Material guide: styralyl acetate — it is in 8.2% of formulas, and the corpus calls it by two names

CAS 93-92-5, 77 suppliers, FEMA 2684. It appears in 78 of 954 formulas, and the corpus calls it both styrallyl acetate and gardenol — the second being what the database's synonym field says. The odour field reads green, leafy, gardenia, rhubarb, musty, fruity, seedy, berry, and one evaluation contains a rare piece of self-denial: 'strong, radiant, herbal-green-fruity, floral similar to gardenia, not tenacious.' Its substantivity really is only 8 hours, and its vapour pressure lands in the heart band I computed, whose median is 24 — this one sits at the short end. And there is something the fields never mention: it is chiral, and what you buy is a racemate.

About a 4 minute read.

The short version

Name: styralyl acetate (1-phenylethyl acetate), also gardenol, CAS 93-92-5, FEMA 2684
Odour type: green; odour: green, leafy, gardenia, rhubarb, musty, fruity, seedy, berry
Strength medium (rank 2), evaluate at 10% or less; substantivity only 8 hours
Suppliers: 77; appears in 78 of 954 formulas (8.2%)
Cramer Class I; oral LD50 4,600 mg/kg
It is chiral, and the fields never say so

The corpus calls it two things

I measured the name-matching problem in the formula corpus, and this material falls into two of its traps at once:

Spelling: the corpus writes styrallyl acetate, the database writes styralyl acetate — one L apart.
Trade name: the corpus also writes gardenol, which is exactly what the database's head_synonym field says.

One material, two names inside one corpus, and one of them differs from the database by a single letter.

Count only one spelling and you underestimate how often it is used. (The 8.2% I computed last time is exactly that — an underestimate.)

The evaluation field says outright that it does not last

odor_descriptions holds six entries, one of which denies itself:

strong, radiant, herbal-green-fruity, floral similar to gardenia, not tenacious.

And the number confirms it: 8 hours at 100%.

Its vapour pressure is 0.203 mmHg, in the heart band I computed (0.01–1 mmHg, median substantivity 24 hours). Eight hours is the short end of that band — the mirror image of acetoin, which sits in the top band and lasts 28.

So its job is clear: a strong, short opening modifier. The notes field calls it a "modifier for florals," and the name gardenol says which direction.

It really does occur in nature

occurrence: clove bud, clove fruit, gardenia flower.

Yu and colleagues analysed Gardenia jasminoides flowers and its variety in Food Chemistry in 2023:

a total of 56 volatile components were identified, and terpenoids and esters were the main compounds to distinguish these species … nine compounds were identified, whose distribution in petals and stamens of G. jasminoides were significantly dissimilar.

Petals and stamens differ in composition — which bears directly on how material is harvested, and most natural records will not tell you.

(That paper also measured drying: flavonoids and phenolics stayed stable after blanching, while iridoids were markedly higher after freeze-drying and hot-air drying.)

And what the fields do not say: it is chiral

The carbon in 1-phenylethyl acetate carries four different groups — there are two mirror-image isomers, and the commercial material is a racemate.

Every field in the database treats it as one material. No (R), no (S), no optical rotation.

Does that matter? Lytra and colleagues measured a different molecule (ethyl 3-hydroxybutanoate in wine) in the Journal of Agricultural and Food Chemistry in 2015, but their result gives the scale:

The olfactory threshold of the S-form in dilute alcohol solution was 21 mg/L, one-third that of the R-form: 63 mg/L. The S- and R-forms had different aromatic nuances.

Two mirror-image molecules, thresholds a factor of three apart, different in character.

(To be clear: that paper did not measure styralyl acetate. I cite it to show how large "a racemate is a mixture of two materials" can be as a sensory fact, not because it tested this one. How far apart this material's two isomers are, I do not know.)

And its natural source is the gardenia flower — plants generally synthesise a single isomer. So the racemate you buy and the compound in the flower are, strictly, not the same thing.

How to use it

Evaluate at 10% or less, and remember it has eight hours. An opening, not a frame.
It is the modifier on the gardenia and green-leaf line. The notes field also says it blends well with woodruff notes.
Mind the spelling when buying. styrallyl/styralyl differ by an L, and gardenol is the same thing.
The green and musty facets overrun the gardenia at higher concentration.
Cramer Class I, oral LD50 4,600 mg/kg, GHS only H227 (combustible liquid). A mild one by this series' standards.
24 months, cool and dark.

What this doesn't establish

I have not smelled it. This is fields, corpus statistics, and two papers.
Lytra 2015 measured ethyl 3-hydroxybutanoate, not this material. I cite their general result that enantiomers' thresholds can differ threefold.
"The commercial material is a racemate" is the norm for synthetic esters of this kind, but I checked no supplier specification.
Yu 2023 is a food chemistry paper about how drying affects gardenia flower composition. I cite the volatile composition and petal/stamen distribution; it does not discuss this compound specifically.
8.2% is an underestimate, because the corpus carries at least two names and I counted one group of one spelling.
I did not check the IFRA text.