Odorous substances. Simple recipes. Odoriferous substances Can a substance be odorous?

Various types of odorous substances used in perfumery can be divided into three categories:

odorous substances of plant origin;
odorous substances of animal origin;
artificial (synthetic) fragrances.

Plant scents There are either liquid, oily, so-called essential oils, or viscous, resinous, which include balms and gum resins. The French call plant essential oils essences.

Essential oils are not concentrated in any particular part of the plant, but are contained in flowers, fruits, leaves, bark, trunk, roots, etc. However, for each individual plant, the essential oil is concentrated in large quantities in some specific part of the plant. The strength of the smell emitted by a plant cannot be used to judge the amount of essential oils, since in nature you can find many plants that have a strong odor but contain negligible amounts of essential oils, and vice versa.

Essential oils are not specific chemical compounds; in their composition they are a mixture of all kinds of complex compounds. The pleasant smell of essential oil is mainly due to the presence of oxygen compounds.

The task of practitioners in the perfume industry is to remove non-contaminants from essential oils. odorous substances and thereby increasing the strength of the aroma. All herbal odorous substances used in perfumery should be as fresh as possible; you need to store them in a free, not too dry room and carefully examine them from time to time in order to promptly remove moldy parts.

From odorous substances animal origin in perfumery the following are used: ambergris, castorin (beaver stream), musk (musk deer stream) and civet (cibet juice). These substances are not perfumery in the proper sense of the word, but serve as an admixture to fix and distribute the finest plant aromas.

Widely used artificial chemical scents. Of these substances, some are synthetic products corresponding in composition to natural odorous substances (for example, vanillin, coumarin, heliotropin, etc.), some artificial substances give completely new odorous products (such as nerolin, mirban oil, etc. .d.). And finally, there are synthetic substances that are similar in smell to natural odorous substances, but in chemical composition are completely different from the latter; for example, ionone, neoviolone are used instead of real violet oil, benzoaldehyde and nitrobenzene - instead of bitter almond oil, salicylic acid methyl ester - instead of wintergreen oil; jasmone - instead of lilac and lily of the valley oils; nerolin - instead of neroli oil, etc.

The processing of artificial odorous substances into various perfume preparations is much simpler, faster and easier than the processing of natural products. This circumstance ensures the widest distribution of artificial odorous substances; in addition, although the price of synthetic odorous substances is quite high, it is fully compensated by a strong concentrated aroma, which can provide a greater yield of product with minimal quantities.

Perfumery preparations can be prepared using artificial odorous substances High Quality, but still they cannot replace completely natural products. Therefore, it is necessary to mix artificial products with natural ones, the aroma of which they increase without displacing it. Artificial odorous substances easily dissolve in the appropriate amount of wine alcohol, but it is still recommended that solutions and tinctures of flower lipsticks be left alone for two to three days for better dissolution. Particularly suitable are the so-called flower oils, for example acacia, carnation, hyacinth, cassia, tuberose, violet, etc. The best of these oils are artificial German jasmine oil and cassia tree oil, which already in a one percent alcohol solution are equal in strength to a strong solution of essential oil obtained from lipstick.

In contrast to essences and extracts obtained from natural odorous substances, we will call solutions made from artificial odorous substances tinctures.

In addition to the actual odorous substances, a number of auxiliary products are used in perfumery. These include wine spirit, glycerin, fatty oils, solid fats, etc. The purity and quality of these substances are essential to the success of the business, as a result of which all these products must be carefully tested. So, for example, wine alcohol must have a strength of at least 90-95°, and must be absolutely free from fusel oils.

The fat required for lipsticks must be fresh, without any foreign odor or rancidity. It is best to melt fat (usually pork fat) yourself at the lowest possible temperature with a small amount of alum and table salt. When the fat has melted, drain the transparent layer from the impurities that have settled to the bottom and, after cooling, wash it with water. It is advisable to leave perfume preparations prepared with alcohol for a more or less long time.

The smells of the surrounding world are extremely diverse. Therefore, their classification presents a certain difficulty, since it is based on a subjective assessment characteristic, for example, of different ages, a certain level of psychological and emotional mood, social status, upbringing, habitual style of perception, and much more.

Despite this, researchers and scientists from different centuries have tried to find criteria and objectively evaluate the numerous manifestations of aromas. Thus, in 1756, Carl Linnaeus divided odors into six classes: aromatic, balsamic, amber musky, garlic, caprylic (or goat), and intoxicating.

In the mid-twentieth century, scientist R. Moncrieff suggested the existence of several types of olfactory chemoreceptors capable of attaching molecules of chemical substances with a certain stereochemical structure. This hypothesis formed the basis of the stereochemical theory of odors, which is based on identifying the correspondence between the stereochemical formula of odorant molecules and their inherent odor.

The experimental substantiation of this theory was carried out by another scientist Eimur, who managed to identify seven different classes among several hundred studied odorous molecules. Each of them contained substances with a similar stereochemical configuration of molecules and a similar odor. All substances with a similar odor, as the scientist’s research proved, also had a geometrically similar molecular shape, different from the molecules of substances with a different odor (Table 1).

Table 1

Classification of primary odors (according to Eimur)

Along with the classification of odors according to Eimur, the approach to classification of odors proposed in the first quarter of the twentieth century by Zwaardemaker is often used. According to it, odorous substances are divided into nine classes:

1 -- essential scents:

amyl acetate ether;

ethyl and methyl esters of butyric, isovaleric, caproic and caprylic acids;

benzyl acetate, acetone, ethyl ether, butyl ether, chloroform.

2 -- aromatic odors:

camphor odors: camphor, borneol, acetic acid boron-veol, eucalyptol;

spicy odors: cinnamaldehyde, eugenol, pepper, cloves, nutmeg;

anise odors: safrole, carvone, salicylic acid methyl ester, carvanol, thymol, menthol;

lemon scents: acetic acid linalool, citral;

almond odors: benzaldehyde, nitrobenzene, cyanide compounds.

3 -- balsamic scents:

floral scents: geraniol, pitronellol, nerol, methylene phenyl glycol, linelool, terpineol, anthranilic acid methyl ester;

lily odors: piperonal, heliotropin, ionone, iron, styrene,

vanilla odors: vanillin, coumarin.

4 -- amber-musky scents: amber, musk, trinitrobutyltoluene.
5 -- garlic smells:

bulbous odors: acetylene, hydrogen sulfide, mercaptan, ichthyol;

arsenic odors: arsenous hydrogen, hydrogen phosphide, cacodyl, trimethylamine;

halide odors: bromine, chlorine.

6 -- burnt smells:

burnt coffee, toasted bread, guaiacol, cresol;

benzene, toluene, xylene, phenol, naphthalene.

Grade 7 - caprylic scents:

caprylic acid and its homologues;

smells of cheese, sweat, rancid oil, cat smell.

8th grade - nasty odors:

necrotic odors;

the smell of bedbugs.

9th grade - sickening smells.

In the second half of the 20th century, studies of the structure of aromatic molecules allowed scientists to propose a classification of odors based on the chemical structure of aromatic substances.

It was later found that the different aroma of odorous substances is due to a chemical composition containing different groups of molecular compounds.

Therefore, depending on the component composition of essential oils, aromas were divided into 10 groups: spicy, floral, fruity, balsamic (resinous), camphor, herbal, woody, citrus, burnt, smelly. aroma smell ethereal fragrant

However, more recent studies have shown that there is not always a direct relationship between the nature of the odorous substance and the chemical structure. Therefore, the traditional classification of Western medicine according to their medical and pharmacological properties was applied to aromatic substances, which is based on the symptomatic orientation of aromatic substances. The merit of this symptomatic classification system lies in the valuable practical information about the medicinal properties of aromas.

Aromatherapists also successfully use the classification of odorous substances according to the degree of their volatility (evaporation rate), proposed by perfumers, noting the existence of the relationship that takes place between the rate of evaporation of the aroma and the effect of the essential oil on the body. Fragrances in this classification are divided into three tones - lower, upper and middle.

