Phenylacetaldehyde (CAS 122-78-1) — Floral Top Note Fragrance Ingredient
Phenylacetaldehyde
CAS 122-78-1
What Is Phenylacetaldehyde?
Phenylacetaldehyde is a fragrant chemical found naturally in many flowers and foods. You’ll encounter its honey-like aroma in perfumes, soaps, and even some chocolates or baked goods. This ingredient matters because it’s a key building block for floral scents, especially hyacinth and rose accords. Its sweet-green character adds natural realism to fragrance compositions.
Safety Profile
USE WITH AWARENESS
What Does Phenylacetaldehyde Smell Like?
Phenylacetaldehyde bursts with an intense green-honey explosion, like crushing hyacinth petals between your fingers with a drop of buckwheat honey. The top note is sharply floral with a narcotic sweetness that quickly mellows into a warm, powdery heart reminiscent of lilac and rosewater. As it dries down, it reveals a subtle almond-like nuance and a clean, soapy undertone that makes it invaluable in floral bouquets. The scent evolves dramatically – from piercingly sweet to softly sophisticated over several hours.
Scent Profile
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used sparingly to enhance the floralcy of the May rose and jasmine heart, adding honeyed depth without overpowering the aldehydic sparkle.
Forms the core of the lily-of-the-valley accord, blending with hydroxycitronellal to create the iconic spring floral effect.
2D Molecular Structure
SMILES: O=CCC1=CC=CC=C1
Chemistry, Properties & Perfumer Guide
The Chemistry
Phenylacetaldehyde is an aromatic aldehyde with the formula C8H8O. It occurs naturally in many essential oils including rose, hyacinth, and citrus. Industrially produced via oxidation of phenylethyl alcohol or partial hydrogenation of cinnamaldehyde. The molecule’s reactivity makes it prone to dimerization, requiring stabilization for perfumery use. Its planar structure allows excellent diffusion through air while the aldehyde group contributes to its distinctive sharpness.
Physical & Chemical Properties
| Boiling Point | 195 °C |
|---|---|
| Density | 1.027 g/cm³ |
| Flash Point | 87 °C |
| Refractive Index | 1.525-1.535 |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-2% | Up to 5% | Floral modifier |
| Soap | 0.1-0.5% | Up to 1% | Stabilized form preferred |
Classic Accords
+ Benzyl Alcohol + Cinnamyl Alcohol = Hyacinth Absolute
Tip: Stabilize with propylene glycol or dipropylene glycol to prevent polymerization in bases.
Alternatives & Comparisons
More stable derivative with similar scent profile but slower evaporation rate, ideal for soap applications.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. IFRA, REACH, EU Cosmetics Regulation standards update periodically. Consult current IFRA Standards Library before formulating. Not legal or regulatory advice.
IFRA Status
No IFRA restrictions (as of Amendment 49).
EU Allergen Declaration
Must be declared when present above 0.01% in leave-on products (Annex III of EU Regulation No 1223/2009).
GHS Classification
H319
H335
RIFM Assessment
RIFM assessment confirms safe use at current industry levels with proper precautions for sensitization potential.
Sustainability
Primarily synthesized from petrochemical sources, though some natural isolates are available from rose oil distillation. Production processes have improved to reduce environmental impact through catalytic oxidation methods. Biotech routes using engineered yeast show promise for sustainable production.
Explore Phenylacetaldehyde
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Industry & Science Data
References
- Bauer et al. (2001). Common Fragrance and Flavor Materials. Wiley-VCH. ISBN 9783527619590
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Mar 2026.
Physicochemical Properties
DTXSID: DTXSID3021483
Physical Properties
| Molecular Weight | 120.151 g/mol🔬 EPA CompTox |
| Density | 1.032 g/cm^3🔬 EPA CTX |
| Boiling Point | 192.625 °C🔬 EPA CTX |
| Melting Point | 36.679 °C🔬 EPA CTX |
| Flash Point | 83 °C🔬 EPA CTX |
| Refractive Index | 1.514 Dimensionless📊 OPERA |
| Molar Volume | 119.569 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 1.749 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | 1.781 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 1.781 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 4.42 Log10 unitless📊 OPERA |
| Water Solubility | 0.025 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.949 mmHg🔬 EPA CTX |
| Viscosity | 1.761 cP📊 OPERA |
| Surface Tension | 35.134 dyn/cm📊 OPERA |
| Thermal Conductivity | 147.162 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 | 2 count💻 Computed |
| Aromatic Rings | 1 count💻 Computed |
| Molar Refractivity | 35.989 cm^3/mol📊 OPERA |
| Polarizability | 14.267 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.
