In short
Methyl nonyl ketone, 2-undecanone, is the main constituent of rue oil. It has a fatty, fruity and waxy odour with a sharp herbal edge.
What Methyl Nonyl Ketone smells like
Methyl nonyl ketone (2-undecanone) is a fatty, waxy and fruity ketone with the herbal bite of rue, in whose oil it occurs naturally. Descriptions vary by grade: a natural grade is described as citrus, fatty and rue; Firmenich as fruity, herbaceous and rue; Bedoukian as rose, citrus and orris-like; and a specification as waxy, fruity and ketonic with fatty pineapple nuances. One reference lists an orange-like note. Its flavour profile includes blue cheese with fatty, waxy notes.
- Leading note
- Fatty-fruity, rue-like
- Clear facets
- Waxy, rue herb
- Supporting facets
- Citrus
- Faint facets
- Orris, pineapple
- Character
- Fatty, waxy, herbal, sharp
What makes Methyl Nonyl Ketone distinctive
Rue. Its fruity waxiness is shared with the aliphatic aldehydes, but the herbal, slightly bitter bite of rue — the plant whose oil it dominates — is its own.
Where the descriptions disagree: Its secondary notes differ markedly by supplier — rose and orris, fatty pineapple, or orange.
How Methyl Nonyl Ketone is used
Used in traces for herbal-fruity and waxy effects, and in rue reconstructions; in flavours, for cheese and fatty-fruity notes.
Typical role: modifier (used in small amounts to change the character of a blend).
How Methyl Nonyl Ketone differs from similar materials
- Octyl Acetate
- Octyl acetate is a lighter, fruity-orange waxy ester; methyl nonyl ketone is fattier, with rue's herbal bite.
Each difference compares the published descriptions of the two materials. Smell varies with grade, supplier and dilution; compare them side by side on blotters before substituting one for another.
Formulation considerations
Powerful and fatty; use sparingly.
Identity and classification
- Type
- Aroma chemical
- Origin
- Occurs in nature
- Odour family
- Green / Fruity
- Note position
- Top to heart note
- Physical form at room temperature
- Liquid
- Also known as
- 2-Undecanone, Undecan-2-one
- CAS number
- 112-12-9
- Molecular formula
- C11H22O
- Molecular weight
- 170.29 g/mol
- IUPAC name
- undecan-2-one
The CAS number, formula and molecular weight are taken from PubChem compound 8163, whose own record lists this CAS number; checked 19 October 2026.
Safety and compliance
Hazard classification of the neat substance, as PubChem summarises it, read 26 October 2026. Companies notifying the ECHA C&L Inventory classify it (1,781 reports): H400 very toxic to aquatic life (84.3% of reports). 271 of the reports find it does not meet the hazard criteria. Unless it is harmonised, this is the notifiers' own classification, not a binding one.
This page is general information, not a safety assessment or a specification. Confirm identity, composition, IFRA status and allergen content from your supplier's documents for the lot you hold.
Materials it works with
-
Methyl Heptenone
Aroma chemical · Citrus / Green — fruity, green, citrus, fatty
-
Aldehyde C-10 (Decanal)
Aroma chemical · Aldehydic / Citrus — aldehydic, waxy, orange peel, fatty
-
Sweet Orange Oil
Essential oil · Citrus / Fruity — citrus, sweet, juicy, orange peel
-
Bergamot Oil (Expressed)
Essential oil · Citrus / Aromatic — citrus, zesty, floral, tea-like
Used in formulas and accords
Used in 1 published formula
Methyl Nonyl Ketone is an ingredient in 1 perfume formula in the Formula & Accord Library.
RUŌOD House Originals
Original compositions by RUŌOD House.
Further reading
Questions about Methyl Nonyl Ketone
Is Methyl Nonyl Ketone natural or synthetic?
The molecule occurs in nature. Commercial Methyl Nonyl Ketone may be made by synthesis or obtained from natural sources, so check the supplier's specification if the distinction matters to you.
What is the CAS number of Methyl Nonyl Ketone?
112-12-9. It was checked against PubChem on 19 October 2026.
Which published formulas use Methyl Nonyl Ketone?
Methyl Nonyl Ketone is used in 1 published formula in the RUŌOD Lab Formula & Accord Library: Iron Rain. Each is listed with a link under "Used in formulas and accords" on this page.
Sources
- PubChem — compound 8163, checked 19 October 2026.
- PubChem — GHS classification (the ECHA C&L Inventory notifications and any harmonised EU entry), read 26 October 2026.
- The Good Scents Company — 2-undecanone (with Firmenich and Bedoukian descriptions) — odour database.
- ChemicalBook — 2-undecanone (CAS 112-12-9) — odour database.
- Parchem — 2-undecanone — distributor's description.
- Olfactory profile: the RUŌOD Lab team's synthesis of the published descriptions above, reviewed 21 October 2026. Evidence: more than one published description. Classification and the short description: revision 1. Descriptions of odour are judgement, not measurement.