Esters are examples. Where are esters used?
If the starting acid is polybasic, then the formation of either full esters is possible - all HO groups are replaced, or acid esters - partial substitution. 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 R 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, nitrate at chromium). Examples in Fig. 2
Rice. 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) 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 hallmarks of organic chemistry).
When the number of C 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 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 included in the esters increases to C 15–30, 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 C 15 H 31 COOC 31 H 63. Chinese wax (a product of cochineal excretion - insects of East Asia) contains ceryl ester of cerotic 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 formed from the trihydric alcohol glycerol HOCH 2 – CH (OH) – CH 2 OH. 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. 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 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 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) is a component of flaxseed 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 from C 9) are 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 glycerol and higher carboxylic acids (C 15–19) 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).
The interaction of carboxylic acid salts with RCl halides 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 well protects animals (especially marine animals - whales or walruses) 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
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 |
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 usually 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, 1999Pustovalova L.M. Organic chemistry. Phoenix, 2003
Esters– functional derivatives of carboxylic acids,
in molecules in which the hydroxyl group (-OH) is replaced by an alcohol residue (-OR)
Esters of carboxylic acids – compounds with the general formula
R-COOR",where R and R" are hydrocarbon radicals.
Esters of saturated monobasic carboxylic acids have a general formula:
Physical properties:
Volatile, colorless liquids
· Poorly soluble in water
· Most often with a pleasant smell
Lighter than water
Esters are found in flowers, fruits, and berries. They determine their specific smell.
They are a component of essential oils (about 3000 e.m. are known - orange, lavender, rose, etc.)
Esters of lower carboxylic acids and lower monohydric alcohols have a pleasant smell of flowers, berries and fruits. Esters of higher monobasic acids and higher monohydric alcohols are the basis of natural waxes. For example, beeswax contains an ester of palmitic acid and myricyl alcohol (myricyl palmitate):
CH 3 (CH 2) 14 –CO–O–(CH 2) 29 CH 3
Aroma. Structural formula. |
Ester name |
Apple |
Ethyl ether 2-methylbutanoic acid |
Cherry |
Amyl formic acid ester |
Pear |
Isoamyl ester of acetic acid |
A pineapple |
Butyric acid ethyl ester (ethyl butyrate) |
Banana |
Isobutyl ester of acetic acid (y isoamyl acetate also resembles the smell of banana) |
Jasmine |
Benzyl ether acetate (benzyl acetate) |
The short names of esters are based on the name of the radical (R") in the alcohol residue and the name of the RCOO group in the acid residue. For example, ethyl acetic acid CH 3 COO C 2 H 5 called ethyl acetate.
Application
· As fragrances and odor enhancers in the food and perfumery (production of soap, perfume, creams) industries;
· In the production of plastics and rubber as plasticizers.
Plasticizers – substances that are introduced into the composition of polymer materials to impart (or increase) elasticity and (or) plasticity during processing and operation.
Application in medicine
At the end of the 19th and beginning of the 20th centuries, when organic synthesis took its first steps, many esters were synthesized and tested by pharmacologists. They became the basis of such medicines as salol, validol, etc. Methyl salicylate was widely used as a local irritant and analgesic, which has now been practically replaced by more effective drugs.
Preparation of esters
Esters can be obtained by reacting carboxylic acids with alcohols ( esterification reaction). The catalysts are mineral acids.
Video “Preparation of ethyl acetyl ether”
Video “Preparation of boronethyl ether”
The esterification reaction under acid catalysis is reversible. The reverse process - the cleavage of an ester under the action of water to form a carboxylic acid and alcohol - is called ester hydrolysis.
RCOOR" + H2O (H+)↔ RCOOH + R"OH
Hydrolysis in the presence of alkali is irreversible (since the resulting negatively charged carboxylate anion RCOO does not react with the nucleophilic reagent - alcohol).
This reaction is called saponification of esters(by analogy with alkaline hydrolysis of ester bonds in fats when producing soap).
Ethers (alkane oxides) can be thought of as compounds formed by replacing both hydrogen atoms of a water molecule with two alkyl radicals or replacing a hydroxyl alcohol with an alkyl radical.
