Material guide · 17
Material guide: cis-3-hexenol — the green of the very second the grass is cut, which is really a plant alarm
· 14 min read
CAS 928-96-1, the lead molecule of the cut-grass smell. Plants only produce these compounds in quantity once their tissue is damaged or stressed, and plant ecology studies them as signals between plants. Sensitivity to it has a genetic component, but the OR2J3 receptor haplotype explains just 26.4%, at the opposite end of the spectrum from beta-ionone's clean 96% case. High strength, 4-hour substantivity, 120 suppliers.
The coumarin guide started on the evening after mowing, with the hay smell that keeps getting sweeter. This one goes back to the second the blade hits. That burst of green in the air has a name: cis-3-hexenol, the leaf alcohol.
What matters
- Cis-3-hexenol is the body of the cut-grass smell, and most green notes in perfumery start from it. High strength — one drop can walk over an entire formula; the database says evaluate at 10% or less.
- Plant ecology studies that green as a signal plants release when wounded; what it does to a human wearing it is a separate question, and not one the literature answers.
- Sensitivity to it has a genetic side too, but the receptor haplotype found so far explains only 26.4%. Put that next to beta-ionone, where a single variant explains 96%, and you see both ends of receptor genetics.
The record
| CAS | 928-96-1 |
| Formula | C₆H₁₂O |
| MW | 100.16 |
| Odour | fresh, green, grassy, foliage, vegetable, herbal, oily, melon rind |
| Odour family | green |
| Strength | high (evaluate at 10% or less) |
| Substantivity | 4 h (neat, on a strip) |
| Specific gravity | 0.846–0.850 (25 °C) |
| Flash point | 61 °C |
| Shelf life | 24 months or longer (cool, dark, sealed) |
| Registers | GRAS, JECFA, CoE, FEMA GRAS, IFRA |
Plain reading: CAS is the material's ID number. Two numbers matter here: strength "high" and substantivity 4 hours. It arrives fast and leaves fast. Set beside coumarin's 364 hours, the pair covers the whole timeline of the mowing smell, first minute to last. And "melon rind" in the descriptors is no typo; diluted far enough, leaf alcohol really does drift toward honeydew skin.
What that green is
Botany has a collective name for these molecules: green leaf volatiles, GLVs. Matsui's 2006 review in Current Opinion in Plant Biology lays out where they come from:
Green leaf volatiles (GLVs) are C₆ aldehydes, alcohols, and their esters formed through the hydroperoxide lyase pathway of oxylipin metabolism. Plants start to form GLVs after disruption of their tissues and after suffering biotic or abiotic stresses. […] it has been postulated that GLVs are important molecules both for signaling within and between plants and for allowing plants and other organisms surrounding them to recognize or compete with each other.
On that account, when a lawn is mowed, what you smell is a whole field of wound signals going off at once. An intact healthy leaf releases little of this; the mower brings it out in volume. Note what the literature is actually about: plant physiology and ecology. It says nothing about effects on the person smelling it, and neither will we.
What perfumery takes from this is the association. Your nose has learned "C₆ molecules that follow tissue damage" as fresh. A trace of leaf alcohol pulls a formula toward just-cut, just-picked. Muguet, violet leaf and fig leaf accords usually have it underneath.
Not everyone receives the same green
OR2J3 variation explained about 26.4% of leaf-alcohol detection differences in one study. That is not a second main story for this plant alarm. The comparison now lives in Why smell research keeps using the same odorants, with blind-test practice in individual differences.
Smelling it
- The database says evaluate at 10% or less, and I go lower still with this one. The first time I put it neat on a strip, all I registered was raw lettuce and sting; "cut grass" itself only showed up around 1%.
- Four hours of substantivity means it lives in the top note. If the green has to survive into the heart, hand it over to something heavier, violet leaf absolute or galbanum.
- Dose changes its job by an order of magnitude: as the lead it reads vegetable patch, as a trace it reads fresh. Most formulas want the second.
- The classic pairing is florals. A few tenths of a percent in a muguet accord and the flower smells picked this morning.
The catalogue family
| Item | What it is |
|---|---|
| (Z)-3-hexen-1-ol (120 suppliers) | the material itself, cis-3; the most widely stocked of the family |
| (E)-2-hexen-1-ol (69 suppliers) | trans-2; green with fruit, leaning green apple |
| (E)-3-hexen-1-ol (15 suppliers) | the trans isomer of the lead; a duller green |
| (Z)-4-hexen-1-ol (10 suppliers) | positional isomer, thinly supplied |
| 3-hexenyl esters (around 5 suppliers each) | leaf alcohol esterified; green plus fruit, common in pear and green-apple work |
One C₆ backbone, and every move of the double bond changes the texture of the green. Read the Z/E and the number in the name carefully before ordering; this family's names are nearly identical.
Regulatory
Listed on GRAS, JECFA, CoE, FEMA GRAS, IFRA. As always, registers carry no limit values. Leaf alcohol is regulatorily uncomplicated; for skin formulae, consult the current IFRA Standards and the supplier's specification.
Buying it
- A small bottle lasts a long time. High strength plus a top-note role means formula doses in the tenths of a percent.
- Check for CAS 928-96-1 or (Z)-3 / cis-3 in the name so you do not land on a trans isomer.
- Make a 1% dilution while you are at it. Its working concentration is lower than you expect.
→ Cis-3-hexenol in the database: full properties, supplier list, suggested pairings. → (E)-2-hexen-1-ol | Search by odour: try "green grassy" for its neighbours.
References
J. F. McRae, J. D. Mainland, S. R. Jaeger, K. A. Adipietro, H. Matsunami & R. D. Newcomb, Genetic variation in the odorant receptor OR2J3 is associated with the ability to detect the "grassy" smelling odor, cis-3-hexen-1-ol, Chemical Senses, 37(7), 585–593 (2012). PMID 22714804
K. Matsui, Green leaf volatiles: hydroperoxide lyase pathway of oxylipin metabolism, Current Opinion in Plant Biology, 9(3), 274–280 (2006). PMID 16595187