Primary alcohols are examples. Alcohols
Structure
Alcohols (or alkanols) are organic substances whose molecules contain one or more hydroxyl groups (-OH groups) connected to a hydrocarbon radical.
According to the number of hydroxyl groups (atomicity), alcohols are divided into:
monatomic
diatomic (glycols)
triatomic.
The following alcohols are distinguished by their nature:
Limiting, containing only limiting hydrocarbon radicals in the molecule
unsaturated, containing multiple (double and triple) bonds between carbon atoms in the molecule
aromatic, i.e., alcohols containing a benzene ring and a hydroxyl group in the molecule, connected to each other not directly, but through carbon atoms.
Organic substances containing hydroxyl groups in the molecule, connected directly to the carbon atom of the benzene ring, differ significantly in chemical properties from alcohols and therefore stand out in an independent class of organic compounds - phenols. For example, hydroxybenzene phenol. We will learn more about the structure, properties and use of phenols later.
There are also polyatomic (polyatomic) containing more than three hydroxyl groups in the molecule. For example, the simplest six-hydric alcohol hexaol (sorbitol).
It should be noted that alcohols containing two hydroxyl groups at one carbon atom are unstable and spontaneously decompose (subject to a rearrangement of atoms) with the formation of aldehydes and ketones: 
Unsaturated alcohols containing a hydroxyl group at the carbon atom linked by a double bond are called ecols. It is easy to guess that the name of this class of compounds is formed from the suffixes -en and -ol, indicating the presence of a double bond and a hydroxyl group in the molecules. Enols, as a rule, are unstable and spontaneously transform (isomerize) into carbonyl compounds - aldehydes and ketones. This reaction is reversible, the process itself is called keto-enol tautomerism. So, the simplest enol - vinyl alcohol isomerizes extremely quickly into acetaldehyde.
According to the nature of the carbon atom to which the hydroxyl group is attached, alcohols are divided into:
Primary, in the molecules of which the hydroxyl group is bonded to the primary carbon atom
secondary, in the molecules of which the hydroxyl group is bonded to a secondary carbon atom
tertiary, in the molecules of which the hydroxyl group is bonded to the tertiary carbon atom, for example:
Nomenclature and isomerism
When forming the names of alcohols, the (generic) suffix -ol is added to the name of the hydrocarbon corresponding to the alcohol. The numbers after the suffix indicate the position of the hydroxyl group in the main chain, and the prefixes di-, tri-, tetra-, etc. indicate their number: 
Starting from the third member of the homologous series, alcohols have an isomerism of the position of the functional group (propanol-1 and propanol-2), and from the fourth - the isomerism of the carbon skeleton (butanol-1; 2-methylpropanol-1). They are also characterized by interclass isomerism - alcohols are isomeric to ethers.
The genus included in the hydroxyl group of alcohol molecules differs sharply from hydrogen and carbon atoms in its ability to attract and hold electron pairs. Due to this, alcohol molecules have polar C-O and O-H bonds.
Physical properties of alcohols
Given the polarity of the O-H bond and a significant partial positive charge localized (focused) on the hydrogen atom, the hydrogen of the hydroxyl group is said to have an "acidic" character. In this it differs sharply from the hydrogen atoms included in the hydrocarbon radical.
It should be noted that the oxygen atom of the hydroxyl group has a partial negative charge and two unshared electron pairs, which makes it possible for alcohols to form special, so-called hydrogen bonds between molecules. Hydrogen bonds arise from the interaction of a partially positively charged hydrogen atom of one alcohol molecule and a partially negatively charged oxygen atom of another molecule. It is due to hydrogen bonds between molecules that alcohols have abnormally high boiling points for their molecular weight. So, propane with a relative molecular weight of 44 is a gas under normal conditions, and the simplest of alcohols is methanol, having a relative molecular weight of 32, under normal conditions a liquid.
The lower and middle members of the series of limiting monohydric alcohols, containing from one to eleven carbon atoms, are liquids. Higher alcohols (starting with C 12 H 25 OH) are solids at room temperature. Lower alcohols have a characteristic alcoholic smell and a burning taste, they are highly soluble in water. As the hydrocarbon radical increases, the solubility of alcohols in water decreases, and octanol is no longer miscible with water.
Chemical properties
The properties of organic substances are determined by their composition and structure. Alcohols confirm the general rule. Their molecules include hydrocarbon and hydroxyl radicals, so the chemical properties of alcohols are determined by the interaction and influence of these groups on each other. The properties characteristic of this class of compounds are due to the presence of a hydroxyl group.
1. Interaction of alcohols with alkali and alkaline earth metals. To identify the effect of a hydrocarbon radical on a hydroxyl group, it is necessary to compare the properties of a substance containing a hydroxyl group and a hydrocarbon radical, on the one hand, and a substance containing a hydroxyl group and not containing a hydrocarbon radical, on the other. Such substances can be, for example, ethanol (or other alcohol) and water. Hydrogen of the hydroxyl group of alcohol molecules and water molecules can be reduced by alkali and alkaline earth metals (replaced by them).
With water, this interaction is much more active than with alcohol, accompanied by a large release of heat, and can lead to an explosion. This difference is explained by the electron-donating properties of the radical closest to the hydroxyl group. Possessing the properties of an electron donor (+I-effect), the radical slightly increases the electron density on the oxygen atom, "saturates" it at its own expense, thereby reducing the polarity of the O-H bond and the "acidic" nature of the hydrogen atom of the hydroxyl group in alcohol molecules according to compared to water molecules.
2. Interaction of alcohols with hydrogen halides. Substitution of a hydroxyl group for a halogen leads to the formation of haloalkanes.
For example:
C2H5OH + HBr<->C2H5Br + H2O
This reaction is reversible.
3. Intermolecular dehydration of alcohols - the splitting of a water molecule from two alcohol molecules when heated in the presence of water-removing agents.
As a result of intermolecular dehydration of alcohols, ethers are formed. So, when ethyl alcohol is heated with sulfuric acid to a temperature of 100 to 140 ° C, diethyl (sulfur) ether is formed.
4. Interaction of alcohols with organic and inorganic acids to form esters (esterification reaction):
The esterification reaction is catalyzed by strong inorganic acids.
For example, when ethyl alcohol and acetic acid react, ethyl acetate is formed - ethyl acetate: 
5. Intramolecular dehydration of alcohols occurs when alcohols are heated in the presence of dehydrating agents to a temperature higher than the temperature of intermolecular dehydration. As a result, alkenes are formed. This reaction is due to the presence of a hydrogen atom and a hydroxyl group at neighboring carbon atoms. An example is the reaction of obtaining ethene (ethylene) by heating ethanol above 140 ° C in the presence of concentrated sulfuric acid.
6. The oxidation of alcohols is usually carried out with strong oxidizing agents, such as potassium dichromate or potassium permanganate in an acidic medium. In this case, the action of the oxidizing agent is directed to the carbon atom that is already associated with the hydroxyl group. Depending on the nature of the alcohol and the reaction conditions, various products can be formed. So, primary alcohols are oxidized first to aldehydes, and then to carboxylic acids: 
Tertiary alcohols are quite resistant to oxidation. However, under harsh conditions (strong oxidizing agent, high temperature), oxidation of tertiary alcohols is possible, which occurs with the breaking of carbon-carbon bonds closest to the hydroxyl group.
