Material guide: geranyl acetate — when a rose changes geraniol's clothes

The geraniol guide covered the sweet side of rose. Give that alcohol to an enzyme in a rose petal and attach an acetyl group. The name merely gains “acetate”, but the smell moves from direct rosy grass toward pear, lavender and a more transparent floral-fruity note.

What matters

• Geranyl acetate is not dilute geraniol. The skeletons are related, but their volatility, solubility and odour differ. Our record calls this one floral, rose, lavender, green, waxy and herbal.
• A 2003 rose study identified RhAAT1. The enzyme converts geraniol to geranyl acetate and also accepts citronellol. It was expressed only in floral tissue and reached its highest transcript level at the flowering stage with peak scent emission.
• It is practically insoluble in water: the estimate is 18.24 mg/L. It dissolves in alcohol, fixed oils and paraffin oil, and only slightly in propylene glycol. Keep it refrigerated and tightly sealed.

Basic data

CAS	105-87-3
Formula	C₁₂H₂₀O₂
Molecular weight	196.29
Odour	floral, rose, lavender, green, waxy, herbal, cooling
Odour family	floral
Strength	medium
Substantivity	24 hours (measured neat)
Appearance	colourless clear liquid
Boiling point	240–245 °C @ 760 mmHg
Flash point	104 °C
Specific gravity	0.900–0.914 @ 25 °C
Refractive index	1.458–1.464 @ 20 °C
Water solubility	18.24 mg/L @ 25 °C (estimated)
Other solubility	soluble in alcohol, fixed oils and paraffin oil; slightly soluble in propylene glycol
Suggested storage	24+ months; refrigerated, tightly sealed
Regulatory listings	JECFA, FEMA GRAS, CoE, FLAVIS

Specific gravity below 1 means a drop floats on water. Floating also tells you it has not dissolved. At 18.24 mg/L, water solubility is about 0.0018%; a water-based product needs a suitable solvent or solubilising system, not more shaking.

How a rose petal turns an alcohol into an ester

In 2003, Shalit and colleagues identified several principal volatile esters in the scented rose cultivar Fragrant Cloud: 2-phenylethyl acetate, cis-3-hexenyl acetate, geranyl acetate and citronellyl acetate. They found RhAAT1 in a rose sequence database, expressed it in E. coli, and confirmed that its enzyme uses acetyl-CoA to acetylate geraniol into geranyl acetate.

The enzyme did not accept every alcohol equally. Citronellol and 1-octanol worked; 2-phenylethyl alcohol and cis-3-hexenol were poor substrates. The other major esters therefore point to additional enzymes. Floral scent is not one assembly line but several neighbouring lines running inside the same flower.

RhAAT1 was also specific in place and time. The study detected expression only in floral tissue, with a maximum at flowering stage 4, when scent emission was highest. Geranyl acetate is not merely something that can be found in a rose: the timing of its biosynthetic machinery tracks the flower's release of scent.

What the nose hears after acetylation

Side-by-side blotters teach more than memorising functional groups:

Material	Centre of the database odour record	Recorded substantivity
Geraniol	rose, citrus, herbal; more direct	36 hours
Geranyl acetate	rose, lavender, green and waxy, with a fruity cast	24 hours

Esterification has not erased the rose. It rounds the edges and adds a sheen somewhere between fruit and leaf. That is an observation about this pair, not a rule that lets you predict the odour of every ester.

Smelling and using it

• Start at 10% in alcohol. It is not brutal neat, but dilution separates the pear-like fruit, lavender and green edges.
• Run a two-bottle test: geraniol at 10% and geranyl acetate at 10%, one blotter each. Smell at 0, 2, 8 and 24 hours. You will hear what the shared skeleton keeps and what the acetate changes.
• In florals it can sit between geraniol, citronellol and linalyl acetate. In fruit accords it pulls pear- and apple-like esters back toward petals instead of candy.
• The 24 hours is a neat blotter record, not a promise that a finished perfume lasts a day. Formula, carrier, skin and test conditions all matter.

Storage and buying

The database recommends refrigeration in a tightly closed container and a shelf life of at least 24 months. Refrigerate, do not freeze. Wipe the neck after use and close it promptly. A cold bottle opened in humid air can collect condensation; let the sealed bottle return toward room temperature before opening.

With 130 suppliers, availability is not the issue. Compare purity, natural versus synthetic origin, and whether the specification lists isomers or accompanying esters. A standard synthetic grade is the cleanest tool for learning structure and odour. Compare natural grades only when reproducing the texture of a specific natural oil is the actual goal.

Regulatory

Listed by JECFA, FEMA GRAS, CoE and FLAVIS. A listing is not a dermal use limit and does not replace finished-product safety assessment. For skin products, consult current IFRA Standards, the supplier SDS and specification.

→ Geranyl acetate in the database: full properties, 130 suppliers and suggested pairings. → Geraniol | Linalyl acetate | Search by odour: try “rose lavender green”.

Reference

M. Shalit et al., Volatile ester formation in roses. Identification of an acetyl-coenzyme A. Geraniol/Citronellol acetyltransferase in developing rose petals, Plant Physiology, 131(4), 1868–1876 (2003). PMID 12692346. doi:10.1104/pp.102.018572