The most important representatives of esters are fats.

Fats, oils

Fats- these are esters of glycerol and higher monoatomic. The common name for such compounds is triglycerides or triacylglycerols, where acyl is a carboxylic acid residue -C(O)R. The composition of natural triglycerides includes residues of saturated acids (palmitic C 15 H 31 COOH, stearic C 17 H 35 COOH) and unsaturated acids (oleic C 17 H 33 COOH, linoleic C 17 H 31 COOH). Higher carboxylic acids, which are part of fats, always have an even number of carbon atoms (C 8 - C 18) and an unbranched hydrocarbon residue. Natural fats and oils are mixtures of glycerides of higher carboxylic acids.

The composition and structure of fats can be reflected by the general formula:

Esterification- the reaction of the formation of esters.

The composition of fats can include residues of both saturated and unsaturated carboxylic acids in various combinations.

Under normal conditions, fats containing residues of unsaturated acids in their composition are most often liquid. They are called oils. Basically, these are fats of vegetable origin - linseed, hemp, sunflower and other oils (with the exception of palm and coconut oils - solid under normal conditions). Less common are liquid fats of animal origin, such as fish oil. Most natural fats of animal origin under normal conditions are solid (fusible) substances and contain mainly residues of saturated carboxylic acids, such as mutton fat.
The composition of fats determines their physical and chemical properties.

Physical properties of fats

Fats are insoluble in water, do not have a clear melting point, and expand significantly when melted.

The aggregate state of fats is solid, this is due to the fact that fats contain residues of saturated acids and fat molecules are capable of dense packing. The composition of oils includes residues of unsaturated acids in cis - configuration, therefore, dense packing of molecules is impossible, and state of aggregation- liquid.

Chemical properties fat

Fats (oils) are esters and are characterized by ester reactions.

It is clear that for fats containing residues of unsaturated carboxylic acids, all reactions of unsaturated compounds are characteristic. They discolor bromine water, enter into other addition reactions. The most important reaction in practical terms is the hydrogenation of fats. Solid esters are obtained by hydrogenation of liquid fats. It is this reaction that underlies the production of margarine, a solid fat from vegetable oils. Conventionally, this process can be described by the reaction equation:

All fats, like other esters, undergo hydrolysis:

Hydrolysis of esters is a reversible reaction. In order to form hydrolysis products, it is carried out in an alkaline environment (in the presence of alkalis or Na 2 CO 3). Under these conditions, the hydrolysis of fats proceeds reversibly, and leads to the formation of salts of carboxylic acids, which are called. fats in an alkaline environment are called saponification of fats.

When fats are saponified, glycerol and soaps are formed - sodium and potassium salts of higher carboxylic acids:

Saponification- alkaline hydrolysis of fats, obtaining soap.

Soaps- mixtures of sodium (potassium) salts of higher limiting carboxylic acids (sodium soap - solid, potassium - liquid).

Soaps are surfactants (abbreviated as surfactants, detergents). The detergent effect of soaps is due to the fact that soaps emulsify fats. Soaps form micelles with pollutants (conditionally, these are fats with various inclusions).

The lipophilic part of the soap molecule dissolves in the pollutant, while the hydrophilic part is on the surface of the micelle. Micelles are charged with the same name, therefore they repel each other, while the pollutant and water turn into an emulsion (practically, this is dirty water).

Soap also occurs in water, which creates an alkaline environment.

Soaps cannot be used in hard and sea water, as the resulting calcium (magnesium) stearates are insoluble in water.

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Introduction

Esters are organic compounds based on oxygen-containing organic carboxylic or inorganic acids.

Esters are widely distributed in nature and play an important role in human life. We encounter them when we smell a flower, which owes its fragrance to the simplest esters. We wash, wash and wash with products that are obtained by processing fats, that is, esters. They are used in a variety of areas of production: they are used to make medicines, paints and varnishes, lubricants, polymers, synthetic fibers, used in aromatherapy and perfume production.

Relevance: This topic is relevant, since esters are used in the food and perfumery and cosmetic industries, are part of the essential oils that form the basis of any smell, are used in aromatherapy and perfume production.

