What Is Aldehyde C-9 (Nonanal)?
Aldehyde C-9, chemically known as nonanal, is a straight-chain, nine-carbon fatty aldehyde. In perfumery it goes by the nickname "rose aldehyde" — because when diluted it simultaneously delivers the waxy, freshly cut face of a rose petal and the oily brightness of orange peel. A single drop can transform the top of a formula. When the top note dissipates, this layer takes the stage — but C-9's real job is to launch that lift in the first place.
How Does It Smell?
- ✓ Waxy, oily brightness
- ✓ Ratioge and mandarin peel membrane
- ✓ The clean face of a wet rose petal
- ✓ Ironed cotton, starched linen feel
- ✓ A green, sharp, faintly metallic spark
- ✓ Overpowering straight from the bottle; elegant when diluted
💭 What Does It Evoke?
Cleanliness · Transparency · Nostalgia · Elegance · Brightness · Cold light
Aldehydes cast light onto a fragrance. C-9 brings a glass-like clarity and a "just-unwrapped, fresh" association to a perfume's opening. That starched white-shirt sensation rooted in classic French perfumery is, in large part, the signature of this family.
Identity & Physical Data
| Property | Value / Note |
|---|---|
| Chemical name | Nonanal (n-nonyl aldehyde, pelargonaldehyde) |
| CAS | 124-19-6 |
| Molecular formula | C9H18O |
| Specific gravity (density) | Approximately 0.82–0.83 g/ml (20°C) — 1 ml ≈ 0.83 g |
| Boiling point | ~190–195°C |
| Flash point (flash point) | ~60–70°C range — classified as flammable; refer to the supplier's MSDS |
| Appearance | Colourless to pale yellow clear liquid |
| Primary weakness | Oxidises on air contact, converting to nonanoic acid (sour, sweaty/cheesy odour) |
Which Fragrance Types and Accords Is It Used In?
Nonanal is not a "lead character"; it is the spotlight that illuminates the stage. It cannot build a fragrance on its own, but used in the right place it makes citrus smell real, rose smell alive, and musk smell clean. It shows no preference for designer or niche; it works everywhere from classic aldehydic florals to modern clean-musk structures.
🧴 Typical Applications
- Aldehydic floral: The classic home of this family. In an aldehyde bouquet built with C-10, C-11 and C-12, C-9 represents the oily-citrus wing.
- Rose accords: Adding a very low dose of C-9 over geraniol, citronellol and phenyl ethyl alcohol gives the rose a "freshly cut stem" effect. This is the reason for its nickname "rose aldehyde".
- Citrus openings: Reinforces the peel/pith side of bergamot, orange and mandarin oils, brightening cologne-style openings.
- Clean musk and fabric accords: C-9 placed over polycyclic musks such as Tonalide sharpens that "freshly laundered" perception.
- Masculine fougère and fresh woody: Adds sharpness and dynamism to the top of a lavender–coumarin structure.
- Room fragrance and home care: Thanks to its high diffusion it registers in a space even at low doses; however, solvent selection is critical.
Well-Known Examples
The fragrances below are classics that place an aldehydic opening at the very heart of their identity. In these compositions C-9 does not work alone but as an aldehyde bouquet together with C-10/C-11/C-12:
- Chanel N°5 — The founding reference of the aldehydic floral family; the aldehydes carry the entire opening.
- YSL Rive Gauche — A cold, metallic-powdery aldehydic opening sitting above a rose–iris heart.
- Estée Lauder White Linen — The textbook example of a starched, clean-linen association.
Where Does C-9 Sit Within the Aldehyde Family?
Fatty aldehydes are named by carbon count. As the chain lengthens the odour shifts towards waxy-soapy; as it shortens it sharpens.
| Material | Chemical name | Character | Typical dose (in composition) |
|---|---|---|---|
| Aldehyde C-8 | Octanal | Very sharp, orange peel, aggressive citrus | 0.005–0.1% |
| Aldehyde C-9 | Nonanal | Waxy-rosy, oily citrus, clean | 0.01–0.3% |
| Aldehyde C-10 | Decanal | Ratioge peel + soapy; the most "classic aldehyde" | 0.01–0.3% |
| Aldehyde C-11 undecylenic | 10-Undecenal | Metallic, fresh, faintly green-waxy | 0.01–0.2% |
| Aldehyde C-12 MNA | 2-Methylundecanal | Powdery, soapy, longer-lasting; the softest of the aldehydes | 0.05–0.5% |
| Aldehyde C-12 lauric | Dodecanal | Very waxy, floral-soapy, violet-tinged | 0.02–0.3% |
How and at What Level Should It Be Used?
