What are aldehydes in fact? The answer is not as simple as it sounds. Ask a sophisticated perfume lover and he will tell you all about the hard-to-describe smelling synthetics that once made Chanel No. 5 so quirky, abstract and avant-garde. A chemist or even an ordinary high school student studying chemistry won't think long and tell you that an aldehyde is an organic compound that contains the -CHO group, or aldehyde group. All aldehydes have common chemical properties, for example, they are easily oxidized to corresponding acids. The silver mirror reaction, which you may remember from your chemistry lessons, is based on this oxidation - when the test glass is heated, a metallic mirror-like coating forms on its surface. . The word aldehyde itself was coined by the German chemist Justus von Liebig as a contraction of the Latin alcohol dehydrogenatus, meaning alcohol without hydrogen. The trivial names of aldehydes * often have either the suffix -al or the root -aldehyde, say caterpillar, giglaldehyde, donut aldehyde. Substances such as vanillin and heliotropin are also chemically aldehydes. And overall, a perfumer has in stock many aldehydes with various odors: melon smells of melon, adoxal - of sea and egg white, citronellal - of lemongrass, lyral - of lily of the valley, triplal - of green grass. And of course, there are also the aldehydes cyclamen, cinnamic, anisic, cumin, mandarin. Okay, you say, but what does that have to do with Chanel? If there are so many aldehydes and they all have different smells, what is that aldehydic note, what does it smell like, which aldehydes does Chanel n � 5 contain? Perfumers love aldehydes and we don't often call our loved ones by their full, proper names. Likewise, what perfumers are used to calling aldehydes are in fact a subgroup and a special case: saturated or so-called fatty aliphatic aldehydes. Their names are usually based on the number of carbon atoms in a molecule. So C-7 aldehyde or heptanal has seven carbon atoms, C-10 aldehyde or decanal has ten, as you might have guessed. Channel # 5 contains a mixture of C-11 undecyl or C-110 undecanal, C-11 undecylenic 10-undecenal and C-12 dodecanal aldehydes. It should be noted that perfumers had used aldehydes long before the creation of this legendary perfume [Chanel n � 5 was launched in 1921]. Most experts in the history of perfumery agree that aldehydes were first used in R�ve D'Or by LT Piver, or rather in its new edition of 1905, created by Pierre Armigeant, then in Some Fleurs Houbigant 1912 and Bouquet de Catherine 1913 from the Moscow manufacturer Alphonse Rallet & Co. As well as Chanel n � 5 these two created by Ernest Beaux, who is also from Moscow. But it is still Chanel which has become the main aldehyde perfume, giving birth to many copies and imitations. Fatty aldehydes have a distinctive waxy odor, similar to the smell of a blown candle. Indeed, the smell of candles is determined by fatty aldehydes, products of incomplete combustion of paraffin. The smell is very intense and strong; it becomes pleasant only when diluted to 1 percent or less. The decanal C-10 smells of zest, the dodecanal C-12 has some notes of lily and violet. The simpler aldehydes, formaldehyde and acetaldehyde, have very aggressive and unpleasant odors and yet flavorers use acetaldehyde for some of their flavors. Hexanal C-6 already has more or less pleasant green and apple notes. Fatty aldehydes with 15 carbon atoms and more have almost no odor. The odor of fatty aldehydes has another common property: a soapy appearance. For a very long time, aldehydes were widely used in soap perfumes, due to their low price, the intensity of their odor, and their ability to mask the unpleasant undertones of a basic soap scent. Very often the smell of aldehyde is associated with abstract cleanliness or the touch of freshly ironed laundry. It is important to understand that aldehydes are not man-made substances, the result of human labor. Many of them occur in nature. For example, decanal can be found in citrus up to 4 percent in orange oil and coniferous oils, in many flower oils, and abundantly in coriander oil. Unsaturated aliphatic aldehydes are also often found in nature and their odor is even more intense. For example, E -2-decenal determines the smell of cilantro and it is a common component of the chemical weapon of bedbugs. Its trans-4, 5-epoxy- E -2-decenal epoxy derivative gives blood its strongly marked metallic appearance. It is the scent that helps a predator to hunt down its prey. In the wave of success of the first aldehyde floral scents, chemists worked hard to synthesize new materials with similar olfactory properties. In 1905, French scientists EEBlaise & L. Huillon Bull. Soc. Chim. Fr. 1905, 33, 928 synthesized ��-undecalactone and a little later, in 1908, similar work was published by two Russian chemists ��. ��. Zhukhov & P. I. Shestakov Journal of the Russian Chemical Society 40, 830, 1908. The substance had a very interesting smell, reminiscent of a peach, warmed by the sun - fruity, waxy, with a creamy coconut undertone. Producers have decided to sell the substance as C-14 aldehyde - to satisfy perfumers' thirst for new number aldehydes on the one hand, and to mislead rivals on the other. Chemically speaking, it was not an aldehyde at all, but a lactone cyclic ester and the number of atoms in the molecule was not 14, but 11. As a Russian anecdote says Yes, you have it all. quite right, only it was not. in chess, but in bridge, and I did not win, but lost. A pretty affair, isn't it C-14 aldehyde made its debut in 1919 at Guerlain Mitsouko. Soon it was followed by similar substances: so called aldehyde C-16 strawberry aldehyde, aldehyde C-18 coconut aldehyde, aldehyde C-20 Raspberry aldehyde and the like. And, in the end, it turns out that almost a third of the aromatics is an aldehyde, but some of the major aldehydes are not aldehydes at all. * Chemists use several types of names. The first type is nomenclature or systematic names. It's a kind of number, an algorithm for recreating the structure of a substance, to understand which atoms are inside the molecule and how they are connected. Each name refers to its one and only corresponding structure and vice versa - each substance has only one systematic name. According to the nomenclature, aldehydes must have the suffix -al. The only downside to such names, but quite significant, is their heaviness. For example Iso E Super from my previous article should be called 1- 1, 2, 3, 4, 5, 6, 7, 8-octahydro-2, 3, 8, 8, -tetramethyl-2-naphthyl ethan -1 a . Just try to imagine what everyday life in the laboratory would be like if chemists only used systematic names: Dr. Jones, could you please pass me this vial with cis-3-? dimethyl methoxy� This is why generally trivial names are used instead. A trivial name is a kind of nickname for a substance. It doesn't tell us anything about its structure, but it's short and easy to remember. Vanillin, dichlorvos, promedol, paraben - all of these names are trivial. Different companies may sell the same substance under different names, that is, trade names. So 2- acetyloxy benzoic acid is a systematic name, acetylsalicylic acid - a trivial name, and aspirin is a trade name. Producers of synthetic perfume products like to give their products beautiful names. Quite often aldehydes real aldehydes get the names with -al at the end. But smart market experts know the passion of perfumers for aldehydes and sometimes an al name is given to something completely different. IFF Clonal is actually a nitrile, Givaudan Captive Mystikal is a carboxylic acid. Exactly the same trick that the producers of aldehyde C-14 once played.