Problem: The topic "Esters" is not studied in detail in school course organic chemistry, and it is not always possible to obtain esters with different odors in a school laboratory due to a lack of equipment and chemicals.

I was wondering if I could get esters from the school lab and create my own scents. This idea formed the basis of this work.

Target: get esters in the school laboratory and create perfume compositions.

Tasks:

1. Study the literature on this topic;

2. Get esters: ethyl ester of acetic acid, isoamyl ester of acetic acid and ethyl ester of butyric acid;

3. Create perfume compositions based on essential oils.

Hypothesis: Under laboratory conditions, it is possible to independently obtain esters and your own aromas.

Research methods:

1) Study of literature;

2) Observation;

3) Experiment.

1. Theoretical part

1.1.1. Complex ethers. Classification and composition

Esters - class organic compounds, derivatives of carboxylic or mineral acids, in which the hydroxyl group -OH of the acid function is replaced by an alcohol residue. They differ from ethers, in which two hydrocarbon radicals are connected by an oxygen atom (R 1 -O-R 2).

Classification and composition of esters. Among the studied and widely used esters, the majority are compounds derived from carboxylic acids. Esters based on mineral (inorganic) acids are not so diverse, because the class of mineral acids is less numerous than carboxylic acids.

When the number of carbon atoms in the original carboxylic acid and alcohol does not exceed 6-8, the corresponding esters are colorless oily liquids, most often with a fruity odor. They form a group of fruit esters. If an aromatic alcohol (containing an aromatic nucleus) is involved in the formation of an ester, then such compounds, as a rule, have a floral rather than fruity odor. All compounds of this group are practically insoluble in water, but readily soluble in most organic solvents. These compounds are interesting for a wide range of pleasant aromas, some of them were first isolated from plants, and later synthesized artificially.

With an increase in the size of the organic groups that make up the esters, up to C 15-30, the compounds acquire the consistency of plastic, easily softened substances. This group is called waxes and is generally odorless. Beeswax contains a mixture of various esters. One of the components of the wax, which was able to isolate and determine its composition, is myricyl ester of palmitic acid C 15 H 31 COOC 31 H 63 . Chinese wax (a product of isolation of cochineal - insects of East Asia) contains ceryl ester of cerotinic acid C 25 H 51 COOS 26 H 53. In addition, waxes contain both free carboxylic acids and alcohols, including large organic groups. Waxes are not wetted by water, soluble in gasoline, chloroform, benzene.

The third group is fats. Unlike the previous two groups based on ROH monohydric alcohols, all fats are esters of the glycerol alcohol HOCH 2 -CH (OH) -CH 2 OH. Carboxylic acids, which are part of fats, as a rule, have a hydrocarbon chain with 9-19 carbon atoms. Animal fats (cow butter, lamb, lard) are plastic fusible substances. They mainly consist of a mixture of stearic and palmitic acid glycerides. Vegetable fats (olive, cottonseed, sunflower oil) are viscous liquids. Vegetable oils contain glycerides of acids with a slightly shorter carbon chain: lauric C 11 H 23 COOH and myristic C 13 H 27 COOH. Such oils can be stored in air for a long time without changing their consistency, and therefore are called non-drying. In contrast, linseed oil contains unsaturated linoleic acid glyceride. When applied in a thin layer to the surface, such an oil dries out under the action of atmospheric oxygen during the polymerization of double bonds, and an elastic film is formed that is insoluble in water and organic solvents. On the basis of linseed oil, natural drying oil is made.

(Glycerides of stearic and palmitic acid(A and B) - components of animal fat. Linoleic acid glyceride (B) - a component of linseed oil)

Esters of mineral acids (alkyl sulfates, alkyl borates containing fragments of lower alcohols C 1-8) are oily liquids, esters of higher alcohols (starting with C 9) are solid compounds.

1.1.2. Preparation and use of esters

The main production method is the interaction of a carboxylic acid and an alcohol (esterification reaction), catalyzed by an acid and accompanied by the release of water.

The esterification reaction under acid catalysis is reversible. reverse process- the cleavage of an ester by the action of water to form a carboxylic acid and an alcohol is called ester hydrolysis.

