Is Cetalox the same as Ambroxan? The chemical registry says no, food-flavour regulation says yes

About a 9 minute read.

On r/DIYfragrance, this question has been asked at least three times.

"So, I'm just looking around a few different websites and there's many different ambroxans, like ambrofix, cetalox, orcanox and few others. From what i've seen and heard, they are basically the same thing but with a different name depending on the manufacturer, but I've also seen comments that they differ slightly in diffusion and scent profile?"

That thread drew 30 replies. A year later somebody opened a new one, 13 replies. Two months ago a third, 7 replies. Adding a related 16-reply thread, I read 23 replies with substance in them.

They do not converge.

Three positions on the forum

One: they are all the same.

"I agree that all the ambroxides are the same - especially once they're in a formula." (beraelen)

"They are the same molecule just different manufacturers. You'll be fine with which ever one you choose." (Salty-Flounder3840)

Two: they differ, and here is how.

"Ambroxan super is more mineralic, kinda gives me a feeling between calone and tonalide mineralicness. ambrofix is more airy, less woody. Orcanox woody, dusty. Ambroxan KAO flakes soft woody, musky, kinda soft airy coumarinic." (Superb_Walk4874)

"Ambrofix is a bit stronger, smoother and longer lasting to my nose without some of the harsher woodiness you find in other forms of Ambroxide. Cetalox is woodier, I think." (CapnLazerz)

Three: they differ, but you cannot tell.

"To me cetalox is quite different from other ambroxides, but of course still in the same general ambroxide direction. You still can successfuly substitute one for the other in a blend with no major difference." (bdrayne)

The second position is the most specific of the three, and the second position disagrees with itself. Superb_Walk4874 calls Ambrox Super mineralic and ambrofix airy. Salty-Flounder3840 calls Ambrox Super "slight warmer" than Ambrofix. CapnLazerz calls Ambrox Super "close/pretty Much identical to Ambrofix". Same comparison, three people, three answers.

Exactly one person raised how you would actually test this.

"Blindly testing ambroxan, Ambrox super, ambrofix Ambrox dl, cetalox I don't think you can understand any difference... And inside a mix? If I make a freshie and someone find me which one I have specifically used I'll give him a medal." (AdministrativePool2)

One reply out of 23 mentions blind testing. Every other scent description was written by somebody who knew what was in front of them.

Exactly one person touched the registry-level fact.

"Cetalox is a racemic mixture of ambroxan." (Lorenzomj)

That reply got buried under the rest of the thread. It is correct.

What the registry numbers say

Start with the three database records.

	CAS	Formula	MW	Suppliers
ambroxan (head_synonym: Ambrofix, Givaudan)	6790-58-5	C16H28O	236.398	61
amber naphthofuran	3738-00-9	C16H28O	236.398	31
ambroxide (head_synonym: Ambrox, Firmenich)	65588-69-4	C15H26O	222.371	1

The first two share a formula, a molecular weight, a logP of 4.70 (est), and an estimated water solubility of 2.436 mg/L at 25 C, matching to three decimal places.

Estimated values agreeing to the last digit usually means one thing: the estimator was handed the same structure.

I pulled the IUPAC names from PubChem.

• CAS 6790-58-5 (CID 10857465): (3aR,5aS,9aS,9bR)-3a,6,6,9a-tetramethyl-2,4,5,5a,7,8,9,9b-octahydro-1H-benzo[e][1]benzofuran
• CAS 3738-00-9 (CID 107166): 3a,6,6,9a-tetramethyl-2,4,5,5a,7,8,9,9b-octahydro-1H-benzo[e][1]benzofuran

Line them up and the difference is the leading (3aR,5aS,9aS,9bR)-. Every other character matches.

Same skeleton. One has all four stereocentres specified, the other has none specified.

And the first synonym PubChem gives for 3738-00-9 is Cetalox.

