trans-2-trans-4-Nonadiene (CAS 56700-78-8) — Top Note Fragrance Ingredient
trans-2-trans-4-Nonadiene
CAS 56700-78-8
What Is trans-2-trans-4-Nonadiene?
trans-2-trans-4-Nonadiene (CAS 56700-78-8) is an aroma chemical used as a fragrance and flavour ingredient. Its odour is described as citrus, fatty and green, placing it within the green family as a top note with high volatility. With a molecular weight of 124.2 (formula C9H16), it is handled by perfumers as a building block for compositions where a citrus character is desired. The data below is compiled from public chemical and regulatory sources.
Safety Profile
HANDLE WITH CARE
What Does trans-2-trans-4-Nonadiene Smell Like?
The odour profile of trans-2-trans-4-Nonadiene is reported as citrus, fatty, green, waxy. The dominant facet is its citrus character, with the remaining notes adding nuance and complexity. As a top note it contributes to the opening of a fragrance. Perceived intensity and exact character depend on concentration, the carrier and the surrounding accord.
Scent Profile
Profile derived from public odour-descriptor data; relative, not absolute.
Chemistry & Properties
The Chemistry
trans-2-trans-4-Nonadiene has the molecular formula C9H16 and a molecular weight of 124.2 g/mol. Its canonical SMILES representation is CCCCC=CC=CC. Its reported log P (XLogP) of 3.31 indicates a lipophilic, oil-soluble molecule, which informs how it partitions in a formula. Physical constants below are drawn from PubChem and EPA CompTox public datasets.
Physical & Chemical Properties
| Molecular Weight | 124.2 g/mol |
|---|---|
| Boiling Point | 151.1 °C |
| Melting Point | -66.84 °C |
| Flash Point | 37.34 °C |
| Density | 0.7648 g/cm³ |
| Vapor Pressure | 3.96 mmHg |
| Water Solubility | 3.802e-05 g/L |
| XLogP | 3.31 |
Perfumer Guide
Alternatives & Comparisons
Ingredients occupying a similar odour space — useful as substitutes or companions when trans-2-trans-4-Nonadiene is unavailable or restricted.
Shares fatty, fruity, green character — a candidate substitute or companion in the same odour space.
Shares citrus, fatty, floral character — a candidate substitute or companion in the same odour space.
Shares fatty, fruity, green character — a candidate substitute or companion in the same odour space.
Safety & Regulatory
⚠ Regulatory Disclaimer
General reference only. IFRA, REACH and EU Cosmetics Regulation standards update periodically. Consult the current IFRA Standards Library before formulating. Not legal or regulatory advice.
IFRA Status
No IFRA restriction recorded in the data set. This is not a guarantee of unrestricted status — always confirm against the current IFRA Standards Library.
GHS Classification
Signal word: Warning
Odour detection threshold (air): 3.936e-08 ppb — a literature-curated value indicating its potency in the vapour phase.
Open trans-2-trans-4-Nonadiene in Fragrance Studio (Pro) for the calibrated vapour-pressure curve, the modelled odour-threshold estimate, and the substitute-matching engine across 2,900+ aromachemicals.
References & Sources
- PubChem Compound Summary (NIH) — search by InChIKey
- EPA CompTox Chemicals Dashboard — physicochemical & fate data
- IFRA Standards Library (49th / 51st Amendment)
Data: PubChem (NIH), EPA CompTox, IFRA. Last reviewed: Jun 2026.
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