RCOOR" + H 2 O ( H+)↔ RCOOH + R"OH

Application

Esters are widely distributed in nature. They find application in engineering and various industries as good solvents. organic matter, plasticizers, flavoring agents.

Ethyl formate and ethyl acetate are used as solvents for cellulose varnishes (based on nitrocellulose and cellulose acetate).

Esters based on lower alcohols and acids are used in Food Industry when creating fruit essences, and esters based on aromatic alcohols - in the perfume industry.

Polishes, lubricants, impregnating compositions for paper (waxed paper) and leather are made from waxes, they are also part of cosmetic creams and medicinal ointments.

Fats, together with carbohydrates, are part of all plant and animal cells, accumulating in the body, play the role of an energy reserve.

Animal and vegetable fats are raw materials for the production of higher carboxylic acids, detergents and glycerin, used in the cosmetic industry and as a component of various lubricants.

Sulfuric acid esters are used in organic synthesis as alkylating agents (introducing an alkyl group into the compound), and phosphoric acid esters are used as insecticides, as well as additives to lubricating oils.

They are the basis of such drugs as salol, validol, etc. As a local irritant and analgesic, methyl salicylate was widely used, which has now been replaced by more effective drugs.

1.2.1. What are perfumes made of?

The word "perfume" comes from the Latin "perfumum" - through the smoke (in ancient times, the premises were fumigated with incense smoke). The history of perfumery goes back centuries. The first perfume maker (and concurrently the world's first chemist) is considered to be a woman named Taputti, her name is mentioned on a clay cuneiform tablet from Ancient Babylon. Together with her assistant Nino, she obtained aromatic oils from flowers and other parts of plants and mixed them.

Ancient people attributed divine and magical powers to aromas. The Egyptians made fragrant ointments and fragrant oils, which accompanied various rituals and complemented women's toilets. The Greeks, who became famous as inquisitive travelers, brought new and exotic flavors from their wanderings. IN ancient rome healing powers were attributed to smells.

Modern perfumery uses a huge range of aromatic substances, both from the ancient and modern arsenal. The composition of one perfume can include more than three hundred different components. The perfumer has hundreds of natural products at his disposal: substances of plant and animal origin, and thousands of chemicals obtained by synthesis (the number of the latter is constantly increasing).

The basis of modern perfumery are numerous fragrant substances of plant origin. Strongly odorous concentrated substances extracted from plants bear the common name essential oils . They are extracted from fresh or dried essential oil plants. The following methods for obtaining essential oils have found the greatest use:

Mechanical method - squeezing oils by pressing the peel and peel of citrus fruits and fruits (orange, tangerine, lemon oils).

Distillation - the distillation of essential oils with water vapor (for example, rose, geranium, peppermint or coriander oils).

Extraction of essential oils with volatile and non-volatile solvents (in particular oils of rose, jasmine, ylang-ylang, etc.).

The method of obtaining essential oils with volatile solvents is called extraction. After distillation of the solvent from the extract oil, a mixture of essential oil, waxes, resins and fats is obtained. An absolute oil is obtained from it by treatment with alcohol and further distillation of the alcohol.

Obtaining oils with the help of non-volatile solvents is called maceration (infusion). This method is used to extract oils from plant flowers containing a small amount of oils (violet, jasmine, lily of the valley, mignonette, etc.).

Extraction of essential oils by enfleurage and dynamic sorption. This method is based on the ability of essential oils released by plants to pass into a gaseous state and then be absorbed by fats or solid sorbents (silica gel or activated carbon), followed by extraction of the sorbents with sulfuric ether.