Each of the proposed classifications reflects the features of a certain similarity of odorous substances, taking as a basis their qualitative or quantitative characteristics, internal or external manifestations and properties. However, it should be noted that until now Western medicine does not have a general classification of odorous substances.

The classification of aromas in Chinese medicine is determined and shaped by the yin-yang relationships that exist in the wu xing system. It naturally finds its place in the general concept of Chinese therapy.

2.2 Chemical structure of odors

Extensive experimental material on the relationship between the odor of compounds and the structure of their molecules (type, number and position of functional groups, size, branching, spatial structure, presence of multiple bonds, etc.) is not yet sufficient to predict the odor of a substance based on these data . Nevertheless, some particular patterns have been identified for certain groups of compounds. The accumulation of several identical functional groups in one molecule (and in the case of compounds of the aliphatic series, different ones) usually leads to a weakening of the odor or even its complete disappearance (for example, when moving from monohydric to polyhydric alcohols). The odor of aldehydes of iso-structure is usually stronger and more pleasant than that of isomers of normal structure.

The size of the molecule has a significant influence on the smell. Typically, neighboring members of a homologous series have a similar odor, and its strength gradually changes when moving from one member of the series to another. When a certain molecule size is reached, the smell disappears. Thus, aliphatic compounds with more than 17-18 carbon atoms are usually odorless. The smell also depends on the number of carbon atoms in the cycle. For example, macrocyclic ketones C5-6 have the smell of bitter almonds or menthol, C6-9 give a transitional smell, C9-12 give the smell of camphor or mint, C13 give the smell of resin or cedar, C14-16 give the smell of musk or peach. , C17-18 is the smell of onions, and compounds with C18 and more either do not smell at all or smell very faintly:

The strength of the aroma also depends on the degree of branching of the chain of carbon atoms. For example, myristic aldehyde has a very weak odor, but its isomer has a strong and pleasant odor:

The similarity of the structures of compounds does not always determine the similarity of their odors. For example, b-naphthol esters with a pleasant and strong odor are widely used in perfumery, but b-naphthol esters have no smell at all:

The same effect is observed in polysubstituted benzenes. Vanillin is one of the most famous aromatic substances, and isovillin smells like phenol (carbolic acid), and even then at elevated temperatures:

The presence of multiple bonds is one of the signs that a substance has an odor. Consider, for example, isoeugenone and eugenone:

Both substances have a distinct clove scent and are widely used in perfumery. Moreover, isoeugenone has a more pleasant odor than eugenone. However, once their double bond is saturated, the smell almost disappears.

The opposite cases are also known. Cyclamenaldehyde (cyclamal) - a substance with a delicate floral odor - one of the most valuable substances, contains a saturated side chain, and forcyclamen, which has a double bond in this chain, has a slight unpleasant odor:

Often the unpleasant odor of a substance is due to the triple bond. However, there is an exception here too. Folion is a necessary component of many perfume compositions - a substance in which the smell of fresh greenery coexists perfectly with a triple bond:

On the other hand, substances that differ in chemical structure may have similar odors. For example, a rose-like odor is characteristic of rosacetate 3-methyl-1-phenyl-3-pentanol, geraniol and its cis-isomer - nerol, rosenoxide.

The degree of dilution of the substance also affects the smell. Thus, some odorous substances in their pure form have an unpleasant odor (for example, civet, indole). Mixing various fragrant substances in a certain ratio can lead to both the appearance of a new smell and its disappearance.

So, in the stereochemical theory (J. Eymour, 1952), the existence of 7 primary odors was assumed, which correspond to 7 types of receptors; the interaction of the latter with molecules of fragrant substances is determined by geometric factors. At the same time, the molecules of fragrant substances were considered in the form of rigid stereochemical models, and the olfactory receptors were considered in the form of holes of various shapes. The wave theory (R. Wright, 1954) postulated that odor is determined by the spectrum of vibrational frequencies of molecules in the range of 500-50 cm-1 (l ~ 20-200 µm). According to the theory of functional groups (M. Betts, 1957), the smell of a substance depends on the general “profile” of the molecule and on the nature of the functional groups. However, none of these theories can successfully predict the odor of aromatic substances based on the structure of their molecules.

The size of the molecule has a great influence on the smell. Typically, similar compounds belonging to the same homologous series smell the same, but the strength of the odor decreases with increasing number of atoms. Compounds with 17-18 carbon atoms are usually odorless.

The smell of cyclic compounds depends on the number of members of the ring. If there are 5-6 of them, the substance smells of bitter almonds or menthol, 6-9 - gives a transitional smell, 9-12 - the smell of camphor or mint, 13 - the smell of resin or cedar, 14-16 - members of the ring cause the smell of musk or peach, 17-18 - onions, compounds with 18 members or more either do not smell at all or very weakly.

The strength of the aroma also depends on the structure of the carbon chain. For example, branched-chain aldehydes smell stronger and more pleasant than their isomeric aldehydes with a normal structure. This point is well illustrated by an example: myristic aldehyde

smells very faint, and its isomer

strong and pleasant.

Compounds of the ionone group have, and in strong dilution, a delicate scent of violets. Apparently one of the reasons for this is the two methyl groups attached to one carbon in the cyclohexane ring. This is what alfairon looks like, which has the most subtle violet smell:

These compounds are the most valuable fragrant substances, widely used in the perfume industry.

Here is another “bridge” between the structure and the smell. It has been established that the most important musky smell for the entire perfume industry is produced by aromatic compounds with the tertiary butyl group, for example, amber musk:

Tertiary carbon atoms can cause a camphorous odor. Many tertiary fatty alcohols have it, as well as hexamethylethane and methyl isobutyl ketone:

The replacement of hydrogen atoms by chlorine obviously acts in the same way as branching. Therefore, the smell of camphor is also inherent in hexachloroethane CCl3 - CCl3.

The position of substituents in the molecule has a great influence on the smell. ?-Naphthol esters with a pleasant and strong odor are widely used in perfumery, while ?-naphthol ethers do not smell at all:

methyl ether-naphthol methyl ether-naphthol

The same effect can be observed in polysubstituted benzenes:

vanillin isovillin

Vanillin is one of the most famous aromatic substances, and isovillin smells like phenol (carbolic acid), and even then at elevated temperatures.

Affects the smell and position of the double bond in the molecule. In isoeugenone

the smell is more pleasant than eugenone itself

However, they both have a distinct clove scent and are both widely used in perfumes and cosmetics. However, once the double bond is saturated, the smell almost disappears.

However, the opposite cases are also known. Cyclamen-aldehyde, a substance with a delicate floral odor, one of the most valuable substances, contains a saturated side chain, and forcyclamen, which has a double bond in this chain, has a weak unpleasant odor:

forcyclamen cyclamen

Often, substances that have an unpleasant odor are due to the triple bond. However, there is an exception here too. Folion (a necessary component of many perfume compositions) is a substance in which the smell of fresh greenery coexists perfectly with the territorial bond:

Obviously, cycles are of great importance for the smell, especially with 15 - 18 units. These compounds are found in natural products, very valuable for their fragrant properties. Thus, the substance muskone was isolated from the glands of the musk deer, and civet was isolated from the glands of the civet cat:

Muscone Cibeton

But this connection is one-way: the smell of musk, for example, is possessed by compounds of other structures. In general, chemists know many structurally different substances with similar odors, and, conversely, often very similar compounds have completely different odors.

Since ancient times, the main “supplier” of natural aromatic substances has been essential oils. These are mixtures of complex composition that are formed in special cells and channels of plants. Essential oils contain various classes of chemical compounds: both aromatic and heterocyclic, but the main component responsible for the smell is terpenes. Natural terpenes can be thought of as substances built from the bricks of isoprene with the general formula:

Rose oil, sandalwood oil, and musk have been known to people since ancient times. The art of producing odors was very highly developed among the ancients: the incense found in the tomb of Pharaoh Tutankhamun has retained its aroma to this day.

No matter how good natural aromatic substances are, you cannot count on them when creating the perfume industry: there are too few of them, and they are not easily obtained, and some have to be imported from abroad. Therefore, chemists were faced with the task of creating them artificially.

