Undecanal is a straight-chain C11 aldehyde used in fragrance and flavor work for its waxy citrus-floral lift and also occurs naturally in essential-oil and plant volatile profiles. The public evidence base is strongest for identity, odor-receptor behavior, and modern fragrance-safety assessment rather than for standalone wellness-style benefits. In the AromaForge archive it matters mainly as a composition marker in rue and other aldehydic profiles, with safety framing led by its irritancy and aquatic-hazard classification rather than by therapeutic claims.
Chemical identity and composition
PubChem and NIST identify undecanal as C11H22O with InChIKey KMPQYAYAQWNLME-UHFFFAOYSA-N. It is the saturated C11 fatty aldehyde in the straight-chain alkanal series and is often sold in perfumery under the trade-style name aldehyde C-11. In local archive context, rue is the clearest high-abundance example, where the stored Jordan profile reports undecanal at 34.69%.
Aroma and practical use
- Use the recorded waxy, aldehydic, citrus, fatty, floral descriptors to explore a blend's scent character; perceived strength also depends on the other ingredients.
- Read the route, preparation and experimental context before using a study finding to choose an oil.
Reported benefits and effects
Findings retain their study context. An animal or laboratory result describes that experiment.
A 2003 olfactory-signaling paper reported undecanal as an inhibitor of human OR17-4 in odorant-receptor antagonism work.
The accessible full-text review states that undecanal was identified as an effective inhibitor for hOR17-4, showing that it can modulate odor perception through receptor antagonism.
This reference does not establish a therapeutic result or a safe use level for a custom oil blend.
A 2025 RIFM fragrance safety assessment treated undecanal as a fragrance ingredient with a dedicated modern toxicology review.
The public PubMed/ScienceDirect record confirms a current RIFM safety assessment for undecanal; accessible companion RIFM material and public hazard sources support irritation-focused safety framing.
The source assessment applies to its specified exposure and preparation; this entry is not an unrestricted-use clearance.
Use concerns and concentration limits
Sensitization concernNot flagged
Not flagged in the current model. This is not proof of absence or unrestricted safety.
Phototoxicity concernNot flagged
Not flagged in the current model. This is not proof of absence or unrestricted safety.
Oxidation concernNot flagged
Not flagged in the current model. This is not proof of absence or unrestricted safety.
Penetration enhancementNot flagged
Not flagged in the current model. This is not proof of absence or unrestricted safety.
No numeric constituent-specific use limit is available here. Missing is not an unrestricted-use clearance.
Public hazard sources classify undecanal as a skin irritant, and ECHA also lists aquatic acute and chronic hazard categories for the substance.
The source assessment applies to its specified exposure and preparation; this entry is not an unrestricted-use clearance.
No direct public citation is attached to this entry.
Because undecanal is an aldehyde and modern safety literature focuses on hazard evaluation rather than consumer benefit, archive copy should avoid framing it as a soothing or therapeutic constituent.
This reference does not establish a therapeutic result or a safe use level for a custom oil blend.
No direct public citation is attached to this entry.
Constituents it may interact with
No constituent-pair interaction is recorded for this identity. The report does not assume either amplification or incompatibility.
How the effects were investigated
odorant-receptor antagonism in human olfaction models
A full-text receptor review states that undecanal had been identified as an inhibitor for human OR17-4, illustrating a receptor-level odor interaction mechanism rather than a therapeutic one.
This reference does not establish a therapeutic result or a safe use level for a custom oil blend.
reactive aldehyde chemistry underlying irritation concern
The 2025 RIFM safety assessment and public hazard classifications treat undecanal within the aliphatic aldehyde safety framework, which is consistent with irritation-driven risk management rather than benefit mechanisms.
The source assessment applies to its specified exposure and preparation; this entry is not an unrestricted-use clearance.
What this report cannot establish
- A reported constituent percentage does not establish an effective human therapeutic dose or the amount absorbed into the body.
- The presence of a constituent does not guarantee a clinical benefit, rash treatment or sleep improvement from a custom blend.
- An unflagged concern or missing use limit does not establish safety for ingestion, inhalation, skin exposure or a particular person.
- A candidate constituent interaction does not establish that two oils amplify one another at the selected proportions.
- Constituent descriptors alone do not establish a precise top, heart or base lifetime in a finished blend.
Known data gaps (6)
- This pass did not verify a high-quality isolated-human efficacy study for undecanal; the accessible literature is much stronger on odor science and hazard assessment.
- No constituent-specific IFRA-style dermal maximum for undecanal was verified from a directly readable public monograph in this pass.
- Most benefit-adjacent claims found during search were mixture-level essential-oil claims rather than isolated undecanal data.
- The 2025 RIFM safety-assessment record for undecanal was located but its sensitization/phototoxicity conclusions and any numeric MAC were not accessible in this or a repeat 2026-07-13 pass; dermal_limit_pct is corrected to null pending full-text access to the RIFM assessment.
- No constituent-specific numeric dermal reference is available here.
- Some findings do not record an explicit exposure route; consult the linked study before applying them to a use.