Material guide: Aurantiol — a reaction product of two other materials, sold as a material, and the mass balance is exact

The last article described a reaction that happens slowly in a bottle: an anthranilate and an aldehyde condensing into a Schiff base.

This article is about someone running that reaction first and selling you the result.

Its name in the database is the instruction manual:

hydroxycitronellal / methyl anthranilate schiff's base

Trade name Aurantiol (Givaudan), CAS 89-43-0, 42 suppliers.

The mass balance is exact

Start with something you can check yourself.

	Molecular weight
Methyl anthranilate	151.17
Hydroxycitronellal	172.27
Less the water molecule that leaves	−18.02
Total	305.42
Aurantiol's recorded molecular weight	305.42

Exactly.

A Schiff base is by definition an aldehyde condensing with a primary amine and losing one water molecule, and here you can watch that water leave. This is not two materials mixed together; it is two molecules joined into one.

The short version

• It is the reaction product of two common materials, and in the corpus 11 formulas put those two in separately while 6 buy this finished one.
• Longevity goes from 88 and 218 hours to 400. Joined, it outlasts either half.
• The strength field says medium, evaluate at 50% or less. Across all 42,225 records, only 12 materials carry a 50% recommendation — most say 10% or 1%.
• The database holds five members of this family, from Givaudan, IFF and Symrise.
• Two of them are built from aldehydes that are now banned: one from Lilial and one from Lyral.
• It is not found in nature, and its odour reads floral, lily, orangeflower, sweet — the aurantium in its name being the botanical genus name for bitter orange.

The basics

Database name	hydroxycitronellal / methyl anthranilate schiff's base
Trade name	Aurantiol (Givaudan)
CAS	89-43-0
Formula	C₁₈H₂₇NO₃
Molecular weight	305.42
Odour	Floral, lily, orangeflower, sweet
Odour family	floral
Strength	Medium (evaluate at 50% or below)
Longevity	400 hours at 100% (neat, at the ceiling)
Appearance	Yellow viscous liquid
Boiling point	162 °C @ 101 mmHg
Flash point	93.9 °C
Vapour pressure	0.004 mmHg @ 20 °C
logP	3.30 (est)
Natural occurrence	Not found in nature
Storage	24 months or longer
Regulatory listings	(blank)
Suppliers	42
Corpus position	Listed directly in 6 formulas (11 more contain both parents separately)

What joining them did

The three side by side:

	MW	Vapour pressure	Longevity	Suppliers
Methyl anthranilate	151.17	0.016 mmHg	88 hours	88
Hydroxycitronellal	172.27	0.003 mmHg	218 hours	53
Aurantiol	305.42	0.004 mmHg	400 hours	42

Longevity goes from 88 and 218 to 400.

That 400 sits at the scale ceiling where 13.3% of materials pile up, so the true figure is only known to be "at least 400". But the direction is clear: the molecule roughly doubles in weight, and it stays longer.

Read the vapour pressure row carefully — 0.004 against 0.003 does not look lower. But those two figures were measured at different temperatures (20 °C against 25 °C) and both are marked as estimates. I will not draw a conclusion from that column.

The longevity column supports a conclusion, and it agrees with the regression we ran. A bigger, heavier molecule leaves a surface less readily.

Why anyone buys the finished one

The last article counted it: 11 corpus formulas put methyl anthranilate and hydroxycitronellal in separately, and 6 list the Schiff base directly.

The same thing done two ways. The difference is time and control.

In the first group the reaction runs slowly in the bottle, and Nicastro's 2022 paper is precisely about how sensitive that process is to conditions — Schiff bases "form and cleave by small variation of the medium". So for those formulas, what the finished product becomes depends on your acidity, water content and how long it sat.

Buying the finished one removes that variable. You get a product whose reaction was completed under controlled conditions, consistent between batches.

This is the classic case of a formula replacing a process with a material. The gain is reproducibility; the cost is that you give up whatever the process itself contributes — including the part that made the original poster say they could not recreate theirs.

Five in the family, two built from banned aldehydes

Aurantiol is not the only methyl anthranilate Schiff base in the database:

Schiff base	House	The aldehyde half	Suppliers	Longevity
Aurantiol	Givaudan	Hydroxycitronellal	42	400 hours
Verdantiol	Givaudan	Lilial	22	400 hours
Lyrame	IFF	Lyral	17	400 hours
Vertosine	Symrise	Ivy carbaldehyde	9	400 hours
(2,4-ivy carbaldehyde Schiff base)	—	Triplal type	9	268 hours

Three houses, five materials, one piece of chemistry.

The second and third rows are worth stopping on. Verdantiol's aldehyde half is Lilial, banned in EU cosmetics since March 2022. Lyrame's aldehyde half is Lyral, banned in the EU since August 2021.