Municipal educational institution "Secondary school No. 45"

Course work

Chemistry of smells.

Checked by: Duda L.N.

Completed by: student of grade 11 “b”

Kovalev Dmitry Vasilievich

Kemerovo.

Introduction

Fragrances

Classification of odorous substances

The relationship between the smell of a substance and its structure

Smell

Fragrant retort

Fragrant esters

Conclusion

Applications

Literature

Introduction

Almost 2000 years ago, the ancient scientist, poet and philosopher Titus Lucretius Carus believed that there were tiny pores of different sizes and shapes in the nasal cavity. Every odorous substance, he reasoned, emits tiny molecules of its own characteristic shape. Odor is perceived when these molecules enter the pores of the olfactory cavity. The recognition of each odor depends on which pores these molecules fit into.

In 1756, M. V. Lomonosov, in his work “A Word on the Origin of Light, Presenting a New Theory of Colors,” put forward the idea that the endings of nerve cells induce vibrations of particles of matter. In this work, he wrote about the “rotary” (oscillatory) movements of ether particles as stimulants of the senses, including sight, taste and smell.

Over the last century, about 30 theories have been proposed, the authors of which tried to explain the nature of smell and its dependence on the properties of the odorous substance. It has now been established that the nature of smell, like the nature of light, has a dual character: corpuscular (depending on the structure of the odorous substance) and wave.

Some identical molecules have different odors, i.e. the main role is played by geometric shape odorant molecules. This is explained by the fact that on the olfactory hairs of the nasal cavity there are holes of five main shapes that perceive five odors (camphor, musk, floral, mint, ethereal), respectively. When a molecule of an odorous substance, similar in configuration to it, enters the hole, then the smell is felt (J. Eimour, 1952). Thus, Lucretius’s speculative conclusion turned out to be scientifically substantiated. There are two more main odors - pungent and putrefactive, but their perception is not related to the shape of the holes, but to a different attitude to the electrical charges of the sheath covering the endings of the olfactory nerves. All existing odors can be obtained by mixing the given seven odors in appropriate combinations and proportions.

According to modern data, molecules of odorous substances absorb and emit waves with a length of 1 to 100 microns, and the human body at normal temperature absorbs and emits waves with a length of 4 to 200 microns. The most important electromagnetic waves have a length of 8 to 14 microns, which corresponds to the wavelength of the infrared part of the spectrum. The absorption of odorants is achieved by ultraviolet rays and the absorption of infrared rays. Ultra-violet rays kill many odors, and this is used to cleanse the air of unnecessary aromas.

These data, as well as the study of the spectrum of odors, give reason to believe that odors have a physical nature, and even approximately indicate their location in the infrared and ultraviolet parts of the scale of electromagnetic oscillations. Thus, Lomonosov’s idea about the “rotary” movements of ether particles as stimulants of the senses has found scientific confirmation.

The above theories made it possible to create devices capable of “smelling” bouquets of odors, identifying varieties of wines, coffee, tobacco, various food products, etc. The characteristics of each smell can now be recorded and reproduced using various technical devices. For example, in Tokyo cinemas, different scenes of a film are accompanied by different smells, the type and intensity of which are determined using a computer and distributed throughout the theater.

Seven colors of the spectrum, seven simple sounds and seven components of smell - this is what makes up the whole variety of colors, sounds and smells. This means that there are general patterns in visual, taste, and olfactory sensations, i.e., you can get a chord not only of sound and color, but also of smell.

Fragrances

By fragrant we usually mean pleasant-smelling organic substances. It is unlikely that anyone will say this about chlorine or mercaptan, although they have their own smell. When substances that smell in general are meant, they are called odorous. From a chemical point of view, there is no difference. But if science studies odorous substances in general, then industry (and primarily the perfume industry) is mainly interested in fragrant substances. True, it is difficult to draw a clear line here. The famous musk - the basis of perfumery - itself smells sharp, even unpleasant, but when added in minute quantities to perfume, it enhances and improves its smell. Indole has a fecal odor, but diluted indole - in the White Lilac perfume - does not evoke such associations.

By the way, fragrant substances differ not only in smell, they all also have a physiological effect: some through the olfactory organs to the central nervous system, others when administered orally. For example, citral, a substance with a pleasant lemon smell, used in perfumery, is also a vasodilator and is used for hypertension and glaucoma.

Many aromatic substances also have an antiseptic effect: a bird cherry branch placed under a cap with swamp water destroys all microorganisms after 30 minutes.

Any division of substances by smell is not very strict: it is based on our subjective sensations. And often what one person likes, another doesn’t like. It is still impossible to objectively evaluate or express the smell of a substance.

It is usually compared with something, say, with the smell of violet, orange, rose. Science has accumulated many empirical evidence linking smell with the structure of molecules. Some authors cite up to 50 or more such “bridges” between structure and smell. There is no doubt that fragrant substances, as a rule, contain one of the so-called functional groups: carbinol -C-OH, carbonyl >C=O, ester and some others.

Esters usually have a fruity or fruity-floral odor, which makes them indispensable in the food industry. After all, they give many confectionery products and soft drinks a fruity smell. The perfume industry has not ignored esters: there is practically not a single composition where they are not included.

Classification of odorous substances

Odoriferous substances occur in many classes of organic compounds.

Their structure is very diverse: they are open-chain compounds of saturated and unsaturated nature, aromatic compounds, cyclic compounds with different numbers of carbon atoms in the cycle. Attempts have been made repeatedly to classify odorous substances by smell, but they have not been successful, since such a distribution into groups faces significant difficulties and lacks a scientific basis. The classification of odorous substances according to their purpose is also very arbitrary, since the same odorous substances have different purposes, for example, for perfumes, confectionery, etc.

It is most convenient to classify odorous substances into groups of organic compounds. Such a classification would make it possible to associate their odor with the structure of the molecule and the nature of the functional group (see appendices, table 1).

The largest group of odorous substances is esters. Many odorous substances belong to aldehydes, ketones, alcohols and some other groups of organic compounds. Esters of lower fatty acids and saturated fatty alcohols have a fruity odor (fruit essences, for example isoamyl acetate), esters of aliphatic acids and terpene or aromatic alcohols - floral (for example, benzyl acetate, terpinyl acetate), esters of benzoic, salicylic and other aromatic acids - mainly sweet balsamic smell.

Among the saturated aliphatic aldehydes one can name, for example, decanal, methylnonylacetaldehyde, among terpenes - citral, hydroxycitronellal, among aromatic ones - vanillin, heliotropin, among fatty aromatics - phenylacetaldehyde, cinnamaldehyde. Of the ketones, the most widespread and important are alicyclic ones, containing a keto group in the cycle (vetion, jasmone) or in the side chain (ionones), and fatty aromatic ones (n-methoxyacetophenone), among alcohols - monohydric terpenes (era-niol, linalool, etc. ) and aromatic (benzyl alcohol).

The relationship between the smell of a substance and its structure

Extensive experimental material on the relationship between the odor of compounds and the structure of their molecules (type, number and position of functional groups, size, branching, spatial structure, presence of multiple bonds, etc.) is not yet sufficient to predict the odor of a substance based on these data . Nevertheless, some particular patterns have been identified for certain groups of compounds. The accumulation of several identical functional groups in one molecule (and in the case of aliphatic compounds, different ones) usually leads to a weakening of the odor or even its complete disappearance (for example, when moving from monohydric to polyhydric alcohols). The odor of aldehydes of iso-structure is usually stronger and more pleasant than that of isomers of normal structure.

