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Melonal

Q: Is Melonal natural or synthetic?

. Extraction: Fully synthetic. Produced via Darzens reaction (condensation of methylheptenone with ethyl chloroacetate, saponification, decarboxylation). Yellow liquid, powerful odor at low concentrations..

POPULAR AND WEIRD / fresh · fruity · sweet

Melonal

Category	POPULAR AND WEIRD
Subcategory	fresh · fruity · sweet
Origin
Volatility	Top Note
Botanical	N/A — synthetic molecule (2,6-dimethyl-5-heptenal)
Appearance	Colorless to pale yellow clear liquid
Odor Strength	High
Producing Countries	N/A — synthetic molecule (manufactured globally)
Pyramid	Top

Sliced watermelon rind in a molecule. Green, tart, wet -- the smell of summer cut open.

Scent
The Full Story
Fun Fact
Extraction & Chemistry
In Perfumery

Scent

Green, wet, and tart. The immediate impression is watermelon rind -- not the sweet pink flesh, but the pale green edge where fruit meets skin. A cucumber-like freshness runs underneath, with faint ozonic qualities at the periphery. More natural-smelling than Calone, less synthetic than Helional. Powerful at threshold; use with a light hand.

Evolution over time

Immediately

Bright green melon burst, watermelon rind, cucumber

After a few hours

Faint green trace, rapidly fading

After a few days

Gone. Melonal is a pure top note with no base persistence.

The Full Story

Melonal (CAS 106-72-9) is 2,6-dimethyl-5-heptenal, a synthetic aldehyde with the formula C9H16O and MW 140.2. It appears as a yellow liquid with a powerful green, melon-rind, and cucumber odor. The molecule has an asymmetric carbon producing two enantiomers, but only the racemic mixture is used commercially.

Melonal is synthesized via a Darzens reaction between 6-methyl-5-hepten-2-one and ethyl chloroacetate, yielding a glycidate that is saponified and decarboxylated to produce the final aldehyde. The process is well-established and the molecule is available from multiple suppliers.

In perfumery, Melonal is used across all fragrance families for marine, melon, cucumber, and green-fruity effects. It is a powerful material -- best used below 1% in concentrates -- that imparts natural-smelling freshness to top notes. Its volatility is high, so it functions strictly as a top note, flashing bright and then receding within the first hour.

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Did You Know?

Did you know?

Melonal's odor threshold is so low that a single drop can scent an entire room. Perfumers typically work with pre-diluted solutions (1-10% in DPG or IPM) to avoid accidental overdosing in formulations.

Extraction & Chemistry

Extraction method: Fully synthetic. Produced via Darzens reaction (condensation of methylheptenone with ethyl chloroacetate, saponification, decarboxylation). Yellow liquid, powerful odor at low concentrations.

Molecular Formula	C9H16O
CAS Number	106-72-9
Botanical Name	N/A — synthetic molecule (2,6-dimethyl-5-heptenal)
IFRA Status	No known restrictions
Synonyms	melon aldehyde, 2,6-dimethyl-5-heptenal, Melozone
Physical Properties
Odor Strength	High
Lasting Power	24 hours
Appearance	Colorless to pale yellow clear liquid
Boiling Point	173 °C @ 760 mmHg
Flash Point	135 °F (57 °C)
Specific Gravity	0.834 to 0.840 @ 25 °C
Refractive Index	1.438 to 1.444 @ 20 °C

In Perfumery

Melonal is a top note modifier used to create melon, cucumber, marine, and green-fruity effects. It is invaluable in aquatic compositions alongside Calone and dihydromyrcenol, and equally effective in fruity florals where it adds a realistic melon quality. Also used to brighten citrus accords with a green-watery edge. Dosage is critical: below 0.5% it reads as natural freshness; above 1% it becomes aggressively green.