Alcohols - nomenclature, preparation, chemical properties. Chemical properties of monohydric and polyhydric alcohols
DEFINITION
Alcohols– compounds containing one or more hydroxyl groups –OH associated with a hydrocarbon radical.
The general formula of the homologous series of saturated monohydric alcohols is C n H 2 n +1 OH. The names of alcohols contain the suffix – ol.
Depending on the number of hydroxyl groups, alcohols are divided into one- (CH 3 OH - methanol, C 2 H 5 OH - ethanol), two- (CH 2 (OH)-CH 2 -OH - ethylene glycol) and triatomic (CH 2 (OH )-CH(OH)-CH 2 -OH - glycerol). Depending on which carbon atom the hydroxyl group is located at, primary (R-CH 2 -OH), secondary (R 2 CH-OH) and tertiary alcohols (R 3 C-OH) are distinguished.
Saturated monohydric alcohols are characterized by isomerism of the carbon skeleton (starting from butanol), as well as isomerism of the position of the hydroxyl group (starting from propanol) and interclass isomerism with ethers.
CH 3 -CH 2 -CH 2 -CH 2 -OH (butanol – 1)
CH 3 -CH (CH 3) - CH 2 -OH (2-methylpropanol - 1)
CH 3 -CH (OH) -CH 2 -CH 3 (butanol - 2)
CH 3 -CH 2 -O-CH 2 -CH 3 (diethyl ether)
Chemical properties of alcohols
1. Discontinuous reactions O-N connections:
— the acidic properties of alcohols are very weakly expressed. Alcohols react with alkali metals
2C 2 H 5 OH + 2K → 2C 2 H 5 OK + H 2
but do not react with alkalis. In the presence of water, alcoholates are completely hydrolyzed:
C 2 H 5 OK + H 2 O → C 2 H 5 OH + KOH
This means that alcohols are weaker acids than water.
- education esters under the influence of mineral and organic acids:
CH 3 -CO-OH + H-OCH 3 ↔ CH 3 COOCH 3 + H 2 O
- oxidation of alcohols under the action of potassium dichromate or permanganate to carbonyl compounds. Primary alcohols are oxidized to aldehydes, which in turn can be oxidized to carboxylic acids.
R-CH 2 -OH + [O] → R-CH = O + [O] → R-COOH
Secondary alcohols are oxidized to ketones:
R-CH(OH)-R’ + [O] → R-C(R’) = O
Tertiary alcohols are more resistant to oxidation.
2. Reaction with breaking of the C-O bond.
- intramolecular dehydration with the formation of alkenes (occurs when alcohols with water-removing substances (concentrated sulfuric acid) are strongly heated):
CH 3 -CH 2 -CH 2 -OH → CH 3 -CH = CH 2 + H 2 O
— intermolecular dehydration of alcohols with the formation of ethers (occurs when alcohols are slightly heated with water-removing substances (concentrated sulfuric acid)):
2C 2 H 5 OH → C 2 H 5 -O-C 2 H 5 + H 2 O
— weak basic properties of alcohols manifest themselves in reversible reactions with hydrogen halides:
C 2 H 5 OH + HBr → C 2 H 5 Br + H 2 O
Physical properties of alcohols
Lower alcohols (up to C 15) are liquids, higher alcohols are solids. Methanol and ethanol are mixed with water in any ratio. With growth molecular weight the solubility of alcohols in water decreases. Alcohols have high boiling and melting points due to the formation of hydrogen bonds.
Preparation of alcohols
The production of alcohols is possible using a biotechnological (fermentation) method from wood or sugar.