The size of the molecule has a significant influence on the smell. Typically, neighboring members of a homologous series have a similar odor, and its strength gradually changes when moving from one member of the series to another. When a certain molecule size is reached, the smell disappears. Thus, aliphatic compounds with more than 17-18 carbon atoms are usually odorless. The smell also depends on the number of carbon atoms in the cycle. For example, macrocyclic ketones C 5-6 have the smell of bitter almonds or menthol, C 6-9 - give a transitional smell, C 9-12 - the smell of camphor or mint, C 13 - the smell of resin or cedar,

C 14-16 - the smell of musk or peach, C 17-18 - the smell of onions, and compounds with C 18 and more either do not smell at all or smell very faintly:

The strength of the aroma also depends on the degree of branching of the chain of carbon atoms. For example, myristic aldehyde has a very weak odor, but its isomer has a strong and pleasant odor:

The similarity of the structures of compounds does not always determine the similarity of their odors. For example, β-naphthol esters with a pleasant and strong odor are widely used in perfumery, while α-naphthol esters do not smell at all:

The presence of multiple bonds is one of the signs that a substance has an odor. Consider, for example, isoeugenone and eugenone:

The opposite cases are also known. Cyclamen-aldehyde (cyclamal) - a substance with a delicate floral odor - one of the most valuable substances, contains a saturated side chain, and forcyclamen, which has a double bond in this chain, has a weak unpleasant odor:

On the other hand, substances that differ in chemical structure may have similar odors. For example, a rose-like odor is characteristic of 3-methyl-1-phenyl-3-pentanol rosacetate, geraniol and its cis-isomer - nerol, rosenoxide.

So, in the stereochemical theory (J. Eymour, 1952), the existence of 7 primary odors was assumed, which correspond to 7 types of receptors; the interaction of the latter with molecules of fragrant substances is determined by geometric factors. At the same time, the molecules of fragrant substances were considered in the form of rigid stereochemical models, and the olfactory receptors were considered in the form of holes of various shapes. The wave theory (R. Wright, 1954) postulated that odor is determined by the spectrum of vibrational frequencies of molecules in the range of 500-50 cm -1 (l ~ 20-200 µm). According to the theory of functional groups (M. Betts, 1957), the smell of a substance depends on the general “profile” of the molecule and on the nature of the functional groups. However, none of these theories can successfully predict the odor of aromatic substances based on the structure of their molecules.

Smell

Until now, the mechanism of action of odorous substances on the olfactory organ has not been fully elucidated. There are various theories, both physical and chemical, in which scientists seek to explain this mechanism.

To perceive a smell, direct contact of the odorant molecule with the olfactory receptors is necessary. In this regard, the necessary properties of an odorous substance are volatility, solubility in lipids and to some extent in water, sufficient ability for adsorption on the olfactory lining, certain limits of molecular weight, etc. But it is not known what physical or chemical properties determine the effectiveness of a substance as an olfactory agent. irritant.

Scientists were able to build a chain from the interaction of an odorous substance with a receptor to the formation in the brain of a clear impression of a certain smell. An important role in this was played by the research of American scientists Richard Axel and Linda Buck, for which they were awarded the 2004 Nobel Prize in Physiology and Medicine.

The key to unraveling the principles of the olfactory system was the discovery of a huge family of approximately a thousand genes that control the functioning of olfactory receptors. An article describing this discovery was published by L. Buck and R. Axel in 1991. More than 3% of the total number of genes in the body are involved in odor recognition. Each gene contains information about one olfactory receptor - a protein molecule that reacts with an odorous substance. Olfactory receptors are attached to the membrane of receptor cells, forming the olfactory epithelium. Each cell contains receptors of only one specific type.

The protein receptor forms a pocket for binding a molecule of a chemical substance that has an odor (odorant). Receptors of different species differ in the details of their structure, so the trap pockets have different shapes. When the molecule gets there, the shape of the receptor protein changes and the process of nerve signal transmission begins. Each receptor can register molecules of several different odorants, the three-dimensional structure of which to one degree or another corresponds to the shape of the pocket, but the signal from different substances differs in intensity. In this case, molecules of the same odorant can activate several different receptors simultaneously.

In addition to the protein receptor, the olfactory epithelium of animals contains another high-molecular component that is also capable of binding odorants. Unlike membrane protein, it is water soluble, and at least part of it is found in the mucus covering the olfactory epithelium. It has been established that it is of nucleoprotein nature. Its concentration in the epithelium is several thousand times greater than that of the membrane receptor, and its specificity for odorous substances is much less. Researchers believe that it is part of a nonspecific system that ensures the cleansing of the olfactory epithelium from various odorous substances after their action ends, which is necessary for the reception of other odors.

In other words, it is assumed that the nucleoprotein, entering the mucus, is capable of increasing its current and thereby increasing the efficiency of cleaning the olfactory epithelium. It is also possible that the nucleoprotein, being in mucus, promotes the dissolution of odorous substances in it and, possibly, performs transport functions.

This combination of receptor diversity and the chemical properties of the molecules with which they interact generates a broad band of signals that create a unique odor fingerprint. Each smell, as it were, receives a code (like a bar code on goods), by which it can be unmistakably recognized the next time.

The sense of smell plays an extremely important role in the lives of both animals and humans. The functions of smell in the life of animals are especially diverse. The sense of smell helps them in searching and choosing food, signals the presence of enemies, and helps with orientation on land and in water (for example, the return of salmon fish to their parent reservoirs, the smell of the water of which they remember).

Known important role sense of smell in search of animals of the opposite sex. In this case, information is carried out through chemicals, so-called pheromones or telergons, which are secreted by special glands. Pheromones are extremely effective biologically active compounds and are characterized by high specificity. Due to these properties, they are, for example, used to attract and kill insects. Typically, each animal is most sensitive to compounds that are especially important to it under normal living conditions. Therefore, each animal species has a special spectrum of odors. Small insects are able to perceive only one smell - the smell of a sexually attractive substance. A bee with a more developed olfactory system can distinguish hundreds of odors. In animals with a highly developed olfactory analyzer, such as dogs, the sense of smell plays a dominant role in many respects.

Despite the fact that animals have a more subtle sense of smell than humans, the range of odors perceived by humans is much wider.

A person can learn to recognize up to 4,000 different odors, and the most sensitive people to them - more than 10 thousand. But this requires special training in recognizing odors. It is known that experienced cooks can determine how well salted it is by smell alone, without tasting the food. How they do this is a mystery, because salt has no smell. Of course, not all people have such abilities.

In human life, the sense of smell does not play such a significant role as in the life of animals, with the exception of cases of blindness and deafness, when compensatory development of the existing sense organs, including smell, occurs. However, inhalation of odorous substances has a very significant physiological effect on the human body. Smells affect performance, change muscle strength (increase - ammonia, sweet and bitter smells), change gas exchange (increase - musk, and decrease - mint, rose, cinnamon, lemon and bergamot oils, etc.), change the rhythms of breathing and pulse ( increase and deepen - oregano oil and unpleasant odors, vanillin, rose and bergamot oil and pleasant odors have the opposite effect), change skin temperature (increase - bergamot and rose oil, vanillin, decrease - unpleasant odors), change blood pressure (increase - unpleasant odors, lower - bergamot and rose oil and pleasant odors), change intracranial pressure (unpleasant odors increase, and pleasant odors decrease), affect hearing (unpleasant - reduce), change the quality of vision (bergamot oil improves vision at dusk, unpleasant odors - worsen).

Human sensitivity to the perception of odors is characterized by the so-called threshold concentration (the minimum concentration of an odorous substance at which an olfactory sensation appears). For many fragrant substances it lies in the range of 10~8-10~p g/l in the air. Human perception of odors (intensity and quality) is individual. In addition, tastes in relation to smells are extremely varied, but to some extent they can be generalized: some prefer the smells of cloves and patchouli, others prefer subtle, sweetish, delicate and fresh floral smells, etc.

Conventionally, odors can be divided into three groups: pleasant, unpleasant and indifferent. A pleasant smell is one that, when inhaled, a person would like to feel it for much longer, which gives pleasure. But there are many odors that are pleasant to some and unpleasant to others, i.e. the psychological definition of the quality of a smell is relative. A definitely unpleasant smell should be considered one that evokes unpleasant ideas in the brain about decomposition and rotting. Indifferent odors are those that are not perceived, to which we are so accustomed that we have ceased to notice them, for example, the usual smell of air, housing, perfume, etc. The concept of indifference sometimes goes so far that even the air of laboratories oversaturated with odors can become indifferent for those who constantly work there.

