Hydroxycitronellal propyleneglycol acetal (CAS 93804-64-9) — Floral Middle-top Note Fragrance Ingredient
Hydroxycitronellal propyleneglycol acetal
CAS 93804-64-9
What Is Hydroxycitronellal propyleneglycol acetal?
Hydroxycitronellal propyleneglycol acetal is a synthetic fragrance ingredient used to enhance floral and citrus notes in perfumes and personal care products. It’s commonly found in fine fragrances, soaps, and shampoos. This molecule helps create long-lasting freshness in perfumery, acting as a fixative that extends the life of lighter top notes while adding a subtle green-floral character.
Safety Profile
USE WITH AWARENESSWhat Does Hydroxycitronellal propyleneglycol acetal Smell Like?
Hydroxycitronellal propyleneglycol acetal opens with a crisp, dewy freshness reminiscent of morning grass with citrus peel undertones. As it evolves, a delicate floral heart emerges – like lily-of-the-valley petals floating in lemon water. The dry-down reveals a soft woody-green character, more tenacious than its parent hydroxycitronellal, with a clean laundry-like finish. Compared to hydroxycitronellal, the acetal form has reduced sweetness and greater diffusion, making it particularly useful for modern fresh-floral compositions where transparency is desired.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used here for its energizing citrus-floral effect that blends seamlessly with rosemary and citrus notes, creating the fragrance’s signature ‘wellness’ accord.
Contributes to the crisp top notes alongside citrus and mint, enhancing the fragrance’s refreshing green character without overpowering the delicate tea accord.
Chemistry, Properties & Perfumer Guide
The Chemistry
Hydroxycitronellal propyleneglycol acetal is a cyclic acetal derived from the reaction of hydroxycitronellal with propylene glycol. This modification increases the molecule’s stability and longevity compared to its aldehyde precursor. The acetal formation protects the reactive aldehyde group while maintaining the desirable floral-citrus odor profile. Industrial synthesis typically involves acid-catalyzed condensation under controlled conditions to prevent polymerization. The resulting material exists as a mixture of stereoisomers, with the cis/trans ratio affecting the precise odor characteristics.
Physical & Chemical Properties
| Appearance | Colorless to pale yellow liquid |
|---|---|
| Solubility | Soluble in alcohol, insoluble in water |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 1-3% | Up to 5% | Floral-fresh compositions |
| Soap | 0.5-1.5% | Up to 2% | Adds freshness stability |
| Shampoo | 0.2-0.8% | Up to 1% | Clean floral effects |
Classic Accords
Tip: Use in citrus-floral bases where you need enhanced diffusion and longevity compared to hydroxycitronellal.
Alternatives & Comparisons
The parent aldehyde offers more sweetness and floral intensity but lacks the stability and diffusion of the acetal form.
For stronger lily-of-the-valley character, though with greater sensitization potential and regulatory restrictions.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No specific restrictions under current IFRA standards (as of 49th Amendment). Use within general acetal guidelines.
GHS Classification
RIFM Assessment
Considered safe for current fragrance use levels based on RIFM evaluation of structural analogs.
Sustainability
As a synthetic material, hydroxycitronellal propyleneglycol acetal avoids natural resource depletion concerns. Modern production methods focus on efficient catalysis and reduced solvent use. Being more stable than hydroxycitronellal, it may reduce overall fragrance load requirements in formulations.
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References
- Bauer, K. et al. (2001). Common Fragrance and Flavor Materials. Wiley-VCH. ISBN 9783527302568
- IFRA Standards Library IFRA 49th Amendment
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
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