In short
Helional is a synthetic aldehyde with a fresh, watery-green and ozonic floral character. It became a signature material of the transparent aquatic and ozonic florals of the 1990s.
What Helional smells like
Helional (IFF) is a fresh, watery, green-floral aldehyde with an ozonic top. IFF describes it as green and floral (cyclamen), with top notes of ozone and new-mown hay; The Good Scents Company lists watery, fresh, green, ozone, cyclamen and hay. Other suppliers describe aldehydic, marine and muguet-like freshness, and one notes a cyclamen and sweet melon profile that is neither rich nor sweet.
- Leading note
- Watery green floral
- Clear facets
- Ozone, cyclamen
- Supporting facets
- New-mown hay
- Faint facets
- Melon
- Character
- Fresh, watery, airy, light
What makes Helional distinctive
The hay. Many ozonic aldehydes are watery and floral; Helional's top note also carries a new-mown-hay softness, which keeps its freshness from reading as purely marine.
How Helional is used
Used for fresh, watery and ozonic florals and green-floral effects, where it lends transparency and lift.
Typical role: lift (adds diffusion and radiance, especially at the top); modifier (used in small amounts to change the character of a blend).
How Helional differs from similar materials
- Floralozone
- Floralozone is a more neutral fresh-air, ocean-breeze note; Helional is greener and more floral, with cyclamen and hay.
- Cyclamen Aldehyde
- Cyclamen aldehyde is greener and more vegetal, with cucumber and melon; Helional is ozonic and hay-like, with cyclamen.
Each difference compares the published descriptions of the two materials. Smell varies with grade, supplier and dilution; compare them side by side on blotters before substituting one for another.
Formulation considerations
Covered by an IFRA Standard.
Identity and classification
- Type
- Aroma chemical
- Origin
- Synthetic
- Odour family
- Aquatic / Floral
- Note position
- Heart note
- Physical form at room temperature
- Liquid
- Also known as
- Heliobouquet
- CAS number
- 1205-17-0
- Molecular formula
- C11H12O3
- Molecular weight
- 192.21 g/mol
- IUPAC name
- 3-(1,3-benzodioxol-5-yl)-2-methylpropanal
The CAS number, formula and molecular weight are taken from PubChem compound 64805, whose own record lists this CAS number; checked 19 October 2026.
Safety and compliance
The IFRA Standards Library lists a Standard covering Helional:
- "alpha-Methyl-1,3-benzodioxole-5-propionaldehyde (MMDHCA)" — Restriction, 49th Amendment, published 2020-01
Limits differ by product category and are set out in the Standard itself; this page does not reproduce them. The list above reflects the library as read on 19 October 2026.
Hazard classification of the neat substance, as PubChem summarises it, read 26 October 2026. It has a harmonised EU classification (Regulation (EC) No 1272/2008, Annex VI): H317 may cause an allergic skin reaction. Companies notifying the ECHA C&L Inventory classify it (1,821 reports): H411 toxic to aquatic life with long lasting effects (97.7% of reports); H317 may cause an allergic skin reaction (42.3% of reports). A skin sensitiser classification concerns handling the neat material and the dose in a finished product; the IFRA Standards, where they apply, set the limits. Unless it is harmonised, this is the notifiers' own classification, not a binding one.
This page is general information, not a safety assessment or a specification. Confirm identity, composition, IFRA status and allergen content from your supplier's documents for the lot you hold.
Materials it works with
-
Calone
Aroma chemical · Aquatic / Metallic — marine, watermelon, ozonic, watery
-
Floralozone
Aroma chemical · Aquatic / Floral — ozonic, marine, floral, airy
-
Hedione
Aroma chemical · Floral / Citrus — jasmine, transparent, citrus, airy
-
Melonal
Aroma chemical · Aquatic / Fruity — melon, watery, green, fresh
Helional is also suggested as a partner on the pages for Cyclamen Aldehyde, Melafleur, Ozofleur, Precyclemone B and Scentenal.
Used in formulas and accords
Used in 18 published formulas
Helional is an ingredient in 18 accords in the Formula & Accord Library.
Further reading
Questions about Helional
Is Helional natural or synthetic?
Helional is synthetic — it is made by chemical synthesis.
What is the CAS number of Helional?
1205-17-0. It was checked against PubChem on 19 October 2026.
Which published formulas use Helional?
Helional is used in 18 published formulas in the RUŌOD Lab Formula & Accord Library, including Açaí Accord, Aperol Spritz Accord and Blue Accord. Each is listed with a link under "Used in formulas and accords" on this page.
Is Helional covered by an IFRA Standard?
Yes. The IFRA Standards Library lists a Standard covering it: "alpha-Methyl-1,3-benzodioxole-5-propionaldehyde (MMDHCA)" — Restriction, 49th Amendment. The limits depend on the product category; read the Standard itself before formulating.
Sources
- PubChem — compound 64805, checked 19 October 2026.
- PubChem — GHS classification (the ECHA C&L Inventory notifications and any harmonised EU entry), read 26 October 2026.
- IFRA — Standards Library, read 19 October 2026.
- IFF — Helional, via SpecialChem — manufacturer's description.
- The Good Scents Company — Helional — odour database.
- Wikipedia — Helional — published perfumery reference.
- Olfactory profile: the RUŌOD Lab team's synthesis of the published descriptions above, reviewed 20 October 2026. Evidence: several independent published descriptions, which agree. Classification and the short description: revision 1. Descriptions of odour are judgement, not measurement.