With prolonged exposure to a certain odor, a person gradually becomes immune to it, and sometimes he stops feeling it, for example, coumarin - after 1-2 minutes, citral - after 7-8 minutes. This phenomenon is called olfactory adaptation. Its duration and depth depend on the intensity and nature of the odor of the odorous substance, as well as the duration of its exposure. With olfactory adaptation, there is a decrease in sensitivity not only to the substance that was used, but also to other odorous substances. The mechanisms of olfactory adaptation are still not entirely clear, since adaptation is a subjective factor that differs greatly from person to person.

Fragrant retort

Let's start with obtaining natural aromatic substances from plants.
Fragrant substances are usually found in plants in the form of small droplets in special cells. They are found not only in flowers, but also in leaves, in the peel of fruits and sometimes even in wood.
The content of essential oils in those parts of plants that are used to obtain them ranges from 0.1% to 10%. The fact that they are called oils should not mislead us. Essential oils have nothing in common with ordinary vegetable oils: flaxseed, sunflower, corn, that is, with liquid fats. They are more or less complex mixtures of fragrant organic substances of various types.

Among them, esters, aldehydes and alcohols of the saturated, unsaturated and aromatic series are especially common.
Terpenes and their derivatives are very important components of essential oils.

Let's consider the formulas of some representatives of this class of compounds: Terpinen– cyclic hydrocarbon. It is found in trace amounts in many essential oils. Limonene– An important component of lemon peel oil. Pinene is the main component of gum turpentine. It serves as the starting compound for the production of synthetic fragrances.
Essential oils are usually very difficult to dissolve in water, but dissolve easily in alcohol. Therefore, alcohol is used in large quantities in the perfume industry as a solvent. Essential oils can be obtained, for example, by extracting them from plant parts with alcohol or other solvents. The most valuable fragrant substances of flowers are obtained by placing alternate layers of solid animal fat and plant parts in a closed chamber on a wire mesh. After some time, the flowers are replaced with new ones so that the fat is saturated with essential oil. With this method (in France it is called “enfleurage”), fat containing essential oils dissolved in it is obtained and this concentrate of fragrant substances is delivered to perfume factories (The essential oils are then extracted from the fat with alcohol. This method is used, for example, to extract essential oils from jasmine and tuberose. - Note Transl.). We will use a third, especially important method for isolating essential oils - steam distillation.
Essential oils themselves are often volatile only at elevated temperatures, and their boiling is accompanied by decomposition. If water vapor is passed through a mass consisting of plants or their parts, the oils are removed along with it and then collected in the distillate in the form of droplets, which have a low density and therefore float on the surface of the water.

Let's get essential oils.

Close the 0.5 liter flask with a rubber stopper with two holes. Into one of them we insert a glass tube drawn at the end, which reaches almost to the bottom of the flask. This tube serves as a safety valve. It should be long enough (about 1 m).

Through another hole we will insert a short elbow of a curved tube with an internal diameter of at least 5 mm (It is best to take a tube with an internal diameter of 8-10 mm. The distance between the flasks should be as short as possible, but it is advisable to disconnect the tube between the flasks by inserting a glass tee in the middle and connecting it to both parts of the tube with short pieces of rubber hose. A piece of rubber hose with a clamp attached to it is attached to the free end of the tee. This allows you to quickly separate or connect both flasks during the experiment. If you have a metal steamer, you can replace the first flask with it. - Note Transl.).

We insert the longer elbow of the same tube through the hole in the stopper into the second flask, so that the tube also reaches almost to the bottom there. In addition, using a glass tube, we connect the second flask with a direct condenser (Liebig or with an external lead coil). It is best to use a separating or dropping funnel as a receiver.
First we get caraway oil. For this we need 20 g of cumin (Caraway can be collected or bought at a pharmacy. - Note Transl.).

Grind it in a mortar with added sand or in an old coffee grinder. Place the caraway seeds in the second flask and add a little water so that it does not completely cover the mass of the caraway seeds. Fill the first flask one-third with water and, to ensure uniform boiling, add several pieces of porous ceramic (“boilers”) to the water.

Now, using a Bunsen burner, first heat the contents of the first and then the second flask to a boil. After this, we will again move the burner under the first flask and heat it as much as possible so that water vapor intensively passes through the second flask, which then enters the refrigerator and from it in the form of condensate into the receiver.

If there are two burners, then you can simultaneously slightly heat the second flask so that the volume of liquid in it does not increase too much as a result of steam condensation.

It is convenient to use a sand bath to heat the second flask, heating it in advance, before water vapor begins to pass through (It is best to heat the second flask so that the volume of liquid in it does not undergo a noticeable increase or decrease. - Approx. Transl.). We will carry out the distillation for at least an hour. During this time, about 100 ml of water collects in the receiver, on the surface of which colorless drops of cumin oil float. We separate the water as completely as possible using a separating funnel and as a result we get about 10 drops of pure caraway oil along with a small amount of water. This amount would be enough to make several bottles of caraway liqueur!

The characteristic smell of cumin oil is given by carvone, of which it contains more than 50%. In addition, it contains limonene, the fragrant substance of lemons. Caraway oil is used primarily to scent soaps and tooth elixirs. It is also added in small quantities to some perfumes.

Using the same device you can isolate essential oils from other plants. To do this, grind them and subject them to steam distillation for 1-2 hours. Of course, the yield will vary depending on the essential oil content. The most interesting thing is to get the following essential oils :

Peppermint oil. From 50 g of dried peppermint we can extract 5-10 drops peppermint oil. It contains, in particular, menthol, which gives it its characteristic smell. Peppermint oil is used in large quantities to make cologne, hair eau de toilette, toothpastes and elixirs. Currently, menthol is mostly obtained by synthesis.

Anise oil we get it from crushed anise. Mixed with peppermint oil and eucalyptus oil, it is included in tooth elixirs and pastes, as well as some soaps.

Clove oil We obtain by steam distilling cloves, which are sold as a spice. An important part of it is eugenol. (Eugenol can be obtained from synthetic vanillin.) Clove oil is an additive to many perfumes and is also used in the manufacture of dental elixirs and soaps.

Lavender oil we will get from 50 g of dried and crushed lavender flowers. This is one of the most important aromatic substances, which, in addition to its use in making lavender water and cologne, is used in the production of perfumes, soaps, hair eau de toilettes, powders, creams, etc.

Spruce oil. Let's collect at least 100-200 g of spruce needles and young shoots. Grind them and, while they are still wet, without first adding water, distill them with water vapor. Typically, the needles contain only a few tenths of a percent of this essential oil. It will delight us with a pleasant aroma in the room. In addition, spruce oil is a favorite agent that adds aroma to various bath preparations.

We leave it to the reader to obtain other aromatic substances from plants. For example, you can steam distill pine, cinnamon, chamomile flowers or other fragrant garden flowers. We will store the resulting products in securely closed test tubes - later we will need them as fragrant substances for the manufacture of cosmetics.

Unfortunately, we will have to refuse to receive aromatic substances contained in perfumes with a subtle, delicate odor - bergamot oil, as well as oils from jasmine flowers and orange flowers - since we do not have the necessary starting substances for this.

However, essential oil with a very subtle aroma is also obtained from lily of the valley flowers. If you manage to collect enough of them, then, of course, it is worth isolating the essential oil from them.

Fragrant esters

Many well-known aromatic substances belong to the class esters. The latter are widespread in nature and produce a wide variety of odors, from the smell of tropical orchids to the characteristic aroma of well-known fruits. We can synthesize these compounds.

Esters are formed by the reaction of alcohols with carbolic acids. At the same time, water is split off

R-OH + NOOS- R 1 R-OOS- R 1 + H 2 O

alcohol + acid ester + water

The reaction proceeds fairly quickly only in the presence of water-removing agents and catalysts. Therefore, a mixture of alcohol and carboxylic acid is boiled for a long time in the presence of sulfuric acid, which acts as a water-removing agent and also catalyzes the reaction.

