Odor profile: Tonka beans - fruits of Dipteryx odorata, a tropical tree native to Central and South America - contain 1-3% of coumarin. Tonka bean absolute contains 90% of coumarin. Depends on the amount, the scent varies from green grassy to sweet tobacco almond.
It is quite difficult to say what ingredient was the first synthetic material to be used in perfumery. The first "experimental" synthetic materials were narrow fractions of essential oils and isolates, individual materials which were isolated from natural sources. Benzaldehyde, which possesses a smell of bitter almond, is sometimes considered among the first synthetic fragrant substances. But much more often this memorable milestone is associated with the substance called Coumarin. Stricktly speaking, coumarin is not something entirely artificial.
Many plants contain coumarin. Besides tonka beans and vanilla, in high concentration coumarin is found in Galium verum, Angelica (Angelica archangelica L), Chinese cassia (Cinnamómum aromáticum), and Sweet grass (Hieróchloe odoráta). Many fruits contain coumarin, for example, sour cherry, strawberry, black currant and apricots. A big measure of coumarin in a plant makes it taste bitter and unattractive to most animals.
August Vogel isolated coumarin for the first time from tonka beans and sweet-clover (we will talk about this one later) in 1820. He mistook coumarin for benzoic acid. In the same year, the French pharmacist Nicholas Jean Baptiste Gaston Guibourt discovered the mistake and named the new compound "Coumarin" (from the French name for tonka beans, coumarou). In 1856, Friedrich Woehler determined the structure of coumarin, and in 1868, William Henry Perkin synthesized it for the first time in the lab. Ten years (1877) later he invented the industrial production of this substance.
In 1884, Paul Parquet, the owner and perfumer of Houbigant, created the perfume Fougère Royale, which is believed to be the first perfume containing synthetic ingredients (its central accord was built of lavender, oak moss and coumarin). Fougère Royale was about 10% coumarin. From that very moment we begin the modern era in perfume history.*
Fougère Royale has given its name to a very big perfume family of "fougeres". Fougere is almost the only "exclusively" masculine perfume genre which still exists and develops (although, according to the opinion of Jean-Paul Guerlain there were only two good fougere perfumes, Jicky and Mouchoir de Monsieur).
About 90% of modern perfumes contain coumarin, you can easily detect it by reviewing the list of ingredients on the perfume packaging. I just made an experiment and randomly chose 10 perfumes and saw coumarin in the composition of 9 of them. Every second perfume has more than 1% of coumarin.
The scent of coumarin is usually described as freshly mown hay. In low concentration coumarin really reminds somewhat of rotting hay, but in a big quantity it has a sweet gourmand, almond-vanillic aroma. Thus gourmand perfumes have it the most. In descriptive lists of perfume notes it might hide behind tonka beans, vanilla, marzipan or tobacco. So called С6 wound compounds, and cis-3-Hexenol among the first, are responsible for its fresh green grassy facet.
From a scientific point of view, coumarin is a lactone, an internal (cyclic) ester. Many lactones, used in perfumery, often have a characteristic fatty waxy scent, reminiscent of coconut and milk. Fragrant substances, which are similar to coumarin by structure, possess a similar scent: nutty, vanillic, creamy gourmand. The use of coumarin is restricted to 1.6% in the final perfume product, and even less, up to 0.1%, in cosmetic products. All similar compounds fall under the same regulations.
Among molecules with similar olfactory characteristics in the illustration above, I would distinguish Tonkene. This compound is a triumph of vibration theory by the renowned perfume critic and bio-chemist Luca Turin. The structure of this ingredient was obtained by a computer simulation on the quest to find a molecule similar to coumarin by its molecular vibration. This compund was synthesized and indeed it was very close by its scent profile to coumarin.
Tonka beans - fruits of Dipteryx odorata, a tropical tree native to Central and South America - contain 1-3% of coumarin. Tonka bean absolute contains 90% of coumarin. On aging tonka beans you can notice small white crystals; this is practically coumarin in its pure form! Tonka beans are used in making desserts, for air freshening and even as an insect repellent. As a flavoring, coumarin has been banned from the food industry in many countries, which I consider as an obvious overdoing; you can find it in absolutely legal cinnamon in the quantity of 1%.
Tonka beans, fruits of Dipteryx odorata
Coumarin has been widely used in flavoring of pipe-tobacco and cigarettes. Its sweet odor is now associated with tobacco scents. While a tobacco absolute does not contain any significant amount of coumarin, it is often paired with coumarin in tobacco accords in perfumes.
One of the most common horror stories about coumarin is that it is а rat poison. It is easy to understand the source of this errancy, but we need to learn a bit of history. It all started when a big disease outbrake connected with the deterioration of blood clotting in cattle was registered in North America at the beginning of the 20th century. It was detected that the silage that was fed to the infected cattle, was made of sweet clover (from the genus Melilotus). In the 1940's, the harmful compound of sweet clover was isolated, it was Dicoumarin, possessing strong anticoagulant properties. After that many similar compounds (4-Hydroxycoumarin derivatives) were described and isolated. In 1948, Warfarin was synthesized. This substance was patented as a rat poison which had enjoyed popularity until more modern rodenticides were invented. In the 1950's, Warfarin had become a popular anticoagulant to prevent thrombosis, heart attacks, strokes, and blood clots.
The Furanocoumarins, or Furocoumarins, also known as Phyto-Coumarins, occur in a variety of plants. They produce a photosensitizing effect. One of them is Bergapten from bergamot, which makes its oil phytotoxic. Even bigger amounts of Bergapten are found in Sosnowsky's hogweed or Heracleum sosnowskyi, a dangerous flowering weed. Bergapten easily penetrates the skin and causes severe sunburns.
Although coumarin has such scary relatives, it is still in a very high demand in perfumery and cooking (mainly in tonka beans and cinnamon).
*"…until modern perfumery began at the end of the nineteenth century, advances were limited to mixtures of natural extractions of local materials, with the occasional incursion of exotic resins and plants imported from distant lands at high prices." T. Sanchez, The Perfumes, The A-Z Guide.
By Mat Yudov