7. Dehydrogenation of alcohols. When alcohol vapor is passed at 200-300 ° C over a metal catalyst, such as copper, silver or platinum, primary alcohols are converted into aldehydes, and secondary ones into ketones:
The presence of several hydroxyl groups simultaneously in an alcohol molecule determines the specific properties of polyhydric alcohols, which are capable of forming bright blue complex compounds soluble in water when interacting with a fresh precipitate of copper(II) hydroxide.
Monohydric alcohols are not able to enter into this reaction. Therefore, it is a qualitative reaction to polyhydric alcohols.
Alcoholates of alkali and alkaline earth metals undergo hydrolysis when interacting with water. For example, when sodium ethoxide is dissolved in water, a reversible reaction occurs
C2H5ONa + HOH<->C2H5OH + NaOH
the balance of which is almost completely shifted to the right. This also confirms that water in its acidic properties ("acidic" nature of the hydrogen in the hydroxyl group) is superior to alcohols. Thus, the interaction of alcoholates with water can be considered as the interaction of a salt of a very weak acid (in this case, the alcohol that formed the alcoholate acts as this) with a stronger acid (this role is played by water).
Alcohols can exhibit basic properties when interacting with strong acids, forming alkyloxonium salts due to the presence of a lone electron pair on the oxygen atom of the hydroxyl group: 
The esterification reaction is reversible (the reverse reaction is ester hydrolysis), the equilibrium shifts to the right in the presence of water-removing agents.
Intramolecular dehydration of alcohols proceeds in accordance with the Zaitsev rule: when water is split off from a secondary or tertiary alcohol, a hydrogen atom is detached from the least hydrogenated carbon atom. So, dehydration of butanol-2 leads to butene-2, but not butene-1.
The presence of hydrocarbon radicals in alcohol molecules cannot but affect the chemical properties of alcohols.
The chemical properties of alcohols due to the hydrocarbon radical are different and depend on its nature. So, all alcohols burn; unsaturated alcohols containing a double C=C bond in the molecule enter into addition reactions, undergo hydrogenation, add hydrogen, react with halogens, for example, decolorize bromine water, etc.
How to get
1. Hydrolysis of haloalkanes. You already know that the formation of haloalkanes in the interaction of alcohols with hydrogen halides is a reversible reaction. Therefore, it is clear that alcohols can be obtained by hydrolysis of haloalkanes - the reaction of these compounds with water.
Polyhydric alcohols can be obtained by hydrolysis of haloalkanes containing more than one halogen atom in the molecule.
2. Hydration of alkenes - the addition of water to the r-bond of the alkene molecule - is already familiar to you. Hydration of propene leads, in accordance with Markovnikov's rule, to the formation of a secondary alcohol - propanol-2
HE
l
CH2=CH-CH3 + H20 -> CH3-CH-CH3
propene propanol-2
3. Hydrogenation of aldehydes and ketones. You already know that the oxidation of alcohols under mild conditions leads to the formation of aldehydes or ketones. Obviously, alcohols can be obtained by hydrogenation (hydrogen reduction, hydrogen addition) of aldehydes and ketones.
4. Oxidation of alkenes. Glycols, as already noted, can be obtained by oxidizing alkenes with an aqueous solution of potassium permanganate. For example, ethylene glycol (ethanediol-1,2) is formed during the oxidation of ethylene (ethene).
5. Specific methods for obtaining alcohols. Some alcohols are obtained in ways characteristic only of them. Thus, methanol is produced in industry by the interaction of hydrogen with carbon monoxide (II) (carbon monoxide) at elevated pressure and high temperature on the surface of the catalyst (zinc oxide).
The mixture of carbon monoxide and hydrogen required for this reaction, also called (think why!) "synthesis gas", is obtained by passing water vapor over hot coal.
6. Fermentation of glucose. This method of obtaining ethyl (wine) alcohol has been known to man since ancient times.
Consider the reaction of obtaining alcohols from haloalkanes - the reaction of hydrolysis of halogen derivatives of hydrocarbons. It is usually carried out in an alkaline environment. The released hydrobromic acid is neutralized, and the reaction proceeds almost to completion.
This reaction, like many others, proceeds by the mechanism of nucleophilic substitution.
These are reactions, the main stage of which is substitution, proceeding under the influence of a nucleophilic particle.
Recall that a nucleophilic particle is a molecule or ion that has an unshared electron pair and is capable of being attracted to a "positive charge" - regions of the molecule with a reduced electron density.
The most common nucleophilic species are molecules of ammonia, water, alcohol, or anions (hydroxyl, halide, alkoxide ion).
The particle (atom or group of atoms) that is replaced as a result of the reaction for a nucleophile is called a leaving group.
The substitution of the hydroxyl group of an alcohol for a halide ion also proceeds by the mechanism of nucleophilic substitution:
CH3CH2OH + HBr -> CH3CH2Br + H20
Interestingly, this reaction begins with the addition of a hydrogen cation to the oxygen atom contained in the hydroxyl group:
CH3CH2-OH + H+ -> CH3CH2-OH
Under the action of the attached positively charged ion, the C-O bond shifts even more towards oxygen, and the effective positive charge on the carbon atom increases.
This leads to the fact that the nucleophilic substitution by the halide ion occurs much more easily, and the water molecule is split off under the action of the nucleophile.
CH3CH2-OH+ + Br -> CH3CH2Br + H2O
Getting ethers
Under the action of sodium alcoholate on bromoethane, the bromine atom is replaced by an alcoholate ion and an ether is formed.
The general nucleophilic substitution reaction can be written as follows:
R - X + HNu -> R - Nu + HX,
if the nucleophilic particle is a molecule (HBr, H20, CH3CH2OH, NH3, CH3CH2NH2),
R-X + Nu - -> R-Nu + X -,
if the nucleophile is an anion (OH, Br-, CH3CH2O -), where X is a halogen, Nu is a nucleophilic particle.
Individual representatives of alcohols and their meaning
Methanol (methyl alcohol CH3OH) is a colorless liquid with a characteristic odor and a boiling point of 64.7 °C. It burns with a slightly bluish flame. The historical name of methanol - wood alcohol - is explained by one of the ways to obtain it - the distillation of hardwoods (Greek - wine, get drunk; substance, wood).
Methanol is very toxic! It requires careful handling when working with it. Under the action of the enzyme alcohol dehydrogenase, it is converted in the body into formaldehyde and formic acid, which damage the retina, cause the death of the optic nerve and complete loss of vision. Ingestion of more than 50 ml of methanol causes death.
Ethanol (ethyl alcohol C2H5OH) is a colorless liquid with a characteristic odor and a boiling point of 78.3 °C. combustible Miscible with water in any ratio. The concentration (strength) of alcohol is usually expressed as a percentage by volume. "Pure" (medical) alcohol is a product obtained from food raw materials and containing 96% (by volume) ethanol and 4% (by volume) water. To obtain anhydrous ethanol - "absolute alcohol", this product is treated with substances that chemically bind water (calcium oxide, anhydrous copper (II) sulfate, etc.).
