In short
Isobutyl quinoline (IBQ) is a powerful, earthy-leathery material and a classic of leather accords. The material sold under this name (CAS 65442-31-1) is chemically mainly 6-sec-butylquinoline, with some of the 8-isomer; 2-isobutylquinoline (CAS 93-19-6) is a different compound.
What Isobutyl Quinoline smells like
The butyl quinolines are extremely powerful, long-lasting leather notes: supplier listings for isobutyl quinoline give leather, earthy, rooty, nutty and mossy with oakmoss and vetiver facets, or earthy, green, animal, leathery and herbal, and one a blend of tanned leather, damp roots, oakmoss and tobacco. Givaudan's isomer Pyralone is described as finer and more tobacco-like than butyl quinoline secondary, with less dry-earthy character. Note: the CAS verified on this page (65442-31-1) is 6-sec-butylquinoline (with some of the 8-isomer), the material suppliers sell as isobutyl quinoline or IBQ; 2-isobutylquinoline (CAS 93-19-6) is a different compound.
- Leading note
- Earthy leather
- Supporting facets
- Green, mossy, rooty, nutty
- Faint facets
- Tobacco, animalic
- Character
- Powerful, dry, tenacious
What makes Isobutyl Quinoline distinctive
Leather without smoke: a green, earthy, mossy hide note of great power.
Where the descriptions disagree: The record's name and 'IBQ' refer to 2-isobutylquinoline, while its verified CAS and PubChem record are 6-sec-butylquinoline; the two are distinct isomers sold under overlapping names.
How Isobutyl Quinoline is used
Used in traces in leather, chypre, woody and tobacco compositions, usually diluted.
Typical role: modifier (used in small amounts to change the character of a blend).
How Isobutyl Quinoline differs from similar materials
- Birch Tar Oil (Rectified)
- Birch tar is the smoked leather; the butyl quinolines are an earthy, green-mossy leather without tar.
- Oakmoss Absolute
- Oakmoss is the earthy-mossy lichen itself; the quinolines carry an oakmoss-like facet inside a powerful leather.
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
Extremely strong and diffusive; dose from dilution. The CAS number most suppliers give, 65442-31-1, identifies 6-sec-butylquinoline, so check the supplier specification for the exact isomer.
Identity and classification
- Type
- Aroma chemical
- Origin
- Synthetic
- Odour family
- Leather / Green
- Note position
- Heart to base note
- Physical form at room temperature
- Liquid
- Also known as
- IBQ, 6-sec-Butylquinoline, Butyl Quinoline Secondary
- CAS number
- 65442-31-1
- Molecular formula
- C13H15N
- Molecular weight
- 185.26 g/mol
- IUPAC name
- 6-butan-2-ylquinoline
The CAS number, formula and molecular weight are taken from PubChem compound 103401, 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 (804 reports): H302 harmful if swallowed (90.8% of reports). 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
-
Styrax Resinoid
Resinoid · Amber / Leather — balsamic, leathery, cinnamic, smoky
-
Labdanum Absolute
Absolute · Amber / Leather — amber, balsamic, leathery, animalic
-
Cedarwood Oil (Texas)
Essential oil · Woody / Leather — woody, smoky, dry, leathery
Isobutyl Quinoline is also suggested as a partner on the pages for Cade Oil (Rectified), Castoreum Absolute, Cumin Seed Oil, Guaiacol, Safraleine and Safranal.
Used in formulas and accords
Used in 21 published formulas
Isobutyl Quinoline is an ingredient in 14 perfume formulas, 6 accords and 1 base in the Formula & Accord Library.
Community formulas
RUŌOD House Originals
Original compositions by RUŌOD House.
Further reading
Questions about Isobutyl Quinoline
Is Isobutyl Quinoline natural or synthetic?
Isobutyl Quinoline is synthetic — it is made by chemical synthesis.
What is the CAS number of Isobutyl Quinoline?
65442-31-1. It was checked against PubChem on 19 October 2026.
Which published formulas use Isobutyl Quinoline?
Isobutyl Quinoline is used in 21 published formulas in the RUŌOD Lab Formula & Accord Library, including Asphalt Peony, Bitter Bridle and Black Saddle. Each is listed with a link under "Used in formulas and accords" on this page.
Sources
- PubChem — compound 103401, 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 — isobutyl quinoline — odour database.
- The Good Scents Company — 6-sec-butyl quinoline — odour database.
- Basenotes — The quinolines (forum) — published perfumery reference.
- 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 2. Descriptions of odour are judgement, not measurement.