What is the significance of esters? Esters: chemical properties and applications. Formation of oxonium compounds

In organic chemistry, there are two main classes of ethers: simple and complex. These are chemical compounds formed during hydrolysis (the elimination of a water molecule). Ethers (also called esters) are obtained by hydrolysis of the corresponding alcohols, and esters (esters) are obtained from the corresponding alcohol and acid.

Despite their similar name, ethers and esters are two completely different classes of compounds. They are obtained in different ways. They have different chemical properties. They also differ in their structural formula. Only some physical properties of their most famous representatives are common.

Physical properties of ethers and esters

Ethers are slightly soluble in water, low-boiling liquids, and are highly flammable. At room temperature, ethers are pleasant-smelling, colorless liquids.

Esters, which have a low molecular weight, are colorless liquids that evaporate easily and have a pleasant smell, often like fruits or flowers. As the carbon chain of the acyl group and alcohol residues increase, their properties become different. Such esters are solids. Their melting point depends on the length of the carbon radicals and the structure of the molecule.

Structure of ethers and esters

Both compounds have an ether bond (-O-), but in esters it is part of a more complex functional group (-COO), in which the first oxygen atom is linked to the carbon atom by a single bond (-O-), and the second by a double bond (-O-). =O).

Schematically it can be depicted like this:

Ether: R–O–R1
Ester: R-COO-R1

Depending on the radicals in R and R1, ethers are divided into:

Symmetric ethers - those in which the alkyl radicals are identical, for example, dipropyl ether, diethyl ether, dibutyl ether, etc.
Asymmetric ethers or mixed ones - with different radicals, for example, ethylpropyl ether, methylphenyl ether, butylisopropyl, etc.

Esters are divided into:

Esters of alcohol and mineral acid: sulfate (-SO3H), nitrate (-NO2), etc.
Esters of alcohol and carboxylic acid, for example, C2H5CO-, C5H9CO-, CH3CO-, etc.

Let's consider the chemical properties of ethers. Ethers have low reactivity, which is why they are often used as solvents. They react only under extreme conditions, or with highly reactive compounds. Unlike esters, esters are more reactive. They easily enter into reactions of hydrolysis, saponification, etc.

Reaction of ethers with hydrogen halides:

Most ethers can be decomposed by hydrobromic acid (HBr) to form alkyl bromides or by reaction with hydroiodic acid (HI) to form alkyl iodides.

CH3-O-CH3 + HI = CH3-OH + CH3I

CH3-OH + HI = CH3I + H2O

Formation of oxonium compounds:

Sulfuric, iodic and other strong acids, when interacting with ethers, form oxonium compounds - higher order compound products.

CH3-O-CH3 + HCl = (CH3)2O ∙ HCl

Reaction of ethers with sodium metal:

When heated with base metals, such as sodium metal, the ethers split into alcoholates and alkyl sodium.

CH3-O-CH3 + 2Na = CH3-ONa + CH3-Na

Autoxidation of ethers:

In the presence of oxygen, ethers slowly autoxidize to form idialkyl peroxide hydroperoxide. Autoxidation is the spontaneous oxidation of a compound in air.

C2H5-O-C2H5 + O2 = CH3-CH(UN)-O-C2H5

Hydrolysis of esters:

In an acidic environment, the ester hydrolyzes, forming the corresponding acid and alcohol.

CH3-COO-C2H5 = CH3-COOH + H2O

Saponification of esters:

At elevated temperatures, esters react with aqueous solutions of strong bases such as sodium or potassium hydroxide, forming carboxylic acid salts. Salts of fatty carboxylic acids are called soaps. A by-product of the saponification reaction is alcohol.

CH3-COO-C2H5 + NaOH = CH3-COONa + C2H5-OH

Transesterification (exchange) reactions:

Esters enter into exchange reactions under the action of alcohol (alcoholysis), acid (acidolysis), or during double exchange, when two esters interact.

CH3-COO-C2H5 + C3H7-OH = CH3-COO-C3H7 + C2H5-OH

CH3-COO-C2H5 + C3H7-COOH = C3H7-COO-C2H5 + CH3-COOH

CH3-COO-C2H5 + C3H7-COO-CH3 = CH3-COO-CH3 + C3H7-COO-C2H5

Reactions with ammonia:

Esters can react with ammonia (NH3) to form an amide and an alcohol. They react with amines according to the same principle.

CH3-COO-C2H5 + NH3 = CH3-CO-NH2 + C2H5-OH

Ester reduction reactions:

Esters can be reduced with hydrogen (H2) in the presence of copper chromite (Cu(CrO2)2).

CH3-COO-C2H5 + 2H2 = CH3-CH2-OH + C2H5-OH

a class of compounds based on mineral (inorganic) or organic carboxylic acids, in which the hydrogen atom in the HO group is replaced by an organic group R . The adjective “complex” in the name of esters helps to distinguish them from compounds called ethers.