In order to make alcohol used for technical purposes unfit for drinking, small amounts of difficult-to-separate poisonous, bad-smelling and disgusting-tasting substances are added to it and tinted. Alcohol containing such additives is called denatured or methylated spirits.
Ethanol is widely used in industry for the production of synthetic rubber, drugs, used as a solvent, is part of varnishes and paints, perfumes. In medicine, ethyl alcohol is the most important disinfectant. Used to make alcoholic beverages.
Small amounts of ethyl alcohol, when ingested, reduce pain sensitivity and block the processes of inhibition in the cerebral cortex, causing a state of intoxication. At this stage of the action of ethanol, water separation in the cells increases and, consequently, urine formation is accelerated, resulting in dehydration of the body.
In addition, ethanol causes the expansion of blood vessels. Increased blood flow in the skin capillaries leads to reddening of the skin and a feeling of warmth.
In large quantities, ethanol inhibits the activity of the brain (the stage of inhibition), causes a violation of coordination of movements. An intermediate product of the oxidation of ethanol in the body - acetaldehyde - is extremely toxic and causes severe poisoning.
The systematic use of ethyl alcohol and drinks containing it leads to a persistent decrease in the productivity of the brain, death of liver cells and their replacement with connective tissue - cirrhosis of the liver.
Ethandiol-1,2 (ethylene glycol) is a colorless viscous liquid. Poisonous. Freely soluble in water. Aqueous solutions do not crystallize at temperatures significantly below 0 ° C, which allows it to be used as a component of antifreeze coolants - antifreezes for internal combustion engines.
Propantriol-1,2,3 (glycerin) is a viscous, syrupy liquid, sweet in taste. Freely soluble in water. Non-volatile As an integral part of esters, it is part of fats and oils. Widely used in cosmetics, pharmaceutical and food industries. In cosmetics, glycerin plays the role of an emollient and soothing agent. It is added to toothpaste to prevent it from drying out. Glycerin is added to confectionery products to prevent their crystallization. It is sprayed on tobacco, in which case it acts as a humectant, preventing the tobacco leaves from drying out and crumbling before processing. It is added to adhesives to keep them from drying out too quickly, and to plastics, especially cellophane. In the latter case, glycerin acts as a plasticizer, acting like a lubricant between polymer molecules and thus giving plastics the necessary flexibility and elasticity.
1. What substances are called alcohols? On what grounds are alcohols classified? Which alcohols should be attributed to butanol-2? butene-3-ol-1? pentene-4-diol-1,2?
2. Write the structural formulas of the alcohols listed in exercise 1.
3. Are there quaternary alcohols? Explain the answer.
4. How many alcohols have the molecular formula C5H120? Write the structural formulas of these substances and name them. Can this formula only correspond to alcohols? Write the structural formulas of two substances that have the formula C5H120 and are not related to alcohols.
5. Name the substances whose structural formulas are given below: 
6. Write the structural and empirical formulas of the substance, whose name is 5-methyl-4-hexene-1-inol-3. Compare the number of hydrogen atoms in a molecule of this alcohol with the number of hydrogen atoms in an alkane molecule with the same number of carbon atoms. What explains this difference?
7. Comparing the electronegativity of carbon and hydrogen, explain why the O-H covalent bond is more polar than the C-O bond.
8. What do you think, which of the alcohols - methanol or 2-methylpropanol-2 - will react more actively with sodium? Explain your answer. Write equations for the corresponding reactions.
9. Write the reaction equations for the interaction of propanol-2 (isopropyl alcohol) with sodium and hydrogen bromide. Name the reaction products and indicate the conditions for their implementation.
10. A mixture of vapors of propanol-1 and propanol-2 was passed over heated copper(II) oxide. What kind of reactions could take place? Write equations for these reactions. What classes of organic compounds do their products belong to?
11. What products can be formed during the hydrolysis of 1,2-dichloropropanol? Write equations for the corresponding reactions. Name the products of these reactions.
12. Write the equations for the reactions of hydrogenation, hydration, halogenation and hydrohalogenation of 2-propenol-1. Name the products of all reactions.
13. Write the equations for the interaction of glycerol with one, two and three moles of acetic acid. Write an equation for the hydrolysis of an ester - an esterification product of one mole of glycerol and three moles of acetic acid.
fourteen*. During the interaction of the primary limiting monohydric alcohol with sodium, 8.96 liters of gas (n.a.) were released. Dehydration of the same mass of alcohol produces an alkene with a mass of 56 g. Establish all possible structural formulas of alcohol.
fifteen*. The volume of carbon dioxide released during the combustion of saturated monohydric alcohol is 8 times greater than the volume of hydrogen released during the action of an excess of sodium on the same amount of alcohol. Determine the structure of alcohol, if it is known that when it is oxidized, a ketone is formed.
The use of alcohols
Since alcohols have a variety of properties, the area of \u200b\u200bapplication is quite extensive. Let's try to figure out where alcohols are used.
Alcohols in the food industry
Alcohol such as ethanol is the basis of all alcoholic beverages. And it is obtained from raw materials that contain sugar and starch. Such raw materials can be sugar beets, potatoes, grapes, as well as various cereals. Thanks to modern technologies in the production of alcohol, it is purified from fusel oils.
Natural vinegar also contains raw materials derived from ethanol. This product is obtained by oxidation with acetic acid bacteria and aeration.
But in the food industry, not only ethanol is used, but also glycerin. This food additive promotes the bonding of immiscible liquids. Glycerin, which is part of liqueurs, is able to give them viscosity and sweet taste.
Also, glycerin is used in the manufacture of bakery, pasta and confectionery products.
The medicine
In medicine, ethanol is simply irreplaceable. In this industry, it is widely used as an antiseptic, as it has properties that can destroy microbes, delay painful changes in the blood, and do not allow decomposition in open wounds.
Ethanol is used by medical professionals before various procedures. This alcohol has the properties of disinfection and drying. During artificial ventilation of the lungs, ethanol acts as a defoamer. And also ethanol can be one of the components in anesthesia.
With a cold, ethanol can be used as a warming compress, and when cooled, as a rubbing agent, since its substances help to restore the body during heat and chills.
In case of poisoning with ethylene glycol or methanol, the use of ethanol helps to reduce the concentration of toxic substances and acts as an antidote.
Alcohols also play a huge role in pharmacology, as they are used to prepare medicinal tinctures and all kinds of extracts.
Alcohols in cosmetics and perfumery
In perfumery, alcohol is also indispensable, since the basis of almost all perfume products is water, alcohol and perfume concentrate. Ethanol in this case acts as a solvent for aromatic substances. But 2-phenylethanol has a floral smell and can replace natural rose oil in perfumery. It is used in the manufacture of lotions, creams, etc.
Glycerin is also the basis for many cosmetics, as it has the ability to attract moisture and actively moisturize the skin. And the presence of ethanol in shampoos and conditioners helps moisturize the skin and makes it easier to comb your hair after washing your hair.
Fuel
Well, alcohol-containing substances such as methanol, ethanol and butanol-1 are widely used as fuel.
