RUŌOD Lab

Hydratropic Aldehyde

Aroma chemical · Green / Floral

green, hyacinth, sharp, floral — top to heart note.

Aroma illustration for Hydratropic Aldehyde: green leaves and spikes of blue hyacinth flowers, for its green and hyacinth notes. It illustrates smell associations, not the material or its source.Skeletal formula of Hydratropic Aldehyde (2-Phenylpropanal), C9H10O, drawn from PubChem's 2D record. Stereochemistry is not shown.
Aroma View: an illustration of what Hydratropic Aldehyde smells like (green, hyacinth), drawn by RUŌOD Lab — not its appearance or its source.Skeletal formula drawn by RUŌOD Lab from PubChem's 2D record (CID 7146). Stereochemistry is not shown; the coloured background is decoration.
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By the RUŌOD Lab TeamRevision 1Updated

In short

Hydratropic aldehyde is 2-phenylpropanal, a sharp green aromatic aldehyde with a hyacinth-like character. It is used in small amounts to give green lift to floral accords.

What Hydratropic Aldehyde smells like

Hydratropic aldehyde (2-phenylpropanal) is a fresh, sharp green aldehyde of the hyacinth type. A fragrance reference describes a fresh, green, leafy-floral, tart, hyacinth odour; The Good Scents Company lists fresh, sharp, green, hyacinth leaf and lilac. It is used in perfumes chiefly for its green hyacinth note.

Leading note
Fresh green hyacinth
Clear facets
Hyacinth leaf
Supporting facets
Lilac, tart
Character
Fresh, sharp, green, tart
  • green
  • hyacinth
  • sharp
  • floral

What makes Hydratropic Aldehyde distinctive

Its tart, leafy freshness. It is the hyacinth aldehyde that leans to the leaf and to lilac, without phenylacetaldehyde's honey or hydrocinnamaldehyde's heavier balsamic body.

How Hydratropic Aldehyde is used

Used for green hyacinth and lilac effects and to freshen spring florals.

Typical role: modifier (used in small amounts to change the character of a blend).

How Hydratropic Aldehyde differs from similar materials

Phenylacetaldehyde
Phenylacetaldehyde is sweeter and honeyed; hydratropic aldehyde is fresher, leafier and tart, with lilac.
Hydrocinnamaldehyde
Its side-chain isomer, hydrocinnamaldehyde, is heavier and balsamic, with a melon-like note; hydratropic aldehyde is the fresher, leafier, more directly hyacinth one.
Trifernal
Trifernal is a bitter, crushed-foliage green; hydratropic aldehyde keeps a floral, lilac-hyacinth character within its greenness.

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

Reactive and prone to oxidation; it is often used in a more stable acetal form. Work from dilution.

Identity and classification

Type
Aroma chemical
Origin
Synthetic
Odour family
Green / Floral
Note position
Top to heart note
Physical form at room temperature
Liquid
Also known as
2-Phenylpropanal, 2-Phenylpropionaldehyde
CAS number
93-53-8
Molecular formula
C9H10O
Molecular weight
134.17 g/mol
IUPAC name
2-phenylpropanal

The CAS number, formula and molecular weight are taken from PubChem compound 7146, whose own record lists this CAS number; checked 19 October 2026.

Safety and compliance

The IFRA Standards Library lists a Standard covering Hydratropic Aldehyde:

  • "2-Phenylpropionaldehyde" — 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. Companies notifying the ECHA C&L Inventory classify it (1,680 reports): H315 causes skin irritation (100% of reports); H319 causes serious eye irritation (100% of reports); H317 may cause an allergic skin reaction (93.2% of reports); H361 suspected of damaging fertility or the unborn child (83.6% 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

Used in formulas and accords

Not currently used in any published formula.

The Formula & Accord Library lists Hydratropic Aldehyde here as soon as a published formula, accord or base uses it.

Further reading

Questions about Hydratropic Aldehyde

Is Hydratropic Aldehyde natural or synthetic?

Hydratropic Aldehyde is synthetic — it is made by chemical synthesis.

What is the CAS number of Hydratropic Aldehyde?

93-53-8. It was checked against PubChem on 19 October 2026.

Is Hydratropic Aldehyde covered by an IFRA Standard?

Yes. The IFRA Standards Library lists a Standard covering it: "2-Phenylpropionaldehyde" — Restriction, 49th Amendment. The limits depend on the product category; read the Standard itself before formulating.

Sources

Your own records, next to the reference

Keep your own record of Hydratropic Aldehyde — supplier, cost, stock, dilutions and where it is used — in RUŌOD Lab's material library.

The material library All materials