Nonanal is like salt in cooking: a little opens up the flavour; too much makes it inedible. The most common mistake with this material is dropping it in neat. A single drop from a pipette is roughly 0.03 g, and in a 100 g trial that already amounts to 0.03% — close to the upper limit.
Usage Level Guide
| Purpose | Level in composition | Note |
|---|---|---|
| Trace touch (reviving a citrus note) | 0.01–0.05% | Imperceptible, yet its absence is felt |
| Freshening a rose accord | 0.02–0.08% | Gives the rose a "just-picked" quality |
| Distinct aldehydic opening | 0.1–0.3% | Use in conjunction with other aldehydes |
| Total aldehyde bouquet (C-8…C-12) | 0.3–1.0% | Exceeding this pushes the fragrance towards soap/detergent |
| Room fragrance / home care | 0.05–0.2% | High diffusion — start low |
These levels apply to the perfume concentrate (composition). When moving to the finished product, factor in the dilution ratio: in an extrait at 20% concentration, a C-9 level of 0.1% in the composition becomes 0.02% in the bottle.
Preparing a Working Solution (Stock)
Nonanal is a liquid raw material; it requires no melting or heating. However, due to the precision required at such low doses, it must always be used in diluted form. The laboratory standard is 10% or 1%.
- Choose your solvent
For alcohol-based perfume use perfumer's ethanol (pure, odourless ethyl alcohol); for oil-based or roll-on applications use DPG (dipropylene glycol) or IPM (isopropyl myristate). DPG and IPM are not fixatives; they are carrier solvents and emollients that indirectly contribute to longevity by slowing volatilisation slightly.
- Prepare a 10% stock
On a precision balance: 1 g nonanal + 9 g solvent = 10 g stock. Always weigh into the solvent and add the aldehyde last; this minimises evaporation loss.
- Prepare a 1% working solution
Take 1 g of the 10% stock and add 9 g of solvent. This is the ideal level for odour evaluation and initial trials. Dip your blotter (scent strip) into this solution — never dip it into the neat material.
- Homogenise
Cap the bottle and shake for 30–60 seconds, or stir on a magnetic stirrer for 5 minutes. Nonanal blends easily in these solvents; no heating is required, and heating is not recommended — elevated temperature accelerates oxidation.
- Label and date
Include: material name, CAS, solvent, percentage and preparation date. Aldehyde solutions deteriorate over time; smell-check every 6 months and discard any stock that smells sour.
- Start low in the formula
If you use 1 g of the 1% solution in a 100 g trial, you achieve 0.01% in the composition. Work upwards from there; reducing concentration afterwards is far more difficult.
Maceration and Cold Filtration
These are two separate steps — do not confuse them:
- Maceration (maturation)
At room temperature (~15–20°C) and in the dark, for 2–6 weeks. This is where the interaction and esterification between alcohol and aroma chemicals takes place. As temperature drops these reactions slow down; this is why maceration is not carried out in a refrigerator. Keep the bottle away from light — aldehydes degrade under light exposure.
- Chilling
After maceration is complete, rest the batch at approximately 0–4°C for 24 hours. The purpose is not longevity; it is to precipitate waxy, insoluble components derived from natural extracts.
- Cold filtration
While still cold, filter through a filter paper of approximately 1 micron. Skipping this step will result in sediment forming at the bottom of the bottle over time and a hazy product. Re-evaluate the scent after filtration.
Solubility, Stability, Safety and Alternatives
Nonanal is an easy material to work with but an easy one to spoil. If stored incorrectly, within six months the bottle in your hand will have ceased to be a perfumery raw material and will have turned into the smell of rancid oil.
Solubility and Blending
- Ethanol: Soluble at all ratios with clarity. The first choice for alcohol-based perfume.
- DPG: Soluble; softens the odour impact; ideal for stock solutions.
- IPM: Soluble; suited to oil-based applications and wherever a skin-glide feel is desired.
- Benzyl benzoate / TEC: Soluble; provides a heavier, more enveloping base.
- Water: Practically insoluble. A solubiliser is essential in any water-containing system.
