Material guide: nerolidol — four layers of isomerism on one CAS, and the database gives cis and trans different odour types

About 5 minutes.

Short version

• Name: nerolidol, 3,7,11-trimethyl-1,6,10-dodecatrien-3-ol, CAS 7212-44-4
• Formula C15H26O, MW 222.37 — a sesquiterpene alcohol
• FEMA 2772, JECFA 1646, FLAVIS 02.018, CoE 67, structure class I, FCC listed Yes
• Odour type: floral; odour: floral, green, waxy, citrus, woody
• Flavour type: green — not the same as its odour type
• Strength: low, rank 1; substantivity 100 hours; vapour pressure 0.001 mmHg
• Assay: 96.00 to 100.00, sum of isomers
• Optical rotation: −2.00 to +2.00
• Suppliers: 54

Four layers of isomerism on one CAS

This is the most layered product I have found in this database.

Layer one: geometric isomers. Nerolidol exists as (E) and (Z), and the database files them as separate records:

Record	CAS	Suppliers	Odour type
Nerolidol (the product)	7212-44-4	54	floral
(E)-nerolidol	40716-66-3	5	floral
(Z)-nerolidol	3790-78-1	3	waxy
(+)-nerolidol	142-50-7	3	—
Nerolidol oxide	1424-83-5	2	—

(E) is floral type and (Z) is waxy type. The database itself puts one molecule's two geometric isomers in different odour families.

Layer two: optical isomers. The rotation field reads −2.00 to +2.00 — a range that crosses zero. The product may be laevorotatory, dextrorotatory or near-racemic, and the specification permits all of it.

Layer three: the product is a mixture. The assay reads "96.00 to 100.00, sum of isomers" — and in what proportion (E) and (Z) make up that 96%, the specification does not say.

Layer four: nature's preference. From the notes field:

The (S)-enantiomer is the commoner and occurs mostly as the (S)-(E)-isomer.

So the "nerolidol" sold by 54 suppliers has freedom on four axes at once.

And layer one has consequences. If (E) is floral and (Z) is waxy, then a shift in isomer ratio is not a purity question; it is an odour question.

("Sum of isomers" came up with Javanol, but that record did not assign different odour types to different isomers. This one does, so the evidence is more direct.)

Strength "low", substantivity 100 hours

Strength field	low (rank 1)
Substantivity	100 hours
Vapour pressure	0.001 mmHg

A quiet, persistent combination. Rank 1 is the bottom of that field, and 100 hours puts it mid-to-late.

I measured this family in The supplier calls it "very faint" and the substantivity field says 394 hours: of the 1,193 well-supplied materials with both a strength and a substantivity value, 189 (15.8%) are low or medium strength with 350+ hours — the class that carries weight. Nerolidol's 100 hours does not reach that threshold, but the character is the same.

It is a ground, not a lead. One line in the odour description field puts it well: used in fragrances for woody, tea-like notes.

Odour type and flavour type disagree

• odor_type: floral
• flavor_type: green

Two fields on one record, giving different classifications. And the taste description is Mosciano's, recorded at 25 ppm:

Green, floral, woody with fruity-citrus and melon nuances.

The flavour use note adds that it is used mostly in tea and peach flavours, also raspberry and other floral-type fruit flavours.

This is not a contradiction; it is two classification systems weighting the same material differently. But read only one field and you take away a different impression.

It is an intermediate in a plant's alarm signal

Chan and colleagues open their 2016 review in Molecules with its biological position:

Nerolidol is a naturally occurring sesquiterpene alcohol that is present in various plants with a floral odor. It is synthesized as an intermediate in the production of (3E)-4,8-dimethyl-1,3,7-nonatriene (DMNT), a herbivore-induced volatile that protects plants from herbivore damage.

The review also confirms the geometric point: "nerolidol exists in two geometric isomers, a trans and a cis form."

The "smell a plant only makes after being eaten" thread has appeared here before. Cis-3-hexenol is exactly that article: the smell of cut grass is a plant alarm signal. Nerolidol sits upstream of the same story — not the alarm itself, but the stock the alarm is made from.

(The body of that review is pharmacological activity, which I am not summarising — it is unrelated to perfumery and outside my competence to assess.)

How to use it

• As a woody, tea-like ground. Low strength and 100 hours mean it does not step forward.
• Ask about isomer ratio when buying. The odour types of (E) and (Z) differ in this database, while the specification guarantees only "96% sum".
• Do not pay for optical rotation. A specification range crossing zero means it is not a controlled parameter.
• It joins four lines at once — floral, green, citrus and woody — because its own odour field carries all four words.
• In a flavour context it is the green tea and peach direction, evaluated at 25 ppm.

What this doesn't establish

• I have not smelled it, and have not compared (E) against (Z) products. "(E) floral, (Z) waxy" is two database records, not a controlled evaluation I ran.
• (Z)-nerolidol has 3 suppliers and (E) has 5, and both records are thinner than the product's. Inferring the effect of isomer ratio in the product from those sparse records is inference, not measurement.
• "Isomer ratio affects odour" is inferred from two records' odour types. I found no quantitative comparison of the two isomers' thresholds or intensities.
• I do not touch the review's pharmacology at all. I quote only its chemical and biological background.
• The DMNT line is one sentence in that review; I did not consult the enzymology literature for the nerolidol-to-DMNT step.
• A rotation range crossing zero does not mean the product is racemic — it means the specification allows that range.
• The odour-type versus flavour-type difference is a result of two classification systems, whose definitions I did not look up.