If the starting acid is polybasic, then the formation of either full esters all HO groups are substituted, or acid esters partial substitution is possible. For monobasic acids, only full esters are possible (Fig. 1).

Rice. 1. EXAMPLES OF ESTERS based on inorganic and carboxylic acid

Nomenclature of esters. The name is created as follows: first the group is indicated R , attached to the acid, then the name of the acid with the suffix “at” (as in the names of inorganic salts: carbon at sodium, nitrate at chromium). Examples in Fig.2

2. NAMES OF ESTERS. Fragments of molecules and 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 result of the reaction between propionic acid and butanol.

If you use trivial ( cm. TRIVIAL NAMES OF SUBSTANCES) is the name of the starting acid, then the name of the compound includes the word “ester”, for example, C 3 H 7 COOC 5 H 11 amyl ester of butyric acid.

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 (the variety of compounds is one of the distinguishing features organic chemistry).

When the number of C atoms in the original carboxylic acid and alcohol does not exceed 68, 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 a fruity odor. All compounds in this group are practically insoluble in water, but easily soluble in most organic solvents. These compounds are interesting because of their wide range of pleasant aromas (Table 1); some of them were first isolated from plants and later synthesized artificially.

Table 1. SOME ESTERS, having a fruity or floral aroma (fragments of the original alcohols in the compound formula and in the name are highlighted in bold)
Ester Formula	Name	Aroma
CH 3 COO C 4 H 9	Butyl acetate	pear
C 3 H 7 COO CH 3	Methyl Butyric acid ester	apple
C 3 H 7 COO C 2 H 5	Ethyl Butyric acid ester	pineapple
C 4 H 9 COO C 2 H 5	Ethyl	crimson
C 4 H 9 COO C 5 H 11	Isoamil isovaleric acid ester	banana
CH 3 COO CH 2 C 6 H 5	Benzyl acetate	jasmine
C 6 H 5 COO CH 2 C 6 H 5	Benzyl benzoate	floral

When the size of the organic groups that make up the esters increases to C 1530, the compounds acquire the consistency of plastic, easily softened substances. This group is called waxes; they are usually odorless. Beeswax contains a mixture of various esters; one of the components of the wax, which was isolated and its composition determined, is the myricyl ester of palmitic acid C 15 H 31 COOC 31 H 63. Chinese wax (a product of cochineal excretion from insects in East Asia) contains ceryl ester of cerotinic acid C 25 H 51 COOC 26 H 53. In addition, waxes also contain free carboxylic acids and alcohols, which include large organic groups. Waxes are not wetted by water and are soluble in gasoline, chloroform, and benzene.

The third group is fats. Unlike the previous two groups based on monohydric alcohols

ROH , all fats are esters of glycerol alcohol HOCH 2 CH(OH)CH 2 OH. Carboxylic acids that make up fats, as a rule, have a hydrocarbon chain with 919 carbon atoms. Animal fats (cow butter, lamb, lard) plastic, fusible substances. Vegetable fats (olive, cottonseed, sunflower oil) viscous liquids. Animal fats mainly consist of a mixture of glycerides of stearic and palmitic acid (Fig. 3A, B). Vegetable oils contain glycerides of acids with a slightly shorter carbon chain length: lauric C 11 H 23 COOH and myristic C 13 H 27 COOH. (like stearic and palmitic these are saturated acids). Such oils can be stored in air for a long time without changing their consistency, and therefore are called non-drying. In contrast, flaxseed oil contains unsaturated linoleic acid glyceride (Figure 3B). When applied in a thin layer to the surface, such oil dries under the influence of atmospheric oxygen during polymerization along double bonds, and an elastic film is formed that is insoluble in water and organic solvents. Natural drying oil is made from linseed oil.

Rice. 3. GLYCERIDES OF STEARIC AND PALMITIC ACID (A AND B) components of animal fat. Linoleic acid glyceride (B) component of linseed oil.

Esters of mineral acids (alkyl sulfates, alkyl borates containing fragments of lower alcohols C 18) oily liquids, esters of higher alcohols (starting from C 9) solid compounds.

Chemical properties of esters. Most characteristic of esters of carboxylic acids is the hydrolytic (under the influence of water) cleavage of the ester bond; in a neutral environment it proceeds slowly and noticeably accelerates in the presence of acids or bases, because H + and HO ions catalyze this process (Fig. 4A), with hydroxyl ions acting more efficiently. Hydrolysis in the presence of alkalis is called saponification. If you take an amount of alkali sufficient to neutralize all the acid formed, then complete saponification of the ester occurs. This process is carried out on an industrial scale, and glycerin and higher carboxylic acids (C 1519) are obtained in the form of alkali metal salts, which are soap (Fig. 4B). Fragments of unsaturated acids contained in vegetable oils, like any unsaturated compounds, can be hydrogenated, hydrogen attaches to double bonds and compounds similar to animal fats are formed (Fig. 4B). Using this method, solid fats are produced industrially based on sunflower, soybean or corn oil. Margarine is made from hydrogenation products of vegetable oils mixed with natural animal fats and various food additives.

