Material guide: dihydromyrcenol — one drop and the whole bottle is 1988

A complaint comes up on the forums with some regularity: I added a little something fresh and the whole bottle turned into a men's fragrance from the eighties. The material named is usually the same one.

The short version

• It smells like fresh lime with a clean floral edge. Clean enough that many people's first reaction is "laundry detergent", and that reaction is well founded, because soap and laundry products use a great deal of it.
• Medium strength, 16 hours on a blotter. It isn't a top note that vanishes, it sits through the heart, so an overdose is hard to walk back.
• A 2009 rat developmental study set a NOEL of 500 mg/kg/day against an estimated human intake of 0.02 mg/kg/day, a margin of 25,000. What makes this material awkward is not toxicity. It is that everybody recognises it.

The basics

CAS	18479-58-8
Chemical name	2,6-dimethyloct-7-en-2-ol
Formula	C₁₀H₂₀O
Molecular weight	156.27
Type	Synthetic single molecule, also made from natural terpenes
Odour	Fresh, citrus, lime, floral, clean, cologne
Odour family	citrus
Strength	Medium (evaluate at 10% or below)
Longevity	16 hours (blotter, neat)
Appearance	Colourless clear liquid
Boiling point	194–197 °C @ 760 mmHg
Flash point	76.11 °C
Specific gravity	0.824–0.830 @ 25 °C
Refractive index	1.434–1.440 @ 20 °C
Water solubility	252.2 mg/L @ 25 °C (est)
Other solubility	Alcohol and paraffin oil; performs well in soap, detergent and antiperspirant bases
Storage	24 months or longer; cool, dry, sealed, away from heat and light
Regulatory	FLAVIS 02.144
Suppliers	53

In plain terms. CAS is the molecule's ID number, unique worldwide and more reliable than any trade name. Specific gravity 0.824 means it floats on water. Refractive index is what QC measures; if you want to know whether your shipment is what it claims, that's the line to check on the COA. A flash point of 76 °C is higher than most citrus materials, which eases shipping classification without making it safe near a flame.

Why it takes over a formula

The "potential uses" field on our database record lists fragrance types including cologne, fern, fresh and clean, ocean sea and pine, plus three that need no explanation — cool water, drakkar noir, azzaro — and one laundry brand, tide.

One clarification matters here. That field is a fragrance-type classification, meaning this material is commonly used to build that kind of smell. It is not a formula disclosure and it does not assert that those specific bottles contain it. Even so, the list makes the point: this molecule is welded to one era's idea of clean.

The reason is timing. From the mid-1980s, men's fragrance swung away from heavy chypres toward aquatics and fougères, and this material supplied exactly what that turn needed — citrus brightness without terpene roughness, and enough alkali tolerance to survive in soap and detergent. Natural lemon or lime oil collapses in a detergent base within hours. This doesn't.

So a beginner's first encounter with it tends to go the same way. The goal was "make it fresher", and the result was "make it somebody else's fresh". That's not a defect in the material. Its signature is simply too legible.

What the rat study found

Politano and colleagues published in the International Journal of Toxicology in 2009. Pregnant Sprague-Dawley rats, 25 per group, dosed orally in corn oil at 0, 250, 500 or 1000 mg/kg/day on gestation days 7 to 17.

At 1000 mg/kg/day, maternal body weight gain fell 5% against controls and feed consumption dropped significantly. Fetal body weight fell about 3%, with reversible delays in ossification of the hindpaw metatarsals and an increase in supernumerary thoracic ribs. The 250 and 500 groups showed none of this.

The authors therefore set maternal and developmental NOELs at 500 mg/kg/day and maternal and developmental NOAELs at 1000 mg/kg/day, concluded that dihydromyrcenol is not a selective developmental toxicant under these conditions, and noted a margin of safety of 25,000 between the reversible delays seen in rats and an estimated daily human exposure of 0.02 mg/kg/day.

Two terms worth unpacking. NOEL is the highest dose at which nothing measurable changed. NOAEL adds the word "adverse": something changed, and the change was judged not to be harm. When the two numbers differ, the gap between them is the band where effects appear but are reversible.

Indoor ozone eats it

The second study changes the setting. Nørgaard and colleagues, Environment International, 2014: a kitchen cleaning cream and a plug-in air freshener were run in a 20 m³ walk-in climate chamber at 0.6 air changes per hour, under low ozone (~5 ppb) and high ozone (~50 ppb).