Thanks to the processing of vegetable raw materials such as sugar cane and corn, it was possible to obtain bioethanol, which is an environmentally friendly biofuel.
Recently, the production of bioethanol has become popular in the world. With its help, a prospect appeared in the renewal of fuel resources.
Solvents, surfactants
In addition to the already listed areas of application of alcohols, it can be noted that they are also good solvents. The most popular in this area are isopropanol, ethanol, methanol. They are also used in the production of bit chemistry. Without them, full-fledged care for a car, clothes, household utensils, etc. is not possible.
The use of spirits in various areas of our activity has a positive effect on our economy and brings comfort to our lives.
Alcohols are a diverse and extensive class of chemical compounds.
Alcohols are chemical compounds whose molecules contain OH hydroxyl groups connected to a hydrocarbon radical.
A hydrocarbon radical is made up of carbon and hydrogen atoms. Examples of hydrocarbon radicals - CH 3 - methyl, C 2 H 5 - ethyl. Often, the hydrocarbon radical is simply denoted by the letter R. But if different radicals are present in the formula, they are denoted by R", R", R""", etc.
The names of alcohols are formed by adding the suffix -ol to the name of the corresponding hydrocarbon.
Alcohol classification
Alcohols are monatomic and polyhydric. If there is only one hydroxyl group in an alcohol molecule, then such an alcohol is called monohydric. If the number of hydroxyl groups is 2, 3, 4, etc., then this is a polyhydric alcohol.
Examples of monohydric alcohols: CH 3 -OH - methanol or methyl alcohol, CH 3 CH 2 -OH - ethanol or ethyl alcohol.
Accordingly, there are two hydroxyl groups in a dihydric alcohol molecule, three in a trihydric alcohol molecule, and so on.
Monohydric alcohols
The general formula for monohydric alcohols can be represented as R-OH.
According to the type of free radical included in the molecule, monohydric alcohols are divided into saturated (saturated), unsaturated (unsaturated) and aromatic alcohols.
In saturated hydrocarbon radicals, carbon atoms are connected by simple C - C bonds. In unsaturated radicals, there are one or more pairs of carbon atoms connected by double C \u003d C or triple C ≡ C bonds.
The composition of saturated alcohols includes saturated radicals.
CH 3 CH 2 CH 2 -OH - saturated alcohol propanol-1 or propylene alcohol.
Accordingly, unsaturated alcohols contain unsaturated radicals.
CH 2 \u003d CH - CH 2 - OH - unsaturated alcohol propenol 2-1 (allylic alcohol)
And the benzene ring C 6 H 5 is included in the aromatic alcohol molecule.
C 6 H 5 -CH 2 -OH - aromatic alcohol phenylmethanol (benzyl alcohol).
Depending on the type of carbon atom associated with the hydroxyl group, alcohols are divided into primary ((R-CH 2 -OH), secondary (R-CHOH-R") and tertiary (RR"R""C-OH) alcohols.
Chemical properties of monohydric alcohols
1. Alcohols burn to form carbon dioxide and water. During combustion, heat is released.
C 2 H 5 OH + 3O 2 → 2CO 2 + 3H 2 O
2. When alcohols react with alkali metals, sodium alcoholate is formed and hydrogen is released.
C 2 H 5 -OH + 2Na → 2C 2 H 5 ONa + H 2
3. Reaction with hydrogen halide. As a result of the reaction, a haloalkane (bromoethane and water) is formed.
C 2 H 5 OH + HBr → C 2 H 5 Br + H 2 O
4. Intramolecular dehydration occurs when heated and under the influence of concentrated sulfuric acid. The result is an unsaturated hydrocarbon and water.
H 3 - CH 2 - OH → CH 2 \u003d CH 2 + H 2 O
5. Oxidation of alcohols. Alcohols do not oxidize at normal temperatures. But with the help of catalysts and when heated, oxidation occurs.
Polyhydric alcohols
As substances containing hydroxyl groups, polyhydric alcohols have chemical properties similar to those of monohydric alcohols, but they react simultaneously with several hydroxyl groups.
Polyhydric alcohols react with active metals, with hydrohalic acids, and with nitric acid.
Obtaining alcohols
Consider methods for obtaining alcohols using the example of ethanol, the formula of which is C 2 H 5 OH.
The oldest of them is the distillation of alcohol from wine, where it is formed as a result of the fermentation of sugary substances. Starch-containing products are also raw materials for the production of ethyl alcohol, which are converted into sugar through the fermentation process, which is then fermented into alcohol. But the production of ethyl alcohol in this way requires a large consumption of food raw materials.
A much more perfect synthetic method for producing ethyl alcohol. In this case, ethylene is hydrated with steam.
C 2 H 4 + H 2 O → C 2 H 5 OH
Among the polyhydric alcohols, glycerin is the best known, which is obtained by splitting fats or synthetically from propylene, which is formed during high-temperature oil refining.
The content of the article
ALCOHOL(alcohols) - a class of organic compounds containing one or more C-OH groups, while the OH hydroxyl group is bonded to an aliphatic carbon atom (compounds in which the carbon atom in the C-OH group is part of the aromatic nucleus are called phenols)
The classification of alcohols is diverse and depends on which feature of the structure is taken as the basis.
1. Depending on the number of hydroxyl groups in the molecule, alcohols are divided into:
a) monoatomic (contain one hydroxyl OH group), for example, methanol CH 3 OH, ethanol C 2 H 5 OH, propanol C 3 H 7 OH
b) polyatomic (two or more hydroxyl groups), for example, ethylene glycol
HO-CH 2 -CH 2 -OH, glycerol HO-CH 2 -CH (OH) -CH 2 -OH, pentaerythritol C (CH 2 OH) 4.
Compounds in which one carbon atom has two hydroxyl groups are in most cases unstable and easily turn into aldehydes, while splitting off water: RCH (OH) 2 ® RCH \u003d O + H 2 O
2. According to the type of carbon atom to which the OH group is bonded, alcohols are divided into:
a) primary, in which the OH group is bonded to the primary carbon atom. The primary carbon atom is called (highlighted in red), associated with only one carbon atom. Examples of primary alcohols - ethanol CH 3 - C H 2 -OH, propanol CH 3 -CH 2 - C H 2 -OH.
b) secondary, in which the OH group is bonded to a secondary carbon atom. The secondary carbon atom (highlighted in blue) is bonded simultaneously to two carbon atoms, for example, secondary propanol, secondary butanol (Fig. 1).
Rice. one. STRUCTURE OF SECONDARY ALCOHOLS
c) tertiary, in which the OH group is bonded to the tertiary carbon atom. The tertiary carbon atom (highlighted in green) is bonded simultaneously to three neighboring carbon atoms, for example, tertiary butanol and pentanol (Fig. 2).
Rice. 2. STRUCTURE OF TERTIARY ALCOHOLS
The alcohol group attached to it is also called primary, secondary, or tertiary, according to the type of carbon atom.
In polyhydric alcohols containing two or more OH groups, both primary and secondary HO groups can be present simultaneously, for example, in glycerol or xylitol (Fig. 3).