The main method of synthesis is the interaction of a carboxylic acid and an alcohol, catalyzed by the acid and accompanied by the release of water. This reaction is the opposite of that shown in Fig. 3A. In order for the process to proceed in the desired direction (ester synthesis), water is distilled (distilled) from the reaction mixture. Through special studies using labeled atoms, it was possible to establish that during the synthesis process, the O atom, which is part of the resulting water, is detached from the acid (marked with a red dotted frame), and not from the alcohol (the unrealized option is highlighted with a blue dotted frame).

Using the same scheme, esters of inorganic acids, for example, nitroglycerin, are obtained (Fig. 5B). Instead of acids, acid chlorides can be used; the method is applicable for both carboxylic (Fig. 5C) and inorganic acids (Fig. 5D).

Interaction of carboxylic acid salts with alkyl halides

RCl also leads to esters (Fig. 5D), the reaction is convenient in that it is irreversible; the released inorganic salt is immediately removed from the organic reaction medium in the form of a precipitate.Use of esters. Ethyl formate HCOOC 2 H 5 and ethyl acetate H 3 COOC 2 H 5 are used as solvents for cellulose varnishes (based on nitrocellulose and cellulose acetate).

Esters based on lower alcohols and acids (Table 1) are used in the food industry to create 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 included in cosmetic creams and medicinal ointments.

Fats, together with carbohydrates and proteins, make up a set of foods necessary for nutrition; they are part of all plant and animal cells; in addition, when they accumulate in the body, they play the role of an energy reserve. Due to its low thermal conductivity, the fat layer protects animals (especially sea whales or walruses) well from hypothermia.

Animal and vegetable fats are raw materials for the production of higher carboxylic acids, detergents and glycerol (Fig. 4), used in the cosmetics industry and as a component of various lubricants.

Nitroglycerin (Fig. 4) is a well-known drug and explosive, the basis of dynamite.

Drying oils are made from vegetable oils (Fig. 3), which form the basis of oil paints.

Esters of sulfuric acid (Fig. 2) are used in organic synthesis as alkylating (introducing an alkyl group into a compound) reagents, and esters of phosphoric acid (Fig. 5) are used as insecticides, as well as additives to lubricating oils.

Mikhail Levitsky

LITERATURE Kartsova A.A. Conquest of matter. Organic chemistry. Khimizdat Publishing House, 1999
Pustovalova L.M. Organic chemistry. Phoenix, 2003

When carboxylic acids react with alcohols (esterification reaction), they form esters:
R 1 -COOH (acid) + R 2 -OH (alcohol) ↔ R 1 -COOR 2 (ester) + H 2 O
This reaction is reversible. The reaction products can interact with each other to form the starting materials - alcohol and acid. Thus, the reaction of esters with water—ester hydrolysis—is the reverse of the esterification reaction. The chemical equilibrium established when the rates of forward (esterification) and reverse (hydrolysis) reactions are equal can be shifted towards the formation of ester by the presence of water-removing substances.

Esters in nature and technology

Esters are widespread in nature and are used in technology and various industries. They are good solvents of 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 flammable liquids with low boiling points and have the odors of various fruits. They are used as solvents for varnishes and paints, and as product flavoring agents in the food industry. For example, the methyl ester of butyric acid has the smell of apples, the ethyl alcohol of this acid has the smell of pineapples, and the isobutyl ester of acetic acid has the smell of bananas:
C 3 H 7 -COO-CH 3 (butyric acid methyl ester);
C 3 H 7 -COO-C 2 H 5 (ethyl butyrate);
CH 3 -COO-CH 2 -CH 2 (isobutyl acetate)
Esters of higher carboxylic acids and higher monobasic alcohols are called waxes. Thus, beeswax consists mainly of palmitic acid ester of myricyl alcohol C 15 H 31 COOC 31 H 63; sperm whale wax – spermaceti – ester of the same palmitic acid and cetyl alcohol C 15 H 31 COOC 16 H 33

Formed as a result of the reaction of two alcohol molecules with each other, these are ethers. The bond is formed through an oxygen atom. During the reaction, a water molecule (H 2 O) is split off, and two hydroxyls interact with each other. According to the nomenclature, symmetrical ethers, that is, consisting of identical molecules, can be called by trivial names. For example, instead of diethyl - ethyl. The names of compounds with different radicals are arranged alphabetically. According to this rule, methyl ethyl ether will sound correct, but vice versa it will not.

