Aldehyde C-10 (Decanal): A Perfumer's Guide to This Citrus-Waxy Aroma Chemical

Aldehyde C-10, better known as decanal, is a colourless to pale-yellow liquid aroma chemical (formula C10H20O, CAS 112-31-2) prized in perfumery for its intense citrus-peel, waxy and slightly fatty odour. It is used in very small quantities to add sparkle and a fresh orange-rind lift to fragrances, cosmetics and candles. It is strictly for external, formulation use — not for eating or applying neat to skin.

What is Aldehyde C-10?

Despite the "C-10" name suggesting a mystery, this is simply decanal, a straight-chain fatty aldehyde with ten carbon atoms and a carbonyl (-CHO) group at the end. The old "Aldehyde C-number" naming comes from classic perfumery, where aldehydes were labelled by their carbon count. Decanal occurs naturally in citrus oils, coriander and several other essentials, which is why it smells so recognisably of fresh orange peel.

On its own, undiluted, it is surprisingly harsh — sharp, greasy and almost soapy. Diluted correctly, it opens up into that bright, zesty character perfumers love in top notes.

Common uses

• Fine fragrance and perfume: A workhorse for citrus, cologne, aldehydic and "clean laundry" style accords. It boosts the natural brightness of orange, lemon and mandarin.
• Soaps and cosmetics: Adds a fresh, radiant top note to soap bases, lotions and other personal-care formulations.
• Candles and home fragrance: Used sparingly within a fragrance blend to lend a lively citrus edge.
• Flavour work: As a food-grade decanal it appears in citrus and fatty flavour profiles, though this must only be done by qualified formulators using food-grade material and legal dosage limits.

How to use it

The golden rule with decanal is less is more. It is extremely powerful, so working with it neat will simply overwhelm your blend.

1. Make a dilution first. Prepare a 1% or 10% solution in perfumer's alcohol or a suitable carrier before you start blending. This gives you control over tiny doses.
2. Dose in drops. Even in a finished perfume, decanal usually sits at a fraction of a percent. Add gradually and smell as you go.
3. Pair it thoughtfully. It sings alongside citrus oils (orange, bergamot, lemon), other aldehydes, and clean musks. It can also freshen up heavier floral or woody bases.
4. Let it settle. Aldehydic top notes evolve over the first few minutes on a smelling strip, so evaluate over time rather than judging the first sniff.

Safety notes

Aldehyde C-10 is a concentrated aroma chemical, so treat it with respect:

• It is meant for external, formulation purposes only. Do not ingest it, and do not apply it undiluted to skin.
• Avoid direct contact with eyes and prolonged skin contact. Wear gloves and work in a well-ventilated space.
• Always follow recognised fragrance-use guidelines and safe dilution limits for skin-contact products.
• Keep tightly closed and well away from children and pets.
• Keep away from open flames — like most aroma chemicals, it is combustible.

If you are new to aroma chemicals, request the COA and MSDS (safety data sheet) before working with the material and read them fully.

Buying and storage tips

Azlok offers Aldehyde C-10 starting at ₹399, with pack sizes from a handy 100 gm bottle right up to 25 kg for regular production users. For most hobbyists and small candle or soap makers, the 100 gm size lasts a long time because you use it in such small amounts.

• Buy for your scale. Because a little goes far, start small unless you are formulating in volume.
• Store cool and dark. Keep it in an airtight amber or well-sealed container, away from heat and sunlight. Aldehydes can oxidise over time.
• Mind the shelf life. This material has roughly a 12-month shelf life; label your bottle with the opening date and use it within that window for the truest odour.
• Avoid air exposure. Close the cap promptly after use to reduce oxidation and evaporation.

FAQ

Is Aldehyde C-10 the same as decanal?

Yes. Aldehyde C-10 is the traditional perfumery name for decanal, a ten-carbon fatty aldehyde with the formula C10H20O and CAS number 112-31-2.

What does Aldehyde C-10 smell like?

It has a strong citrus-peel character with waxy, fatty and slightly soapy undertones. In dilution it reads as bright, fresh orange rind; neat, it is quite harsh.

How much should I use in a fragrance?

Very little. Most formulators use it at a fraction of a percent, working from a 1% or 10% dilution. Add drop by drop and smell frequently, because it is easy to overdose.

Can I apply Aldehyde C-10 directly to my skin?

No. It is a concentrated raw material for external formulation use only. It should be diluted and used within a finished product that follows safe fragrance-use limits, never applied neat.

How should I store it and how long does it last?

Keep it tightly sealed in a cool, dark place away from heat and light. Its shelf life is around 12 months, so use it within that period for the best odour quality.