Perfumes: The scents of Chemistry

The odor molecules

“A woman's perfume with a woman's scent”. It was based on this audacious request from French fashion designer Gabrielle Chanel, better known as Coco Chanel, that the renowned chemist and perfumer Ernest Beaux created Chanel N.5 in 1921. The composition combined flower essences with aldehydes, substances obtained by chemical synthesis. The perfumer used around 80 substances to satisfy the designer's requirements and the result was an intense and very sensual perfume.

The use of synthetic ingredients marked the beginning of modern perfumery at the end of the 19th century and enriched perfumers' palettes with new scent notes. In the 1920s, the study of molecules was the passport for the production of fragrances on an industrial scale. Today, manufacturers have more than three thousand synthetic perfume molecules at their disposal and the perfumery industry generates seven billion euros annually.

The fragrance of a perfume is a complex system of substances that were originally extracted from plants or wild animals. To give you an idea, five tons of roses are needed to obtain one kilo of this essential oil and eight million jasmines to obtain the same amount. The sale of natural musk oil, on the other hand, is limited to 300 kilos per year, in order to preserve the musk deer species.

In fact, the hunting of this small deer was banned by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) in 1979, although some countries, such as Russia, have national laws that authorize it within certain limits.

Concerns about the conservation of biodiversity, in particular endangered species of fauna and flora, led the perfume industry to chemistry laboratories, where synthetic products are now created that constitute an alternative to those of plant or animal origin. And these are, perhaps, the two major contributions of synthetic chemistry to the perfumery industry: the preservation of biodiversity and the massification of perfumes, since the synthesis of aromas in the laboratory made their production considerably cheaper.

Launched on May 5, 1921, Chanel No. 5 is still successful today. Symbol of refinement and elegance, the perfume has in its formula rosewood essential oil, jasmine de Grasse, orange blossom and sandalwood. A century after its launch, it remains simultaneously a classic and contemporary perfume, and is the best-selling worldwide.

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The royal perfumer of Mesopotamia

She was a woman and worked as a cook at the Royal Palace. It was on the kitchen counter that, among utensils to prepare food, he developed techniques to arrive at the beer formula, but also of perfumes, ointments and cosmetics. Tapputi-Belatekallim, was born in Babylon in the year 1200 BC and is considered the first perfumer and the first woman in the area of chemistry.

A clay tablet found by archaeologists, dated approximately 1200 BC, shows that this woman adapted kitchen equipment and used different plants to create various aromatic essences. His experiments were based on trial and error, leaving records of how certain elements reacted when combined, the dosages needed, and the desired temperatures.

Also responsible for cleaning the palace, Tapputi also created perfumed oils. To obtain these results, boil water several times, diluting different combinations of flowers, leaves, and myrrh. These oils were also used to perfume deceased kings and nobles, so that their body odor would remain bearable until the end of the long and elaborate funeral rituals.

It is said that the famous queen of Egypt - Cleopatra (60 BC - 30 BC) - had perfumes, oils and creams to protect herself from the arid desert climate. During the Roman Empire (27 BC - 476 AD), the most affluent and comfort-loving population abused perfumed essences and oils in their baths.

It is not certain when the concept of perfume originated, whose word derives from the Latin per fumun or pro fumun, which means 'through smoking'. With the fall of the Roman Empire and the advent of Christianity, the use of perfumes as an additive to the body was banned, since it was associated with pagan rituals.

The revival of perfumery in the West was due to merchants who traveled to the Indies in search of spices, such as cinnamon, pepper, and musk. In the 16th century and after the discovery of the distillation of raw materials, the demand for perfumes was so high that Dominican friars began to dedicate themselves to this process in the monasteries in Florence. Catherine de Medici (1519-1589), queen of France, had her group of perfumers coming from Italy. It was the beginning of the perfumery industry in France.

In the 18th century, perfumes were already manufactured in specialized houses run by pharmacists. It was at this time that, at the hands of Italians living in the city of Cologne, Germany, “Eau de Cologne” was created and became very popular.

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The chemistry of perfumes

The preparation of a perfume basically comprises the following components: denatured ethanol (C2H6O), essence or fragrance, fixative, propylene glycol (C3H8O2) and distilled water (H20). The fragrance, on the other hand, can be synthetic or natural.

Essences from natural sources are being replaced by synthetic compounds, the result of the awareness for sustainability that is transversal to all sectors of activity. It is estimated that, of the 3,000 fragrances available to perfumers, less than 5% come directly from natural sources, according to the article Chemistry Perfumes your Daily Life published in the scientific journal Journal of Chemical Education. This means that, in addition to greater compatibility with resources, there is greater cost efficiency. According to the same article, thanks to this option for synthetic compounds, the fragrance now only represents 3% of the price of a perfumed product, with the evident effects on the final cost and making perfumes accessible to everyone.

Basically, a perfume consists of a combination of fragrances, distributed according to an olfactory pyramid. The so-called “notes” of a perfume vary according to the volatility of its compounds.

The future of perfumery depends on chemistry and its scientists to invent molecules that have never been synthesized or smelled before. If it's the perfumer's job to create a perfume using the available fragrance notes, it's up to the chemist to expand the palette of notes to be used.

However, grouping smells or molecules by molecules is far from simply a way to provide cheaper copies of natural odors. Adding subtle nuances to raw materials - which can be a simple flower, for example - is to give them character and an interpretation that can result in a unique perfume. And that's what makes the work of the chemical scientist so exciting in the art of perfumery.

Perfumers can create the scent of a non-existent abstract flower with the combination of fragrances, but it's synthetic chemistry that offers the potential to create completely new smells. It was precisely this combination of natural essences with the concentration of synthetic aldehydes, whose scent is not found in nature, that made Chanel No. 5 so special.

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Olfaction: the most chemical of the senses

Sometimes the smell of a perfume, a flower or an orange pie is enough to travel back in time and remain in a happy memory. The least studied of our senses - smell - is closely linked to our emotions and behaviors and it is it that allows us to decipher chemical odor messages.

We can't smell all the smells, just the elements that release chemical particles into the atmosphere. We smell the scent of an apple, for example, but not glass or metal.

Smells are volatile odor molecules that spread through the air, penetrate the nostrils and reach a group of olfactory cells found in the olfactory epithelium, the innermost part of the nose, close to the base of the skull.

Olfactory cells have specific receptor molecules for certain odor molecules and when both meet, the olfactory cell transforms the chemical message carried by the odor molecule into electrical impulses that reach the brain through the olfactory bulb. But it is in the olfactory cortex that odor information is interpreted, identifying the smell that entered through the nose.

Sensory information is stored by the hippocampus to be later remembered and is also sent to the hypothalamus, which allows us to search for food, for example, through smell.

Like any sensory experience, olfactory perception awakens emotional and behavioral experiences in human beings. In fact, after all this, I just want to say: “chemistry” begins with the sense of smell...