The melting range backs it up

The previous article used melting point to calculate solubility. Here melting point has a second use, and what matters is not the value but the width of the range.

	Melting point
6790-58-5	74.00-75.00 C
3738-00-9	75.00-85.00 C

A pure substance melts sharply. Mix something in and the melting point drops and spreads into a range. That is freezing-point depression, and it is school chemistry. A 1-degree range and a 10-degree range are telling you about purity, not temperature.

A 10-degree range fits a registry entry that specifies no stereochemistry.

A brake here. A wide melting range can only tell you it is not a single pure substance; it cannot identify which isomers are present in what proportion. The vendor copy quoted on the forum calls it "racemic Cetalox", but that is the vendor's description, and I have no third-party analysis to check it against.

Except that food-flavour regulation calls them one substance

Everything so far points at two things. Then I looked at the regulatory fields and the direction reversed.

	FEMA	Council of Europe	JECFA	FLAVIS
ambroxan 6790-58-5	3471	10514	none	none
amber naphthofuran 3738-00-9	3471	10514	1240	13.072

FEMA assigned the same number. The Council of Europe assigned the same number.

So "is Cetalox the same as Ambroxan" has two answers, both correct.

• Ask the Chemical Abstracts Service: no. Specifying stereochemistry or not splits it into two entries.
• Ask food-flavour regulation: yes. Same FEMA 3471, same CoE 10514.

Part of why the forum's three positions never settle is that each of them is standing on an answer that genuinely holds.

Which name maps to which number

I searched the trade names across the database's name, head_synonym, synonyms, notes and supplier fields together.

Trade name	Resolves to
Ambrofix (Givaudan)	6790-58-5, written directly in head_synonym
Orcanox	6790-58-5, appears in that record only
Cetalox	appears under both 6790-58-5 and 3738-00-9
Ambrox Super	appears under both 6790-58-5 and 3738-00-9
Ambrexol	not found anywhere in the database

Ambrofix and Orcanox have a clean assignment. Cetalox and Ambrox Super turn up in the supplier text of both records.

That is less a database error than a picture of the market. Those two names are not consistently attached to one CAS number in the supply chain. Asking "which one is Cetalox" gets an answer that depends on who sold it to you.

What the third record is

The 65588-69-4 record carries "ambrox (Firmenich)" in head_synonym, the original trademark. Its formula is C15H26O, one CH2 short of the other two.

I checked PubChem (CID 196435): 6,6,9a-trimethyl-.... Trimethyl, not tetramethyl.

PubChem agrees with the database, so the suspect part is the label rather than the formula field. The molecule sitting under the name "Ambrox" at this number has one fewer methyl group than the Ambrox everybody is talking about. It has one supplier, so you will not meet it in practice, but a beginner searching "ambrox" will hit it.

Whether you can smell it is a different question

The registry split explains the names. It says nothing about noses.

Laska and Teubner ran a direct experiment in Chemical Senses in 1999: 20 subjects, 10 enantiomer pairs, forced-choice triangular test. As a group the subjects reached significance on alpha-pinene, carvone and limonene only. Menthol, fenchone, rose oxide, camphor, alpha-terpineol, beta-citronellol and 2-butanol, seven pairs, they could not distinguish.

The paper's own conclusion is explicit: enantioselective odour receptors may exist for some but not all volatile enantiomers, so chiral recognition may not be a general phenomenon.

Rose oxide sits in the failed group. That is a material perfumers reach for constantly.

The distance from "different stereochemistry" to "you can smell it" is real, and most of the time it does not get crossed.

This molecule may be one of the exceptions

In 2025, Takase and colleagues published in Communications Biology something nobody had managed before: identifying the human receptor behind the smell of ambergris.

They landed on OR7A17, tuned to (-)-Ambroxide.

The next part of that paper matters more to some readers than to others.