Structure

Due to the variety of alcohols that react, their interaction can result in the formation of ethers that differ significantly in structure. The general formula for the structure of these compounds looks like this: R-O-R ´. The letters “R” stand for alcohol radicals, that is, simply put, the rest of the hydrocarbon part of the molecule except the hydroxyl. If an alcohol has more than one such group, it can form several bonds with different compounds. Alcohol molecules can also have cyclic fragments in their structure and generally represent polymers. For example, when cellulose reacts with methanol and/or ethanol, ethers are formed. The general formula of these compounds when reacting with alcohols of the same structure looks the same (see above), but the hyphen is removed. In all other cases, it means that the radicals in the ether molecule can be different.

Cyclic ethers

A special type of ethers are cyclic. The best known among them are oxyethane and tetrahydrofuran. The formation of ethers of this structure occurs as a result of the interaction of two hydroxyls of one molecule of a polyhydric alcohol. As a result, a cycle is formed. Unlike linear ethers, cyclic ethers are more capable of forming hydrogen bonds, and therefore they are less volatile and more soluble in water.

Properties of ethers

In physical terms, ethers are volatile liquids, but there are quite a lot of crystalline representatives.

These compounds are poorly soluble in water, and many of them have a pleasant odor. There is one quality due to which ethers are actively used as organic solvents in laboratories. The chemical properties of these compounds are quite inert. Many of them do not undergo hydrolysis - the reverse reaction that occurs with the participation of water and leads to the formation of two alcohol molecules.

Chemical reactions involving ethers

Chemical reactions of ethers are generally only feasible at high temperatures. For example, when heated to a temperature above 100 o C, methylphenyl ether (C 6 H 5 -O-CH 3) reacts with hydrobromic (HBr) or hydroiodic acid (HI) to form phenol and bromomethyl (CH 3 Br) or iodomethyl (CH 3 I), respectively.

Many representatives of this group of compounds, in particular methyl ethyl and diethyl ether, can react in the same way. A halogen usually attaches to a shorter radical, for example:

C 2 H 5 -O-CH 3 + HBr → CH 3 Br + C 2 H 5 OH.

Another reaction that ethers undergo is interaction with Lewis acids. This term refers to a molecule or ion that is an acceptor and combines with a donor that has a lone pair of electrons. Thus, boron fluoride (BF 3) and tin chloride (SnCI 4) can act as such compounds. Interacting with them, ethers form complexes called oxonium salts, for example:

C 2 H 5 -O-CH 3 + BF 3 → -B(-)F 3 .

Methods for preparing ethers

The preparation of ethers occurs in different ways. One method is to dehydrate alcohols using concentrated sulfuric acid (H 2 SO 4) as a dewatering agent. The reaction takes place at 140 o C. In this way, only compounds from one alcohol are obtained. For example:

C 2 H 5 OH + H 2 SO 4 → C 2 H 5 SO 4 H + H 2 O;
C 2 H 5 SO 4 H + HOC 2 H 5 → C 2 H 5 -O-C 2 H 5 + H 2 SO 4.

As can be seen from the equations, the synthesis of diethyl ether proceeds in 2 steps.

Another method for the synthesis of ethers is the Williamson reaction. Its essence lies in the interaction of potassium or sodium alcoholate. This is the name given to the products of replacement of the proton of the hydroxyl group of an alcohol with a metal. For example, sodium ethoxide, potassium isopropylate, etc. Here is an example of this reaction:

CH 3 ONa + C 2 H 5 Cl → CH 3 -O-C 2 H 5 + KCl.

Esters with double bonds and cyclic representatives

As in other groups of organic compounds, compounds with double bonds are found among the ethers. Among the methods for obtaining these substances there are special ones that are not typical for saturated structures. They involve the use of alkynes, at the triple bond of which oxygen is added and vinyl esters are formed.

Scientists have described the preparation of ethers of a cyclic structure (oxiranes) using the method of oxidation of alkenes with peracids containing a peroxide residue instead of a hydroxyl group. This reaction is also carried out under the influence of oxygen in the presence of a silver catalyst.

The use of ethers in laboratories involves the active use of these compounds as chemical solvents. Diethyl ether is popular in this regard. Like all compounds of this group, it is inert and does not react with substances dissolved in it. Its boiling point is just over 35 o C, which is convenient when quick evaporation is necessary.

Compounds such as resins, varnishes, dyes, and fats easily dissolve in ethers. Phenol derivatives are used in the cosmetics industry as preservatives and antioxidants. In addition, esters are added to detergents. Among these compounds, representatives with a pronounced insecticidal effect were found.

Cyclic ethers of complex structure are used in the production of polymers (glycolide, lactide, in particular) used in medicine. They perform the function of a biosorbable material, which, for example, is used for vascular bypass.

Cellulose ethers are used in many areas of human activity, including in the restoration process. Their function is to glue and strengthen the product. They are used in the restoration of paper materials, paintings, and fabrics. There is a special technique that involves dipping old paper into a weak (2%) solution of methylcellulose. Esters of this polymer are resistant to chemical reagents and extreme environmental conditions, non-flammable, and therefore are used to impart strength to any materials.