In addition to these types of plant raw materials, fragrant substances are also used, called resins and balms . These are complex mixtures of organic compounds found in many plants. They are used in perfumery in the form of infusions and solutions and are a kind of odor fixatives that help to increase the duration of the perfume smell. These include benzoin, styrax, balsam, as well as resins isolated from rose flowers, cistus, and other resinous substances. Raw materials of animal origin - it's musk, amber and beaver stream. Unlike most plant substances, they give off odors that do not qualify as "pleasant" odors. It is enough to feel the musk once, and recoil, pinching your nostrils until you suffocate, to understand that the animal components of the perfume, if they are necessary, should be dosed. SYNTHETIC AROMATIC SUBSTANCES- this is a large group of organic compounds obtained by chemical or physico-chemical methods from plant products or synthesized from various chemical raw materials. Individual fragrances obtained by chemical synthesis are commonly referred to as synthetic fragrances. They are woven with separate notes into the fabric of the composition of fragrant substances and enhance its durability.

The warmth and color of natural raw materials, the durability and originality of chemical raw materials - the most desirable combination in order for perfumery to develop in the right direction.

1.2.2. Aroma classification and composition structure

Today, there are several models for classifying fragrances: each perfumer tries to improve old models or invent something of his own. Some categories in each of the existing classifications coincide, but something differs significantly. One of the most popular is the classification of fragrances by the French community of perfumers.

CLASSIFICATION OF FRAGRANCES OF THE FRENCH COMMUNITY OF PERFUMERS

In 1990, a whole Perfume Committee (Comite Francais De Parfum). The result of their collection was a classification that has gained great popularity and is now used by many perfume houses and scent connoisseurs.

The French distributed the groups of aromas as follows.

Citrus: the basis is made up of essential oils extracted from citrus fruits - lemon, orange, mandarin, bergamot, pomelo, grapefruit, tangerine, yuzu and citron).

Floral: aromas of flowers - jasmine, narcissus, lilac, rose, lily of the valley, violet, tuberose.

woody: aromas of warm shades - patchouli, cedar, sandalwood, vetiver.

Eastern: amber, as well as aromas with cistus-labdanum, powdery, vanilla and animal accents.

Leather: there are few aromas of this family, they are distinguished by dryness and peculiar skin odors with an admixture of flowers.

Shipra: perfumes, created in 1917 by Francois Coty, unite the whole family under their command; here you can catch notes of oakmoss, bergamot, patchouli.

Fougère: notes of oak and tree moss, lavender, bergamot, coumarin.

The principle of dividing fragrances into families is clear: they are united by identical notes that are mixed in different proportions.

The structure of the perfume composition

Each composition consists of three gradually revealing aroma notes. The top note is called the head note by perfumers. The middle note is called the heart note or center note. The final note is the base or main note, it is also called the fund. All three notes open at different times, this process is called the life span of a perfume note.

Top notes of the fragrance

The initial smell of perfume does not last long, no longer than 20 minutes - the top notes of the fragrance evaporate first. Their task is to create a mood, so they sound light and filled with shades of freshness and greenery. It is the peak that we hear first, its notes intrigue us, prepare us for the main smell.

heart notes

Bright and light initial notes gradually turn into heart notes. It is the heart of the scent that determines the character of the fragrance and its recognizability. When creating a perfume composition, the heart note of the heart is first composed, on which the remaining components are then strung.

The heart of the fragrance can be anything - fruity, floral, amber, oriental, woody, musky, etc. Sometimes synthetic materials are used that create odors that do not exist in nature.

Loop notes

Heart chords fade over time and turn into a warm and velvety sound of plume shades. They are felt the longest, the strength and durability of the aroma, its timbre and saturation depend on them.

The sillage will not change, it will disappear along with the fragrance. The base note contains substances that remain on the skin for a long time and have the most low level evaporation. Woolen clothes that have been stained with perfume can retain the smell of perfume for months. The final notes of the fragrance stay on the hair very well, so you need to be careful when applying “heavy” spicy smells to your head.

As a rule, cloying or oily-sweet smells are used as materials for the plume - sandalwood, oriental spices, vanilla, patchouli, cedar. Musk and amber are often used, which help the fragrance of the perfume blend organically with the smell of human skin. The trail of perfume "rounds" the sound of the perfume composition and gives it sensuality.

2. Practical part

2.1. Obtaining esters

1. Obtaining acetic ethyl ether (ethyl acetate).

Equipment: a device for obtaining haloalkanes, a tripod, a spirit lamp, a measuring cylinder, a measuring tube.

