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!