Some examples of the use of specific representatives of ethers

Ethers are used in many areas of human activity. For example, as an additive to motor oil (diisopropyl ether), coolant (diphenyl oxide). In addition, these compounds are used as intermediate products for the production of drugs, dyes, and aromatic additives (methylphenyl and ethylphenyl ethers).

An interesting ether is dioxane, which has good solubility in water and allows this liquid to be mixed with oils. The peculiarity of its production is that two molecules of ethylene glycol are connected to each other via hydroxyl groups. As a result, a six-membered heterocycle with two oxygen atoms is formed. It is formed under the action of concentrated sulfuric acid at 140 o C.

Thus, ethers, like all classes of organic chemistry, are distinguished by great diversity. Their feature is chemical inertness. This is due to the fact that, unlike alcohols, they do not have a hydrogen atom on oxygen, so it is not so active. For the same reason, ethers do not form hydrogen bonds. It is because of these properties that they are able to mix with various kinds of hydrophobic components.

In conclusion, I would like to note that diethyl ether is used in genetics experiments to euthanize fruit flies. This is just a small part of where these connections are used. It is quite possible that in the future, based on ethers, a number of new durable polymers with an improved structure compared to existing ones will be produced.

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Ministry of Health of the Sverdlovsk Region

Pharmaceutical branch of GBOU SPO "SOMK"

Department of Chemistry and Pharmaceutical Technology

Esters in everyday life

Petrukhina Marina Aleksandrovna

Supervisor:

Glavatskikh Tatyana Vladimirovna

Ekaterinburg

Introduction

2. Physical properties

5. Esters in perfumery

9. Getting soap

Conclusion

Introduction

Complex ethers are derivatives of oxoacids (both carboxylic and mineral, in which the hydrogen atom in the OH group is replaced by an organic group R (aliphatic, alkenyl, aromatic or heteroaromatic); they are also considered as acyl derivatives of alcohols.

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 (the variety of compounds is one of the hallmarks of organic chemistry).

Goals and objectives

1. Find out how widely esters are used in everyday life. Areas of application of esters in human life.

2. Describe the various methods for preparing esters.

3. Find out how safe it is to use esters in everyday life.

Subject of study

Esters. Methods for obtaining them. Use of esters.

1. Basic methods for obtaining esters

Esterification is the interaction of acids and alcohols under conditions of acid catalysis, for example, the production of ethyl acetate from acetic acid and ethyl alcohol:

Esterification reactions are reversible; a shift in equilibrium towards the formation of the target products is achieved by removing one of the products from the reaction mixture (most often by distilling off more volatile alcohol, ether, acid or water).

Reaction of anhydrides or halides of carboxylic acids with alcohols

Example: obtaining ethyl acetate from acetic anhydride and ethyl alcohol:

(CH3CO)2O + 2 C2H5OH = 2 CH3COOC2H5 + H2O

Interaction of acid salts with haloalkanes

RCOOMe + R"Hal = RCOOR" + MeHal

Addition of carboxylic acids to alkenes under acid catalysis conditions:

RCOOH + R"CH=CHR"" = RCOOCHR"CH2R""

Alcoholysis of nitriles in the presence of acids:

RC+=NH + R"OH RC(OR")=N+H2

RC(OR")=N+H2 + H2O RCOOR" + +NH4

2. Physical properties

If the number of carbon atoms in the original carboxylic acid and alcohol does not exceed 6-8, then 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 a fruity odor. All compounds in this group are practically insoluble in water, but easily soluble in most organic solvents. These compounds are interesting because of their wide range of pleasant aromas, some of which were first isolated from plants and later synthesized artificially.

When the size of the organic groups that make up the esters increases to C15-30, the compounds acquire the consistency of plastic, easily softened substances. This group is called waxes; they are usually odorless. Beeswax contains a mixture of various esters; one of the components of the wax, which was isolated and its composition determined, is the myricyl ester of palmitic acid C15H31COOC31H63. Chinese wax (a product of cochineal excretion - insects of East Asia) contains ceryl ester of cerotic acid C25H51COOC26H53. Waxes are not wetted by water and are soluble in gasoline, chloroform, and benzene.

3. Some information about individual representatives of the ester class

Esters of formic acid

HCOOCH3 -- methyl formate, bp = 32°C; solvent for fats, mineral and vegetable oils, cellulose, fatty acids; acylating agent; used in the production of some urethanes and formamide.

HCOOC2H5 -- ethyl formate, bp = 53°C; cellulose nitrate and acetate solvent; acylating agent; a fragrance for soap, it is added to some types of rum to give it a characteristic aroma; used in the production of vitamins B1, A, E.

HCOOCH2CH(CH3)2 -- isobutyl formate; somewhat reminiscent of the smell of raspberries.