Let us carry out the esterification reaction in a device for obtaining haloalkanes and esters. We put ethyl alcohol, acetic acid in a ratio of 1: 1 and concentrated sulfuric acid into the reaction flask. Sulfuric acid used as a water remover. Since the esterification reaction is reversible, the water must be removed. Pour a saturated solution of table salt into the refrigerator. In this solution, the solubility of the ether is minimal. When the mixture is heated, volatile acetic ethyl ester is formed. It condenses in the refrigerator. It is lighter than water and salt solution, so it forms the top layer of the liquid.

CH 3 COOH + C 2 H 5 OH = H 2 O+CH 3 COOC 2 H 5

1 - two-necked reactor flask

2 - air cooler

3 - refrigerator receiver with a narrowed bottom

4 - gas outlet tube

5 - cap

2. Obtaining isoamyl ester of acetic acid (isoamyl acetate) and ethyl ester of butyric acid (ethyl butyrate).

To obtain esters in small quantities, we use a simple device. 1. 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. At the same time, it must be taken into account that a gap of at least 1.5–2 mm must be left around a narrow test tube in order to exclude excess pressure during heating.

2. Now pour into a wide test tube 0.5-2 ml of alcohol and approximately the same amount of carboxylic acid, with thorough cooling, add 5-10 drops of concentrated sulfuric acid.

3. Insert the inner tube, fill it with snow and fix the assembled instrument in the stand. The device must be placed away from yourself and not bent over the opening of the test tube, because if heated carelessly, splashing of acid is possible. Then, on the smallest fire of the spirit stove, we will boil the mixture for at least 15 minutes.

The longer the heating, the better the yield. The inner tube filled with snow serves as a reflux condenser. As the snow melts, you need to replace the test tubes with new ones with fresh snow and continue heating.

Even before the completion of the experiment, we can smell the pleasant smell of the resulting ester, which is still superimposed by the pungent smell of hydrogen chloride. After cooling, the reaction mixture is neutralized with a dilute soda solution and separated using a separating funnel. With this method, we got:

1) isoamyl ester of acetic acid (with a pear smell);

2) butyric acid ethyl ester (pineapple scent).

2.2. Compilation of perfume compositions

Initially, the research part was based on the idea of ​​obtaining esters from various carboxylic acids and alcohols available in the school laboratory. Then these ethers should be combined into different compositions. But the synthesis of esters turned out to be quite difficult, so I tried to get at least one ester in order to get the hang of working with laboratory equipment, and decided to combine perfumes from essential oils, which are sold in pharmacies and stores.

I needed:

1. Two bases (alcohol and oil);

2. Several essential oils;

3. Paper strips for sampling;

4. Clogged vessels;

5. Pipettes.

Create your own formula

On a strip of paper, I mixed the top, middle, and base notes. I listened to its sound and continued to experiment until I got the scent I liked.

Then you need to mix the top, heart and base notes, pour into a bottle and leave for 15 minutes.

Next, select basis- alcohol with water or vegetable oil. The alcohol base will create a very persistent perfume, but it must be kept for almost a month. And on the basis of oil, the aroma will be softer, somewhat weaker and disappear faster. But oil-based perfumes can not be kept for a month, but used immediately.

Oil base

As an oil base, I took a substance widely used in perfumery, polysorbate-20, which can dissolve both water and oil.

After choosing the right combinations, I mixed the oils in a test tube, then added polysorbate-20. The amount of base should be equal to the mixture of perfume oils. After that, pure water was added to the test tube. The amount of water must be at least 50% of the volume of the base with the oil mixture.

The perfume is almost ready, it remains only to pour it into a bottle and put it in a dark, cool place for two or three days. Over time, the smell of perfume will become much richer and richer.

On an oil basis, I received 2 fragrances:

№1. Lavender - 2 k.

Rose - 2 K.

Patchouli - 2 k.

№2. Patchouli - 3 k.

Neroli - 2 k.

Bergamot - 1 k.

Alcohol base

The technique with an alcohol base is the same, the only difference is in the proportions. If you take oil as a basis, then the ratio "oil base - essential oils" should be 1:1. If the alcohol base, then the ratio is as follows: alcohol-70%, water -5%, essential oils -25%. Then mix everything and let it brew for 3-4 weeks in a dark place.