Laboratory methods for producing alcohols include:
- hydration of alkenes (the reaction occurs when heated and in the presence of concentrated sulfuric acid)
CH 2 = CH 2 + H 2 O → CH 3 OH
— hydrolysis of alkyl halides under the influence of aqueous solutions of alkalis
CH 3 Br + NaOH → CH 3 OH + NaBr
CH 3 Br + H 2 O → CH 3 OH + HBr
— reduction of carbonyl compounds
CH 3 -CH-O + 2[H] → CH 3 – CH 2 -OH
Examples of problem solving
EXAMPLE 1
| Exercise | The mass fractions of carbon, hydrogen and oxygen in the molecule of saturated monohydric alcohol are 51.18, 13.04 and 31.18%, respectively. Derive the formula of alcohol. |
| Solution | Let us denote the number of elements included in the alcohol molecule by the indices x, y, z. Then, the alcohol formula is general view will look like - C x H y O z . Let's write down the ratio: x:y:z = ω(С)/Ar(C): ω(Н)/Ar(Н) : ω(О)/Ar(О); x:y:z = 51.18/12: 13.04/1: 31.18/16; x:y:z = 4.208: 13.04: 1.949. Let's divide the resulting values by the smallest, i.e. at 1.949. We get: x:y:z = 2:6:1. Therefore, the alcohol formula is C 2 H 6 O 1. Or C 2 H 5 OH is ethanol. |
| Answer | The formula of saturated monohydric alcohol is C 2 H 5 OH. |
Derivatives of hydrocarbons, the molecules of which contain one or more hydroxyl groups OH.
All alcohols are divided into monatomic And polyatomic
Monohydric alcohols
Monohydric alcohols- alcohols that have one hydroxyl group.
There are primary, secondary and tertiary alcohols:
U primary alcohols the hydroxyl group is located at the first carbon atom, the secondary carbon atom is at the second, etc.
Properties of alcohols, which are isomeric, are similar in many ways, but they behave differently in some reactions.
By comparing the relative molecular mass of alcohols (Mr) with the relative atomic masses of hydrocarbons, it can be noted that alcohols have a higher boiling point. This is explained by the presence of a hydrogen bond between the H atom in the OH group of one molecule and the O atom in the -OH group of another molecule.
When alcohol is dissolved in water, hydrogen bonds are formed between the alcohol and water molecules. This explains the decrease in the volume of the solution (it will always be less than the sum of the volumes of water and alcohol separately).
Most a prominent representative chemical compounds of this class are ethanol. Its chemical formula is C 2 H 5 -OH. Concentrated ethanol(aka - wine spirit or ethanol) is obtained from diluted solutions by distillation; It has an intoxicating effect, and in large doses it is a strong poison that destroys living liver tissue and brain cells.
Formic alcohol (methyl) It should be noted that ethanol useful as a solvent, preservative, and a means of lowering the freezing point of any drug. Another equally famous representative of this class is methyl alcohol (it is also called - or woody methanol ). Unlike woody ethanol
deadly even in the smallest doses! First it causes blindness, then it simply “kills”!
Polyhydric alcohols Polyhydric alcohols
- alcohols having several OH hydroxyl groups. Dihydric alcohols are called alcohols containing two hydroxyl groups (OH group); alcohols containing three hydroxyl groups - trihydric alcohols
. In their molecules, two or three hydroxyl groups are never attached to the same carbon atom. Polyhydric alcohol - glycerin Dihydric alcohols also called glycols , since they have a sweet taste - this is typical for all
Polyhydric alcohols polyhydric alcohols with a small number of carbon atoms - these are viscous liquids, - higher alcohols. Polyhydric alcohols solids can be obtained by the same synthetic methods as.
saturated polyhydric alcohols
1. Preparation of alcohols Obtaining ethyl alcohol
(or wine alcohol) by fermentation of carbohydrates:
C 2 H 12 O 6 => C 2 H 5 -OH + CO 2 The essence of fermentation is that one of the simplest sugars - glucose, produced technically from starch, under the influence of yeast fungi, breaks down into ethyl alcohol and carbon dioxide. It has been established that the fermentation process is caused not by the microorganisms themselves, but by the substances they secrete -. To obtain ethyl alcohol, vegetable raw materials rich in starch are usually used: potato tubers, bread grains, rice grains, etc.
