The reduction of alcohols to hydrocarbons is carried out by interacting with hydroiodic acid in the presence of red phosphorus, which serves to regenerate hydroiodic acid.

HOCH 2 (CHOH) 4 CH 2 OH + 12HJ → CH 3 (CH 2) 4 CH 3 + 6J 2 + 6H 2 O

Sorbitol n-Hexane

2P + 3J 2 = 2PJ 3 PJ 3 + 3H 2 O = 3HJ + H 3 PO 3

    1. Interaction with alkali and alkaline earth metals.

Like water, alcohols react with alkali and alkaline earth metals, as well as with magnesium, to form alcoholates and hydrogen.

2 (CH 3) 3 COH + 2K → 2 (CH 3) 3 COK + H 2

2 CH 3 OH + Mg → (CH 3 O) 2 Mg + H 2

Alkali metal alcoholates are used as bases in cleavage reactions from alkyl halides leading to the formation of alkenes.

The reactions of alcohols with carbonyl compounds, aldehydes and ketones, as well as with acids - the esterification of acids to form esters, are usually considered when describing the properties of carbonyl compounds and acids, respectively, and therefore will not be considered in this section.

2.15. Dihydric alcohols

Geminal diols - 1,1-diols containing two OH groups at the same carbon atom, are unstable and decompose with the elimination of water and the formation of a carbonyl compound:

The equilibrium in this process is shifted towards the formation of a ketone or aldehyde, so the geminal diols themselves are usually called hydrates of ketones or aldehydes if hydrogen is present instead of one of the radicals. Vicinal diols - 1,2 - diols containing two OH groups at the adjacent carbon atoms, are stable compounds. Hereinafter, the term 1,2-diols will be used for dihydric alcohols containing hydroxyl groups at adjacent carbon atoms.

2.16. Obtaining diols

One of the most simple methods obtaining 1,2-diols is the hydroxylation of alkenes under the action of potassium permanganate. Since potassium permanganate is a strong oxidizing agent capable of not only hydroxylating the double bond, but also cleaving the resulting vicinal diol, careful control of the reaction conditions is necessary. Optimum results are achieved when carrying out the reaction in a weakly alkaline medium (pH≈8) at low temperature with a dilute aqueous solution of KmnO 4 .

Other possible preparation methods may include the hydrolysis of vicinal dihalides:

2.17. Properties of diols

For diols, the same reactions are characteristic as for monohydric alcohols. In addition, 1,2-diols exhibit some specific properties due to the presence of two adjacent hydroxyl groups. They will be discussed in this section.

Dehydration of 1,2-diols can proceed in two directions: 1) formation of dienes; 2) formation of cyclic ethers. Both of these reactions are catalyzed by acids. Dehydration of two-tertiary or two-secondary 1,2-diols proceeds easily when heated with concentrated HBr.

The formation of cyclic esters or cyclodehydration of 1,2-diols leads to the formation of 1,4-dioxane if the 1,2-diol is 1,2-ethanediol (ethylene glycol); in this case, the six-membered ring is formed from two moles of 1,2-ethanediol.

1,4- and 1,5-diols cyclize under these conditions with the formation of five- and six-membered rings:

A qualitative reaction to 1,2-diols is a test with copper hydroxide in an alkaline medium. In this case, the dissolution of copper hydroxide is observed and a solution is obtained, colored in a deep Blue colour, due to the formation of the Cu(II) chelate complex.

2.18. trihydric alcohols

The most important of the trihydric alcohols is glycerol - propanetriol-1,2,3, which is part of lipids in the form of esters with higher saturated and unsaturated acids.

Glycerol

the primary alcohol group of glycerol (CH 2 OH) is more active than the secondary alcohol group (CHOH) and can be selectively converted to chloride or acid by the action of reagents such as hydrogen chloride or nitric acid, respectively.