They analysed genetic variation in OR7A17 and found that non-functional alleles of this receptor are prevalent in human populations, especially in East Asia. People without a functional copy can still detect (-)-Ambroxide, but they find it less pleasant.

The paper's opening points the same way. Historical accounts indicate that some populations, particularly in East Asia, used ambergris without regard for its odour quality.

Here is how that lands on the forum. The same board carries a 16-reply thread titled "Is ambroxan on its own supposed to smell weak?". One person writes that ambrofix is airy while another writes that Ambrox Super is mineralic. Some of the spread in these descriptions may not be in the bottle.

The limit needs saying plainly. Takase and colleagues measured pleasantness, not the ability to discriminate two stereoisomers. It cannot be read as "East Asian noses cannot tell Cetalox from Ambroxan." What it supports is that how agreeable this material smells varies with a gene, and that the variant is common in East Asia.

What the corpus shows

Of 954 published formulas, 95 contain an amber ether, 10.0%. One formula in ten.

Those 95 use 15 different spellings. Grouped:

Spelling	Occurrences
Ambroxan	31
Cetalox	27
Ambrofix	23
Ambrox / Ambrox DL	12
amber naphthofuran	2

The most common single name covers under a third of the cases.

One more thing worth recording. Not one of the 95 formulas uses two different spellings at once. Every one picks a name and stays with it.

If these materials filled roles in a formula that the others could not, you would expect somebody to layer Cetalox and Ambrofix in the same perfume. Zero out of 954 do.

Median dose is 0.50%, 90th percentile 2.00%, maximum 17%.

What you can actually do

• Buy on CAS, not trade name. 6790-58-5 is the stereochemically specified one, 3738-00-9 is the unspecified one. If a vendor lists only a trade name, ask.
• Ambrofix and Orcanox are 6790-58-5. Those two names are unambiguous in the data.
• Cetalox and Ambrox Super need checking. Both names appear under both CAS numbers.
• One of them is enough. No formula in the corpus uses two. Starting with 6790-58-5 is the straightforward choice because it has more suppliers, 61 against 31.
• Start at 0.5%. That is the corpus median.
• If it smells weak or unremarkable to you, the material is not necessarily the problem. The OR7A17 loss-of-function allele is common in East Asia and what it affects is pleasantness.
• Comparing two of them means blind testing. One reply in 23 raised it, and every specific scent description was written with the label visible.

My own stumble: I first searched for cetalox in the name field only, got nothing, and nearly wrote that the database has no record of it. The name field genuinely does not have it. The synonyms and supplier fields do. This is the second time in a month I have fallen into the same hole; last time it was sotolon.

What this doesn't establish

• I did not run a blind test. Nothing here comes from my own nose. What I checked was registry numbers, formulae, melting points, regulatory numbers, suppliers and a formula corpus.
• I have no independent evidence that Cetalox is racemic. I confirmed that its CAS entry specifies no stereochemistry and that its melting range is 10 degrees wide. The racemic claim comes from vendor copy.
• A wide melting range only rules out a single pure substance; it does not identify the composition. Ten degrees is consistent with several stereoisomers and equally with other impurities.
• I did not read the underlying evaluation documents behind the shared FEMA 3471 and CoE 10514. A shared number means the regulator treated them as one evaluation subject, not that it found their odours identical.
• Laska 1999 did not include ambroxide among its ten pairs. I used it for the general point that chirality does not guarantee discriminability.
• Takase 2025 measured pleasantness, not discrimination, and I did not get to per-population allele frequencies beyond the abstract-level statement about East Asia.
• The forum's scent descriptions cannot be reproduced from here. Terms like "mineralic" and "dusty" move with lot, purity and dilution.
• The database's water solubility and logP are estimates. Their exact agreement was one of my reasons for inferring a shared structure, but agreement between estimates is not agreement between measurements.
• On the 65588-69-4 labelling problem I only verified that the formula matches PubChem. What that CAS is actually sold as in the market, I did not check.