I got 3 flavors based on alcohol:

№3. Jasmine - 3 k.

Neroli - 3 k.

Mandarin - 4 to.

№4. Melissa - 3 k.

Lavender - 3 k.

Bergamot - 2 k.

Mandarin - 6 k.

№5. Lavender - 2 k.

Bergamot - 1 k.

Cedar - 3k.

Mandarin - 1 k.

Conclusion

Conclusions and results

As a result research work esters were obtained: ethyl acetate, ethyl butyrate with the smell of pineapple, isoamyl acetate with the smell of pear, as well as 5 different aromatic compositions, two of which are oil-based and three are alcohol-based. I wanted to have a perfume that only I have, and it turned out to be very possible. Thus, the hypothesis put forward by me at the beginning of the work was confirmed.

Preparing a wonderful aroma from essential oils, it turns out, is not so difficult. Of course, you need to start with the most important thing - the theoretical knowledge that I gathered from various textbooks and sites on the Internet. It is clear that for complete success it is necessary to gain some experience, but, in any case, now I have gathered a small “collection” of fragrances that I like.

I realized that in the course of my work I managed to acquire two most important tools: knowledge and skills on this topic, and now I can give gifts to my friends and relatives in the form of perfumes designed specifically for them. I will create and create new flavors!

List of used literature and Internet resources

http://www.izuminki.com/

http://www.krugosvet.ru/

http://orpheusmusic.ru/

https://en.wikipedia.org/

http://www.himhelp.ru/

O. S. Gabrielyan, Chemistry. Profile level. 10th grade, 11th grade.

However, it should be noted that their use has a huge positive value on the human body, and is necessary to use in the same way as carbohydrates with proteins.

What are these esters?

Esters, or as esters are also called, are derivatives of oxo acids (carbon, as well as inorganic compounds) that have a general formula, and, in fact, are products that interchange the hydrogen atoms of hydroxyls - OH with an acidic function for a hydrocarbon residue (aliphatic, alkenyl, aromatic or heteroaromatic), they are also considered as acetyl derivatives of alcohols.

The most common esters and their scope

• Acetates are esters of acetic acid that are used as solvents.
• Lactates are lactic acids and have organic uses.
• Butyrates - oil, also have organic applications.
• Formates - formic acid, but due to the high capacity of toxins, is not particularly used.
• It is also worth mentioning solvents based on isobutyl alcohol, as well as synthetic fatty acids, and alkylene carbonates.
• Methyl acetate - it is produced as a wood - alcohol solution. During the production of polyvinyl alcohol, it is formed as an additional product. For the ability to dissolve, it is used as a substitute for acetone, but has higher toxic properties.
• Ethyl acetate - this ester is formed using the esterification method at wood chemistry enterprises, during the processing of synthetic and wood chemical acetic acid. You can also get ethyl acetate based on methyl alcohol. Ethyl acetate has the ability to dissolve most polymers, as does acetone. If necessary, you can buy Ethyl acetate in Kazakhstan. His abilities are great. So, Its advantage over acetone is that it has a fairly high boiling point and lower volatility. It is worth adding 15-20% ethyl alcohol and the ability to dissolve increases.
• Propyl acetate - similar to ethyl acetate in the ability to dissolve.
• Amyl acetate - its aroma resembles the smell of banana oil. Scope - lacquer thinner, because it dissolves slowly.
• Esters with fruit aroma.
• Vinyl acetate - the field of application is the preparation of glue, paints and resins.
• Sodium and potassium salts form soaps.

Having considered and studied a little the advantages and scope of use of esters, you understand that they are a great necessity in human life. Contribute to the development in many areas of activity.

Fats and oils are natural esters that are formed by a triatomic alcohol - glycerol and higher fatty acids with an unbranched carbon chain containing an even number of carbon atoms. In turn, sodium or potassium salts of higher fatty acids are called soaps.