Dehydration of glycerol gives the simplest unsaturated aldehyde - acrolein (propenal):

Just like ethylene glycol, glycerol gives a qualitative reaction characteristic of 1,2-diols with copper hydroxide in an alkaline medium

2.19. ETHERS

ETHER NOMENCLATURE

According to the IUPAC nomenclature, ethers are considered as alkoxyalkanes. The parent structure is determined by the longest alkyl group:

OBTAINING ETHERS

There are two general methods for obtaining ethers: intermolecular dehydration of alcohols and nucleophilic substitution of halogen in alkyl halides by the action of alkali metal alcoholates (Williamson reaction). Both of these methods have been described above.

2.20. ETHER PROPERTIES

In chemical terms, ethers are characterized by high inertness with respect to many reagents, especially basic ones. They are not split by organometallic compounds, hydrides and amides of alkali metals, as well as complex hydrides of boron and aluminum. Therefore, compounds such as diethyl ether, tetrahydrofuran, dimethoxyethane, diethylene glycol dimethyl ether, dioxane and others are widely used as solvents in reactions with the above compounds.

Ethers form very strong complexes with Lewis acids - BF 3 , AlBr 3 , SbCl 5 , SbF 5 , etc. composition 1:1, in which they act as Lewis bases

In relation to strong acids, esters exhibit the properties of bases (in this case, Bronsted bases) and form dialkyloxonium salts

The most famous and used in human life and in industry substances belonging to the category of polyhydric alcohols are ethylene glycol and glycerin. Their research and use began several centuries ago, but their properties are in many ways inimitable and unique, which makes them indispensable to this day. Polyhydric alcohols are used in many chemical syntheses, industries and areas of human life.

The first "acquaintance" with ethylene glycol and glycerin: the history of obtaining

In 1859, through a two-stage process of reacting dibromoethane with silver acetate and then treating the ethylene glycol diacetate obtained in the first reaction with caustic potash, Charles Wurtz first synthesized ethylene glycol. Some time later, a method was developed for the direct hydrolysis of dibromoethane, but on an industrial scale at the beginning of the twentieth century, the dihydric alcohol 1,2-dioxyethane, also known as monoethylene glycol, or simply glycol, was obtained in the United States by hydrolysis of ethylene chlorohydrin.

To date, both in industry and in the laboratory, a number of other methods are used, new, more economical from a raw material and energy point of view, and environmentally friendly, since the use of reagents containing or releasing chlorine, toxins, carcinogens and other dangerous for environment and human matter, is declining with the development of "green" chemistry.

The pharmacist Carl Wilhelm Scheele discovered glycerin in 1779, and Theophile Jules Peluz studied the composition of the compound in 1836. Two decades later, the structure of the molecule of this trihydric alcohol was established and substantiated in the works of Pierre Eugene Marseille Vertelot and Charles Wurtz. Finally, twenty years later, Charles Friedel carried out the complete synthesis of glycerol. Currently, the industry uses two methods for its production: through allyl chloride from propylene, and also through acrolein. The chemical properties of ethylene glycol, like glycerin, are widely used in various fields chemical production.

The structure and structure of the connection

The molecule is based on an unsaturated hydrocarbon skeleton of ethylene, consisting of two carbon atoms, in which a double bond has been broken. Two hydroxyl groups were added to the vacated valence sites at the carbon atoms. The formula of ethylene is C 2 H 4, after breaking the crane bond and adding hydroxyl groups (after several stages), it looks like C 2 H 4 (OH) 2. This is ethylene glycol.

The ethylene molecule has a linear structure, while the dihydric alcohol has a kind of trans configuration in the placement of hydroxyl groups in relation to the carbon backbone and to each other (this term is fully applicable to the position relative to the multiple bond). Such a dislocation corresponds to the most remote location of hydrogens from functional groups, lower energy, and hence the maximum stability of the system. Simply put, one OH group looks up and the other looks down. At the same time, compounds with two hydroxyls are unstable: at one carbon atom, being formed in the reaction mixture, they are immediately dehydrated, turning into aldehydes.