In addition, the reaction mixture is often saturated with hydrogen chloride gas. We can more easily obtain the same result by adding table salt, which forms hydrogen chloride with sulfuric acid.
Esters are also prepared in the presence of concentrated hydrochloric acid or anhydrous zinc chloride, but with lower yield.

We will use these additives in cases where the original organic substances are decomposed by concentrated sulfuric acid, which can be detected by the darkening of the reaction mixture and an unpleasant pungent odor.

Let's get esters.

To obtain esters in small quantities, we use a simple device. Insert a narrow test tube into a wide test tube so that one third of the wide test tube in its lower part remains empty. The easiest way to strengthen a narrow test tube is with a few pieces of rubber cut from a hose or cork. It is necessary to take into account that around a narrow test tube it is necessary to leave a gap of at least 1.5-2 mm in order to prevent excess pressure during heating.

Now pour 0.5-2 ml of alcohol and approximately the same amount of carboxylic acid into a wide test tube; with thorough cooling (in ice water or cold running water), add 5-10 drops of concentrated sulfuric acid and, in some cases, a few more grains of table salt.

Let's insert the inner test tube, fill it with cold water or, better yet, pieces of ice, and secure the assembled device in a regular rack or in a test tube rack.

Then, on the device itself, you need to place it away from yourself and do not lean over the opening of the test tube (as when conducting any other experiment!), because careless heating may cause splashing of acid. On low heat, use a Bunsen burner to boil the mixture for at least 15 minutes (add “boilers” "!). The longer the heating, the better the yield.

An inner tube filled with water serves as a reflux condenser. If its contents become too hot, then you need to pause the experiment, after cooling, fill the inner test tube with ice again and continue heating (It is more convenient to continuously pass cold running water through the inner test tube. To do this, you need to select a stopper with two glass tubes inserted into it. - Approx. Transl.). Even before the completion of the experiment, we can often smell the pleasant smell of the resulting ester, which is still superimposed by the pungent smell of hydrogen chloride (therefore, there is no need to sniff the reaction mixture when bringing the test tube opening closer to you!).

After cooling, neutralize the reaction mixture with a diluted soda solution. We can now detect the odor of pure ether, and also notice many small oily droplets of ester floating on the surface of the aqueous solution, while the unreacted starting materials are mostly contained in the solution or form a crystalline precipitate. According to the given recipe we get the following broadcasts:

Ethyl methanate(ethyl formate, formic ethyl ester), formed from ethanol (ethyl alcohol) and methane (formic) acid. This ester is added to some types of rum to give it a characteristic aroma.

Butyl ethanate(butyl acetate, butyl acetate) - from butanol (butyl alcohol) and ethanoic (acetic acid).

Isobutyl ethane(isobutyl acetate, acetic isobutyl ether) is formed from 2-methylpropanol-1 (isobutyl alcohol) and ethanoic acid, respectively. Both of the latter esters have a strong fruity odor and are an integral part of perfume compositions with the aroma of lavender, hyacinths and roses.

Pentylethanate(amyl acetate, amyl acetate) - from pentanol, that is, amyl alcohol (Poison!), and ethanoic acid.

Isopentyl ethanate(isoamyl acetate, acetic isoamyl ester) - from 3-methylbutanol-1, that is, isoamyl alcohol (Poison!), and ethanoic acid. These two esters smell like pears in dilute solution. They are part of fantasy perfumes and serve as solvents in nail polishes.

Methyl butanoate(methyl butyrate, methyl butyrate) - from methanol (methyl alcohol) and butanoic (butyric) acid. Its smell is reminiscent of ranet.

Ethyl butanoate(ethyl butyrate; ethyl butyrate) - from ethyl alcohol and butanoic acid. It has a characteristic pineapple smell.

Pentylbutanate(amyl butyrate, butyramyl ether) - from pentanol (amyl alcohol) and butanoic acid (alcohol is poisonous!).

Isopentyl butanate(isoamyl butyrate, butyroisoamyl ether) - from 3-methylbutanol-1 (isoamyl alcohol) and butanoic acid (alcohol is poisonous!). The last two esters have the smell of pears.

Among aromatic acid esters There are also substances with a pleasant aroma. In contrast to the fruity smell of aliphatic esters, they are dominated by balsamic, so-called animal odors or odors of exotic flowers. We synthesize some of these important aromatic substances.

Methyl and ethyl benzoate we obtain from methyl or ethyl alcohol, respectively, and benzoic acid. Let's carry out the experiment according to the above recipe and take as starting substances alcohol and about 1 g of crystalline benzoic acid. These esters resemble balms in smell and are included in perfume compositions with the scents of fresh hay, Russian leather (yufti), cloves, ylang-ylang and tuberose.

Pentyl benzoate(amyl benzoate, benzoamyl ether) and isopentyl benzoate(isoamyl benzoate, benzoinoisoamyl ether) smell of clover and ambergris - a peculiar secretion from the digestive tract of the whale. They are used for perfumes with an oriental flavor. To obtain these substances, we esterify benzoic acid with amyl or isoamyl alcohol (Poison!) in the presence of concentrated hydrochloric acid, because side reactions are possible in the presence of sulfuric acid.

Ethyl salicylate The smell is reminiscent of green periwinkle oil, which we already met earlier. However, it has a less pungent odor. It is used to make cassia-scented perfumes and Chypre-type perfumes. We will obtain this ester from ethyl alcohol and salicylic acid by heating with table salt and sulfuric acid.

Pentylsalicylate(amyl salicylate) and isopentyl salicylate(isoamyl salicylate) have a strong orchid smell. They are often used to create clover, orchid, camellia and carnation scents, as well as fancy scents, especially in soap scenting. In these two cases we will also carry out esterification in the presence of hydrochloric acid.

Also worthy of attention benzylmethanate(benzyl formate), benzyl ethanate(benzylacetate) and benzylbutanate(benzyl butyrate). All these esters are formed from aromatic benzyl alcohol and the corresponding carboxylic acids - methane (formic), ethane (acetic) or butanoic (butyric).

Since benzyl alcohol is difficult to find commercially, we will obtain it ourselves from commercial benzaldehyde, used in perfumery to create the aroma of bitter almonds.

In a water bath with continuous stirring, we will heat 10 g of benzaldehyde with a concentrated solution of potassium hydroxide for 30 minutes. (Caution: lye causes skin burns!)

As a result of the reaction, benzyl alcohol and potassium salt of benzoic acid are formed:

2C 6 H 5 -CHO + KOH = C 6 H 5 COOK + C 6 H 5 -CH 2 -OH

benzaldehyde potassium benzoate benzyl alcohol

After cooling, add 30 ml of water. In this case, potassium benzoate dissolves, and benzyl alcohol is released as an oil, forming the top layer. Separate it in a separating funnel and heat it in our simple esterification apparatus with the above carboxylic acids while adding sulfuric acid and table salt. The resulting esters have a strong jasmine scent and are used in the manufacture of many perfumes.

Preparative preparation of ester.

We will obtain one of the esters in a fairly pure state and in larger quantities. Let's choose for this methyl salicylate– an aromatic substance that gives the aroma of periwinkle oil.

To do this, we will need a 50-100 ml round-bottomed flask, a refrigerator or a homemade cooling device that replaces it, a separating funnel as a receiver, a curved glass tube, a burner and a tripod with accessories, as well as a water bath.

Place 10 g of salicylic acid and 15 ml of methanol in a round-bottomed flask. (Caution! Poison!).

Cool the mixture with cold water and carefully, in small portions, add 5 ml of concentrated sulfuric acid. Close the flask with a rubber stopper with a reflux condenser inserted into it. Then we will heat the contents of the flask in a boiling water bath for 2 hours. Let the reaction mixture cool and pour it into a cup containing 100 ml of cold water, preferably with pieces of ice. Stir, pour the mixture into a separatory funnel and shake vigorously several times. In this case, methyl salicylate is released from the mixture, which can be collected. However, the product obtained in this way – from 5 to 10 g – still contains impurities. It can be purified by fractional distillation. Using the above method, you can independently synthesize other esters in slightly larger quantities, but we do not need this, since their smell is especially pleasant when highly diluted. On the contrary, in a concentrated state they often have an unpleasant, pungent odor.