When carboxylic acids interact with alcohols ( esterification reaction) esters are formed:

This reaction is reversible. The reaction products can interact with each other to form the initial substances - alcohol and acid. Thus, the reaction of esters with water - ester hydrolysis - is the reverse of the esterification reaction. The chemical equilibrium, which is established when the rates of direct (esterification) and reverse (hydrolysis) reactions are equal, can be shifted towards the formation of ether by the presence of water-removing agents.

Esters in nature and technology

Esters are widely distributed in nature and are used in engineering and various industries. They are good solvents organic substances, their density is less than the density of water, and they practically do not dissolve in it. Thus, esters with a relatively small molecular weight are highly flammable liquids with low boiling points and smell of various fruits. They are used as solvents for varnishes and paints, flavorings of food industry products. For example, butyric acid methyl ester has the smell of apples, the ethyl ester of this acid has the smell of pineapples, isobutyl ester of acetic acid has the smell of bananas:

Esters of higher carboxylic acids and higher monobasic alcohols are called waxes. So, beeswax is the main
together from an ester of palmitic acid and myricyl alcohol C 15 H 31 COOC 31 H 63 ; sperm whale wax - spermaceti - an ester of the same palmitic acid and cetyl alcohol C 15 H 31 COOC 16 H 33.

Fats

The most important representatives of esters are fats.

Fats- natural compounds that are esters of glycerol and higher carboxylic acids.

The composition and structure of fats can be reflected by the general formula:

Most fats are formed by three carboxylic acids: oleic, palmitic and stearic. Obviously, two of them are limiting (saturated), and oleic acid contains a double bond between carbon atoms in the molecule. Thus, the composition of fats can include residues of both saturated and unsaturated carboxylic acids in various combinations.

Under normal conditions, fats containing residues of unsaturated acids in their composition are most often liquid. They are called oils. Basically, these are fats of vegetable origin - linseed, hemp, sunflower and other oils. Less common are liquid fats of animal origin, such as fish oil. Most natural fats of animal origin under normal conditions are solid (fusible) substances and contain mainly residues of saturated carboxylic acids, for example, mutton fat. So, palm oil is a solid fat under normal conditions.

The composition of fats determines their physical and chemical properties. It is clear that for fats containing residues of unsaturated carboxylic acids, all reactions of unsaturated compounds are characteristic. They decolorize bromine water, enter into other addition reactions. The most important reaction in practical terms is the hydrogenation of fats. Solid esters are obtained by hydrogenation of liquid fats. It is this reaction that underlies the production of margarine, a solid fat from vegetable oils. Conventionally, this process can be described by the reaction equation:

hydrolysis:

Soaps

All fats, like other esters, undergo hydrolysis. The hydrolysis of esters is a reversible reaction. To shift the equilibrium towards the formation of hydrolysis products, it is carried out in an alkaline environment (in the presence of alkalis or Na 2 CO 3). Under these conditions, the hydrolysis of fats proceeds irreversibly and leads to the formation of salts of carboxylic acids, which are called soaps. Hydrolysis of fats in an alkaline environment is called saponification of fats.

When fats are saponified, glycerol and soaps are formed - sodium or potassium salts of higher carboxylic acids:

Crib

Esters are derivatives of oxo acids (both carboxylic and mineral) RkE (= O) l (OH) m, (l ≠ 0), which are formally products of substitution of hydrogen atoms of hydroxyls -OH of the acid function for a hydrocarbon residue (aliphatic, alkenyl, aromatic or heteroaromatic); are also considered as acyl derivatives of alcohols. In the IUPAC nomenclature, esters also include acyl derivatives of chalcogenide analogs of alcohols (thiols, selenols, and tellurols)

They differ from ethers, in which two hydrocarbon radicals are connected by an oxygen atom (R1-O-R2).

General formula esters:

Esters nomenclature.

The name is created as follows: first, the R group attached to the acid is indicated, then the name of the acid with the suffix "at" (as in the names of inorganic salts: carbon at sodium, nitr at chromium). Examples in fig. 2

Rice. 2. NAMES OF ESTERS. Fragments of molecules and their corresponding fragments of names are highlighted in the same color. Esters are usually thought of as reaction products between an acid and an alcohol, for example, butyl propionate can be thought of as the reaction product of propionic acid and butanol.