Isomerism and nomenclature. The general formula of ethers is ROR(I) ((C n H 2 n +1) 2 O) or C n H 2 n +1 OC k H 2 k +1, where nk(R 1 OR 2) (II). The latter are often called mixed ethers, although (I) is a special case of (II).
Ethers are isomeric to alcohols (functional group isomerism). Here are examples of such connections:
H 3 C ABOUT CH 3 dimethyl ether; C 2 H 5 OH ethyl alcohol;
H 5 C 2 ABOUT C 2 H 5 diethyl ether; C 4 H 9 OH butyl alcohol;
H 5 C 2 ABOUT C 3 H 7 ethylpropyl ether; C 5 H 11 OH amyl alcohol.
In addition, isomerism of the carbon skeleton is common for ethers (methyl propyl ether and methyl isopropyl ether). Optically active ethers are few in number.
Methods for preparing ethers
1. Interaction of halogen derivatives with alcoholates (Williamson reaction).
C 2 H 5 ОNa+I C 2 H 5 H 5 C 2 ABOUT C 2 H 5 +NaI
2. Dehydration of alcohols in the presence of hydrogen ions as catalysts.
2C 2 H 5 OHH 5 C 2 ABOUT C 2 H 5
3. Partial reaction to produce diethyl ether.
P first stage:
IN second stage:
Physical properties of ethers
The first two simplest representatives - dimethyl and methyl ethyl ethers - are gases under normal conditions, all the rest are liquids. Their boiling point is much lower than the corresponding alcohols. Thus, the boiling point of ethanol is 78.3C, and H 3 COCH 3 is 24C, respectively (C 2 H 5) 2 O is 35.6C. The fact is that ethers are not capable of forming molecular hydrogen bonds, and, consequently, of molecule association.
Chemical properties of ethers
1. Interaction with acids.
(C 2 H 5) 2 O +HCl[(C 2 H 5) 2 OH + ]Cl .
Ether plays the role of a base.
2. Acidolysis – interaction with strong acids.
H 5 C 2 ABOUT C 2 H 5 + 2H 2 SO 4 2C 2 H 5 OSO 3 H
ethylsulfuric acid
H 5 C 2 ABOUT C 2 H 5 +HIC 2 H 5 OH+ C 2 H 5 I
3. Interaction with alkali metals.
H 5 C 2 ABOUT C 2 H 5 + 2NaC 2 H 5 ONa+ C 2 H 5 Na
Individual representatives
Ethyl ether (diethyl ether) is a colorless transparent liquid, slightly soluble in water. Mixes with ethyl alcohol in any ratio. T pl =116.3С, saturated vapor pressure 2.6610 4 Pa (2.2С) and 5.3210 4 Pa (17.9С). The cryoscopic constant is 1.79, the ebulioscopic constant is 1.84. Ignition temperature is 9.4С, forms an explosive mixture with air at 1.71 vol. % (lower limit) – 48.0 vol. % (upper limit). Causes rubber swelling. Widely used as a solvent, in medicine (inhalation anesthesia), addictive to humans, poisonous.
Esters of carboxylic acids Preparation of esters of carboxylic acids
1. Esterification of acids with alcohols.
Hydroxyl acid is released in water, while alcohol gives away only a hydrogen atom. The reaction is reversible; the same cations catalyze the reverse reaction.
2. Interaction of acid anhydrides with alcohols.
3. Interaction of acid halides with alcohols.
Some physical properties of esters are given in Table 12.
Table 12
Some physical properties of a number of esters
Radical structure |
Name |
Density |
|||
methyl formate | |||||
ethyl formate | |||||
methyl acetate | |||||
ethyl acetate | |||||
n-propyl acetate | |||||
n-butyl acetate |
Esters of lower carboxylic acids and simple alcohols are liquids with a refreshing fruity odor. Used as flavoring agents for preparing drinks. Many ethers (ethyl acetate, butyl acetate) are widely used as solvents, especially for varnishes.
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:
- Symmetrical 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 using 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