Know it better! What are aldehydes

Two weeks ago I’ve got an email from a Chemist in the Bottle reader. She suggested few topics that could and probably will be discussed sooner or later. She asked a question that I hope she’ll find the right answer in this post. What are aldehydes and if there’s only one aldehyde or are there more?  That’s a great question to ask, so a hat tip to you! Many of you dear perfumistas are aldehyde lovers but have you ever wandered what actually aldehydes are? No? Leave it to me then, it’s lesson time!

When a chemist thinks of aldehydes he means a specific group of organic (carbon based) chemical compounds that contain an aldehydic group CHO placed at the end of any alkyl chain or aryl group, here represented by R. Because chemistry is so advanced our R can be particularly anything that is organic. Nowadays hundrets of thousands aldehydes are known and more new are being obtained as we speak. Of course not all of them are dissolved in your perfume, that would be bad, really! The first time when aldehydes were used in perfumery was an eponymous act of creating Chanel No. 5. 

The most popular aldehydes used in modern perfumery vary between 7 to 13 carbon atoms (the carbon from aldehydic group is counted in). Heptanal (C7, shown below) has a green, herbal aroma;  C8, octanal smells like an orange, nonanal with 9 carbons has the aroma of roses. Decanal C10 has an intensive aroma of orange peel (rind) whiles it’s other form called Citral smells like lemons. C11 has the clean, aldehyde-associated smell and C12 brings the aroma of violets and lilies. The candle like, waxy grapefruit vibe can be provided by C13 aldehyde. Sometimes C14 aldehyde is also used in creating a fragrance – this one smells like peach.

In Chanel No. 5, C10, C11 and C12 were used. But there are many more options than these few listed above. There’s also a benzaldehyde posessing a scent of almonds. Cinnamaldehyde, as it’s name indicates, smells like a cinnamon. Not all aldehydes are used in their original form. Some need to be reduced to alcohols to gain the right aroma or intensity. Some higher mass aldehydes are not being used in perfumery because they’re simply too heavy to effuse their molecules. If something is supposed to smell it must be a volatile compound.

You may also ask where do you find all those aldehydes. They occur naturally in volatile, aromatic oils but extracting them might be a problem because many compounds of different profiles can be found in these. Chemistry posesses some effective methods of separations. Many aldehydes as well as other chemicals are being obtained in the laboratory on the way of synthesis from lower mass reactants. This method is usually very effective and quite cheap. Hope that next time you’ll decide to reach for No.5 or No.22 you’ll remember what you read here about aldehydes so that you’ll be able to say that you know it better!

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23 thoughts on “Know it better! What are aldehydes

  1. hajusuuri says:

    Fascinating! You have managed to explain aldehydes to a layperson in an easy to understand manner. Great job!!!

  2. poodle says:

    That was helpful. Thanks! Would you say that aldehydes tend to smell less like the real thing which makes them distinct in perfumes? Or are some of them exactly like the real thing?

    • lucasai says:

      Glad you’ve found it helpful. They usually smell close to the real thing they were sourced from but depending on the nose the recognition between an aldehyde and natural smell differs. Those artificially obtained are easier to recognize, they have a smell less close to the natural one

  3. Amy (PerfumedLady) says:

    Love this article! But then, I love aldehydes! They are fascinating to me because they are all around us, not just in perfumes. Thank you for pointing out their organic origin; important point to understand.

  4. Rich says:

    All this is reminding me of a bit of high school chemistry (a long time ago). You said that aldehydes can be reduced to alcohols. Does this mean that alcohols are oxidized to aldehydes (or is that acid? like wine to vinegar?). Is this a problem when perfumes are exposed to air?

    • lucasai says:

      Yes exactly! Aldehydes are reduced to alcohols and vice versa alcohols can be oxidized to aldehydes, and aldehydes can be oxidized to carboxylic acids.
      The exposure to air in a bottle is very small, it’s bigger in the bottles with stoppers, but generally air can change perfume, but the process requires many years

  5. TF says:

    I am also a chemistry student and a perfume lover, so I find these posts really interesting and appreciate that you are educating all the other perfumistas about the beautiful discipline behind our beautiful perfumes!

  6. Natalie says:

    Ooh, I feel so learned!

  7. malsnano86 says:

    OH HEY!!! THIS is your blog! How exciting.

    I love aldehydes. I’ve been puzzling for some time over the fact that although there’s no rose in the notes list for the gorgeously aldehydic La Myrrhe, it smells very rosy to me. Perhaps it includes the rose-overtone aldehyde. (No way to find out, probably.)

    • lucasai says:

      Yep, that’s my blog, my baby 🙂 Aldehydes are one of the widely loved notes in perfum. Maybe the rose vibe was created my combination of other aromas, who knows.

  8. Fascinating and educational. As I was a poor chemistry student back in the day (ok, I just didn’t feel like paying attention at the time!), this information is invaluable in trying to understand this industry.

  9. Fascinating and informative, thank you!

    I’m a chemistry-phobe, it just goes right over my head but I actually understood this, so thank you for such a clear, informative guide!

  10. perfumista'teknik says:

    Hey Lucas!
    What a great article! Very informative yet simple! I’ve been thinking lately about aldehydes and asking myself about No 5- it’s so great to know more now!
    What a great page as well- just found it, as I’ve looking for some review of yu son/altaia- and it’s exactly a page that I’ve been searching for lately: perfume + a chemical side of it(even though I was realllly bad in chemistry in highschool). I’ll be coming back here to read more!
    Great job, thank you for that!

  11. […] in a Flash’ and ‘Know it Better’ series of articles dissecting compounds like aldehydes or coumarin.  A clean, clear, easy navigable site that has a wealth of research there for the […]

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