2. Hydration of ethylene in the presence of sulfuric or phosphoric acid
CH 2 =CH 2 + KOH => C 2 H 5 -OH
3. When haloalkanes react with alkali:
4. During the oxidation of alkenes
5. Hydrolysis of fats: in this reaction the well-known alcohol is obtained - glycerol
By the way, glycerol It is included in many cosmetic products as a preservative and as a means to prevent freezing and drying!
Properties of alcohols
1) Combustion: Like most organic substances, alcohols burn to form carbon dioxide and water:
C 2 H 5 -OH + 3O 2 -->2CO 2 + 3H 2 O
When they burn, a lot of heat is released, which is often used in laboratories (laboratory burners). Lower alcohols burn with an almost colorless flame, while higher alcohols have a yellowish flame due to incomplete combustion of carbon.
2) Reaction with alkali metals
C 2 H 5 -OH + 2Na --> 2C 2 H 5 -ONa + H 2
This reaction releases hydrogen and produces alcoholate sodium Alcoholates They are similar to salts of a very weak acid, and they are also easily hydrolyzed. Alcoholates are extremely unstable and when exposed to water they decompose into alcohol and alkali. From this it follows that monohydric alcohols do not react with alkalis!
3) Reaction with hydrogen halide
C 2 H 5 -OH + HBr --> CH 3 -CH 2 -Br + H 2 O
This reaction produces a haloalkane (bromoethane and water). This chemical reaction of alcohols is caused not only by the hydrogen atom in the hydroxyl group, but by the entire hydroxyl group! But this reaction is reversible: for it to occur, you need to use a water-removing agent, such as sulfuric acid.
4) Intramolecular dehydration (in the presence of catalyst H 2 SO 4)
In this reaction, under the action of concentrated sulfuric acid and heating occurs. During the reaction, unsaturated hydrocarbons and water are formed.
The abstraction of a hydrogen atom from an alcohol can occur in its own molecule (that is, a redistribution of atoms in the molecule occurs). This reaction is intermolecular dehydration reaction. For example, like this:
During the reaction, ether and water are formed.
If you add a carboxylic acid, such as acetic acid, to an alcohol, an ether will form. But esters are less stable than ethers. If the reaction of the formation of an ether is almost irreversible, then the formation of an ester is a reversible process. Esters easily undergo hydrolysis, breaking down into alcohol and carboxylic acid.
6) Oxidation of alcohols.
Alcohols are not oxidized by atmospheric oxygen at ordinary temperatures, but when heated in the presence of catalysts, oxidation occurs. An example is copper oxide (CuO), potassium permanganate (KMnO 4), chromium mixture. The action of oxidizing agents produces different products and depends on the structure of the original alcohol. Thus, primary alcohols are converted into aldehydes (reaction A), secondary alcohols are converted into ketones (reaction B), and tertiary alcohols are resistant to oxidizing agents.
Concerning , since they have a sweet taste - this is typical for all, they have a sweetish taste, but some of them are poisonous. Properties of polyhydric alcohols similar to monohydric alcohols, while the difference is that the reaction does not proceed one at a time to the hydroxyl group, but several at once.
One of the main differences is polyhydric alcohols easily react with copper hydroxide. This produces a transparent solution of a bright blue-violet color. It is this reaction that can detect the presence of a polyhydric alcohol in any solution.
Interact with nitric acid:
From point of view practical application The reaction with nitric acid is of greatest interest. Emerging nitroglycerine And dinitroethylene glycol used as explosives and trinitroglycerin- also in medicine, as a vasodilator.
Ethylene glycol
Ethylene glycol - typical representative , since they have a sweet taste - this is typical for all. Its chemical formula is CH 2 OH - CH 2 OH. - dihydric alcohol. This is a sweet liquid that can dissolve perfectly in water in any proportions. Chemical reactions can involve either one hydroxyl group (-OH) or two simultaneously.