Classification affiliation

The chemical properties of ethylene glycol are determined by its origin from the group of polyhydric alcohols, namely the subgroup of diols, that is, compounds with two hydroxyl fragments at neighboring carbon atoms. A substance that also contains several OH substituents is glycerol. It has three alcohol functional groups and is the most common representative of its subclass.

Many compounds of this class are also obtained and used in chemical production for various synthesis and other purposes, but the use of ethylene glycol is on a more serious scale and is involved in almost all industries. This issue will be discussed in more detail below.

physical characteristics

The use of ethylene glycol is explained by the presence of a number of properties that are inherent in polyhydric alcohols. This distinctive features characteristic only for this class of organic compounds.

The most important of the properties is the unlimited ability to mix with H 2 O. Water + ethylene glycol gives a solution with a unique characteristic: its freezing point, depending on the diol concentration, is 70 degrees lower than that of pure distillate. It is important to note that this dependence is non-linear, and upon reaching a certain quantitative content of glycol, the opposite effect begins - the freezing point rises with increasing percentage solute. This feature has found application in the production of various antifreezes, anti-freeze liquids that crystallize at extremely low thermal characteristics of the environment.

Except in water, the dissolution process proceeds well in alcohol and acetone, but is not observed in paraffins, benzenes, ethers and carbon tetrachloride. Unlike its aliphatic ancestor - such a gaseous substance as ethylene, ethylene glycol is a syrup-like, transparent liquid with a slight yellow tint, sweetish in taste, with an uncharacteristic odor, practically non-volatile. Freezing of one hundred percent ethylene glycol occurs at - 12.6 degrees Celsius, and boiling - at +197.8. Under normal conditions, the density is 1.11 g/cm 3 .

Acquisition Methods

Ethylene glycol can be obtained in several ways, some of them today have only historical or preparative significance, while others are actively used by humans on an industrial scale and not only. Following in chronological order Let's take a look at the most important ones.

The first method for obtaining ethylene glycol from dibromoethane has already been described above. The formula of ethylene, the double bond of which is broken, and the free valences are occupied by halogens, the main starting material in this reaction, in addition to carbon and hydrogen, has two bromine atoms in its composition. The formation of an intermediate compound at the first stage of the process is possible precisely due to their elimination, i.e., replacement by acetate groups, which, upon further hydrolysis, turn into alcohol groups.

In the process of further development of science, it became possible to obtain ethylene glycol by direct hydrolysis of any ethanes substituted by two halogens at neighboring carbon atoms, using aqueous solutions of metal carbonates from alkali group or (less environmentally friendly reagent) H 2 O and lead dioxide. The reaction is quite "labor-intensive" and proceeds only at significantly elevated temperatures and pressures, but this did not prevent the Germans from using this method during the world wars to produce ethylene glycol on an industrial scale.

The method of obtaining ethylene glycol from ethylene chlorohydrin by its hydrolysis with coal salts of alkali group metals also played a role in the development of organic chemistry. With an increase in the reaction temperature to 170 degrees, the yield of the target product reached 90%. But there was a significant drawback - the glycol had to be somehow extracted from the salt solution, which is directly associated with a number of difficulties. Scientists have solved this issue by developing a method with the same starting material, but breaking the process into two stages.

The hydrolysis of ethylene glycol acetates, which was previously the final stage of the Wurtz method, became a separate method when it was possible to obtain the starting reagent by oxidizing ethylene in acetic acid with oxygen, that is, without the use of expensive and completely unecological halogen compounds.

There are also many methods for the production of ethylene glycol by oxidizing ethylene with hydroperoxides, peroxides, organic peracids in the presence of catalysts (osmium compounds), etc. There are also electrochemical and radiation-chemical methods.