HCOOCH2CH2CH(CH3)2 -- isoamyl formate (isopentyl formate) solvent of resins and nitrocellulose.

HCOOCH2C6H5 -- benzyl formate, bp = 202°C; has a jasmine scent; used as a solvent for varnishes and dyes.

HCOOCH2CH2C6H5 -- 2-phenylethyl formate; has the smell of chrysanthemums.

Esters of acetic acid

CH3COOCH3 -- methyl acetate, bp = 58°C; its dissolving ability is similar to acetone and is used in some cases as its substitute, but it is more toxic than acetone.

CH3COOC2H5 -- ethyl acetate, bp = 78°C; like acetone, it dissolves most polymers. Compared to acetone, its advantage is a higher boiling point (lower volatility).

CH3COOC3H7 -- n-propyl acetate, boiling point = 102 °C; its dissolving ability is similar to ethyl acetate.

CH3COOC5H11 -- n-amyl acetate (n-pentyl acetate), bp = 148°C; It smells like a pear and is used as a varnish solvent because it evaporates more slowly than ethyl acetate.

CH3COOCH2CH2CH(CH3)2 -- isoamyl acetate (isopentyl acetate), used as a component of pear and banana essences.

CH3COOC8H17 -- n-octyl acetate has the odor of oranges.

Esters of butyric acid

C3H7COOC2H5 -- ethyl butyrate, bp = 121.5°C; has a characteristic pineapple smell.

C3H7COOC5H11 -- n-amyl butyrate (n-pentyl butyrate) and C3H7COOCH2CH2CH(CH3)2 -- isoamyl butyrate (isopentyl butyrate) have a pear odor.

Esters of isovaleric acid

(CH3)2CHCH2COOCH2CH2CH(CH3)2 -- isoamyl isovalerate (isopentylisovalerate) has an apple odor.

4. Technical application of esters

Esters have many technical applications. Due to their pleasant smell and harmlessness, they have long been used in confectionery and perfumery, and are widely used as plasticizers and solvents.

Thus, ethyl-, butyl- and amyl acetates dissolve celluloid (nitrocellulose adhesives); Dibutyl oxalate is a plasticizer for nitrocellulose.

Glycerol acetates serve as cellulose acetate gelatinizers and perfume fixatives. Esters of adipic and methyladipic acids find similar applications.

High molecular weight esters, such as methyl oleate, butyl palmitate, isobutyl laurate, etc., are used in the textile industry for the treatment of paper, wool and silk fabrics; terpinyl acetate and methyl cinnamic acid ester are used as insecticides.

5. Esters in perfumery

The following esters are used in perfumery and cosmetics production:

Linalyl acetate is a colorless, transparent liquid with an odor reminiscent of bergamot oil. It is found in the oils of clary sage, lavender, bergamot, etc. It is used in the manufacture of compositions for perfumes and fragrances for cosmetics and soaps. The starting material for the production of linalyl acetate is any essential oil containing linalool (coriander and other oils). Linalyl acetate is prepared by acetylation of linalool with acetic anhydride. Linalyl acetate is purified from impurities by double distillation under vacuum.

Terpinyl acetate is produced by the reaction of terpineol with acetic anhydride in the presence of sulfuric acid. Perfume compositions and fragrances for soaps with a floral scent are prepared from it.

Benzyl acetate in diluted form has an odor reminiscent of jasmine. It is found in some essential oils and is the main component of oils extracted from jasmine, hyacinth, and gardenia flowers. In the production of synthetic fragrances, benzyl acetate is produced by reacting benzyl alcohol or benzyl chloride with acetic acid derivatives. Perfume compositions and fragrances for soap are prepared from it.

Methyl salicylate is part of cassia, ylang-ylang and other essential oils. In industry, it is used to make compositions and fragrances for soaps as a product with an intense odor reminiscent of ylang-ylang. It is obtained by reacting salicylic acid and methyl alcohol in the presence of sulfuric acid.

6. Use of esters in the food industry

In the production of milk and cream substitutes, confectionery products, chewing gum, icing and fillings - the recommended rate is up to 5 g/kg. Sorbitan monostearate is also added to dietary supplements. In the non-food industry, E491 is added in the manufacture of medicines, cosmetic products (creams, lotions, deodorants), and for the production of emulsions for plant treatment.

Sorbitan Monostearate

Food additive E-491 group of stabilizers. Can be used as an emulsifier (for example, as part of instant yeast).

ester pharmaceutical soap

Characteristics: E491 is obtained synthetically by direct esterification of sorbitol with stearic acid with the simultaneous formation of sorbitol anhydrides.

