Synthetic — manufactured globally by multiple fragrance chemical suppliers
Pyramid
Top
Bitter pith over clean zest — the peel of a pink grapefruit twisted over cold glass. Methyl pamplemousse is a synthetic acetal (CAS 67674-46-8) that delivers the tart, soapy-green bite of grapefruit without the photosensitivity or oxidative fragility of natural grapefruit oil.
Tart, bitter grapefru it peel with a soapy-green undercurrent. Drier and more austere than natural grapefru it oil, which retains sulfurous and aldehydic qualities. A faint violet-woody undertone sits beneath the citrus, giving it more complexity than a simple terpene aldehyde. Less sweet thanlemon chemicals, less floral than bergamot, and without the sulfurous snap of thioterpineol (grapefruit mercaptan, the molecule actually responsible for natural grapefruit aroma). Moderate diffusion; limited tenacity.
Evolution over time
Immediately
Immediately
Sharp, bitter grapefruit peel. Clean and tart, with a soapy-green edge. The bitterness is pronounced — more rind than juice.
After a few hours
After a few hours
The citrus bite softens. A faint woody-violet undertone becomes perceptible, and the soapy facet smooths into something cleaner and more abstract. The grapefruit character fades but does not disappear entirely.
After a few days
After a few days
Nearly gone. A faint, clean, slightly waxy residue — the ghost of citrus zest on dry paper. Substantivity is limited by the molecule's relatively high vapour pressure (0.214 mmHg at 25°C).
The Full Story
Methyl pamplemousse is the dimethyl acetal of Traveal (2,2,5-trimethyl-4-hexenal). Its IUPAC name is 6,6-dimethoxy-2,5,5-trimethylhex-2-ene. The acetal structure makes it chemically stable in alkaline bases — soaps, detergents, powder formulations — where natural citrus oils degrade rapidly. That stability, combined with a clean grapefruit-peel bitterness, made it a common synthetic citruses in both fine fragrance and functional perfumery.
What It Smells Like
On a blotter, the opening is sharp and bitter — grapefru it peel, not juice. A soapy, slightly woody undertone emerges with in minutes, along with a faint green-violet quality that distinguishes it from simple citrus aldehydes. Compared tobergamot, methyl pamplemousse is drier, more bitter, and lacks bergamot's tea-like sweetness. Compared to nootkatone — the sesquiterpene ketone found naturally in grapefruit — it is greener and more overtly zesty, where nootkatone tends toward woody-ambery territory. Substantivity is limited: roughly two hours on a blotter at 100%.
Chemistry
Molecular formula: C₁₁H₂₂O₂. Molecular weight: 186.29. CAS: 67674-46-8. EINECS: 266-885-2. Specific gravity: 0.865–0.885 at 25°C. Refractive index: 1.430–1.450 at 20°C. Boiling point: 214–215°C at 760 mmHg. Flash point: 83°C (TCC). Colourless to pale yellow liquid. The molecule is synthesised by acetalization of Traveal (2,2,5-trimethyl-4-hexenal) with methanol. Commercial preparations may contain trace amounts of the unreacted aldehyde precursor.
Commercial Names
Sold as Methyl Pamplemousse (various suppliers), Amarocit (trade name), Pomelocit, Pamplerom. Not a captive molecule — widely available on the open market from multiple fragrance-chemical suppliers.
This note in Première Peau. Gravitas Capitale · Nuit Elastique · Rose Monotone. Sample all seven extraits in the Discovery Set.
Methyl pamplemousse is one of the very few synthetic aroma chemicals that remains stable in strongly alkaline soap bases (pH 9–11) while retaining its citrus character. Most natural citrus oils — including grapefruit — degrade rapidly under these conditions through oxidation and polymerisation of their terpene components. This alkali resistance is a direct consequence of the acetal functional group, which is hydrolytically stable at high pH but cleaves under acidic conditions. The irony: the molecule survives industrial soap but falls apart in an acidic household cleaner.
Extraction & Chemistry
Extraction method: Synthetic. Methyl pamplemousse is produced by acid-catalysed acetalization of Traveal (2,2,5-trimethyl-4-hexenal) with methanol. The reaction yields the dimethyl acetal (6,6-dimethoxy-2,5,5-trimethylhex-2-ene) as a colourless to pale yellow liquid at high purity (98–100% assay). No natural source exists — this molecule does not occur in grapefruit or any other plant material. It was developed as a stable synthetic alternative to natural grapefruit oil's key olfactory characteristics.
Molecular Formula
C₁₁H₂₂O₂ (MW 186.29)
CAS Number
67674-46-8
Botanical Name
N/A — synthetic molecule
IFRA Status
Not restricted under IFRA 51st Amendment. No use limits in any category. The molecule is considered safe for use in all fine fragrance and functional applications at standard perfumery concentrations.
Top-note modifier and citrus brightener. Methyl pamplemousse provides the bitter-zesty opening in modern colognes and fresh-citrus compositions. Its primary functi on is structural: it sharpens and lifts citrus accords without the oxidative instability or IFRA-restricted phototoxicity of cold-pressed grapefru it oil. Typical dosage in fine fragrance: 0.1–2% of the concentrate, though formul as can push to 10% for maximum impact. Average use sits around 1%. Beyond citrus constructions, methyl pamplemousse is a booster in vetiver accords — the bitter-green overlap between grapefru it and vetiver reinforces the natural qualities of vetiverol and vetivone. Its alkali stability makes it indispensable in functional perfumery: soaps, powder detergents, and cleaning products where terpene-based citruses collapse. Related synthetic grapefru it materials include nootkatone (CAS 4674-50-4), which delivers a woodier, more ambery grapefru it quality, and thioterpineol (grapefru it mercaptan, CAS 71159-90-5), which reproduces the sulfurous juiciness of fresh-cut grapefru it flesh at extremely low concentrations.
