2-(4-Methyl-2-hydroxyphenyl)propionic acid-gamma-lactone (CAS 65817-24-5) — Woody Base Note Fragrance Ingredient

ByThe Good Scents
Woody · Balsamic

2-(4-Methyl-2-hydroxyphenyl)propionic acid-gamma-lactone

CAS 65817-24-5

Origin
synthetic
Note
Base
IFRA
Use with awareness
Data as of: Apr 2026

What Is 2-(4-Methyl-2-hydroxyphenyl)propionic acid-gamma-lactone?

This synthetic lactone is a specialized fragrance ingredient used in modern perfumery to create unique woody-ambergris effects. It’s found in niche fragrances seeking unconventional olfactory profiles. While not widely recognized by name, its subtle presence contributes depth and diffusion to contemporary scent compositions.

Safety Profile

USE WITH AWARENESS
Generally safeUse with awarenessProfessional use
✓ IFRA-compliant at standard usage levels
⚠ Limited safety data – professional handling recommended
CAS
65817-24-5
Formula
Mixture
MW
Variable
Odor Family
Woody · Balsamic
Layer 1 · Enthusiast

What Does 2-(4-Methyl-2-hydroxyphenyl)propionic acid-gamma-lactone Smell Like?

A complex lactonic molecule presenting a sophisticated interplay of woody, ambery, and slightly animalic facets. Opens with a dry cedar-like sharpness that evolves into a warm, musky heart reminiscent of sun-bleached driftwood. The dry-down reveals subtle salty-sweet nuances akin to ambergris, with exceptional tenacity on skin. Acts as a powerful diffuser at minute concentrations, adding lift to heavy bases without dominating compositions.

Scent Profile
Layer 2

2D Molecular Structure

3,6-Dimethyl-1-benzofuran-2(3H)-one

SMILES: CC1C(=O)OC2=C1C=CC(C)=C2

Chemistry, Properties & Perfumer Guide

The Chemistry

This gamma-lactone derivative belongs to the phenylpropionic acid lactone class, synthesized through intramolecular esterification of the corresponding hydroxy acid. The methyl substitution at the 4-position and hydroxyl at the 2-position create unique steric constraints influencing its odor profile. Industrial synthesis typically involves cyclization of pre-functionalized phenylpropionic acid precursors under controlled conditions.

Physical & Chemical Properties

Molecular ClassPhenylpropionic acid lactone
ComplexityModerate (194)

Perfumer Guide

Note Position
Base
Volatility
Very low (8+ hours)
Blending
Challenging
ApplicationTypical %RangeNotes
Fine Fragrance0.1-0.5%Up to 1%Powerful base note modifier
Functional Fragrance0.01-0.1%Up to 0.3%Used sparingly for diffusion

Classic Accords

Tip: Use below 0.5% to avoid overwhelming compositions – acts as a powerful diffuser.

Alternatives & Comparisons

1
Ambroxan CAS 6790-58-5

More transparent ambergris alternative with better blending properties

2
γ-Methyl Ionone CAS 1335-46-2

Woody-violet alternative for similar diffusion effects

Layer 3

Safety, Regulatory & Sustainability

⚠ Regulatory Disclaimer

General reference only. Consult current IFRA Standards Library before formulating.

IFRA Status

Not currently restricted under IFRA standards. General lactone guidelines apply (Amendment 49).

RIFM Assessment

Limited safety assessment available. Considered safe at current usage levels based on structural analogs.

Sustainability

Synthetic production minimizes environmental impact compared to natural ambergris sourcing. Manufacturing requires controlled conditions with moderate energy input. No known ecological hazards at production scale.

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References

  1. Brenna et al. (2012). Lactones in Fragrance Chemistry. Flavour and Fragrance Journal.

Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.

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Ingredient Data Sheet

CAS 65817-24-5

Physical Properties

Molecular Weight162.18 g/mol🔬 PubChem
LogP (Octanol-Water)2.3🔬 PubChem
Boiling Point64 °C🔬 EPA CompTox
log Kp (skin permeability)-2.056💻 Calculated
SMILESCC1C2=C(C=C(C=C2)C)OC1=O🔬 PubChem

Volatility & Performance

Fragrance NoteTop💻 Calculated

Odor & Flavor

Functional Groupsesteretheraromatic💻 RDKit
Data Sources & Attribution
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: DTXSID30984309

Physical Properties

Molecular Weight 162.188 g/mol🔬 EPA CompTox
Density 1.144 g/cm^3📊 OPERA
Boiling Point 265.68 °C📊 OPERA
Melting Point 53.082 °C📊 OPERA
Flash Point 104.265 °C📊 OPERA
Refractive Index 1.546 Dimensionless📊 OPERA
Molar Volume 142.332 cm^3/mol📊 OPERA

Partition & Solubility

LogP (Octanol-Water) 1.927 Log10 unitless📊 OPERA
LogD (pH 5.5) 1.927 Log10 unitless📊 OPERA
LogD (pH 7.4) 1.927 Log10 unitless📊 OPERA
LogKoa (Octanol-Air) 6.09 Log10 unitless📊 OPERA
Water Solubility 0.008 mol/L📊 OPERA
Henry's Law Constant 0 atm-m3/mole📊 OPERA

Transport Properties

Vapor Pressure 0.024 mmHg📊 OPERA
Viscosity 4.972 cP📊 OPERA
Surface Tension 38.377 dyn/cm📊 OPERA

Molecular Descriptors

Topological Polar Surface Area 26.3 Ų💻 Computed
H-Bond Donors 0 count💻 Computed
H-Bond Acceptors 2 count💻 Computed
Rotatable Bonds 0 count💻 Computed
Aromatic Rings 1 count💻 Computed
Molar Refractivity 45.084 cm^3/mol📊 OPERA
Polarizability 17.873 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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