p-Isobutyl-alpha-methyl hydrocinnamaldehyde (CAS 6658-48-6) — Floral Heart Note Fragrance Ingredient

ByThe Good Scents
Floral · Sweet

p-Isobutyl-alpha-methyl hydrocinnamaldehyde

CAS 6658-48-6

Origin
synthetic
Note
Heart
IFRA
Generally safe
Data as of: Apr 2026

What Is p-Isobutyl-alpha-methyl hydrocinnamaldehyde?

p-Isobutyl-alpha-methyl hydrocinnamaldehyde is a synthetic fragrance ingredient used to add floral and powdery notes to perfumes. You’ll encounter it in various personal care products and fine fragrances. This molecule matters because it helps create sophisticated, long-lasting scent profiles that evolve beautifully on skin.

Safety Profile

GENERALLY SAFE
Generally safeUse with awarenessProfessional use
✓ Safe in regulated concentrations
⚠ Potential skin sensitizer – patch test recommended
CAS
6658-48-6
Formula
Mixture
MW
Variable
Odor Family
Floral · Sweet
Layer 1 · Enthusiast

What Does p-Isobutyl-alpha-methyl hydrocinnamaldehyde Smell Like?

This aldehyde delivers a complex bouquet that opens with soft floralcy reminiscent of lily-of-the-valley, transitioning to a powdery heart with subtle almond undertones. The dry-down reveals a warm, slightly woody character that lingers close to the skin. Its evolution resembles the unfolding of a silk handkerchief – first crisp, then softening into comforting warmth.

Scent Profile
Layer 2

2D Molecular Structure

3-(p-Cumenyl)-2-methylpropionaldehyde

SMILES: CC(C)CC1=CC=C(CC(C)C=O)C=C1

Chemistry, Properties & Perfumer Guide

The Chemistry

p-Isobutyl-alpha-methyl hydrocinnamaldehyde belongs to the phenylpropanoid class of aromatic aldehydes. It’s synthesized through Friedel-Crafts acylation followed by reduction and methylation steps. The alpha-methyl group creates steric hindrance that affects its reactivity and olfactory properties. As a synthetic molecule, it doesn’t occur naturally but mimics structural elements found in floral absolutes.

Physical & Chemical Properties

Perfumer Guide

Note Position
Heart
Volatility
Medium (2-4 hours)
Blending
Good
ApplicationTypical %RangeNotes
Fine Fragrance1-3%Up to 5%Floral-powdery modifier
Soap0.5-1%Up to 2%Stable in alkaline conditions

Classic Accords

Tip: Use with citrus top notes to brighten its powdery character.

Alternatives & Comparisons

1
Helional CAS 1205-17-0

More marine and ozonic character while maintaining similar floralcy.

2
Lilial CAS 80-54-6

Classic lily aldehyde with stronger floral impact but similar powdery dry-down.

Layer 3

Safety, Regulatory & Sustainability

⚠ Regulatory Disclaimer

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

IFRA Status

No current IFRA restrictions. Listed on IFRA Transparency List.

RIFM Assessment

RIFM has evaluated similar phenylpropanoid aldehydes as safe at current usage levels.

Sustainability

As a synthetic material, this aldehyde avoids agricultural impacts associated with natural materials. Its production requires petrochemical feedstocks but benefits from efficient modern organic synthesis methods with good atom economy.

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References

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

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    Ingredient Data Sheet

    CAS 6658-48-6

    Physical Properties

    Molecular Weight204.31 g/mol🔬 PubChem
    LogP (Octanol-Water)3.8🔬 PubChem
    Boiling Point257 °C🔬 EPA CompTox
    Vapor Pressure0.0013 mmHg @ 25°C📊 OPERA
    Flash Point70 °C🔬 EPA CompTox
    Involatility Index0.0001💻 Calculated
    log Kp (skin permeability)-1.248💻 Calculated
    SMILESCC(C)CC1=CC=C(C=C1)CC(C)C=O🔬 PubChem

    Volatility & Performance

    Fragrance NoteBase💻 Calculated
    Volatility ClassVery slow💻 Calculated
    Persistence Score6 / 5💻 Calculated

    Odor & Flavor

    Primary Descriptorsfloralsweet• leffingwell
    Functional Groupsaldehydearomatic💻 RDKit

    Regulatory Status

    IFRA ListedYes — see IFRA Standards for category limits⚖️ IFRA 51
    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: DTXSID4052346

    Physical Properties

    Molecular Weight 204.313 g/mol🔬 EPA CompTox
    Density 0.933 g/cm^3🔬 EPA CTX
    Boiling Point 257 °C🔬 EPA CTX
    Melting Point -4.4 °C🔬 EPA CTX
    Flash Point 70 °C🔬 EPA CTX
    Refractive Index 1.496 Dimensionless📊 OPERA
    Molar Volume 219.167 cm^3/mol📊 OPERA

    Partition & Solubility

    LogP (Octanol-Water) 3.933 Log10 unitless📊 OPERA
    LogD (pH 5.5) 3.933 Log10 unitless📊 OPERA
    LogD (pH 7.4) 3.933 Log10 unitless📊 OPERA
    LogKoa (Octanol-Air) 6.77 Log10 unitless📊 OPERA
    Water Solubility 0 mol/L🔬 EPA CTX
    Henry's Law Constant 0 atm-m3/mole📊 OPERA

    Transport Properties

    Vapor Pressure 0.001 mmHg🔬 EPA CTX
    Viscosity 5.72 cP📊 OPERA
    Surface Tension 32.73 dyn/cm📊 OPERA
    Thermal Conductivity 131.444 mW/(m*K)📊 OPERA

    Molecular Descriptors

    Topological Polar Surface Area 17.07 Ų💻 Computed
    H-Bond Donors 0 count💻 Computed
    H-Bond Acceptors 1 count💻 Computed
    Rotatable Bonds 5 count💻 Computed
    Aromatic Rings 1 count💻 Computed
    Molar Refractivity 63.987 cm^3/mol📊 OPERA
    Polarizability 25.366 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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