Characterization of general chemical properties

The chemical properties of ethylene glycol are determined by its functional groups. The reactions may involve one hydroxyl substituent or both, depending on the process conditions. The main difference in reactivity lies in the fact that due to the presence of several hydroxyls in a polyhydric alcohol and their mutual influence, stronger ones appear than those of monoatomic "brothers". Therefore, in reactions with alkalis, the products are salts (for glycol - glycolates, for glycerol - glycerates).

IN Chemical properties ethylene glycol, as well as glycerin, includes all reactions of alcohols from the category of monohydric. Glycol gives full and partial esters in reactions with monobasic acids, glycolates, respectively, are formed with alkali metals, and in a chemical process with strong acids or their salts, acetic acid aldehyde is released - due to the elimination of a hydrogen atom from a molecule.

Reactions with active metals

The interaction of ethylene glycol with active metals (standing after hydrogen in the chemical series of tension) at elevated temperatures gives ethylene glycolate of the corresponding metal, plus hydrogen is released.

C 2 H 4 (OH) 2 + X → C 2 H 4 O 2 X, where X is an active divalent metal.

for ethylene glycol

It is possible to distinguish a polyhydric alcohol from any other liquid using a visual reaction that is characteristic only for this class of compounds. To do this, freshly precipitated (2), which has a characteristic blue tint, is poured into a colorless solution of alcohol. When the mixed components interact, the precipitate dissolves and the solution turns into a deep blue color - as a result of the formation of copper glycolate (2).

Polymerization

The chemical properties of ethylene glycol have great importance for the production of solvents. The intermolecular dehydration of the mentioned substance, that is, the elimination of water from each of the two glycol molecules and their subsequent combination (one hydroxyl group is completely eliminated, and only hydrogen is removed from the other), makes it possible to obtain a unique organic solvent - dioxane, which is often used in organic chemistry, despite its high toxicity.

Exchange of hydroxyl for halogen

When ethylene glycol reacts with hydrohalic acids, the replacement of hydroxyl groups by the corresponding halogen is observed. The degree of substitution depends on the molar concentration of hydrogen halide in the reaction mixture:

NO-CH 2 -CH 2 -OH + 2HX → X-CH 2 -CH 2 -X, where X is chlorine or bromine.

Getting ethers

In the reactions of ethylene glycol with nitric acid (of a certain concentration) and monobasic organic acids (formic, acetic, propionic, butyric, valeric, etc.), complex and, accordingly, simple monoesters are formed. At others, the concentration of nitric acid is di- and trinitroesters of glycol. Sulfuric acid of a given concentration is used as a catalyst.

The most important derivatives of ethylene glycol

Valuable substances that can be obtained from polyhydric alcohols using simple ones (described above) are ethylene glycol ethers. Namely: monomethyl and monoethyl, the formulas of which are NO-CH 2 -CH 2 -O-CH 3 and NO-CH 2 -CH 2 -O-C 2 H 5, respectively. In terms of chemical properties, they are in many ways similar to glycols, but, like any other class of compounds, they have unique reaction features that are unique to them:

  • Monomethylethylene glycol is a colorless liquid, but with a characteristic disgusting odor, boiling at 124.6 degrees Celsius, perfectly soluble in ethanol, other organic solvents and water, much more volatile than glycol, and with a density lower than that of water (of the order 0.965 g/cm3).
  • Dimethylethylene glycol is also a liquid, but with a less characteristic odor, a density of 0.935 g / cm 3, a boiling point of 134 degrees above zero and a solubility comparable to the previous homologue.

The use of cellosolves - as ethylene glycol monoethers are generally called - is quite common. They are used as reagents and solvents in organic synthesis. They are also used for anti-corrosion and anti-crystallization additives in antifreezes and motor oils.

Applications and pricing policy of the product range

The cost at factories and enterprises involved in the production and sale of such reagents fluctuates on average about 100 rubles per kilogram of such chemical compound like ethylene glycol. The price depends on the purity of the substance and the maximum percentage of the target product.