Rice. 3. COMBINATION OF PRIMARY AND SECONDARY OH-GROUPS IN THE STRUCTURE OF POLYATOMIC ALCOHOLS.
3. According to the structure of organic groups linked by an OH group, alcohols are divided into saturated (methanol, ethanol, propanol), unsaturated, for example, allyl alcohol CH 2 \u003d CH - CH 2 -OH, aromatic (for example, benzyl alcohol C 6 H 5 CH 2 OH) containing an aromatic group in the R group.
Unsaturated alcohols, in which the OH group "adjoins" the double bond, i.e. bound to a carbon atom that simultaneously participates in the formation of a double bond (for example, vinyl alcohol CH 2 \u003d CH–OH), are extremely unstable and isomerize immediately ( cm.ISOMERIZATION) to aldehydes or ketones:
CH 2 \u003d CH–OH ® CH 3 -CH \u003d O
Nomenclature of alcohols.
For common alcohols with a simple structure, a simplified nomenclature is used: the name of the organic group is converted into an adjective (using the suffix and the ending " new”) and add the word “alcohol”:
In the case when the structure of the organic group is more complex, the rules common to all organic chemistry are used. Names compiled according to such rules are called systematic. In accordance with these rules, the hydrocarbon chain is numbered from the end to which the OH group is closest. Next, this numbering is used to indicate the position of various substituents along the main chain, the suffix “ol” and a number indicating the position of the OH group are added to the end of the name (Fig. 4):
Rice. four. SYSTEMATIC NAMES OF ALCOHOLS. Functional (OH) and substituent (CH 3) groups, as well as their corresponding digital indices, are highlighted in different colors.
The systematic names of the simplest alcohols are made according to the same rules: methanol, ethanol, butanol. For some alcohols, trivial (simplified) names that have developed historically have been preserved: propargyl alcohol HCє C–CH 2 –OH, glycerol HO–CH 2 –CH (OH)–CH 2 –OH, pentaerythritol C (CH 2 OH) 4, phenethyl alcohol C 6 H 5 -CH 2 -CH 2 -OH.
Physical properties of alcohols.
Alcohols are soluble in most organic solvents, the first three simplest representatives - methanol, ethanol and propanol, as well as tertiary butanol (H 3 C) 3 COH - are miscible with water in any ratio. With an increase in the number of C atoms in the organic group, the hydrophobic (water-repellent) effect begins to affect, the solubility in water becomes limited, and at R containing more than 9 carbon atoms, it practically disappears.
Due to the presence of OH groups, hydrogen bonds form between alcohol molecules.
Rice. 5. HYDROGEN BONDS IN ALCOHOLS(shown by dotted line)
As a result, all alcohols have a higher boiling point than the corresponding hydrocarbons, for example, T. kip. ethanol + 78 ° C, and T. kip. ethane –88.63°C; T. kip. butanol and butane +117.4°C and –0.5°C, respectively.
Chemical properties of alcohols.
Alcohols are distinguished by various transformations. The reactions of alcohols have some general patterns: the reactivity of primary monohydric alcohols is higher than secondary ones, in turn, secondary alcohols are chemically more active than tertiary ones. For dihydric alcohols, in the case when OH groups are located at neighboring carbon atoms, an increased (in comparison with monohydric alcohols) reactivity is observed due to the mutual influence of these groups. For alcohols, reactions are possible that take place with the cleavage of both C–O and O–H bonds.
1. Reactions proceeding through the О–Н bond.
When interacting with active metals (Na, K, Mg, Al), alcohols exhibit the properties of weak acids and form salts called alcoholates or alkoxides:
2CH 3 OH + 2Na® 2CH 3 OK + H 2
Alcoholates are chemically unstable and hydrolyze under the action of water to form alcohol and metal hydroxide:
C 2 H 5 OK + H 2 O ® C 2 H 5 OH + KOH
This reaction shows that alcohols are weaker acids compared to water (a strong acid displaces a weak one), in addition, when interacting with alkali solutions, alcohols do not form alcoholates. However, in polyhydric alcohols (in the case when OH groups are attached to neighboring C atoms), the acidity of alcohol groups is much higher, and they can form alcoholates not only when interacting with metals, but also with alkalis:
HO–CH 2 –CH 2 –OH + 2NaOH ® NaO–CH 2 –CH 2 –ONa + 2H 2 O
When the HO groups in polyhydric alcohols are attached to non-adjacent C atoms, the properties of alcohols are close to monohydric, since the mutual influence of HO groups does not appear.
When interacting with mineral or organic acids, alcohols form esters - compounds containing the R-O-A fragment (A is the acid residue). The formation of esters also occurs during the interaction of alcohols with anhydrides and acid chlorides of carboxylic acids (Fig. 6).
Under the action of oxidizing agents (K 2 Cr 2 O 7, KMnO 4), primary alcohols form aldehydes, and secondary alcohols form ketones (Fig. 7)
Rice. 7. FORMATION OF ALDEHYDES AND KETONES DURING THE OXIDATION OF ALCOHOLS
The reduction of alcohols leads to the formation of hydrocarbons containing the same number of C atoms as the initial alcohol molecule (Fig. 8).
Rice. eight. RECOVERY OF BUTANOL
2. Reactions taking place at the C–O bond.
In the presence of catalysts or strong mineral acids, alcohols are dehydrated (water is split off), while the reaction can go in two directions:
a) intermolecular dehydration with the participation of two alcohol molecules, while the C–O bonds in one of the molecules are broken, resulting in the formation of ethers - compounds containing the R–O–R fragment (Fig. 9A).
b) during intramolecular dehydration, alkenes are formed - hydrocarbons with a double bond. Often, both processes—the formation of an ether and an alkene—occur in parallel (Fig. 9B).
In the case of secondary alcohols, during the formation of an alkene, two directions of the reaction are possible (Fig. 9C), the predominant direction is that in which hydrogen is split off from the least hydrogenated carbon atom during condensation (marked with the number 3), i.e. surrounded by fewer hydrogen atoms (compared to atom 1). Shown in fig. 10 reactions are used to produce alkenes and ethers.
The breaking of the C–O bond in alcohols also occurs when the OH group is replaced by a halogen, or an amino group (Fig. 10).
Rice. ten. REPLACEMENT OF OH-GROUP IN ALCOHOLS WITH HALOGEN OR AMINE GROUP
The reactions shown in fig. 10 are used to produce halocarbons and amines.
Getting alcohols.
Some of the reactions shown above (Fig. 6,9,10) are reversible and, under changing conditions, can proceed in the opposite direction, leading to the production of alcohols, for example, during the hydrolysis of esters and halocarbons (Fig. 11A and B, respectively), as well as hydration alkenes - by adding water (Fig. 11B).
Rice. eleven. PRODUCTION OF ALCOHOLS BY HYDROLYSIS AND HYDRATION OF ORGANIC COMPOUNDS
The hydrolysis reaction of alkenes (Fig. 11, scheme B) underlies the industrial production of lower alcohols containing up to 4 carbon atoms.