Ethylene glycol- its solutions are widely used as an anti-icing agent ( antifreeze). Ethylene glycol solution freezes at a temperature of -34 0 C, which in the cold season can replace water, for example, for cooling cars.
With all the benefits ethylene glycol It must be taken into account that this is a very strong poison!
We've all seen glycerol. It is sold in pharmacies in dark vials and is a viscous, colorless liquid with a sweetish taste. - This trihydric alcohol
. It is very soluble in water and boils at a temperature of 220 0 C. glycerol are in many ways similar to the properties of monohydric alcohols, but glycerin can react with metal hydroxides (for example, copper hydroxide Cu(OH) 2), resulting in the formation of metal glycerates - chemical compounds, similar to salts.
The reaction with copper hydroxide is typical for glycerin. The chemical reaction produces a bright blue solution copper glycerate
Emulsifiers
Emulsifiers- This with a small number of carbon atoms - these are viscous liquids,, esters and other complex chemical substances, which when mixed with other substances, such as fats, form stable emulsions. By the way, everyone cosmetical tools are also emulsions! Substances that are artificial waxes (pentol, sorbitan oleate), as well as triethanolamine and lecithin are often used as emulsifiers.
Solvents
Solvents- These are substances used mainly for the preparation of hair and nail varnishes. They are presented in a small range, since most of these substances are highly flammable and harmful to the human body. The most common representative solvents is acetone, as well as amyl acetate, butyl acetate, isobutylate.
There are also substances called thinners. They are mainly used together with solvents for the preparation of various varnishes..
The content of the article
ALCOHOLS(alcohols) - a class of organic compounds containing one or more C–OH groups, with the hydroxyl group OH bonded to an aliphatic carbon atom (compounds in which the carbon atom in the C–OH group is part of the aromatic ring are called phenols)
The classification of alcohols is varied and depends on which structural feature is taken as a basis.
1. Depending on the number of hydroxyl groups in the molecule, alcohols are divided into:
a) monohydric (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, eliminating water: RCH(OH) 2 ® RCH=O + H 2 O
2. Based on 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. A carbon atom (highlighted in red) that is bonded to just one carbon atom is called primary. Examples of primary alcohols - ethanol CH 3 - C H 2 –OH, propanol CH 3 –CH 2 – C H2–OH.
b) secondary, in which the OH group is bonded to a secondary carbon atom. A secondary carbon atom (highlighted in blue) is bonded to two carbon atoms at the same time, for example, secondary propanol, secondary butanol (Fig. 1).
Rice. 1. STRUCTURE OF SECONDARY ALCOHOLS
c) tertiary, in which the OH group is bonded to the tertiary carbon atom. Tertiary carbon atom (highlighted green) is bonded simultaneously to three neighboring carbon atoms, for example, tertiary butanol and pentanol (Fig. 2).
Rice. 2. STRUCTURE OF TERTIARY ALCOHOLS
According to the type of carbon atom, the alcohol group attached to it is also called primary, secondary or tertiary.
In polyhydric alcohols containing two or more OH groups, both primary and secondary HO groups may 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 connected by an OH group, alcohols are divided into saturated (methanol, ethanol, propanol), unsaturated, for example, allyl alcohol CH 2 =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 is “adjacent” to the double bond, i.e. bonded to a carbon atom simultaneously involved in the formation of a double bond (for example, vinyl alcohol CH 2 =CH–OH), are extremely unstable and immediately isomerize ( cm ISOMERIZATION) to aldehydes or ketones:
CH 2 =CH–OH ® CH 3 –CH=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 ending “ new") and add the word "alcohol":
In the case where the structure of an organic group is more complex, 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 located closest. Next, this numbering is used to indicate the position of various substituents along the main chain; at the end of the name, the suffix “ol” and a number indicating the position of the OH group are added (Fig. 4):
Rice. 4. 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 follow 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, glycerin 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 СОН - are mixed with water in any ratio. With an increase in the number of C atoms in the organic group, a hydrophobic (water-repellent) effect begins to take effect, solubility in water becomes limited, and when R contains more than 9 carbon atoms, it practically disappears.
