You may not know their name yet, but your nose has certainly smelled them already… Who? Aldehydes, these synthetic compounds with a not so glamorous name but with a characteristic smell and multiple nuances. Discover all the facets of these warm and metallic notes, which have revolutionized modern perfumery.
The origins of aldehydes
The aldehy-what?
To understand what aldehydes are, you have to look at the chemistry. Don’t frown, no need to find your old schoolbooks! In organic chemistry, an aldehyde is a molecule made up of a particular grouping of atoms. It is a chemical compound that belongs to the carbonyl family. In fact, the aldehyde is a double bond between an oxygen atom and a carbon atom. When we talk about aldehydes, we mean a linear chain of carbon. They are mostly synthetic molecules that are created in the laboratory, but they exist naturally in the zest of citrus fruits and even in some fruits.
The discovery
Aldehydes were discovered at the beginning of the 19th century, and more precisely in 1835. It is a German chemist, Baron Von Liebig, who first isolated these molecules. Known for his work in organic chemistry, his discoveries have greatly influenced industrial agriculture and modern perfumery. In 1903, the chemist Auguste Darzens manages to synthesize aldehydes to reproduce them. But his process is still uncertain, and the quality and quantity of the molecules are not entirely satisfactory. A new and much more reliable process was developed about fifteen years later thanks to new technological discoveries. It is from 1910 that the industrial production of aldehydes begins.
The use of aldehydes in perfumery
From the 1900’s to today
In their early days, aldehydes were rarely used. And when they are, it is with great moderation and with the simple aim of stabilizing the formulas. It was not until the genius and audacity of certain perfumers that these molecules with their typical odor became known. It is the case of Robert Bienaimé who created in 1912 the fragrance Quelques fleurs, for the house Houbigant. This precursor nose then offered an important place to synthetic molecules such as hydroxycitronella which evokes lily of the valley… and C12 aldehyde! Creativity pays off and success is important. This resolutely modern fragrance for its time will influence other perfumers, and in particular Ernest Beaux, the nose of the famous Gabrielle Chanel.
For her, he created the iconic N°5 in 1921. For the first time in a composition, aldehydes are widely perceptible. They give the fragrance a powerful wake, an artificial and “metallic” aspect. Very quickly afterwards, aldehydes were used in many great perfumes, until the 90s. But after so many years at the top, the beloved molecules end up getting tired. Faced with new gourmand fragrances, they are abandoned by noses that favor more reassuring and regressive facets. But aldehydes are far from having said their last word! It is thanks to niche perfumery that these molecules will come back to the forefront, reworked in a more modern way.
But what do aldehydes smell like?
In perfumery, aldehydes are considered as an olfactory facet that will be combined with the ingredients of a composition to form a fragrance. In terms of smell, they are all different and will each bring particular notes to a perfume. Aldehydes are in fact categorized by the number of carbon atoms they contain. We will thus find C6, C7, C8 aldehydes… Up to C12! And each of them will diffuse a different scent. Thus, the C11 evokes the odor of candle, the C10 smells good orange when another spreads off a perfume of green apple… The C12, used in the famous N°5, delivers a metallic and hot perfume, so much so that it is compared to a hot iron.
The aldehyde accords
According to the classification of olfactory families, the aldehyde facet is part of the floral family. We often speak of aldehydes as laboratory flowers. This is how they were used in the first compositions, to give power and sensuality to floral bouquets. Some perfumers even say that these molecules “make flowers sing”! Aldehydes bring volume and freshness to compositions, with a metallic aspect that reveals a certain brilliance, as if they made the fragrances vibrate. In addition to floral fragrances, these notes are also very well suited to chypre compositions and woody scents, to reinforce their power and stability.
Did you know about aldehydes, these molecules with a very particular smell?
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