We can verify this by rinsing the test tubes in which the esters were prepared or stored several times with water. After washing, they still smell, and the smell even becomes even more pleasant. However, independently synthesized aromatic substances, of course, cannot be used to prepare fruit essences - because they may be contaminated with impurities. And the perfumes we prepare, alas, will be inferior in quality to the factory ones, which are usually very complex compositions.

Fragrant alkanals from soap.

Among modern synthetic aromatic substances, a special place is occupied by the highest alkanali(aldehydes) and alkanols(alcohols) containing from 7 to 20 carbon atoms. They have a characteristic fresh smell, usually slightly reminiscent of wax. This made it possible to create on their basis many new compositions with unique fantasy scents.

World-famous perfumes - for example, the French Soir de Paris and Chanel No. 5 - owe their aroma to these compounds. Similar perfumes are also produced in the GDR.

Higher alkanals and alkanols are important intermediates and are obtained by synthesis from fatty acids under the action of hydrogen under high pressure. Alkanals are also formed in a contaminated state during the joint dry distillation of salts of fatty acids with a salt of methane (formic) acid. In a similar way, we have already obtained acetone from gray wood vinegar powder.
Let's heat a few grams of finely chopped kernel soap or, better yet, ready-made soap flakes with approximately an equal amount of sodium methate (formate) in a large test tube or small flask. We will pass the released vapors through a direct refrigerator and collect the condensate in the receiver.

With careful heating, we will obtain a light, cloudy distillate that has a pleasant, fresh smell with a hint of waxy smell. Along with water and other substances, it contains several higher alkanals. If the reaction mass is heated too much, decomposition products are formed, which, on the contrary, have an unpleasant odor.

Fruit essence and isovaleric acid from isoamyl alcohol.

Pour 3 ml of 3-methylbutanol-1, also called isoamyl alcohol, into a test tube. (Caution! Poison!) Thoroughly cool the contents of the test tube with ice water or at least very cold water. Then carefully, in small portions, add 5 ml of concentrated sulfuric acid. In this case, the mixture acquires a reddish tint. If it turns black, the experiment will fail.

At the same time, we will reassemble the device that we have already used to obtain methyl salicylate. Pour a solution of 10-12 g of potassium dichromate in 15 ml of water into the flask. Carefully, in small portions (at a distance from yourself!), We will add the mixture from the test tube to it. This will begin a violent reaction, and at the same time we will first detect a faint odor reminiscent of bananas, and later an intense fruity odor. We will heat the flask in a boiling water bath for about an hour. The liquid will turn dark green. After cooling, opening the flask, we will feel the depressing smell of valerian. If we now add about 25 ml of water and distill with a direct refrigerator, we will get a distillate consisting of several layers. 3-methylbutanoic or isovaleric acid is dissolved in the aqueous layer (prove the acidic reaction!). Above the water layer is usually a layer of lighter oil. This is isopentyl isopentanate (isoamyl isovalerate) - isoamyl ester of isovaleric acid.

Chromic mixture - a mixture of potassium dichromate and sulfuric acid - is a strong oxidizing agent. When it acts, it first forms from isoamyl alcohol isovaleraldehyde and further from it isovaleric acid. An ester is obtained by reacting the resulting acid with an unreacted alcohol.

Isovaleric acid is the main component of valerian root tincture and hence its name. The mentioned aldehyde and ester are used in perfumery and in the production of fruit essences.

The aroma of lilac from turpentine!

Wandering through the forest, we more than once saw cuts on the trunks of pine trees that resembled a fish spine. We know it's true extract resin. It flows from wounded areas and accumulates in small pots mounted on tree trunks. Resin is an important raw material for the chemical industry. When distilled with water steam, it is separated into a distillate - gum turpentine and the residue after its distillation - rosin, which is used, in particular, for soldering, as an additive in paper making, in the production of varnishes, sealing wax, shoe polishes and for many other purposes. A turpentine often used to dilute drying oil. Its main component is pinene, also found in many other essential oils.

From aromatic substances of the terpene family pinene It doesn't have the most pleasant smell. However, in the skillful hands of chemists, it can be transformed into magnificent aromatic substances with a floral aroma, which in nature are found only in very small quantities in expensive essential oils extracted from rare flowers. In addition, camphor is obtained from pinene in large quantities, which is used in medicine for the manufacture of ointments, and also - as we already know - in the production of celluloid.

Let's try to obtain one of the most important fragrant substances ourselves - alcohol terpineol, having the smell of lilac.

Pour 15 ml of pure into a 100 ml Erlenmeyer flask, be sure to gum turpentine and 30 ml of nitric acid, previously diluted twice with water. We close the flask with a stopper with a vertical glass tube 20 cm long and place it in a bath of cold water.

We will conduct the experiment in a fume hood or in the open air, since toxic nitrous gases may be released. Therefore, the flask must remain open! Let the mixture stand for two days, vigorously shaking it as often as possible. As soon as brownish gases appear and the contents of the flask warm up, stop shaking and cool the flask in a bowl of cold water.

At the end of the reaction, the contents of the flask consist of two layers, both reddish brown. The top layer is a viscous, foamy mass. It contains turpentine and terpine, formed from pinene as a result of the addition of two water molecules to it. The nitric acid forming the lower layer contains only a small amount of soluble transformation products. Neutralize the reaction mass with a diluted soda solution (be careful - foaming!) and separate the top layer of oil. To do this, pour the contents of the flask into a cup and carefully scoop out the top layer with a spoon. You can also suck out the bottom layer with a pipette (Do not suck out with your mouth under any circumstances. Vacuum in the pipette is created using a bulb or a water-jet pump. It is most convenient to draw liquid into the pipette with a syringe (without a needle), tightly connected to the pipette with a piece of rubber hose. - Approx. Transl. ).

You should not use a separating funnel because the top layer is too viscous. Then the separated viscous mass with an excess of diluted (approximately 10%) sulfuric acid will be heated for an hour at reflux. We use the same simple device as when obtaining methyl salicylate. After cooling, neutralize again with a soda solution. At the same time, we will feel a strong smell of lilac, which is still superimposed by the smells of unreacted turpentine and various impurities. The whole process is reflected in the following diagram: Technical terpineol It is used to scent soaps, and when thoroughly cleaned, it becomes an indispensable component of many perfumes.

Perfume

So, we synthesized and studied the properties of a number of fragrant substances. However, comparing their smell with the aroma of expensive perfumes bought in a store, one cannot help but be disappointed. The fact is that factory perfumes are given their aroma by more than one substance. Modern perfumes are a product of mixing many compositions, each of which again contains many aromatic substances of both natural and synthetic origin. For example, a new composition with the scent of lilac has the following composition:

Terpineol 11% Ylang-ylang oil 1% Phenylethyl alcohol 11% Bouvardie 1% Lilac 1094 11.5% Benzyl acetate 1% Heliotropin 6.5% Amyl cinnamaldehyde 1% Hydroxycitronellal 6.5% Anisaldehyde 0.3% Cinnamic alcohol 4.5 % Methyl anthranilate 0.2% Civet infusion 0.8%

Only by mixing several similar compositions do you get real perfumes. To create such works of perfume art, you need not only many years of experience, but also the ability to create and the talent of an artist.

For a long time and is still generally recognized as an international center from which new fashions in perfumery spread, the city of Suresnes in France (Surenes is now a western suburb of Paris, located on the left bank of the Seine. - Translator's note). However, at present, valuable synthetic fragrances are being exported in ever-increasing quantities from the GDR, even to this capital of perfumery. Ready-made perfumes from the GDR and Soviet Union are also not inferior to world-famous French brands today and are in great demand on the world market.