If the trivial name of the starting acid is used, then the word “ether” is included in the name of the compound, for example, C 3 H 7 COOC 5 H 11 is the amyl ester of butyric acid.

Homologous series of esters.

The general formula of esters is R1--CO---R2, where R1 and R2 are carbohydrate radicals. Esters are derivatives of acids in which H in the hydroxyl is replaced by a radical. Esters are named after acids and alcohols. who are involved in education

H-CO-O-CH3-- methyl formate or formic acid methyl ester or formic methyl ester.

CH3-CO-O-C2H5 - ethyl acetate or ethyl ester of acetic acids or, acetic ethyl ester..

C3H7-CO-O-CH3 - butyric acid methyl ester or methyl butyrate

С3Н7-СО-О-С2Н5 - butyric acid ethyl ester or ethyl butyrate

In short, you need to write off the table of carboxylic acids. and to them the name of the salt (formic - formate, acetic - acetate, propionic - propinate. Butyrate, valeric - valeriate, caproic - capronate., enanthic - enanthonate, oxalic - oxalate. malonic - malonate. succinic - succinate .... Look how the names of the ethers are formed.

CH3- CO-O (this is acetic acid without H) --C5H11- (this is the monovalent radical pentyl (amyl) - table) this is the name of this ester.

Acetic amyl ester, amine ester of acetic acid. amyl acetate. See more.

CH3CH2CH2CH2-CO-O (pentanoic or valeric acid) ---C4H9 (this is butyl) - butyl valerate, valerian-butyl ester, butyl ester of valeric acid.

Isomerism.

Esters are characterized by isomerism of the hydrocarbon skeleton. For example, propyl acetate and isopropyl acetate are isomers. Since the ester molecule contains two hydrocarbon radicals - in the acid residue and in the alcohol residue - then isomerism of each of the radicals is possible. For example, propyl acetate and isopropyl acetate (alcohol isomerism) or ethyl butyrate and ethyl isobutyrate (acid radical isomerism) are isomers.

physical properties. Esters are colorless liquids, slightly soluble or completely insoluble in water, have a specific odor (in small concentrations - pleasant, often fruity or floral). Esters of higher alcohols and higher acids are solids.

Chemical properties . The most characteristic reaction for esters is hydrolysis. Hydrolysis occurs in the presence of acids or alkalis. When an ester is hydrolyzed in the presence of acids, a carboxylic acid and an alcohol are formed:

During the hydrolysis of an ester in the presence of alkalis, a salt of a carboxylic acid and an alcohol are formed:

Ways to get.

Methods for obtaining esters. Main products and areas of their application. Conditions for the reaction of esterification of organic acids with alcohols. process catalysts. Features of the technological design of the esterification reaction unit.

1. Interaction of acids with alcohols:

This is the most common way to obtain esters.

2. Synthesis of esters by aldehyde condensation:

The synthesis of esters from aldehydes (Tishchenko's reaction) is carried out in the presence of aluminum alcoholate activated with iron chloride or, better, with aluminum chloride and zinc oxide. This method is of industrial importance.

3. Addition of organic acids to alkenes:

4. Synthesis of esters by dehydrogenation of alcohols:

5. Obtaining esters by the method of interesterification.

This reaction has two varieties: the exchange reaction between ether and alcohol by alcohol radicals (alcoholysis reaction):

and the exchange reaction of acid radicals at the alcohol group of the ester:

6. Synthesis of esters from acid anhydrides and alcohols:

7. Interaction of ketones with alcohols:

8. Interaction between acid halides and alcohols:

9. Reaction between silver or potassium salts of acids and aliphatic halogen derivatives:

10. Reaction of acids with aliphatic diazo compounds

Application.

Some esters are used as solvents (ethyl acetate is of the greatest practical importance). Due to their pleasant smell, many esters are used in the food and cosmetic industries. Esters of unsaturated acids are used for the production of Plexiglas, the most widely used for this purpose is methyl methacrylate.

On the topic

"Ethers and Complexes"

Completed by: Manzhieva A.A.