragrance’s notorious asphalt-like darkness, contributing to its controversial ‘forbidden’ aura alongside cannabis and oud notes.
2D Molecular Structure
SMILES: CC1=C2C=CC=CC2=CC=C1
Chemistry, Properties & Perfumer Guide
The Chemistry
1-Methylnaphthalene belongs to the polycyclic aromatic hydrocarbon (PAH) class, structurally similar to naphthalene but with a methyl group at position 1. It’s produced through petroleum refining or coal tar distillation. The compound lacks chirality due to its planar structure. Industrial synthesis typically involves alkylation of naphthalene using methanol or methyl chloride in the presence of acid catalysts.
Physical & Chemical Properties
| Boiling Point | 244-246 °C |
|---|---|
| Melting Point | -30 °C |
| Flash Point | 82 °C |
| Density | 1.025 g/cm³ |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | <0.1% | 0.01-0.5% | Extreme caution required |
| Functional Fragrance | Not used | N/A | Avoid in consumer products |
Classic Accords
Tip: Use in trace amounts only for avant-garde compositions requiring extreme smokiness.
Alternatives & Comparisons
Slightly less harsh isomer with similar smoky character but reduced medicinal sharpness. Preferred when slightly softer effect is desired.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not specifically restricted by IFRA but falls under general PAH limitations.
GHS Classification
RIFM Assessment
Not currently evaluated by RIFM due to limited fragrance use.
Sustainability
Primarily petroleum-derived with significant environmental concerns regarding PAH persistence. Synthetic alternatives are preferred when possible. Not considered sustainable due to fossil fuel origin and potential bioaccumulation.
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References
- PubChem Compound Summary for 1-Methylnaphthalene CID 7002
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorIngredient Data Sheet
CAS 90-12-0Physical Properties
| Molecular Weight | 142.2 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 3.9🔬 PubChem |
| Boiling Point | 232.2 °C🔬 EPA CompTox |
| Vapor Pressure | 23 mmHg @ 25°C📊 OPERA |
| Flash Point | 93.3 °C🔬 EPA CompTox |
| Involatility Index | 2.0788💻 Calculated |
| log Kp (skin permeability) | -0.798💻 Calculated |
| SMILES | CC1=CC=CC2=CC=CC=C12🔬 PubChem |
Volatility & Performance
| Fragrance Note | Heart💻 Calculated |
| Volatility Class | Fast💻 Calculated |
| Persistence Score | 0.5 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | earthygreenmedicinal• leffingwell |
| Functional Groups | aromatic💻 RDKit |
| 1-Methylnaphthalene has an earthy, phenolic odor.📖 Fenaroli | |
Sensory Thresholds
| Odor Detection Threshold | 0.0106 ppm (n=3)📖 van Gemert |
Regulatory Status
| IOFI Classification | Nature Identical📖 Fenaroli |
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: DTXSID9020877
Physical Properties
| Molecular Weight | 142.201 g/mol🔬 EPA CompTox |
| Density | 1.021 g/cm^3🔬 EPA CTX |
| Boiling Point | 242.997 °C🔬 EPA CTX |
| Melting Point | -22.125 °C🔬 EPA CTX |
| Flash Point | 82.109 °C🔬 EPA CTX |
| Refractive Index | 1.617 Dimensionless📊 OPERA |
| Molar Volume | 139.824 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 3.875 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | 3.902 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 3.902 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 5.01 Log10 unitless📊 OPERA |
| Water Solubility | 0 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0 atm-m3/mole🔬 EPA CTX |
Transport Properties
| Vapor Pressure | 0.064 mmHg🔬 EPA CTX |
| Viscosity | 3.879 cP📊 OPERA |
| Surface Tension | 37.821 dyn/cm📊 OPERA |
| Thermal Conductivity | 126.246 mW/(m*K)📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 0 Ų💻 Computed |
| H-Bond Donors | 0 count💻 Computed |
| H-Bond Acceptors | 0 count💻 Computed |
| Rotatable Bonds | 0 count💻 Computed |
| Aromatic Rings | 2 count💻 Computed |
| Molar Refractivity | 48.92 cm^3/mol📊 OPERA |
| Polarizability | 19.394 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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