Ethanol is also formed during the so-called alcoholic fermentation of sugars, for example, glucose C 6 H 12 O 6. The process proceeds in the presence of yeast fungi and leads to the formation of ethanol and CO 2:
C 6 H 12 O 6 ® 2C 2 H 5 OH + 2CO 2
Fermentation can produce no more than a 15% aqueous solution of alcohol, since yeasts die at a higher concentration of alcohol. Alcohol solutions of higher concentration are obtained by distillation.
Methanol is produced industrially by the reduction of carbon monoxide at 400°C under a pressure of 20–30 MPa in the presence of a catalyst consisting of oxides of copper, chromium, and aluminum:
CO + 2 H 2 ® H 3 SON
If instead of hydrolysis of alkenes (Fig. 11) oxidation is carried out, then dihydric alcohols are formed (Fig. 12)
Rice. 12. OBTAINING DIATOMIC ALCOHOLS
The use of alcohols.
The ability of alcohols to participate in a variety of chemical reactions allows them to be used to obtain all kinds of organic compounds: aldehydes, ketones, carboxylic acids, ethers and esters used as organic solvents, in the production of polymers, dyes and drugs.
Methanol CH 3 OH is used as a solvent, and in the production of formaldehyde used to produce phenol-formaldehyde resins, methanol has recently been considered as a promising motor fuel. Large volumes of methanol are used in the production and transportation of natural gas. Methanol is the most toxic compound among all alcohols, the lethal dose when taken orally is 100 ml.
Ethanol C 2 H 5 OH is the starting compound for the production of acetaldehyde, acetic acid, and also for the production of esters of carboxylic acids used as solvents. In addition, ethanol is the main component of all alcoholic beverages, it is also widely used in medicine as a disinfectant.
Butanol is used as a solvent for fats and resins, in addition, it serves as a raw material for the production of aromatic substances (butyl acetate, butyl salicylate, etc.). In shampoos, it is used as a component that increases the transparency of solutions.
Benzyl alcohol C 6 H 5 -CH 2 -OH in the free state (and in the form of esters) is found in the essential oils of jasmine and hyacinth. It has antiseptic (disinfecting) properties, in cosmetics it is used as a preservative for creams, lotions, dental elixirs, and in perfumery as a fragrant substance.
Phenethyl alcohol C 6 H 5 -CH 2 -CH 2 -OH has a rose smell, is found in rose oil, and is used in perfumery.
Ethylene glycol HOCH 2 -CH 2 OH is used in the production of plastics and as an antifreeze (an additive that reduces the freezing point of aqueous solutions), in addition, in the manufacture of textile and printing inks.
Diethylene glycol HOCH 2 -CH 2 OCH 2 -CH 2 OH is used to fill hydraulic brake devices, as well as in the textile industry when finishing and dyeing fabrics.
Glycerin HOCH 2 -CH(OH) -CH 2 OH is used to produce polyester glyptal resins, in addition, it is a component of many cosmetic preparations. Nitroglycerin (Fig. 6) is the main component of dynamite used in mining and railway construction as an explosive.
Pentaerythritol (HOCH 2) 4 C is used to produce polyesters (pentaphthalic resins), as a hardener for synthetic resins, as a plasticizer for polyvinyl chloride, and also in the production of tetranitropentaerythritol explosive.
The polyhydric alcohols xylitol HOCH2–(CHOH)3–CH2OH and sorbitol HOCH2– (CHOH)4–CH2OH have a sweet taste and are used instead of sugar in the manufacture of confectionery for diabetics and obese people. Sorbitol is found in rowan and cherry berries.
Mikhail Levitsky
Alcohols- these are derivatives of hydrocarbons, the molecules of which contain one or more hydroxyl OH - groups associated with a saturated carbon atom.
Nomenclature: systematic - the ending - ol is added to the name of the corresponding hydrocarbon, the position of the OH group is indicated by a number; use trivial names.
CLASSIFICATION
By the number of OH - groups alcohols are divided into
● monoatomic
● diatomic (diols) 
● triatomic (triols)
● polyhydric (polyols)
Depending on the position of OH groups distinguish
● primary
● secondary
● tertiary
Depending on the nature of the radical R distinguish
● rich
● unsaturated
● aromatic
● alicyclic
isomerism
1. Carbon skeleton
2. The position of the functional group:
3. Interclass isomerism (alcohols are isomeric to the class of ethers)
§3. Methods for obtaining monohydric alcohols.
1. Hydration of alkenes
Depending on the structure of the unsaturated hydrocarbon, primary, secondary and tertiary alcohols can be formed:
ethylene ethanol
propylene 2-propanol
methylpropene 2-methyl-2-propanol
2. Hydrolysis of halogen derivatives; carried out under the action of an aqueous solution of alkali:
3. Hydrolysis of esters:
4. Recovery of carbonyl compounds:
5. Some specific receiving methods:
a) obtaining methanol from synthesis gas (pressure - 50 - 150 atm, temperature - 200 - 300 ° C, catalysts - oxides of zinc, chromium, aluminum):
b) obtaining ethanol by fermentation of sugars:
Physical Properties
Methyl alcohol is a colorless liquid with a characteristic alcohol odor.
T bale \u003d 64.7 ° C, burns with a pale flame. Strongly poisonous.
Ethyl alcohol is a colorless liquid with a characteristic alcoholic odor.
T bale \u003d 78.3 o C
Alcohols C 1 - C 11 - liquids, C 12 and above - solids.
alcohols C 4 - C 5 have a suffocating sweet smell;
higher alcohols are odorless.
The relative density is less than 1, i.e. lighter than water.
Lower alcohols (up to C 3) are miscible with water in any ratio.
With an increase in the hydrocarbon radical, the solubility in water decreases, and the hydrophobicity of the molecule increases.
Alcohols are capable of intermolecular association:
In this regard, the boiling and melting points of alcohols are higher than those of the corresponding hydrocarbons and halogen derivatives.
The ability of ethyl alcohol to form hydrogen bonds underlies its antiseptic properties.
§5. Chemical properties of monohydric alcohols.
The characteristic reactions of alcohols are determined by the presence of a hydroxyl group in their molecule, which determines their significant reactivity.
1. Interaction with alkali metals:
R-OMe metal alcoholates are colorless solids, easily hydrolyzed by water. They are strong bases.
2.Basic properties
3. Formation of ethers:
4. Formation of esters
with inorganic acids:
with organic acids
5. Reaction of alcohols with hydrogen halides:
The use of phosphorus halides:
6. Dehydration reactions of alcohols.
The splitting of water from alcohols occurs in the presence of acids or over catalysts at elevated temperatures.
The dehydration of alcohols proceeds according to Zaitsev's empirical rule: preferably, hydrogen is split off from the least hydrogenated β-carbon atom.
1) Dehydration of primary alcohols proceeds under harsh conditions:
2) Dehydration of secondary alcohols:
3) Dehydration of tertiary alcohols:
7. Oxidation (oxidizing agents - KMnO 4, K 2 Cr 2 O 7 in an acidic environment)
8.Dehydrogenation of alcohols:
Dihydric alcohols (diols)
Ways to get.
1. Ethylene oxidation
2. Hydrolysis of the dihalogen derivative
Physical properties:
Ethylene glycol is a viscous colorless liquid, sweet in taste, soluble in water; anhydrous ethylene glycol is hygroscopic.
