2-Methyl quinoline (CAS 91-63-4) — Woody Middle to base Note Fragrance Ingredient
2-Methyl quinoline
CAS 91-63-4
What Is 2-Methyl quinoline?
2-Methyl quinoline is a synthetic aromatic compound used in perfumery for its leathery, smoky, and slightly animalic character. It’s found in niche fragrances aiming for unconventional or vintage effects. This ingredient matters because it adds depth and complexity to leather accords, creating a sophisticated edge that modern synthetics often lack.
Safety Profile
USE WITH AWARENESSWhat Does 2-Methyl quinoline Smell Like?
2-Methyl quinoline unfolds with an initial burst of sharp, medicinal smokiness reminiscent of antique apothecary cabinets. Within minutes, it reveals a complex heart of tarry leather and bitter almond, with an unsettling but fascinating animalic undertone. The dry-down lingers as a phantom of charred wood and stale tobacco, leaving an almost nostalgic trail. Its evolution mirrors the transformation of fresh rawhide into aged leather goods.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used to recreate the legendary Russian leather effect, contributing birch tar-like smokiness without the restricted material’s drawbacks.
Provides the crucial burnt-rubber facet that makes this leather masterpiece simultaneously harsh and irresistible.
Amplifies the galbanum’s green bitterness into a dangerous, almost violent leather chypre structure.
Bridges the violet flower and leather accord with its floral-leather duality.
Creates the illusion of sawdust and circus animal hides through careful dosing with vanillin.
2D Molecular Structure
SMILES: CC1=NC2=C(C=CC=C2)C=C1
Chemistry, Properties & Perfumer Guide
The Chemistry
2-Methyl quinoline belongs to the quinoline class of heterocyclic aromatic compounds, characterized by a benzene ring fused to a pyridine ring. Industrially synthesized via Skraup or Doebner-Miller reactions using aniline derivatives. The methyl group at position 2 significantly alters odor profile compared to unsubstituted quinoline, reducing harshness while enhancing leathery aspects. Unlike many fragrance molecules, it lacks chirality due to its planar aromatic structure.
Physical & Chemical Properties
| Boiling Point | 247 °C |
|---|---|
| Density | 1.058 g/cm³ |
| Refractive Index | 1.616 |
| Flash Point | 107 °C |
| Vapor Pressure | 0.03 mmHg at 25°C |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.1-0.5% | Up to 1% | Exceeding 1% risks overwhelming composition |
| Leather Accord | 0.3-2% | Up to 3% | Always balanced with smoother materials |
| Tobacco Accord | 0.05-0.3% | Up to 0.5% | Provides ashy nuance |
| Fougère | 0.01-0.1% | Trace amounts | Adds vintage character |
Classic Accords
Tip: Always pre-dilute to 10% in ethanol before incorporating to prevent crystallization in final formula.
Alternatives & Comparisons
Softer, more floral-leather character with less medicinal harshness. Preferred for modern leather accords.
Harsher and more rubbery, used when extreme animalic effects are desired in trace amounts.
More tobacco-like with less leather impact, useful for smokier tobacco reconstructions.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
IFRA 49th Amendment restricts to 0.25% in leave-on products due to sensitization potential. No restrictions for rinse-off.
EU Allergen Declaration
Not listed in EU allergen regulation (EC) No 1223/2009.
GHS Classification
RIFM Assessment
RIFM evaluation confirms safe use at IFRA-restricted levels, with no evidence of phototoxicity or genotoxicity.
Sustainability
Synthesized from petrochemical precursors with relatively low environmental impact due to small usage volumes. No known natural sources, making synthetic production the only viable route. Manufacturing requires careful control of quinoline byproducts which can be aquatic toxins.
Explore 2-Methyl quinoline
Browse essential oils and aroma compounds.
Browse on iHerb →Affiliate disclosure: we may earn a small commission at no extra cost to you.
References
- Arctander, S. (1969). Perfume and Flavor Chemicals. Montclair, NJ.
- IFRA Standards (2021). 49th Amendment. IFRA 49
- Bickers et al. (2003). A toxicologic and dermatologic assessment of quinolines. Food Chem Toxicol. PMID 12804648
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorIngredient Data Sheet
CAS 91-63-4Physical Properties
| Molecular Weight | 143.18 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 2.6🔬 PubChem |
| Boiling Point | 247.6 °C🔬 EPA CompTox |
| Vapor Pressure | 0.0095 mmHg @ 25°C📊 OPERA |
| Flash Point | 79.4 °C🔬 EPA CompTox |
| Involatility Index | 0.0009💻 Calculated |
| log Kp (skin permeability) | -1.727💻 Calculated |
| SMILES | CC1=NC2=CC=CC=C2C=C1🔬 PubChem |
Volatility & Performance
| Fragrance Note | Heart💻 Calculated |
| Volatility Class | Very slow💻 Calculated |
| Persistence Score | 3.3 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | fishyherbaltobacco• leffingwell |
| Functional Groups | aromatic💻 RDKit |
| “The odor of the commercial product may vary considerably from that of the purified product. There are fishy, "ashtray"-like odors which seem to give way to sweeter, oily herbaceous notes in pure material. The tenacity is good, but the poor grade material has generally unpleasant terminal notes. Light amine-type notes in the initial odor and "extinguished cigar"-odor in the terminal notes are characteristic of commercial grade material.”📖 Arctander | |
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: DTXSID3040271
Physical Properties
| Molecular Weight | 143.189 g/mol🔬 EPA CompTox |
| Density | 1.058 g/cm^3🔬 EPA CTX |
| Boiling Point | 247.278 °C🔬 EPA CTX |
| Melting Point | -1.793 °C🔬 EPA CTX |
| Flash Point | 79.386 °C🔬 EPA CTX |
| Refractive Index | 1.625 Dimensionless📊 OPERA |
| Molar Volume | 133.048 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 2.59 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | 2.302 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 2.576 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 5.74 Log10 unitless📊 OPERA |
| Water Solubility | 0.017 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.009 mmHg🔬 EPA CTX |
| Viscosity | 4.671 cP📊 OPERA |
| Surface Tension | 41.653 dyn/cm📊 OPERA |
| Thermal Conductivity | 139.156 mW/(m*K)📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 12.89 Ų💻 Computed |
| H-Bond Donors | 0 count💻 Computed |
| H-Bond Acceptors | 1 count💻 Computed |
| Rotatable Bonds | 0 count💻 Computed |
| Aromatic Rings | 2 count💻 Computed |
| Molar Refractivity | 47.012 cm^3/mol📊 OPERA |
| Polarizability | 18.637 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.