Due to the presence of OH groups, hydrogen bonds arise between alcohol molecules.
Rice. 5. HYDROGEN BONDS IN ALCOHOLS(shown in dotted line)
As a result, all alcohols have more heat boiling point than that of the corresponding hydrocarbons, for example, T. bp. ethanol +78° C, and T. boil. ethane –88.63° C; T. kip. butanol and butane, respectively, +117.4° C and –0.5° C.
Chemical properties of alcohols.
Alcohols have a variety of 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, increased (compared to monohydric alcohols) reactivity is observed due to the mutual influence of these groups. For alcohols, reactions are possible that involve the breaking of both C–O and O–H bonds.
1. Reactions occurring at the O–H 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, when exposed to water, hydrolyze 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 the 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 HO groups in polyhydric alcohols are attached to non-adjacent C atoms, the properties of alcohols are close to monoatomic ones, 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 molecule of the original alcohol (Fig. 8).
Rice. 8. BUTANOL RESTORATION
2. Reactions occurring at the C–O bond.
In the presence of catalysts or strong mineral acids, dehydration of alcohols (elimination of water) occurs, and the reaction can proceed in two directions:
a) intermolecular dehydration involving two alcohol molecules, in which the C–O bonds of one of the molecules are broken, resulting in the formation of ethers—compounds containing the R–O–R fragment (Fig. 9A).
b) intramolecular dehydration produces alkenes - 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 reaction directions are possible (Fig. 9B), the predominant direction is in which, during the condensation process, hydrogen is split off from the least hydrogenated carbon atom (marked by 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 cleavage of the C–O bond in alcohols also occurs when the OH group is replaced by a halogen or amino group (Fig. 10).
Rice. 10. REPLACEMENT OF OH-GROUP IN ALCOHOLS WITH HALOGEN OR AMINO GROUP
The reactions shown in Fig. 10 is used for the production of halocarbons and amines.
Preparation of alcohols.
Some of the reactions shown above (Fig. 6,9,10) are reversible and, when conditions change, 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 by hydration alkenes - by adding water (Fig. 11B).
Rice. eleven. OBTAINING ALCOHOLS BY HYDROLYSIS AND HYDRATION OF ORGANIC COMPOUNDS
The hydrolysis reaction of alkenes (Fig. 11, Scheme B) is the basis industrial production lower alcohols containing up to 4 C atoms.
Ethanol is also formed during the so-called alcoholic fermentation of sugars, for example, glucose C 6 H 12 O 6. The process occurs in the presence of yeast 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 at a higher concentration of alcohol the yeast fungi die. Higher concentration alcohol solutions 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 copper, chromium, and aluminum oxides:
CO + 2 H 2 ® H 3 COH
If instead of hydrolysis of alkenes (Fig. 11) oxidation is carried out, then dihydric alcohols are formed (Fig. 12)
Rice. 12. PREPARATION OF DIOHOMIC ALCOHOLS
Use of alcohols.
The ability of alcohols to participate in a variety of chemical reactions allows them to be used to produce 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, as well as in the production of formaldehyde, used to obtain phenol-formaldehyde resins, in Lately Methanol is considered as a promising motor fuel. Large volumes of methanol are used in production and transportation natural gas. Methanol is the most toxic compound among all alcohols, lethal dose when taken orally – 100 ml.
Ethanol C 2 H 5 OH is the starting compound for the production of acetaldehyde, acetic acid, as well as for the production of esters of carboxylic acids used as solvents. In addition, ethanol is the main component of all alcoholic beverages; it is 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 fragrant 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 contained in essential oils 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 scent, 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 for finishing and dyeing fabrics.