Chemical properties
The reactions are basically similar to the reactions of monohydric alcohols, and the reactions can proceed at one or two hydroxyl groups.
1. Acid properties; ethylene glycol is a stronger acid than ethanol
(pKa = 14.8). Formation of glycolates
2. Substitution reactions for halogens
3. Formation of ethers
4. Dehydration
5. Oxidation
Trihydric alcohols (triols)
Ways to get.
1. Hydrolysis of fats
2. From allyl chloride
Physical properties:
Glycerin is a viscous liquid with a sweet taste. Let's not limitedly dissolve in water, ethanol; does not dissolve in ether, anhydrous glycerin is hygroscopic (absorbs up to 40% of moisture from the air).
Chemical properties
The reactions are basically similar to the reactions of monohydric alcohols, and the reactions can proceed with one, two or three hydroxyl groups at once.
1. Acid properties; Glycerin is a stronger acid than ethanol and ethylene glycol. pKa = 13.5.
Forms a chelate complex with copper hydroxide:
2. Substitution reactions
3. Dehydration
The use of alcohols
Methanol and ethanol are used as solvents, as well as starting materials in the synthesis of organic substances. Ethanol is used in pharmacy for the preparation of tinctures, extracts; in medicine - as an antiseptic.
Ethylene glycol is used to produce synthetic polyester fibers (for example, lavsan), as well as antifreeze (50% solution) - an antifreeze liquid for cooling internal combustion engines.
Glycerin is used as a component of cosmetic preparations and ointments. Glycerol trinitrate is a drug used to treat angina pectoris.
Glycerol trinitrate is used in the manufacture of explosives (dynamite).
The use of glycerin in the food and textile industry.
Before proceeding to the study of alcohols, it is necessary to understand the nature -OH group and its effect on neighboring atoms.
functional groups called groups of atoms that determine the characteristic chemical properties of a given class of substances.
The structure of alcohol molecules R-OH. The oxygen atom, which is part of the hydroxyl group of alcohol molecules, differs sharply from hydrogen and carbon atoms in its ability to attract and hold electron pairs. Alcohol molecules have polar bonds C-O and O-H.
Given the polarity of the O-H bond and the significant positive charge on the hydrogen atom, the hydrogen of the hydroxyl group is said to have " acid" character. In this it differs sharply from the hydrogen atoms included in the hydrocarbon radical. The oxygen atom of the hydroxyl group has a partial negative charge and two lone electron pairs, which allows alcohol molecules to form hydrogen bonds.
By chemical properties phenols differ from alcohols, which is caused by the mutual influence of the hydroxyl group and the benzene nucleus (phenyl - C 6 H 5) in the phenol molecule. This effect is reduced to the fact that the π-electrons of the benzene nucleus partially involve the unshared electron pairs of the oxygen atom of the hydroxyl group into their sphere, as a result of which the electron density at the oxygen atom decreases. This decrease is compensated for by a greater polarization of the О-Н bond, which in turn leads to an increase in the positive charge on the hydrogen atom:
Therefore, the hydrogen of the hydroxyl group in the phenol molecule has acidic character.
The influence of atoms in the molecules of phenol and its derivatives is mutual. The hydroxyl group affects the density of the π-electron cloud in the benzene ring. It decreases at the carbon atom associated with the OH group (i.e., at the 1st and 3rd carbon atoms, metaposition) and increases at the neighboring carbon atoms - 2, 4, 6th - ortho- and pair- provisions.
The hydrogen atoms of benzene in the ortho and para positions become more mobile and are easily replaced by other atoms and radicals.
Aldehydes have the general formula 
where is the carbonyl group
The carbon atom in the carbonyl group is sp 3 hybridized. Atoms directly connected to it are in the same plane. Due to the high electronegativity of the oxygen atom compared to the carbon atom, the C=O bond highly polarized due to the shift of the electron density of the π-bond to oxygen:
Under the influence of the carbonyl carbon atom in aldehydes, the polarity of the C-H bond increases, which increases the reactivity of this H atom.
carboxylic acids contain a functional group
Called the carboxyl group, or carboxyl. It is named so because it consists of a carbonyl group.
and hydroxyl -OH.
In carboxylic acids, the hydroxyl group is bonded to a hydrocarbon radical and a carbonyl group. The weakening of the bond between oxygen and hydrogen in the hydroxyl group is explained by the difference in the electronegativity of carbon, oxygen, and hydrogen atoms. The carbon atom acquires some positive charge. This carbon atom attracts an electron cloud from the oxygen atom of the hydroxyl group. Compensating for the shifted electron density, the oxygen atom of the hydroxyl group pulls the electron cloud of the neighboring hydrogen atom towards itself. The O-H bond in the hydroxyl group becomes more polar and the hydrogen atom becomes more mobile.
Limit monohydric and polyhydric alcohols
alcohols(or alkanols) are organic substances whose molecules contain one or more hydroxyl groups (-OH groups) connected to a hydrocarbon radical.
According to the number of hydroxyl groups(atomicity) alcohols are divided into:
· monatomic, for example:
· diatomic(glycols), for example:
· Triatomic, for example:
By the nature of the hydrocarbon radical the following alcohols are distinguished:
· Limit containing only saturated hydrocarbon radicals in the molecule, for example:
· Unlimited containing multiple (double and triple) bonds between carbon atoms in the molecule, for example:
· aromatic, i.e. alcohols containing a benzene ring and a hydroxyl group in the molecule, connected to each other not directly, but through carbon atoms, for example:
Organic substances containing hydroxyl groups in the molecule, directly bonded to the carbon atom of the benzene ring, differ significantly in chemical properties from alcohols and therefore stand out in an independent class of organic compounds - phenols. For example:
There are also polyatomic(polyhydric) alcohols containing more than three hydroxyl groups per molecule. For example, the simplest six-hydric alcohol hexanol (sorbitol):
Isomerism and nomenclature of alcohols
When forming the names of alcohols, a (generic) suffix is added to the name of the hydrocarbon corresponding to the alcohol -ol. The numbers after the suffix indicate the position of the hydroxyl group in the main chain, and the prefixes di-, tri-, tetra-, etc. indicate their number:
In the numbering of carbon atoms in the main chain the position of the hydroxyl group is priority before the position of multiple bonds:
Starting from the third member of the homologous series, alcohols have functional group position isomerism(propanol-1 and propanol-2), and from the fourth - isomerism of the carbon skeleton(butanol-1, 2-methylpropanol-1). They are also characterized by interclass isomerism - alcohols are isomeric to ethers:
Alcohols can form hydrogen bonds both between alcohol molecules and between alcohol and water molecules.
Hydrogen bonds arise from the interaction of a partially positively charged hydrogen atom of one alcohol molecule and a partially negatively charged oxygen atom of another molecule. It is due to hydrogen bonds between molecules that alcohols have abnormally high boiling points for their molecular weight. So, propane with a relative molecular weight of 44 under normal conditions is a gas, and the simplest of alcohols is methanol, having a relative molecular weight of 32, under normal conditions it is a liquid.