If using a magnetic stirrer, low-to-medium speed for 5–10 minutes is sufficient. Heating is not required and is not recommended.
Stability: Oxygen Is the Biggest Enemy
Nonanal reacts with atmospheric oxygen, converting to nonanoic acid. The result: a sour, oily, sweaty/cheesy odour and inexplicable deterioration in the formula. Ways to protect against this:
- Keep the bottle as full as possible; oxidation accelerates as headspace increases. Transfer to a smaller bottle as the level drops.
- Amber glass bottle, tight cap, cool dark shelf. (This refers to raw material storage — do not confuse it with the maceration of finished perfume.)
- If possible, blanket the headspace with nitrogen.
- Adding a trace amount of antioxidant (e.g. tocopherol/BHT) to the formula can extend shelf life; confirm the dosage against your supplier's recommendation.
- Aldehydes can cause colour change (yellowing) over time with amines and certain extract components; separate stability testing is essential in soap and high-pH bases.
IFRA, Allergens and Safety
Nonanal does not appear on the EU list of classic fragrance allergens requiring declaration on the label. However, this does not mean "use without limit." IFRA limits are set not by total fragrance oil level but by individual materials and product category (leave-on / rinse-off). Permitted levels for deodorant, face cream, candle and room fragrance differ from one another.
One further point: safety depends on the molecule and the usage level, not the source. The distinction "natural = safe, synthetic = risky" is technically incorrect. The strictest restrictions apply to naturally derived components (oakmoss, citral, eugenol); natural bergamot oil is phototoxic and can cause pigmentation in sunlight. Conversely, some pure synthetics have a very clean allergenic profile. Nonanal from both natural and synthetic sources is the same molecule — and behaves the same way.
Laboratory Safety
- Nonanal and, in particular, the high-grade ethanol and room-fragrance solvents such as DPM/MMB that you use to dilute it are flammable (low flash point). Keep away from open flames and heat sources.
- Be mindful of static electricity; use earthing/grounding when transferring large volumes.
- Good ventilation is essential. Aldehydes irritate the respiratory tract at high concentrations.
- Wear nitrile gloves and protective goggles. Neat aldehyde causes skin and mucous membrane irritation.
- Cosmetic and perfumery fragrance oils are not food products; they are neither edible nor drinkable. A "food grade" label applies to food flavourings and does not constitute a safety assurance for a cosmetic fragrance oil.
- If you intend to sell cosmetic products in Turkey, ÜTS company registration and product notification are required. This process is subject to official fees; the claim that "registration is free" is incorrect. Notification steps and responsible person/manufacturer obligations are separate topics; refer to the official source published by TİTCK for current fees and procedures.
Trade Names and Alternatives
Nonanal is most commonly sold under generic names in the industry. You may encounter the following names in supplier catalogues:
- Aldehyde C-9 (the most common perfumery name)
- Nonanal / n-Nonanal
- Pelargonaldehyde
- Nonyl aldehyde
Closely related alternatives and complementary materials:
- Aldehyde C-10 (Decanal): More soapy and closer to orange peel. The most natural companion to C-9.
- Aldehyde C-8 (Octanal): Sharper and more aggressive citrus; the harsh sibling of C-9.
- Aldehyde C-12 MNA: Powdery, soft and longer-lasting; choose this when you want an aldehydic effect without the sharpness.
- Undecavertol: Green-floral, aldehydic in feel but considerably softer — a gentler alternative.
- Melonal: A melon-green toned aldehyde; for those who want fruity brightness rather than citrus.
For current purity values, technical data sheets and packaging options for this raw material, consult the supplier information on the esans.com.tr product page.
Frequently Asked Questions
The most common questions about Aldehyde C-9, with concise, actionable answers.
What does Aldehyde C-9 smell like?
Why is it called "rose aldehyde"?
What is the difference between Aldehyde C-9 and C-10?
How much should I use in a formula?
Do aldehydes make a perfume last longer?
Why has my nonanal started smelling sour over time?
Is Aldehyde C-9 a solid or a liquid? Does it need to be melted?
Can Aldehyde C-9 be used in summer fragrances?
Why is nonanal sold in such small packaging?
My perfume turned hazy after I added an aldehyde — is C-9 the cause?
Should I use DPG or IPM — and which one is a fixative?
Is Aldehyde C-9 harmful to skin?
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