Glycerol HOCH 2 –CH(OH)–CH 2 OH is used to produce polyester glyphthalic 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 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 the explosive tetranitropentaerythritol.
Polyhydric alcohols xylitol СОН2–(СНН)3–CH2ОН and sorbitol СОН2– (СНН)4–СН2ОН have a sweet taste; they are used instead of sugar in production confectionery for diabetics and people suffering from obesity. Sorbitol is found in rowan and cherry berries.
Mikhail Levitsky
Not a single holiday is complete without alcoholic drinks. And, of course, everyone knows that any strong drink contains drinking ethyl alcohol. It is this substance that brings a person a feeling of pleasant euphoria and relaxation and the most severe symptoms of intoxication in case of its excessive use. But some alcohol brings death with it.
This is due to the production of surrogate alcohol, which uses not ethyl alcohol, but methyl alcohol, a toxic and extremely poisonous product. Both types of connections are practically no different in appearance, the only difference is their chemical composition. Let's figure out what the formula of drinking alcohol is in chemistry and what is the difference between it and methyl alcohol.
To avoid fatal poisoning, you should distinguish ethyl alcohol from methyl alcohol
The origins of acquaintance with alcohol go back to the legendary biblical past. Noah, having tasted fermented grape juice, experienced the feeling of a hangover for the first time. It is from this moment that the triumphant march of alcoholic products begins, the development of wine culture and numerous alcohol experiments.
Spiritus vini is the name given to drinking alcohol, which was created by distillation. That is, the distillation and evaporation of a liquid, followed by the deposition of vapor into a liquid form.
The ethanol formula was established in 1833
The starting point for winemaking and alcohol production was the 14th century.. It was from this time that the production of the “magic” liquid began in various countries with the creation and development of numerous techniques. The important stages in the spread of ethanol, as drinking alcohol is scientifically called, and its development include the following years:
- XIV century (30s). Wine alcohol was first discovered by the French alchemist Arnaud de'Villger, and the scientist was able to isolate it from wine.
- XIV century (80s). An Italian merchant introduced the ethyl alcohol compound to the ancient Slavs, bringing this substance to Moscow.
- XVI century (20s). The legendary Swiss doctor and alchemist Paracelsus began to study the properties of ethanol and discovered its main ability - to put people to sleep.
- XVIII century. For the first time, the hypnotic properties of ethyl alcohol were tested on humans. With his help, a patient who was being prepared for a complex operation was euthanized for the first time.
From that moment on, the rapid growth of the alcohol and vodka industry began. In our country alone, until the beginning of the revolution, more than 3,000 alcohol factories were actively operating. True, during the Second World War their number decreased sharply, by almost 90%. The revival began only in the late 40s of the last century. They began to remember ancient technologies and develop new ones.
Types of alcohol
Alcohol has many various modifications. Some types of alcohol come into close contact with food technologies, others are poisonous. To find out their action and influence on human body, you should understand their main characteristics.
Food (or drinking)
Or ethyl alcohol. It is obtained by rectification (the process of separating multicomponent mixtures using heat exchange between liquid and steam). The raw materials for its preparation are taken different kinds grains The chemical formula of drinking ethyl alcohol is as follows: C2H5OH.
How does ethyl alcohol work?
Food alcohol, which is part of alcohol, is perceived in most cases as vodka. It is precisely this that many individuals abuse, leading themselves to persistent alcohol dependence.
Food ethanol also has its own varieties (they depend on the types of raw materials that were used). The classification of drinking alcohol has the following types:
First grade alcohol (or medicinal)
It is not used to produce alcoholic beverages. This connection is intended for use exclusively in medical purposes as an antiseptic, disinfection of operating rooms and surgical instruments.
Alpha
High grade alcohol compound. For its production, selected high-quality wheat or rye is taken. It is on the basis of Alpha alcohol that elite super-premium alcoholic drinks are produced. For example:
- Bacardi rum;
- Absolut vodka;
- Jack Daniels whiskey;
- Johnnie Walker whiskey.