The properties of organic substances are determined by their composition and structure. Alcohols confirm the general rule. Their molecules include hydrocarbon and hydroxyl radicals, so the chemical properties of alcohols are determined by the interaction and influence of these groups on each other.
Characteristic properties for this class of compounds due to the presence of a hydroxyl group.
1. Interaction of alcohols with alkali and alkaline earth metals. To identify the effect of a hydrocarbon radical on a hydroxyl group, it is necessary to compare the properties of a substance containing a hydroxyl group and a hydrocarbon radical, on the one hand, and a substance containing a hydroxyl group and not containing a hydrocarbon radical, on the other. Such substances can be, for example, ethanol (or other alcohol) and water. Hydrogen of the hydroxyl group of alcohol molecules and water molecules can be reduced by alkali and alkaline earth metals (replaced by them):
2. Interaction of alcohols with hydrogen halides. Substitution of a hydroxyl group for a halogen leads to the formation of haloalkanes. For example:
This reaction is reversible.
3. Intermolecular dehydration of alcohols- splitting of a water molecule from two alcohol molecules when heated in the presence of water-removing agents:
As a result of intermolecular dehydration of alcohols, ethers are formed. So, when ethyl alcohol is heated with sulfuric acid to a temperature of 100 to 140 ° C, diethyl (sulfur) ether is formed.
4. Interaction of alcohols with organic and inorganic acids to form esters ( esterification reaction):
esterification reaction catalyzed by strong inorganic acids.
For example, when ethyl alcohol and acetic acid react, ethyl acetate is formed - ethyl acetate:
5. Intramolecular dehydration of alcohols occurs when alcohols are heated in the presence of dehydrating agents to a temperature higher than the intermolecular dehydration temperature. As a result, alkenes are formed. This reaction is due to the presence of a hydrogen atom and a hydroxyl group at neighboring carbon atoms. An example is the reaction of obtaining ethene (ethylene) by heating ethanol above 140 ° C in the presence of concentrated sulfuric acid:
6. Alcohol oxidation usually carried out with strong oxidizing agents, for example, potassium dichromate or potassium permanganate in an acidic medium. In this case, the action of the oxidizing agent is directed to the carbon atom that is already associated with the hydroxyl group. Depending on the nature of the alcohol and the reaction conditions, various products can be formed. So, primary alcohols are oxidized first to aldehydes, and then to carboxylic acids:
At oxidation of secondary alcohols ketones are formed:
Tertiary alcohols are quite resistant to oxidation. However, under harsh conditions (strong oxidizing agent, high temperature), oxidation of tertiary alcohols is possible, which occurs with the breaking of carbon-carbon bonds closest to the hydroxyl group.
7. Dehydrogenation of alcohols. When alcohol vapor is passed at 200-300 ° C over a metal catalyst, such as copper, silver or platinum, primary alcohols are converted into aldehydes, and secondary ones into ketones:
8. The presence in the alcohol molecule at the same time several hydroxyl groups the specific properties of polyhydric alcohols are determined, which are capable of forming bright blue complex compounds soluble in water when interacting with a fresh precipitate of copper (II) hydroxide. For ethylene glycol, you can write:
Monohydric alcohols are not able to enter into this reaction. Therefore she is qualitative reaction to polyhydric alcohols.
Chemical properties of alcohols - compendium
Individual representatives of alcohols and their meaning
methanol(methyl alcohol CH 3 OH) is a colorless liquid with a characteristic odor and a boiling point of 64.7 ° C. It burns with a slightly bluish flame. The historical name of methanol - wood alcohol is explained by one of the ways to obtain it by the method of distillation of hardwoods (Greek methy - wine, to get drunk; hule - substance, wood).
Methanol requires careful handling when working with it. Under the action of the enzyme alcohol dehydrogenase, it is converted in the body into formaldehyde and formic acid, which damage the retina, cause the death of the optic nerve and complete loss of vision. Ingestion of more than 50 ml of methanol causes death.
ethanol(ethyl alcohol C 2 H 5 OH) is a colorless liquid with a characteristic odor and a boiling point of 78.3 ° C. combustible Miscible with water in any ratio. The concentration (strength) of alcohol is usually expressed as a percentage by volume. "Pure" (medical) alcohol is a product obtained from food raw materials and containing 96% (by volume) ethanol and 4% (by volume) water. To obtain anhydrous ethanol - "absolute alcohol", this product is treated with substances that chemically bind water (calcium oxide, anhydrous copper (II) sulfate, etc.).
In order to make alcohol used for technical purposes unfit for drinking, small amounts of difficult-to-separate poisonous, bad-smelling and disgusting-tasting substances are added to it and tinted. Alcohol containing such additives is called denatured, or methylated spirits.
Ethanol is widely used in industry for the production of synthetic rubber, drugs, used as a solvent, is part of varnishes and paints, perfumes. In medicine, ethyl alcohol is the most important disinfectant. Used to make alcoholic beverages.
Small amounts of ethyl alcohol, when ingested, reduce pain sensitivity and block the processes of inhibition in the cerebral cortex, causing a state of intoxication. At this stage of the action of ethanol, water separation in the cells increases and, consequently, urine formation is accelerated, resulting in dehydration of the body.
In addition, ethanol causes the expansion of blood vessels. Increased blood flow in the skin capillaries leads to reddening of the skin and a feeling of warmth.
In large quantities, ethanol inhibits the activity of the brain (the stage of inhibition), causes a violation of coordination of movements. An intermediate product of the oxidation of ethanol in the body - acetaldehyde - is extremely toxic and causes severe poisoning.
The systematic use of ethyl alcohol and drinks containing it leads to a persistent decrease in the productivity of the brain, death of liver cells and their replacement with connective tissue - cirrhosis of the liver.
Ethandiol-1,2(ethylene glycol) is a colorless viscous liquid. Poisonous. Freely soluble in water. Aqueous solutions do not crystallize at temperatures significantly below 0 °C, which makes it possible to use it as a component of non-freezing coolants - antifreezes for internal combustion engines.
Prolactriol-1,2,3(glycerin) - a viscous syrupy liquid, sweet in taste. Freely soluble in water. Non-volatile As an integral part of esters, it is part of fats and oils.
Widely used in cosmetics, pharmaceutical and food industries. In cosmetics, glycerin plays the role of an emollient and soothing agent. It is added to toothpaste to prevent it from drying out.
Glycerin is added to confectionery products to prevent their crystallization. It is sprayed on tobacco, in which case it acts as a humectant, preventing the tobacco leaves from drying out and crumbling before processing. It is added to adhesives to keep them from drying out too quickly, and to plastics, especially cellophane. In the latter case, glycerin acts as a plasticizer, acting like a lubricant between polymer molecules and thus giving plastics the necessary flexibility and elasticity.
The lower and middle members of a series of limiting monohydric alcohols containing from 1 to 11 carbon atoms are liquids. Higher alcohols (starting with C 12 H 25 OH) are solids at room temperature. Lower alcohols have a characteristic alcoholic smell and a burning taste, they are highly soluble in water. As the hydrocarbon radical increases, the solubility of alcohols in water decreases, and octanol is no longer miscible with water.
Reference material for passing the test:
periodic table
Solubility table
