Filbertone

What Filbertone smells like

JECFA, as published by PubChem, describes 5-methyl-2-hepten-4-one as a colourless liquid with a hazelnut, metallic, buttery odour. PubChem links the compound to natural-product occurrence data (LOTUS). Fraterworks describes a rich, warm hazelnut with creamy, toasted nuances and subtle woody undertones, the molecule that contributes to the smell of hazelnuts and a minor part of the smell of chocolate; at about 0.1% it gives fresh, fruity, green and nutty nuances.

Leading note

Hazelnut

Supporting facets

Metallic, buttery

Character

Nutty

• hazelnut
• nutty
• metallic
• buttery

What makes Filbertone distinctive

The hazelnut itself, with a metallic, buttery edge, rather than a general roasted-nut pyrazine note.

Concentration and dilution

Fraterworks sells it pure and as a 1% solution in DPG, and says it must be used with extreme precision in minute quantities.

How Filbertone is used

Fraterworks uses it to add nutty, gourmand effects and to enhance chocolate, vanilla and woody compositions, in minute, precise amounts.

Typical role: modifier (used in small amounts to change the character of a blend).

How Filbertone differs from similar materials

2-Ethyl-3,5(6)-dimethylpyrazine

The pyrazine is a general toasted-nut and chocolate note; Filbertone is the hazelnut itself, with a buttery, metallic edge.

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

Very potent; the formulas use it at 1%. The natural hazelnut odorant is one enantiomer; this number does not specify which.

Identity and classification

Type

Aroma chemical

Origin

Occurs in nature

Odour family

Gourmand

Note position

Heart note

Physical form at room temperature

Liquid

Also known as

(E)-5-Methylhept-2-en-4-one, 5-Methyl-2-hepten-4-one

CAS number

81925-81-7

Molecular formula

C8H14O

Molecular weight

126.2 g/mol

IUPAC name

(E)-5-methylhept-2-en-4-one

The CAS number, formula and molecular weight are taken from PubChem compound 5362588, whose own record lists this CAS number; checked 24 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 (375 reports): H315 causes skin irritation (88.3% of reports); H319 causes serious eye irritation (88.3% of reports); H317 may cause an allergic skin reaction (88% of reports); H226 flammable liquid and vapor (16.5% of reports). 1 of the reports find it does not meet the hazard criteria. A skin sensitiser classification concerns handling the neat material and the dose in a finished product; the IFRA Standards, where they apply, set the limits. 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

• 2,3,5-Trimethylpyrazine

  Aroma chemical · Gourmand — roasted, nutty, cocoa, earthy

• Vanillin

  Aroma chemical · Gourmand / Amber — vanilla, sweet, creamy

• Cacao Absolute

  Absolute · Gourmand — chocolate, cocoa, roasted, bitter

Filbertone is also suggested as a partner on the pages for 5-Methyl-6,7-dihydro-5H-cyclopentapyrazine, Chocovan and Tamanu Oil.

Used in formulas and accords

Used in 6 published formulas

Filbertone is an ingredient in 3 perfume formulas and 3 accords in the Formula & Accord Library.

Community formulas

• Banana Bread

  Community Formula · listed as “Filbertone 1%”, at 1%

• Hazelnut Accord

  Community Formula · Accord · listed as “Filbertone 1%”, at 1%

• Roasted Chestnut Accord

  Community Formula · Accord · listed as “Filbertone 1% (81925-81-7)”, at 1%

• Soy Sauce Accord

  Community Formula · Accord · listed as “Filbertone 1%”, at 1%

RUŌOD House Originals

Original compositions by RUŌOD House.

• Iron Rain

  RUŌOD House Creation · listed as “Filbertone 1% DPG”, at 1% in DPG

• Praline Smoke

  RUŌOD House Original · listed as “Filbertone 1% DPG”, at 1% in DPG

Further reading

• Building a Gourmand Accord: Vanilla, Caramel and Beyond

  The materials of gourmand perfume — vanillin, ethyl maltol, coumarin, lactones, roasted notes — how to keep them wearable, and color and crystal problems.

Questions about Filbertone

Sources

• PubChem — compound 5362588, checked 24 October 2026.
• PubChem — GHS classification (the ECHA C&L Inventory notifications and any harmonised EU entry), read 26 October 2026.
• PubChem — 5-Methyl-2-hepten-4-one (CID 5362588): JECFA organoleptic description — odour database.
• Fraterworks — Filbertone — distributor's description.
• Olfactory profile: the RUŌOD Lab team's synthesis of the published descriptions above, reviewed 26 October 2026. Evidence: more than one published description. Classification and the short description: revision 1. Descriptions of odour are judgement, not measurement.