Lux
To produce drinking ethanol of this level, potatoes and grain are used, taking into account that the output volume of potato starch should not exceed 35%. The alcohol compound is passed through several stages of filtration. Premium vodka is produced from it. Such as:
- Husky;
- Rainbow;
- Beluga;
- Mammoth;
- Nemiroff;
- Stolichnaya;
- Russian gold;
- Russian standard.
These vodka drinks have several degrees of protection. They have a special bottle shape, specially designed holograms, and a unique cap.
How to check the quality of vodka products
Extra
On its basis, classic and familiar vodka of the mid-price segment is made. This drinking alcohol is diluted (its strength in undiluted form is about 95%) and, in addition, is subjected to additional purification. The final product has a lower content of esters and methanol. Alcohol based on this compound is considered an environmentally friendly product, although not as expensive as alcohol based on Alpha or Lux.
Basis
Practically not inferior to vodka ethanols Extra and Alpha. It has the same high strength (about 95%). Vodka made from this drinking alcohol is the most popular product, since it is the most accessible (middle price segment of the market). This brand of alcohol is produced from potatoes and grain, taking into account that the volume of potato starch in the resulting product does not exceed 60%.
Ethyl alcohol is widely used in medicine
Alcohol of the highest purification category
It is made from a mixture of the following products:
- corn;
- potato;
- molasses;
- sugar beet.
This connection is technological process undergoes minimal processing and filtering from various impurities and fusel oils. It is used to make cheap economy-class vodka, various tinctures and liqueurs.
Methyl alcohol (or technical)
A colorless, transparent substance, similar in smell to classic ethanol. But, unlike the latter, methanol is a highly toxic compound. The chemical formula of methanol (or wood alcohol) is CH3OH. If it enters the human body, this compound causes acute poisoning. A fatal outcome cannot be ruled out.
What is methyl alcohol
According to statistics, about 1,500 cases of methyl alcohol poisoning are diagnosed annually. Every fifth intoxication resulted in the death of a person.
Methyl alcohol has nothing to do with the production of alcoholic beverages and Food Industry. But surrogate alcohol is often diluted with this cheap product in order to reduce the cost of the resulting product. When interacting with organic structures Methanol turns into a terrible poison that has already destroyed many lives.
How to distinguish alcohols
It is extremely difficult to distinguish poisonous industrial alcohol from drinking alcohol. It is for this reason that cases of fatal poisoning occur. When, under the guise of ethanol, methanol is used to prepare alcoholic beverages.
But it is still possible to distinguish alcohol compounds. There are simple ways to do this that you can apply at home.
- With the help of fire. This is the easiest verification method. Just set fire to an alcoholic drink. Ethanol burns with a blue flame when burned, but the color of burning methanol is green.
- Using potatoes. Fill a piece with alcohol raw potatoes and leave for 2-3 hours. If the color of the vegetable has not changed, the vodka is of excellent quality and can be safely consumed for its intended purpose. But in the case when the potatoes have acquired a pinkish tint, this is a consequence of the presence of industrial alcohol in the alcohol.
- Using copper wire. The wire should be heated red-hot and lowered into the liquid. If there is a pungent, repulsive odor when it fizzes, there is methanol in the alcohol. Ethyl alcohol will not smell at all.
- Measuring the boiling point. Should be using regular thermometer measure the boiling point of alcohols. Please note that methanol boils at +64⁰С, and ethanol – at +78⁰С.
- Using baking soda and iodine. Pour the alcohol to be tested into a transparent container. Add a pinch of regular soda to it. Stir well and add iodine to it. Now hold the liquid up to the light. If there is sediment in it, this is evidence of the “purity” of the alcohol. Ethanol, when interacting with iodoform (iodine + soda), gives a yellowish suspension. But methanol does not change at all and remains transparent.
