(+-)-Ethyl 3-mercapto-2-methylbutanoate (CAS 888021-82-7) — Citrus Top to middle Note Fragrance Ingredient

ByThe Good Scents
Citrus · Sweet

(+-)-Ethyl 3-mercapto-2-methylbutanoate

CAS 888021-82-7

Origin
synthetic
Note
Top to middle
IFRA
Use with awareness
Data as of: Apr 2026

What Is (+-)-Ethyl 3-mercapto-2-methylbutanoate?

(+-)-Ethyl 3-mercapto-2-methylbutanoate is a synthetic aroma compound used in modern perfumery to create tropical fruit effects, particularly in fragrances aiming for passionfruit or grapefruit nuances. Consumers encounter it in fruity-floral perfumes and some tropical-inspired body care products. This mercaptan derivative matters because it provides an intense, diffusive fruity character at very low concentrations, allowing perfumers to create photorealistic tropical effects without using actual fruit extracts which are often unstable or unavailable.

Safety Profile

USE WITH AWARENESS
Generally safeUse with awarenessProfessional use
✓ Effective at extremely low doses (ppb range)
⚠ Contains sulfur – may cause skin sensitivity
CAS
888021-82-7
Formula
Mixture
MW
Variable
Odor Family
Citrus · Sweet
Layer 1 · Enthusiast

What Does (+-)-Ethyl 3-mercapto-2-methylbutanoate Smell Like?

This sulfurous ester explodes with an intensely juicy, almost electric passionfruit burst – think of biting into an overripe tropical fruit where the sweetness borders on fermentation. The initial punch gradually softens into a more rounded grapefruit-peel character with a subtle savory edge reminiscent of freshly cut bell peppers. In drydown, it leaves a faintly musky, skin-like trail that helps anchor brighter top notes. At ultra-low concentrations, it behaves like nature’s own special effects generator for tropical fruit illusions.

Scent Profile

In Famous Fragrances

Fragrance associations may not reflect actual formulations.

Eau de Soleil Blanc(Tom Ford, 2016)

Used in trace amounts to amplify the solar floralcy, creating the illusion of sun-warmed tropical flowers without overwhelming citrus freshness.

Mango Skin(Maison Margiela, 2020)

Provides the hyperrealistic mango-peel effect in the opening, blending with lactonic notes to simulate fruit at perfect ripeness.

Layer 2

2D Molecular Structure

Butanoic acid, 3-mercapto-2-methyl-, ethyl ester

SMILES: CCOC(=O)C(C)C(C)S

Chemistry, Properties & Perfumer Guide

The Chemistry

This chiral thioester belongs to the family of branched-chain sulfur-containing fruit aroma compounds. The racemic mixture (±) form is typically used in perfumery. Synthesized via esterification of 3-mercapto-2-methylbutanoic acid with ethanol, often using Mitsunobu conditions. The thiol group at position 3 is responsible for its extremely low odor threshold (0.1 ng/L in air). The methyl branch at C2 introduces steric hindrance that modifies volatility and tenacity compared to linear analogs.

Physical & Chemical Properties

AppearanceColorless to pale yellow liquid
Odor Threshold0.1 ng/L in air

Perfumer Guide

Note Position
Top to middle
Volatility
Moderate (2-4 hours)
Blending
Challenging
ApplicationTypical %RangeNotes
Fine Fragrance0.01-0.1%Up to 0.5%Used in extreme dilution for tropical effects
Functional Fragrance0.001-0.01%Up to 0.05%Shampoos, conditioners where stability allows

Classic Accords

Tip: Always pre-dilute to 1% or lower before incorporation – direct use can overwhelm a formula.

Alternatives & Comparisons

1
Ethyl 2-methyl-3-furyl disulfide CAS 65530-53-2

For more roasted tropical fruit effects when a cooked/jammy character is desired rather than fresh-cut fruit.

Layer 3

Safety, Regulatory & Sustainability

⚠ Regulatory Disclaimer

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

IFRA Status

Not currently restricted by IFRA, though sulfur-containing compounds require careful handling.

GHS Classification

H315 Skin irritation H319 Eye irritation

RIFM Assessment

Under evaluation by RIFM. Preliminary data suggests safe use at current industry levels.

Sustainability

As a synthetic material, production avoids agricultural land use. However, synthesis requires careful waste management of sulfur byproducts. Some manufacturers are developing greener catalytic processes to reduce environmental impact.

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References

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

    Report a data error

    Ingredient Data Sheet

    CAS 888021-82-7

    Physical Properties

    Molecular Weight162.25 g/mol🔬 PubChem
    LogP (Octanol-Water)1.7🔬 PubChem
    Boiling Point203 °C🔬 EPA CompTox
    Vapor Pressure0.871 mmHg @ 25°C📊 OPERA
    Flash Point78 °C🔬 EPA CompTox
    Involatility Index0.0737💻 Calculated
    log Kp (skin permeability)-2.483💻 Calculated
    SMILESCCOC(=O)C(C)C(C)S🔬 PubChem

    Volatility & Performance

    Fragrance NoteTop💻 Calculated
    Volatility ClassSlow💻 Calculated
    Persistence Score0.5 / 5💻 Calculated

    Odor & Flavor

    Primary Descriptorscitrussweet• leffingwell
    Functional Groupsesteretherthiol💻 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: DTXSID70889228

    Physical Properties

    Molecular Weight 162.25 g/mol🔬 EPA CompTox
    Density 1.07 g/cm^3📊 OPERA
    Boiling Point 205.53 °C📊 OPERA
    Melting Point -22.248 °C📊 OPERA
    Flash Point 82.008 °C📊 OPERA
    Refractive Index 1.455 Dimensionless📊 OPERA
    Molar Volume 162.366 cm^3/mol📊 OPERA

    Partition & Solubility

    LogP (Octanol-Water) 1.91 Log10 unitless📊 OPERA
    LogD (pH 5.5) 1.91 Log10 unitless📊 OPERA
    LogD (pH 7.4) 1.875 Log10 unitless📊 OPERA
    LogKoa (Octanol-Air) 3.94 Log10 unitless📊 OPERA
    Water Solubility 0.021 mol/L📊 OPERA
    Henry's Law Constant 0 atm-m3/mole📊 OPERA

    Transport Properties

    Vapor Pressure 0.491 mmHg📊 OPERA
    Viscosity 1.397 cP📊 OPERA
    Surface Tension 28.961 dyn/cm📊 OPERA

    Molecular Descriptors

    Topological Polar Surface Area 26.3 Ų💻 Computed
    H-Bond Donors 1 count💻 Computed
    H-Bond Acceptors 3 count💻 Computed
    Rotatable Bonds 3 count💻 Computed
    Aromatic Rings 0 count💻 Computed
    Molar Refractivity 44.067 cm^3/mol📊 OPERA
    Polarizability 17.47 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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