Flavor ingredient regulatory record
3-Oxobutanal dimethyl acetal
3-Oxobutanal dimethyl acetal is a ketone in the fruity family, FEMA GRAS under FEMA number 3381 (CAS 5436-21-5). Its odor is sweet, fruity, caramel, nutty.
- FEMA
- 3381
- CAS
- 5436-21-5
- JECFA
- 593
- EU FL
- 06.038
- Formula
- C6H12O3
GRAS status: FEMA GRAS, publication 6. Recorded by FDA in the Substances Added to Food inventory under CAS 5436-21-5.
Structure
Identity
Also known as: 2-Butanone, 4,4-dimethoxy-, Acetoacetaldehyde, 1-(dimethyl acetal), 4,4-Dimethoxy-2-butanone, Acetoacetaldehyde dimethyl acetal, 1,1-Dimethoxy-3-butanone, 3-Oxobutyraldehyde dimethyl acetal, β-Oxobutyraldehyde dimethyl acetal, Formylacetone dimethyl acetal, Acetylacetaldehyde dimethyl acetal, 3-Oxobutyraldehyde 1-(dimethyl acetal), NSC 21538, NSC 59721.
Can 3-Oxobutanal dimethyl acetal be labeled natural?
Nature makes 3-Oxobutanal dimethyl acetal, which is why the US label turns on process. A natural route gives natural flavor; synthesis gives artificial 3-Oxobutanal dimethyl acetal, same molecule. The EU and UK follow the same logic without a middle class; Mercosur and Mexico label synthetic 3-Oxobutanal dimethyl acetal identical-to-natural.
- United States
- Natural or artificial, by process
- European Union and UK
- Natural only from natural material
- Mercosur and Mexico
- Natural or identical-to-natural
How each market defines the classes: natural vs artificial flavor under 21 CFR 101.22.
Regulatory status, with citations
United States
3-Oxobutanal dimethyl acetal is FEMA GRAS under FEMA number 3381. It is cited in the Code of Federal Regulations at 21 CFR 172.515.
European Union and United Kingdom
Listed on the Union List of flavouring substances as FL 06.038, Annex I Part A under Regulation (EC) 1334/2008, evaluation status approved (JECFA). The UK retains the same list.
JECFA (WHO / FAO)
JECFA number 593, evaluated at the 53rd meeting in 1999. no safety concern at current levels of intake.
Other US flags
Not on the California Proposition 65 list.
TSCA Inventory status
A flavor ingredient is also an industrial chemical. 3-Oxobutanal dimethyl acetal appears on the EPA Toxic Substances Control Act Chemical Substance Inventory under CAS 5436-21-5, where EPA names it 2-Butanone, 4,4-dimethoxy-.
Active in US commerce
EPA designates this substance active, so no Notice of Activity Form B is required before manufacturing. What active and inactive mean.
EPA publishes no regulatory flags on this listing. What the flags mean.
From the EPA non-confidential TSCA Inventory, July 2026 release. EPA also maintains a confidential portion it does not publish. Search the Inventory by CAS number.
Odor and taste
Odor: Sweet, fruity, caramel, nutty.
Where it is used
3-Oxobutanal dimethyl acetal is used in beverage, confection, bakery and desserts, typically as a fruity note.
Structurally similar flavor ingredients
Flavor ingredients with a GRAS determination closest to 3-Oxobutanal dimethyl acetal by structure. Whether one can replace it is a sensory and regulatory call; the reformulation tool works that through.
| Material | FEMA | Similarity | Occurrence |
|---|---|---|---|
| Isobutyl acetate | 2175 | 87% | In nature |
| 2-Acetoxy-3-butanone | 3526 | 78% | In nature |
| Propyl acetate | 2925 | 75% | In nature |
More ketones in this index
(E)-1,5-Octadien-3-one · 4-Hexen-3-one · Epoxy oxophorone · Propiophenone · 2,3-Undecadione · 3-Penten-2-one
3-Oxobutanal dimethyl acetal FAQ
Is 3-Oxobutanal dimethyl acetal FEMA GRAS?
Yes. The FEMA Expert Panel lists 3-Oxobutanal dimethyl acetal as GRAS under FEMA number 3381. The Code of Federal Regulations lists it at 21 CFR 172.515.
What are the FEMA and CAS numbers for 3-Oxobutanal dimethyl acetal?
3-Oxobutanal dimethyl acetal is FEMA 3381, CAS 5436-21-5. Its flavor category is fruity.
How is 3-Oxobutanal dimethyl acetal described, and where does it show up?
Flavorists describe 3-Oxobutanal dimethyl acetal as sweet, fruity, caramel, nutty. It is used in beverage, confection, bakery and desserts.
What did JECFA conclude about 3-Oxobutanal dimethyl acetal?
JECFA evaluated 3-Oxobutanal dimethyl acetal at the 53rd meeting in 1999 under JECFA number 593. The panel concluded: no safety concern at current levels of intake.
Is 3-Oxobutanal dimethyl acetal on the EU Union List?
Yes. FL 06.038 is the Union List entry for 3-Oxobutanal dimethyl acetal, annex I Part A, under Regulation 1334/2008, and the UK keeps the same list.
Does 3-Oxobutanal dimethyl acetal count as natural in the US and the EU?
The process decides for 3-Oxobutanal dimethyl acetal. It occurs in nature, so a natural-source, natural-process material is natural flavor in the US and synthetic 3-Oxobutanal dimethyl acetal is artificial. The EU and UK follow the same logic without a middle class; Mercosur and Mexico label synthetic 3-Oxobutanal dimethyl acetal identical-to-natural.
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Sources and attribution. The identity and regulatory facts on this page are taken from the FDA Substances Added to Food inventory, a US government record, which lists this substance as 3-OXOBUTANAL, DIMETHYL ACETAL under CAS 5436-21-5 and carries its FEMA number, its JECFA flavor number. The inventory is searchable at FDA. FDA records its technical effect as flavoring agent or adjuvant.
A FEMA GRAS conclusion is reached by the Expert Panel of the Flavor and Extract Manufacturers Association of the United States, and the FEMA number names that conclusion. FEMA publishes its own entry for this substance in the FEMA Flavor Library, which is the authoritative record of what the Panel decided and is worth reading alongside this page.
Ambrose Compliance is not affiliated with, endorsed by, or sponsored by FEMA. FEMA and FEMA GRAS are used here as identifiers for a published regulatory determination, not as marks of any relationship between FEMA and Ambrose.
About this page. Facts come from the FDA Substances Added to Food inventory, the Code of Federal Regulations, the EPA TSCA Inventory, the EU Union List, JECFA and the Ambrose database, with FEMA's published determination cited where it applies; parts of the text are written by Ambrose AI, which can make mistakes. Check the cited source before relying on anything here. This is not regulatory or legal advice.