In short
p-Tolylacetaldehyde, sold as lilac acetaldehyde, is a powerful aldehyde with a green-fruity, sweet floral odour. It is phenylacetaldehyde with a para methyl group.
What p-Tolylacetaldehyde smells like
JECFA, as published by PubChem, describes p-tolylacetaldehyde as a colourless oily liquid with a powerful, refreshing, green-fruity, forest-like, sweet floral odour. PubChem lists lilac acetaldehyde among its synonyms. That is the only published description gathered here.
- Leading note
- Green floral
- Supporting facets
- Fruity, forest-like
- Character
- Powerful, refreshing
What makes p-Tolylacetaldehyde distinctive
Phenylacetaldehyde's green, but sweeter and more forest-like.
How p-Tolylacetaldehyde is used
Its documented use is as a flavouring agent, evaluated by JECFA; PubChem lists lilac acetaldehyde among its names. In perfumery it is used for the powerful green-fruity, sweet floral note JECFA describes, in lilac and other green floral accords.
Typical role: modifier (used in small amounts to change the character of a blend).
How p-Tolylacetaldehyde differs from similar materials
- Phenylacetaldehyde
- Phenylacetaldehyde is the sharp, green hyacinth aldehyde; p-tolylacetaldehyde is described as green-fruity, forest-like and sweeter.
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
Aldehydes of this kind are often kept as dilutions or acetals for stability.
Identity and classification
- Type
- Aroma chemical
- Origin
- Synthetic
- Odour family
- Floral / Green
- Note position
- Top to heart note
- Physical form at room temperature
- Liquid
- Also known as
- Lilac acetaldehyde, 4-Methylphenylacetaldehyde
- CAS number
- 104-09-6
- Molecular formula
- C9H10O
- Molecular weight
- 134.17 g/mol
- IUPAC name
- 2-(4-methylphenyl)acetaldehyde
The CAS number, formula and molecular weight are taken from PubChem compound 61006, whose own record lists this CAS number; checked 24 October 2026.
Safety and compliance
Hazard classification of the neat substance, as PubChem summarises it, read 26 October 2026. Companies notifying the ECHA C&L Inventory classify it (356 reports): H317 may cause an allergic skin reaction (89.3% of reports); H318 causes serious eye damage (10.7% 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
-
Phenylacetaldehyde
Aroma chemical · Green / Floral — green, honeyed, hyacinth, floral
-
Terpinen-4-ol
Aroma chemical · Aromatic / Spicy — spicy, herbal, woody, earthy
-
Heliotropin
Aroma chemical · Powdery / Gourmand — powdery, almond, vanilla, floral
Used in formulas and accords
Used in 2 published formulas
p-Tolylacetaldehyde is an ingredient in 1 perfume formula and 1 accord in the Formula & Accord Library.
Community formulas
RUŌOD House Originals
Original compositions by RUŌOD House.
Further reading
Questions about p-Tolylacetaldehyde
Is p-Tolylacetaldehyde natural or synthetic?
p-Tolylacetaldehyde is synthetic — it is made by chemical synthesis.
What is the CAS number of p-Tolylacetaldehyde?
104-09-6. It was checked against PubChem on 24 October 2026.
Which published formulas use p-Tolylacetaldehyde?
p-Tolylacetaldehyde is used in 2 published formulas in the RUŌOD Lab Formula & Accord Library: Bell Glass and Narcotic Floral Accord. Each is listed with a link under "Used in formulas and accords" on this page.
Sources
- PubChem — compound 61006, checked 24 October 2026.
- PubChem — GHS classification (the ECHA C&L Inventory notifications and any harmonised EU entry), read 26 October 2026.
- PubChem — Lilac acetaldehyde (CID 61006): JECFA organoleptic description — odour database.
- Olfactory profile: the RUŌOD Lab team's synthesis of the published descriptions above, reviewed 26 October 2026. Evidence: few published descriptions; treat the detail with caution. Classification and the short description: revision 1. Descriptions of odour are judgement, not measurement.