The use of ethylene glycol is not limited to any one area. So, as a raw material it is used in the production of organic solvents, artificial resins and fibers, liquids that freeze at low temperatures. It is involved in many industrial sectors, such as automotive, aviation, pharmaceutical, electrical, leather, tobacco. Its importance for organic synthesis is undeniably weighty.

It is important to remember that glycol is a toxic compound that can cause irreparable harm to human health. Therefore, it is stored in sealed vessels made of aluminum or steel with a mandatory inner layer that protects the container from corrosion, only in vertical positions and in rooms that are not equipped with heating systems, but with good ventilation. Term - no more than five years.

Have general formula C n H 2n (OH) 2 . The simplest glycol is ethylene glycol HO-CH 2 -CH 2 -OH.

Nomenclature

The names of glycols are formed from the names of the corresponding hydrocarbons with the suffixes -diol or -glycol:

H O - C H 2 - C H 2 - O H (\displaystyle (\mathsf (HO(\text(-))CH_(2)(\text(-))CH_(2)(\text(-))OH)))- 1,2-ethanediol, ethylene glycol

H O - C H 2 - C H 2 - C H 2 - O H (\displaystyle (\mathsf (HO(\text(-))CH_(2)(\text(-))CH_(2)(\text(-))CH_ (2)(\text(-))OH)))- 1,3-propanediol, 1,3-propylene glycol

Physical and chemical properties

Lower glycols are colorless transparent liquids with a sweetish taste. Anhydrous glycols are hygroscopic. Due to the presence of two polar OH groups in glycol molecules, they have high viscosity, density, melting and boiling points.

Lower glycols are highly soluble in water and organic solvents (alcohols, ketones, acids and amines). At the same time, glycols themselves are good solvents for many substances, with the exception of aromatic and higher saturated hydrocarbons.

Glycols have all the properties of alcohols (form alcoholates, ethers and esters), while the hydroxyl groups react independently of each other to form a mixture of products.

With aldehydes and ketones, glycols form 1,3-dioxolanes and 1,3-dioxanes.

Getting and using

Glycols are synthesized in several main ways:

  • hydrolysis of the corresponding dichloroalkanes
C l - C H 2 - C H 2 - C l → 200 o C 10 M P a N a 2 C O 3 H O - C H 2 - C H 2 - O H (\displaystyle (\mathsf (Cl(\text(-))CH_(2 )(\text(-))CH_(2)(\text(-))Cl(\xrightarrow[(200^(o)C\ 10MPa)](Na_(2)CO_(3)))HO(\text (-))CH_(2)(\text(-))CH_(2)(\text(-))OH)))
  • oxidation of alkenes with potassium permanganate:
  • hydration of oxiranes (epoxides)

Glycols serve as solvents and plasticizers. Ethylene glycol and propylene glycol are used as antifreeze and hydraulic fluids. Due to the high boiling point (for example, 285 ° C for triethylene glycol), glycols have found use as a brake fluid. Glycols are used to obtain various ethers, polyurethanes, etc.

alcohols(or alkanols) are organic substances whose molecules contain one or more hydroxyl groups (-OH groups) connected to a hydrocarbon radical.

Alcohol classification

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, bound friend with a friend 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 in the molecule. For example, the simplest six-hydric alcohol hexaol (sorbitol)

Nomenclature and isomerism of alcohols

When forming the names of alcohols, the (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. - their number:

In the numbering of carbon atoms in the main chain, the position of the hydroxyl group takes precedence over the position of multiple bonds:

Starting with the third term 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:

Let's give a name to alcohol, the formula of which is given below:

Name construction order:

1. The carbon chain is numbered from the end to which the -OH group is closer.
2. The main chain contains 7 C atoms, so the corresponding hydrocarbon is heptane.
3. The number of -OH groups is 2, the prefix is ​​"di".
4. Hydroxyl groups are at 2 and 3 carbon atoms, n = 2 and 4.

