Material guide · 95
Material guide: laevo-rose oxide, sharing a FEMA number with the racemic version while FLAVIS splits them
· 16 min read
CAS 3033-23-6, the (2S,4R) configuration, 8 suppliers against 77 for the racemic version. Its physical fields match the racemic almost exactly: molecular weight, logP 2.90, specific gravity, refractive index and vapour pressure are all identical. Three things differ. The odour field adds metallic and powdery; the substantivity field reads 388 hours where the racemic reads greater than 8, measured under entirely different conditions; and FLAVIS gives it its own 13.170 while FEMA 3236 and Council of Europe 2269 are shared with the racemic. It appears 4 times in 954 published formulas.
In short: the single-configuration version of the same molecule as racemic rose oxide, with almost identical physical properties. It earns an entry because two of its three differences from the racemic are data problems rather than differences in the material.
Fields
| Field | Value |
|---|---|
| CAS | 3033-23-6 |
| First synonym | L-rose oxide |
| Configuration | (2S,4R), i.e. (-)-cis |
| Formula | C10H18O, MW 154.253 |
| Appearance | colorless clear liquid (est) |
| Assay | 99.00 to 100.00 |
| Boiling point | 71-73 C @ 12 mmHg; 182 C @ 760 mmHg |
| Flash point | 67.78 C |
| logP | 2.90 (est) |
| Vapour pressure | 0.551 mmHg @ 25 C (est) |
| Specific gravity | 0.865-0.873 @ 25 C |
| Refractive index | 1.450-1.457 @ 20 C |
| Water solubility | 63.97 mg/L @ 25 C (est) |
| Odour type | floral |
| Odour | rose; cortex; green; floral; geranium; powdery; metallic |
| Strength | high, recommend smelling in a 1.00% solution or less (rank 3) |
| Substantivity | 388 hours (10% in dipropylene glycol) |
| Occurrence | Rosa damascena; Rosa centifolia; rose oil; Persian cyclamen; Oregon grape-holly |
| Suppliers | 8 |
| Regulatory | FEMA 3236, CoE 2269, FLAVIS 13.170 |
| Note | Blends well with damascones. Vitalizes intensely all the aldehyde notes. Gives depth in the citrus areas |
Side by side with the racemic
The racemic cis form (#35233, CAS 16409-43-1) has 77 suppliers and is the one you meet in practice.
| (Z)-rose oxide, racemic | This material | |
|---|---|---|
| CAS | 16409-43-1 | 3033-23-6 |
| Formula | C10H18O | C10H18O |
| MW | 154.253 | 154.253 |
| logP | 2.90 (est) | 2.90 (est) |
| Vapour pressure | 0.551 mmHg (est) | 0.551 mmHg (est) |
| Specific gravity | 0.865-0.873 | 0.865-0.873 |
| Refractive index | 1.450-1.457 | 1.450-1.457 |
| Strength rank | 3 | 3 |
| FEMA | 3236 | 3236 |
| CoE | 2269 | 2269 |
| FLAVIS | 13.037 | 13.170 |
| Suppliers | 77 | 8 |
Eight rows match exactly, decimal places of the estimates included. FEMA and the Council of Europe assign one number; FLAVIS assigns two.
(The same split showed up in the amber ethers, where CAS divided into two and FEMA and CoE merged. Two unrelated materials producing the same structure is worth recording.)
Three differences, two of them data problems
One: the wording of the assay field.
The racemic reads "99.00 to 100.00 sum of isomers"; this one reads "99.00 to 100.00" without those words.
Their presence or absence is the difference between "this number governs a total" and "this number names a configuration". For working out what a spec sheet in front of you means, this field is more reliable than the trade name.
Two: the substantivity field.
| Field text | substantivity_hr | |
|---|---|---|
| Racemic | > 8 hours (100% neat) | 8.0 |
| This material | 388 hours (10% in dipropylene glycol) | 388.0 |
Same molecule, 8 against 388, a factor of 48.5.
The difference is not in the molecule. One was measured neat and is a greater-than lower bound; the other is a point value at 10% in dipropylene glycol. No conversion exists between the two protocols.
The substantivity_hr column puts both in the same slot, so sorting on it places rose oxide at both the longest-lasting and the shortest-lasting end of the list.
That is a field problem, not a property of the material.
Three: the odour field.
| Odour | |
|---|---|
| Racemic | green; rose; red rose; spicy; fresh; geranium; vegetable; floral; herbal; camphoreous |
| This material | rose; cortex; green; floral; geranium; powdery; metallic |
Shared: rose, green, floral, geranium. Racemic only: spicy, fresh, vegetable, herbal, camphoreous. This one only: cortex, powdery, metallic.
This one looks like a real difference, and it needs handling carefully. When Laska and Teubner measured human discrimination of 10 enantiomer pairs in Chemical Senses in 1999, rose oxide was among the seven pairs subjects could not distinguish. The two descriptions come from different evaluators in different years (1995 against 1989), written by people who knew what they were smelling.
I will not treat those two lists as evidence that anybody can tell them apart.
Cis is the one doing the work
Wang and colleagues studied lychee-like aroma in grapes in Food Chemistry in 2026 using metabolomics and molecular sensory analysis, and identified cis-rose oxide and citronellol as the key volatiles. The paper says cis-rose oxide, not rose oxide generically.
This material is (2S,4R), that is (-)-cis, and sits on the cis side.
So a supplier writing "laevo" is naming a real configurational distinction rather than a marketing term. Whether it is worth buying is a separate question.
The occurrence field
Rosa damascena, Rosa centifolia, rose oil, Persian cyclamen, Oregon grape-holly.
Compare the racemic's field: cistus oil, elder flower oil, geranium oils from several plant parts (Indian leaf oil at 0.74%, Cuban rose-scented geranium at 5.50%), ginger, lemon balm, canned lychee.
The racemic field carries percentages and this one does not. The two entries were recorded to different depths, which is a common gap inside one database.
Corpus
Across 954 published formulas, rose oxides appear in 76, or 8.0%. Of those, laevo-rose oxide is written 4 times; adding the single cis-rose oxide, five uses specify a configuration.
94% of uses are written as plain rose oxide with no configuration.
The overall median dose is 0.500%, and 74% of uses sit below 1%.
Four formulas is too few, so I am not computing a dose figure for this material on its own.
What this doesn't establish
- I have not smelled it, and I have not compared it against the racemic.
- The two odour lists are not a controlled comparison. Different evaluators, different years, not blind.
- I cannot assess where the 388-hour figure came from. All I know is that the condition was 10% in dipropylene glycol while the racemic entry was measured neat.
- I cannot say which of 8 and 388 is closer to practice, only that they are not comparable.
- The eight matching physical rows were part of my reason for inferring one molecule, but most of those are estimates, and agreeing estimators is not agreeing measurements.
- Wang 2026 studied grapes and shows cis is a key volatile, without comparing a single enantiomer against a racemic mixture.
- Laska 1999 tested (+) against (-), not this material against a racemic mixture.
- I could not find citable figures for how far the odour thresholds differ between cis and trans, or between (+)-cis and (-)-cis. That is the biggest gap here.
- Four formulas in the corpus is not enough to say anything about dosing.