So what about a Schiff base built from a banned aldehyde?

I do not know, and this article will not guess. That is a specific regulatory question whose answer depends on the Schiff base's own status in the annexes, not on its feedstock's status. The database's regulatory field is blank for all five, so it cannot be answered there.

One thing can be said: if you own anything from this family, check that Schiff base's compliance on its own rather than inferring it from its starting materials. How to check is here.

And the reverse holds too: Aurantiol's starting materials not being banned does not mean Aurantiol carries no restriction. Both directions get checked separately.

About that 50%

The strength field reads medium, evaluate at 50% or below in solution.

That figure is unusual. Materials in this series mostly carry a 10% recommendation (cineole, omega-pentadecalactone, ethyl vanillin) or 1% (gamma-undecalactone, alpha-ionone).

Counting across the database: only 12 materials carry a 50% recommendation.

That means it is comparatively mild. A material you have to push down to 1% to evaluate and a material you can evaluate at 50% differ by an order of magnitude of fifty in strength.

And it lasts 400 hours at the same time. Mild and persistent are not the same axis — this is another version of strong is not diffusive.

The orange flower in its name

The odour field reads floral, lily, orangeflower, sweet.

The name Aurantiol comes from Citrus aurantium, the bitter orange, and orangeflower genuinely does appear among its descriptors. But the natural occurrence field reads not found in nature — this molecule is not in orange blossom.

Its case differs slightly from heliotropin's, though: both of its parents do genuinely occur in nature. Methyl anthranilate is in orange blossom, grapes and many flowers; hydroxycitronellal is synthetic, but its skeleton comes from citronellal.

So it is an example of building something nature does not make out of parts nature does.

Smelling it and using it

• It can be evaluated at high concentration. Fifty percent or below is rare on a palette. Even so, start at 10% the first time, because the sweetness is easier to judge lower down.
• It is a yellow viscous liquid. The colour carries into a finished product, so test before using it in anything meant to be clear, and viscous means weighing takes patience.
• Smell it beside both parents. This is the three-way comparison most worth running in this whole series — methyl anthranilate, hydroxycitronellal, and what they become joined. You will smell directly what "reaction" means.
• It stays to the end. Four hundred hours.
• Watch its relationship with water. A Schiff base forms by losing water, and it can be hydrolysed back. In a product containing water, verify its stability; the water article is relevant.

Buying and storage

Forty-two suppliers. Buy on CAS 89-43-0.

On naming, keep this family apart: Aurantiol, Verdantiol, Lyrame and Vertosine are four different materials sharing one amine and paired with different aldehydes. Buy on the CAS number, not on the words "Schiff base".

Shelf life 24 months or longer, flash point 93.9 °C.

Regulatory and safety

Four GHS statements: H315 causes skin irritation, H319 causes serious eye irritation, H335 may cause respiratory irritation, H411 toxic to aquatic life with long lasting effects.

Acute toxicity: oral rat LD50 above 5,000 mg/kg.

Something worth knowing: searching PubMed for this material by its trade name returns nothing. Forty-two suppliers sell it, and the indexed literature is zero. Its aldehyde half, by contrast, has plenty — Silvestre and colleagues' Spanish multicentre study in Contact Dermatitis in 2019 is one: 23 centres, five years, 19,588 patients patch tested with the Spanish baseline series, of whom 1,590 (8.1%) reacted positively to a fragrance marker. Among the 1,013 who went on to a full fragrance series, geraniol was the most frequent allergen.

That paper contains a further finding useful to anyone reading this kind of data: of 436 FM I-positive patients, 184 (42%) had no positive reaction at all to the fragrance series, and the authors note that negative results were more common when individual fragrances were patch tested at low concentrations. Their recommendation is to raise the test concentrations for individual fragrances.

That study did not test this Schiff base; it tested the family its feedstock belongs to. It is here to make two points: the family has real sensitization literature, and this Schiff base itself does not.

Check current IFRA Standards for the limit — here is how. The database's regulatory field is blank, and that does not mean there is no restriction.

→ Aurantiol in the database: full physical data, 42 suppliers and suggested blends. → Search by odour: try "floral orangeflower lily".

References

G. Nicastro et al., Controlled Hydrolysis of Odorants Schiff Bases in Low-Molecular-Weight Gels, International Journal of Molecular Sciences, 23(6), 3105 (2022). PMID 35328526. doi:10.3390/ijms23063105

J. F. Silvestre et al., Sensitization to fragrances in Spain: A 5-year multicentre study (2011–2015), Contact Dermatitis, 80(2), 94–100 (2019). PMID 30430587. doi:10.1111/cod.13152