Only in the time of our great-grandmothers were pure or mixed floral scents, such as lilac, roses, and daffodils, the most beloved. Later, the smell of orchids came into fashion, and today fantasy perfumes are almost exclusively preferred, having a fresh floral aroma with a faint “animal” tint, bringing the smell of perfume closer to the smell of human skin. When making such perfumes, a so-called leading scent is first created, usually using natural or synthetic citrus or bergamot oil. Then, for contrast, higher aldehydes are added to create a bright, expressive shade.
You can’t do without the fresh smell of greenery and, for a smooth transition to it, a floral smell. The “animal” smell, the body odor, is provided by the addition of synthetic substances such as ambergris and musk. These substances, in addition, give the aroma persistence. They help ensure that the volatile components of perfume do not disappear too quickly and last longer on the skin or dress.

In conclusion, we will make our own perfume according to the laws of current fashion.

Let's make perfume.

To create a leading scent, we will first need citrus oil, which we get from the peels of lemons or oranges. It is so rich in essential oils that they are very easy to isolate. To do this, it is enough to mechanically destroy the membrane of the cells that contain the oil and collect the droplets released. For this purpose, grate the peel, wrap it in a pureed form in a piece of durable cloth and carefully squeeze it out. In this case, a cloudy liquid consisting of water and oil droplets seeps through the fabric. Mix approximately 2 ml of this liquid with 1 ml of the distillate we obtained from the soap. The latter contains higher fatty aldehydes and has a refreshing odor, slightly reminiscent of wax.

Now we need another floral shade. We will create it by adding 2-3 drops of lily of the valley oil or substances synthesized by us to the mixture - isopentyl salicylate(isoamyl salicylate) or terpineol. A drop (literally) of methyl salicylate, caraway oil, as well as a small addition of vanilla sugar improves the aroma. Finally, dissolve this mixture in 20 ml of pure (not denatured) alcohol or as a last resort an equal volume of vodka and our perfume will be ready. Although they have a pleasant aroma, it is still hardly worth wearing them, because it is difficult for them to compete with factory perfumes. The reader can try to independently select the composition of other perfumes, using the aromatic substances described above and obtained by him.

Conclusion

It is unlikely that substances that have no odor exist in nature. Stones, wood, materials that we are accustomed to thinking of as odorless, under appropriate conditions, exhibit their own odor. However, many people do not feel or do not pay attention to some of the smells around us.

Literature

1. Voitkevich S. A. “The relationship between the structure of fragrant substances and their smell” // Journal of the All-Union Chemical Society named after. D. I. Mendeleev. - 1969. - No. 2. - P. 196-203.

2. Voitkevich S.I. “Chemistry and technology of fragrant substances of the USSR” // “Oil and fat industry”. - 1967.-No. 10.-S. 36-40.

3. Kasparov G. N. “Fundamentals of the production of perfumes and cosmetics.” - 2nd ed., revised. and additional - Moscow, “Agropromizdat”, 1988.

4. Samsonov S. N. “How odors are perceived” // “Science and Life”. - 1988. - No. 4. - P. 12-18.

5. Friedman R. A. “Perfumes and cosmetics.” - Moscow, “Food Industry”, 1975.

6. Kheifits L. A., Dashunin V. M. “Fragrant substances and other products for perfumery.” - Moscow, “Chemistry”, 1994.

7. “Chemical encyclopedia: 5 volumes.” - “Moscow”, “Soviet Encyclopedia”, 1988. - T. 1.

8. Shulov L. M., Kheifits L. A. “Fragrant substances and intermediate products of perfumery and cosmetic production” - Moscow, “Agrokhimizdat”, 1990.

9. Materials from the site http://alhimik.ru

10. Materials from the site http://ermine.narod.ru

scientific work

Classification of odorous substances

Odoriferous substances occur in many classes of organic compounds.

The largest group of odorous substances are esters. Many odorous substances belong to aldehydes, ketones, alcohols and some other groups of organic compounds. Esters of lower fatty acids and saturated fatty alcohols have a fruity odor (fruit essences, for example isoamyl acetate), esters of aliphatic acids and terpene or aromatic alcohols - floral (for example, benzyl acetate, terpinyl acetate), esters of benzoic, salicylic and other aromatic acids - mainly sweet balsamic scent.

Among the saturated aliphatic aldehydes one can name, for example, decanal, methylnonylacetaldehyde, among the terpenes - citral, hydroxycitronellal, among the aromatic ones - vanillin, heliotropin, among the fatty aromatics - phenylacetaldehyde, cinnamaldehyde. Of the ketones, the most widespread and important are alicyclic ones, containing a keto group in the cycle (vetion, jasmone) or in the side chain (ionones), and fatty aromatic ones (n-methoxyacetophenone), among alcohols - monohydric terpenes (era-niol, linalool, etc. .) and aromatic (benzyl alcohol).

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There are a huge number of different odorous substances in nature, and there is hardly a person who could know all the odors. It is known that, for example, people who are far from chemistry do not know such odors that are well known to chemists (the smell of picric acid or formaldehyde). Our knowledge of odorous substances is still so insufficient that we do not have a uniform classification of odors according to their quality. There are about 50 pure basic odors, from which all other odors are formed through various combinations.

The Dutch scientist Zwaardemaker proposed that all existing odorous substances be divided into nine classes. I. Essential odors. These include the smells of fruit essences used in perfumery: apple, pear, etc., as well as beeswax and esters. II. Aromatic smells are the smell of camphor, bitter almonds, lemon. III. Balsamic scents are the scent of flowers (jasmine, lily of the valley, etc.), vanillin, etc. IV. Ambro-musky scents are the smell of musk, amber. This also includes many odors of animals and some mushrooms. V. Garlic odors: the smell of ichthyol, vulcanized rubber, stinking resin, chlorine, bromine, iodine, etc.

VI. Burnt odors: roasted coffee, tobacco smoke, pyridine, benzene, phenol (carbolic acid), naphthalene. VII. Caprylic odors and the smell of cheese, sweat, rancid fat VIII. Nasty odors are the odors of certain narcotic substances obtained from nightshade plants (the smell of henbane) IX. Nauseating odors, cadaverous smell, etc.

The source of odors are solid, liquid and gaseous bodies. Essential oils (the main odorous principle contained in plants) have for the most part a pleasant odor and are characterized by high volatility. Odors of animal origin are distinguished by their persistence: the olfactory sensation they cause lasts for a long time. Most of the odors of this group have an unpleasant stench. Odors of mineral origin are not cause a pronounced olfactory sensation and are predominantly indifferent. The source of odors are solid, liquid and gaseous bodies. Essential oils (the main odorous “principal” contained in plants) have for the most part a pleasant odor and are characterized by high volatility. Odors of animal origin are distinguished by their persistence: the olfactory sensation they evoke lasts for a long time. Most of the odors in this group have an unpleasant stench. Odors of mineral origin do not cause a pronounced olfactory sensation and are predominantly indifferent.

Odorous substances are highly volatile; they continuously separate particles from the external environment that determine the olfactory sensation. The particles released by these bodies are so small that odorous substances can emit an odor for a long time and lose very little weight. There is a known case where valerian root, preserved in a museum for 200 years, retained its smell. The extraordinary volatility of odorous substances, as well as the infinitely small sizes of the particles they separate, favor the spread of odors in the air. Particles of odorous substances are retained and absorbed by other bodies. Odorous substances are highly volatile; they continuously separate particles from the external environment that determine the olfactory sensation. The particles released by these bodies are so small that odorous substances can emit an odor for a long time and lose very little weight. There is a known case where valerian root, preserved in a museum for 200 years, retained its smell. The extraordinary volatility of odorous substances, as well as the infinitely small sizes of the particles they separate, favor the spread of odors in the air. Particles of odorous substances are retained and absorbed by other bodies.

The degree of their absorption depends not only on the nature of the odor, but also on chemical composition and the colors of those objects that absorb the smell. Silk and woolen fabrics, peat, charcoal (especially in the form of dried, powdery mass) absorb odors most strongly; paper fabrics and paper absorb odors less strongly. Under the influence of oxygen, odors decompose. Therefore, in order to eliminate odors (deodorization), they use chemical mixtures that release oxygen, or a mixture of clean air with ozone. Heat and humidity favor the spread of odors and enhance their effect. However, humidity should not exceed known limits, since excess moisture weakens the intensity of odors. Material taken from the site:

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