Phenylacetaldehyde 2,4-dihydroxy-2-methylpentane acetal (CAS 67633-94-7) — Floral Heart Note Fragrance Ingredient
Phenylacetaldehyde 2,4-dihydroxy-2-methylpentane acetal
CAS 67633-94-7
What Is Phenylacetaldehyde 2,4-dihydroxy-2-methylpentane acetal?
Phenylacetaldehyde 2,4-dihydroxy-2-methylpentane acetal is a synthetic fragrance ingredient used to add floral-honey nuances to perfumes. It’s found in fine fragrances and personal care products. This molecule matters because it provides stability to phenylacetaldehyde’s delicate floral character while enhancing its honeyed sweetness, making fragrances last longer without losing their natural appeal.
Safety Profile
USE WITH AWARENESSWhat Does Phenylacetaldehyde 2,4-dihydroxy-2-methylpentane acetal Smell Like?
Opens with a burst of waxy-green hyacinth absolute, quickly settling into a narcotic floral heart reminiscent of orange blossom petals dipped in honey. The dry-down reveals a subtle powdery-musky undertone that lingers like the memory of spring flowers. Compared to free phenylacetaldehyde, this acetal form is rounder and more tenacious, with less of the sharp green edges.
2D Molecular Structure
SMILES: CC1CC(C)(C)OC(CC2=CC=CC=C2)O1
Chemistry, Properties & Perfumer Guide
The Chemistry
This phenylacetaldehyde acetal belongs to the class of cyclic acetals, formed by reacting phenylacetaldehyde with 2-methyl-2,4-pentanediol. The acetal formation protects the reactive aldehyde group while maintaining the floral character. Synthesized via acid-catalyzed condensation, it offers improved stability over the parent aldehyde. The structure features a six-membered 1,3-dioxane ring with pendant phenyl and methyl groups.
Physical & Chemical Properties
| Appearance | Colorless to pale yellow liquid |
|---|---|
| Boiling Point | Not available |
| Density | Not available |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-2% | Up to 5% | Floral modifier |
| Soap | 0.1-0.5% | Up to 1% | Stable in alkaline systems |
| Shampoo | 0.05-0.2% | Up to 0.5% | Provides floral lift |
Classic Accords
Tip: Use in floral bouquets to add diffusion and honeyed nuances without the instability of free phenylacetaldehyde.
Alternatives & Comparisons
More volatile but less honeyed, useful when a brighter floral top note is desired.
Offers greater water solubility for applications requiring better dispersion in aqueous systems.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not currently restricted under IFRA standards. Considered safe at typical usage levels.
RIFM Assessment
Not currently evaluated by RIFM. Considered safe based on structural analogs.
Sustainability
As a synthetic material, this acetal avoids the agricultural impacts of natural floral absolutes. Production typically involves petrochemical feedstocks, though green chemistry routes using bio-based phenylacetaldehyde are being explored. Offers efficient scent delivery compared to natural extracts.
Explore Phenylacetaldehyde 2,4-dihydroxy-2-methylpentane acetal
Browse essential oils and aroma compounds.
Browse on iHerb →Affiliate disclosure: we may earn a small commission at no extra cost to you.
References
- Bauer et al. (2001). Common Fragrance and Flavor Materials. Wiley-VCH.
- Arctander, S. (1969). Perfume and Flavor Chemicals. Allured Publishing.
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorIngredient Data Sheet
CAS 67633-94-7Physical Properties
| Molecular Weight | 220.31 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 3.2🔬 PubChem |
| Boiling Point | 267.7 °C🔬 EPA CompTox |
| Vapor Pressure | 0.0051 mmHg @ 25°C📊 OPERA |
| Flash Point | 94.5 °C🔬 EPA CompTox |
| Involatility Index | 0.0004💻 Calculated |
| log Kp (skin permeability) | -1.772💻 Calculated |
| SMILES | CC1CC(OC(O1)CC2=CC=CC=C2)(C)C🔬 PubChem |
Volatility & Performance
| Fragrance Note | Heart💻 Calculated |
| Volatility Class | Very slow💻 Calculated |
| Persistence Score | 4.6 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | balsamicfloralgreen• leffingwell |
| Functional Groups | etheraromatic💻 RDKit |
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: DTXSID3052351
Physical Properties
| Molecular Weight | 220.312 g/mol🔬 EPA CompTox |
| Density | 0.996 g/cm^3🔬 EPA CTX |
| Boiling Point | 267.7 °C🔬 EPA CTX |
| Melting Point | 48.446 °C📊 OPERA |
| Flash Point | 94.5 °C🔬 EPA CTX |
| Refractive Index | 1.488 Dimensionless📊 OPERA |
| Molar Volume | 225.248 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 3.9 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | 3.271 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 3.271 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 7.06 Log10 unitless📊 OPERA |
| Water Solubility | 0.002 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.005 mmHg🔬 EPA CTX |
| Viscosity | 7.359 cP📊 OPERA |
| Surface Tension | 35.081 dyn/cm📊 OPERA |
| Thermal Conductivity | 124.682 mW/(m*K)📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 18.46 Ų💻 Computed |
| H-Bond Donors | 0 count💻 Computed |
| H-Bond Acceptors | 2 count💻 Computed |
| Rotatable Bonds | 2 count💻 Computed |
| Aromatic Rings | 1 count💻 Computed |
| Molar Refractivity | 64.853 cm^3/mol📊 OPERA |
| Polarizability | 25.71 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.