Application: E-491 is used as an emulsifier in the production of baked goods, drinks, sauces in quantities up to 5 g/kg. In the production of ice cream and liquid tea concentrates - up to 0.5 g/l. In the Russian Federation, sorbitan monostearate is also used as a consistency stabilizer, thickener, texturizer, and binding agent in liquid tea concentrates, fruit and herbal decoctions in amounts up to 500 mg/kg. In the production of milk and cream substitutes, confectionery products, chewing gum, icing and fillings - the recommended rate is up to 5 g/kg. Sorbitan monostearate is also added to dietary supplements. In the non-food industry, E491 is added in the manufacture of medicines, cosmetic products (creams, lotions, deodorants), and for the production of emulsions for plant treatment.

Effect on the human body: the permissible daily intake is 25 mg/kg body weight. E491 is considered a low-hazard substance, does not cause danger if it comes into contact with the skin or gastric mucosa, and has a mild irritant effect on them. Excessive consumption of E491 can lead to fibrosis, growth retardation, and liver enlargement.

Lecithin (E-322).

Characteristics: antioxidant. In industrial production, lecithin is obtained from soybean oil production waste.

Application: as an emulsifier, food additive E-322 is used in the production of dairy products, margarine, bakery and chocolate products, as well as glazes. In the non-food industry, lecithin is used in the production of fatty paints, solvents, vinyl coatings, cosmetics, as well as in the production of fertilizers, pesticides and paper processing.

Lecithin is found in foods that contain a large amount of fat. These are eggs, liver, peanuts, some types of vegetables and fruits. Also, a huge amount of lecithin is found in all cells of the human body.

Effect on the human body: lecithin is an essential substance for the human body. However, despite the fact that lecithin is very beneficial for humans, consuming it in large quantities can lead to undesirable consequences - the occurrence of allergic reactions.

Esters of glycerol and resin acids (E445)

They belong to the group of stabilizers and emulsifiers designed to maintain the viscosity and consistency of food products.

Application: glycerol esters are approved for use on the territory of the Russian Federation and are widely used in the food industry in the production of:

Marmalade, jam, jelly,

Fruit fillers, sweets, chewing gums,

Low calorie foods

Low-calorie oils,

Condensed cream and dairy products,

Ice cream,

Cheeses and cheese products, puddings,

Jelly meat and fish products, and other products.

Effect on the human body: numerous studies have proven that the use of the E-445 supplement can lead to a decrease in blood cholesterol and weight. Esters of resin acids can be allergens and cause skin irritation. The additive E445 used as an emulsifier can lead to irritation of the mucous membranes of the body and upset the stomach. Glycerol esters are not used in the production of baby food.

7. Esters in the pharmaceutical industry

Esters are components of cosmetic creams and medicinal ointments, as well as essential oils.

Nitroglycerin (Nitroglycerinum)

Cardiovascular drug Nitroglycerin is an ester of nitric acid and the trihydric alcohol glycerol, so it can be called glycerol trinitrate.

Nitroglycerin is obtained by adding a mixture of nitric and sulfuric acids to the calculated amount of glycerin.

The resulting nitroglycerin is collected as an oil above the acid layer. It is separated, washed several times with water, a diluted soda solution (to neutralize the acid) and then again with water. After this, it is dried with anhydrous sodium sulfate.

The reaction of nitroglycerin formation can be schematically represented as follows:

Nitroglycerin is used in medicine as an antispasmodic (coronary dilator) agent for angina pectoris. The drug is available in bottles of 5-10 ml of 1% alcohol solution and in tablets that contain 0.5 mg of pure nitroglycerin in each tablet. Store bottles with nitroglycerin solution in a cool place protected from light, away from fire. List B.

Acetylsalicylic acid (Aspirin, Acidum acetylsalicylicum)

A white crystalline substance, slightly soluble in water, highly soluble in alcohol and alkali solutions. This substance is obtained by reacting salicylic acid with acetic anhydride:

Acetylsalicylic acid has been widely used for more than 100 years as a medicine - antipyretic, analgesic and anti-inflammatory.

Phenyl salicylate (salol, Phenylii salicylas)

Also known as salicylic acid phenyl ester (Figure 5).

Rice. 6 Scheme for obtaining phenyl salicylate.

Salol is an antiseptic, breaking down in the alkaline contents of the intestine, releasing salicylic acid and phenol. Salicylic acid has an antipyretic and anti-inflammatory effect, phenol is active against pathogenic intestinal microflora. Has some uroantiseptic effect. Compared to modern antimicrobial drugs, phenyl salicylate is less active, but has low toxicity, does not irritate the gastric mucosa, and does not cause dysbacteriosis or other complications of antimicrobial therapy.

Diphenhydramine (Diphenhydramine, Dimedrolum)

Another name: 2-dimethylaminoethyl ether benzhydrol hydrochloride). Diphenhydramine is prepared by reacting benzhydrol and dimethylaminoethyl chloride hydrochloride in the presence of alkali. The resulting base is converted to hydrochloride by the action of hydrochloric acid.