Name of alcohol: heptanediol-2,4

Physical properties of alcohols

Alcohols can form hydrogen bonds both between alcohol molecules and between alcohol and water molecules. Hydrogen bonds arise during 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. Thus, propane with a relative molecular weight of 44 under normal conditions is a gas, and the simplest of the alcohols is methanol, having a relative molecular weight of 32, under normal conditions a liquid.

The lower and middle members of a series of limiting monohydric alcohols containing from 1 to 11 carbon atoms-liquid. Higher alcohols (starting from C12H25OH) solids at room temperature. Lower alcohols have an alcoholic smell and a burning taste, they are highly soluble in water. As the carbon radical increases, the solubility of alcohols in water decreases, and octanol is no longer miscible with water.

Chemical properties of alcohols

Properties organic matter determined by their composition and structure. Alcohols confirm general rule. Their molecules include hydrocarbon and hydroxyl groups, so the chemical properties of alcohols are determined by the interaction of these groups with 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)
  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 dehydrationalcohols- splitting off 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. So, when ethyl alcohol is heated with sulfuric acid to a temperature of 100 to 140 ° C, diethyl (sulfur) ether is formed.
  4. The interaction of alcohols with organic and inorganic acids with the formation of 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:

  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:
    When secondary alcohols are oxidized, ketones are formed:

    Tertiary alcohols are quite resistant to oxidation. However, under harsh conditions (strong oxidizer, heat) 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. Qualitative reaction to polyhydric alcohols.
    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. For ethylene glycol, you can write:

    Monohydric alcohols are not able to enter into this reaction. Therefore, it is a qualitative reaction to polyhydric alcohols.

Getting alcohols:

The use of alcohols

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 the alcohol used in technical purposes, unsuitable 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 brain activity (inhibition stage), causes impaired 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 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.


Individual representatives

methanol(methyl, wood alcohol) - a colorless liquid with a slight alcohol odor. A large number of it is used in the production of formaldehyde, formic acid, methyl and dimethylaniline, methylamines and many dyes, pharmaceuticals, and fragrances. Methanol is a good solvent, therefore it is widely used in the paint and varnish industry, as well as in the oil industry for the purification of gasoline from mercaptans, for the isolation of toluene by azeotropic distillation.

ethanol(ethyl, wine alcohol) - a colorless liquid with a characteristic alcohol odor. Ethyl alcohol is used in large quantities in the production of divinyl (processed into synthetic rubbers), diethyl ether, chloroform, chloral, high purity ethylene, ethyl acetate and other esters used as solvents for varnishes and fragrances (fruit essences). As a solvent, ethyl alcohol is widely used in the production of pharmaceutical, fragrance, coloring and other substances. Ethanol is a good antiseptic.

propyl and isopropyl alcohols. These alcohols, as well as their esters, are used as solvents. In some cases, they replace ethyl alcohol. Isopropyl alcohol is used to make acetone.

Butyl alcohol and its esters are used in large quantities as solvents for varnishes and resins.

Isobutyl alcohol used to obtain isobutylene, isobutyric aldehyde, isobutyric acid, and also as a solvent.

Primary amyl and isoamyl alcohols make up the bulk of fusel oil (by-products in the production of ethyl alcohol from potatoes or cereals). Amyl alcohols and their esters are good solvents. Isoamyl acetate (pear essence) is used in the manufacture soft drinks and some confectionery.

Lecture number 15.Polyhydric alcohols

polyhydric alcohols. Classification. Isomerism. Nomenclature. Dihydric alcohols (glycols). trihydric alcohols. Glycerol. Synthesis from fats and propylene. The use of glycol and glycerin in industry.

Two hydroxyl groups cannot be on the same carbon atom; such compounds easily lose water, turning into aldehydes or ketones:

This property is common to all gem-diols. Sustainability gem-diols increases in the presence of electron-withdrawing substituents. An example of sustainable gem-diol is a chloral hydrate.