Hexyl 2-hydroxypropionate (CAS 20279-51-0) — Green Top to middle Note Fragrance Ingredient

ByThe Good Scents
Green · Sweet

Hexyl 2-hydroxypropionate

CAS 20279-51-0

Origin
synthetic
Note
Top to middle
IFRA
Generally safe
Data as of: Apr 2026

What Is Hexyl 2-hydroxypropionate?

Hexyl 2-hydroxypropionate is a synthetic ester used in perfumery to create fresh, fruity, and slightly floral notes. It’s commonly found in personal care products like body washes, shampoos, and air fresheners. This ingredient matters because it adds a crisp, green-fruity character that blends well with citrus and floral compositions, making fragrances feel more vibrant and natural.

Safety Profile

GENERALLY SAFE
Generally safeUse with awarenessProfessional use
✓ No known major safety concerns
⚠ Always patch test new formulations
CAS
20279-51-0
Formula
Mixture
MW
Variable
Odor Family
Green · Sweet
Layer 1 · Enthusiast

What Does Hexyl 2-hydroxypropionate Smell Like?

Hexyl 2-hydroxypropionate opens with a burst of fresh green apple peel and unripe pear, transitioning to a subtle floral heart reminiscent of lily-of-the-valley. The dry-down reveals a clean, slightly woody undertone with a whisper of citrus zest. Its character is like walking through an orchard at dawn – dewy, crisp, and alive with potential.

Scent Profile

In Famous Fragrances

Fragrance associations may not reflect actual formulations.

Eau Dynamisante(Clarins, 1987)

Used here to amplify the invigorating citrus-greenery effect, pairing with bergamot and geranium for a tonic-like freshness.

Un Jardin Sur Le Nil(Hermès, 2005)

Provides the ‘just-picked’ green mango facet that makes this aquatic garden composition so distinctive.

Layer 2

2D Molecular Structure

Hexyl 2-hydroxypropanoate

SMILES: CCCCCCOC(=O)C(C)O

Chemistry, Properties & Perfumer Guide

The Chemistry

Hexyl 2-hydroxypropionate is an ester formed from hexanol and lactic acid. While not found in nature, it mimics certain fruity esters occurring in apples and pears. Industrial synthesis typically involves esterification under acidic conditions. Its molecular structure allows both hydrophilic and lipophilic interactions, contributing to its diffusive yet substantive character in fragrance compositions.

Physical & Chemical Properties

AppearanceColorless liquid
Odor StrengthMedium
SolubilitySoluble in alcohol, oils; slightly soluble in water

Perfumer Guide

Note Position
Top to middle
Volatility
Medium (2-4 hours)
Blending
Good
ApplicationTypical %RangeNotes
Fine Fragrance1-3%Up to 5%For fresh top notes
Functional Products0.5-2%Up to 3%In shampoos, soaps

Classic Accords

Tip: Use with citrus oils to prevent harshness in the top notes.

Alternatives & Comparisons

1
Hexyl acetate CAS 142-92-7

More intensely fruity (pear-like) but less tenacious. Better for immediate impact formulations.

Layer 3

Safety, Regulatory & Sustainability

⚠ Regulatory Disclaimer

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

IFRA Status

Not restricted under current IFRA standards.

RIFM Assessment

Considered safe for current use levels based on RIFM evaluation.

Sustainability

As a synthetic material, hexyl 2-hydroxypropionate has consistent quality without natural sourcing variations. Production can utilize green chemistry principles to minimize waste. Being fully biodegradable, it doesn’t accumulate in the environment.

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References

  1. Bauer et al. (2001). Common Fragrance and Flavor Materials. Wiley-VCH.

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

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Ingredient Data Sheet

CAS 20279-51-0

Physical Properties

Molecular Weight174.24 g/mol🔬 PubChem
LogP (Octanol-Water)2.2🔬 PubChem
Boiling Point222 °C🔬 EPA CompTox
Vapor Pressure0.0126 mmHg @ 25°C📊 OPERA
Flash Point87.4 °C🔬 EPA CompTox
Involatility Index0.001💻 Calculated
log Kp (skin permeability)-2.201💻 Calculated
SMILESCCCCCCOC(=O)C(C)O🔬 PubChem

Volatility & Performance

Fragrance NoteHeart💻 Calculated
Volatility ClassVery slow💻 Calculated
Persistence Score3.1 / 5💻 Calculated

Odor & Flavor

Primary Descriptorsfloralsweet• leffingwell
Functional Groupsesteralcoholether💻 RDKit

Sensory Thresholds

Odor Detection Threshold42.4146 ppm (n=2)📖 van Gemert
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: DTXSID90864931

Physical Properties

Molecular Weight 174.24 g/mol🔬 EPA CompTox
Density 0.965 g/cm^3📊 OPERA
Boiling Point 229.211 °C📊 OPERA
Melting Point -18.744 °C📊 OPERA
Flash Point 93.33 °C📊 OPERA
Refractive Index 1.44 Dimensionless📊 OPERA
Molar Volume 178.461 cm^3/mol📊 OPERA

Partition & Solubility

LogP (Octanol-Water) 2.266 Log10 unitless📊 OPERA
LogD (pH 5.5) 2.266 Log10 unitless📊 OPERA
LogD (pH 7.4) 2.226 Log10 unitless📊 OPERA
LogKoa (Octanol-Air) 6.63 Log10 unitless📊 OPERA
Water Solubility 0.074 mol/L🔬 EPA CTX
Henry's Law Constant 0 atm-m3/mole📊 OPERA

Transport Properties

Vapor Pressure 0.025 mmHg📊 OPERA
Viscosity 5.496 cP📊 OPERA
Surface Tension 32.265 dyn/cm📊 OPERA
Thermal Conductivity 153.701 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 6 count💻 Computed
Aromatic Rings 0 count💻 Computed
Molar Refractivity 47.013 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.

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