It has antihistamine, antiallergic, antiemetic, hypnotic, and local anesthetic effects.

Vitamins

Vitamin A palmitate (Retinyl palmitate) is an ester of retinol and palmitic acid. It is a regulator of keratinization processes. As a result of using products containing it, skin density and elasticity increase.

Vitamin B15 (pangamic acid) is an ester of gluconic acid and dimethylglycine. Participates in the biosynthesis of choline, methionine and creatine as a source of methyl groups. for circulatory disorders.

Vitamin E (tocopherol acetate) is a natural antioxidant that prevents vascular fragility. An essential fat-soluble component for the human body, it comes mainly as part of vegetable oils. Normalizes reproductive function; prevents the development of atherosclerosis, degenerative-dystrophic changes in the heart muscle and skeletal muscles.

Fats are mixtures of esters formed by the trihydric alcohol glycerol and higher fatty acids. General formula of fats:

The common name for such compounds is triglycerides or triacylglycerols, where acyl is a carboxylic acid residue -C(O)R. Carboxylic acids that make up fats usually have a hydrocarbon chain with 9-19 carbon atoms.

Animal fats (cow butter, lamb, lard) are plastic, fusible substances. Vegetable fats (olive, cottonseed, sunflower oil) are viscous liquids. Animal fats mainly consist of a mixture of glycerides of stearic and palmitic acid (Fig. 9A, 9B).

Vegetable oils contain glycerides of acids with a slightly shorter carbon chain length: lauric acid C11H23COOH and myristic acid C13H27COOH. (like stearic and palmitic acids, these are saturated acids). Such oils can be stored in air for a long time without changing their consistency, and therefore are called non-drying. In contrast, flaxseed oil contains unsaturated linoleic acid glyceride (Figure 9B).

When applied in a thin layer to the surface, such oil dries under the influence of atmospheric oxygen during polymerization along double bonds, and an elastic film is formed that is insoluble in water and organic solvents. Natural drying oil is made from linseed oil. Animal and vegetable fats are also used in the production of lubricants.

Rice. 9 (A, B, C)

9. Getting soap

Fats, as esters, are characterized by a reversible hydrolysis reaction catalyzed by mineral acids. With the participation of alkalis (or alkali metal carbonates), the hydrolysis of fats occurs irreversibly. The products in this case are soaps - salts of higher carboxylic acids and alkali metals.

Sodium salts are solid soaps, potassium salts are liquid soaps. The reaction of alkaline hydrolysis of fats, and in general of all esters, is also called saponification.

Saponification of fats can also occur in the presence of sulfuric acid (acid saponification). This produces glycerol and higher carboxylic acids. The latter are converted into soaps by the action of alkali or soda.

The starting materials for soap production are vegetable oils (sunflower, cottonseed, etc.), animal fats, as well as sodium hydroxide or soda ash. Vegetable oils are preliminarily hydrogenated, i.e. they are converted into solid fats. Fat substitutes are also used - synthetic carboxylic fatty acids with a large molecular weight.

Soap production requires large quantities of raw materials, so the task is to obtain soap from non-food products. The carboxylic acids necessary for soap production are obtained by oxidation of paraffin. By neutralizing acids containing from 10 to 16 carbon atoms per molecule, toilet soap is obtained, and from acids containing from 17 to 21 carbon atoms, laundry soap and soap for technical purposes are obtained. Both synthetic soap and soap made from fats do not clean well in hard water. Therefore, along with soap from synthetic acids, detergents are produced from other types of raw materials, for example, from alkyl sulfates - salts of esters of higher alcohols and sulfuric acid.

10. Fats in cooking and pharmaceuticals

Salomas is a solid fat, a product of hydrogenation of sunflower, peanut, coconut, palm kernel, soybean, cottonseed, as well as rapeseed oil and whale oil. Food lard is used for the production of margarine products, confectionery, and bakery products.

In the pharmaceutical industry for the manufacture of drugs (fish oil in capsules), as a basis for ointments, suppositories, creams, emulsions.

Conclusion

Esters are widely used in the technical, food and pharmaceutical industries. Products and products of these industries are widely used by people in everyday life. People are exposed to esters by consuming certain foods and medications, using perfumes, clothing made from certain fabrics, and certain insecticides, soaps, and household chemicals.

Some representatives of this class of organic compounds are safe, others require limited use and caution when used.

In general, we can conclude that esters occupy a strong position in many areas of human life.

List of sources used

1. Kartsova A.A. Conquest of matter. Organic chemistry: manual - St. Petersburg: Khimizdat, 1999. --272 p.

2. Pustovalova L.M. Organic chemistry. -- Rostov n/d: Phoenix, 2003 -- 478 p.

3. http://ru.wikipedia.org

4. http://files.school-collection.edu.ru

5. http://www.ngpedia.ru

6. http://www.xumuk.ru

7. http://www.ximicat.com

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