Both products emitted terpenes, dihydromyrcenol among them, alongside limonene, geraniol and linalool. At high ozone those terpenes decayed as they consumed the ozone, and a set of oxygenated reaction products appeared: formaldehyde, acetaldehyde, acetone, 4-acetyl-1-methylcyclohexene, 6-methyl-5-heptene-2-one, 3-isopropenyl-6-oxo-heptanal and 4-oxopentanal.

The authors judged that at high ozone, the plug-in air freshener produced formaldehyde and 4-oxopentanal at concentrations warranting concern about sensory irritation and airflow limitation respectively. Peak particle mass reached 81 μg/m³ for the cleaning cream and 24 μg/m³ for the air freshener, though the authors did not consider the particles themselves likely to cause acute airway effects given their organic composition and concentration.

Read this one carefully. It tested cleaning products and a plug-in, not perfume. The 50 ppb ozone level was set deliberately high. The authors themselves close by saying that testing under conditions mimicking real user behaviour is warranted. What it does establish is concrete: terpene alcohols like this one do not sit inertly in a room. They react with whatever ozone is present, and the reaction products are not necessarily gentler than the molecule you started with.

Smell it against these

Material	Direction	Blotter hours
Linalool	The joint between citrus and floral, soft	12
Citral	Lemon peel, bright and sharp	12
Dihydromyrcenol	Lime, clean, soapy	16
Geranyl acetate	Pear and lavender floral	24

Line those four up and "fresh" stops being one direction. Citral's brightness is pointed and stings a little. This one's brightness is flat, like something that has been washed. The difference reads far more clearly on paper than in prose.

When you smell it

• Start at 10%. Neat, it reads as a cleaning product. Dilution is what lets the floral side come forward.
• Give it time. Sixteen hours on a blotter means it is still there long after the first impression. Judging it in the first ten minutes gets it wrong.
• Put it next to lime oil once. The natural oil is more dimensional up front and collapses faster. This is flat, clean and durable, which is exactly why detergent formulators reach for it.
• Add less than you think. The "my bottle became somebody else's fragrance" complaint is almost always an overdose. Try 0.5% and climb only if you need to.

Buying and storage

It goes by many names: Dihydromyrcenol, Dihydro Myrcenol, DHM, Lymolene (an IFF trade name), and the systematic 2,6-dimethyl-7-octen-2-ol. When a trade name returns nothing, CAS 18479-58-8 always finds it. That's the same problem covered in material names mislead.

Purity specs commonly run 95% to 99%+. DRT and Sigma-Aldrich list ≥99%, Lluch lists 98%. The difference is smellable on this material; lower-purity lots carry a terpenic roughness at the edges. Some suppliers also sell DHM tops and DHM bottoms, the front and back distillation cuts, which differ in both smell and price. Ask which one you're buying.

The flash point of 76 °C is friendlier than most citrus materials, but store it cool, dry, sealed and out of the light. Labelled shelf life is 24 months or longer.

Regulatory and safety

The database records FLAVIS 02.144, and EFSA has handled this structural class across several flavouring group evaluations (the FGE.18 and FGE.90 series). On acute toxicity, oral rat LD50 is 3,600 mg/kg and dermal rabbit LD50 is greater than 5,000 mg/kg. GHS classification is combustible liquid (H227) and serious eye irritation (H319), so wear eye protection when handling.

A flavour listing, an animal toxicology dataset and skin-contact formulation safety are three separate questions. For skin and consumer products, check current IFRA Standards, the supplier SDS and the rules for your finished product type. None of the three substitutes for the other two.

→ Dihydromyrcenol in the database: full physical data, 53 suppliers and suggested blends. → Search by odour: try "lime fresh floral".

References

V. T. Politano et al., Evaluation of the developmental toxicity of dihydromyrcenol in rats, International Journal of Toxicology, 28(2), 80–87 (2009). PMID 19482832. doi:10.1177/1091581809333892

A. W. Nørgaard et al., Ozone-initiated VOC and particle emissions from a cleaning agent and an air freshener: risk assessment of acute airway effects, Environment International, 68, 209–218 (2014). PMID 24769411. doi:10.1016/j.envint.2014.03.029