- Using potassium permanganate. Add a few crystals of potassium permanganate to the alcohol being tested. Once it dissolves and the liquid turns pink, heat it. If gas bubbles begin to be released when heated, you have poisonous methyl alcohol.
But it is worth considering that all these and similar household methods will not work if technical alcohol is initially mixed with ethanol in one product. In this case, only chemical examination can help. And a responsible approach to purchasing alcohol.
If assistance is not provided, death from methanol poisoning occurs after 2-3 hours
To avoid purchasing potentially dangerous alcohol, buy alcohol only in trusted places and specialized stores that inspire trust. Avoid underground shops and small stalls. This is where counterfeit products often spread.
Ways to use ethanol
Ethyl alcohol is used not only in the beloved alcohol industry. Its uses are varied and quite interesting. Check out just a few of the major uses for ethanol:
- fuel (rocket internal combustion engines);
- chemical (base for the manufacture of many different drugs);
- perfumery (when creating various perfume compositions and concentrates);
- paint and varnish (as a solvent, included in antifreeze, household cleaning chemicals, windshield washers);
- food (except for the production of alcohol, it is successfully used in the production of vinegar and various flavorings);
- medicine (the most popular area of application, as an antiseptic for the disinfection of wounds, during artificial ventilation of the lungs as an antifoam, is part of anesthesia and anesthesia, various medicinal tinctures, antibiotics and extracts).
By the way, ethyl alcohol is also used as an antidote for methanol poisoning. This is an effective antidote in case of industrial alcohol intoxication. It would be useful to recall the main signs of poisoning by alcohol surrogates:
- severe headache;
- profuse debilitating vomiting;
- piercing pain in the abdomen;
- feeling of complete weakness, immobility;
- respiratory depression, a person sometimes cannot even take a breath.
By the way, you can encounter exactly the same symptoms in the case of ordinary alcohol intoxication. Therefore, you should focus on the quantity alcohol taken. Industrial alcohol causes the development of this symptomatology when it enters the human body even in small quantities (from 30 ml, this is the standard volume of an ordinary glass).
In this case, you should immediately call Ambulance. Remember that if qualified assistance is not provided, the risk of death is very high.
To summarize, we can understand that being able to understand the types of alcohol and distinguish a toxic compound from drinking ethanol is very important. Do not forget that even if you consume a tiny amount of toxic methanol, you are putting your life at risk and bringing your body to a fatal point.
Which contain one or more hydroxyl groups. Depending on the number of OH groups, these are divided into monohydric alcohols, trihydric alcohols, etc. Most often, these complex substances are considered as derivatives of hydrocarbons, the molecules of which have undergone changes, because one or more hydrogen atoms have been replaced by a hydroxyl group.
The simplest representatives of this class are monohydric alcohols, general formula which looks like this: R-OH or
Cn+H 2n+1OH.
- Alcohols containing up to 15 carbon atoms are liquids, 15 or more are solids.
- Solubility in water depends on the molecular weight; the higher it is, the less soluble the alcohol is in water. Thus, lower alcohols (up to propanol) are mixed with water in any proportions, while higher alcohols are practically insoluble in it.
- The boiling point also increases with increasing atomic mass, for example, t kip. CH3OH = 65 °C, and boiling point. C2H5OH =78 °C.
- The higher the boiling point, the lower the volatility, i.e. the substance does not evaporate well.
Data physical properties saturated alcohols with one hydroxyl group can be explained by the occurrence of intermolecular hydrogen bonds between individual molecules of the compound itself or alcohol and water.
Monohydric alcohols are capable of entering into such chemical reactions:
Having examined the chemical properties of alcohols, we can conclude that monohydric alcohols are amphoteric compounds, because they can react with alkali metals, exhibiting weak properties, and with hydrogen halides, exhibiting basic properties. All chemical reactions involve breaking the O-H or C-O bond.
Thus, saturated monohydric alcohols are complex compounds with one OH group that do not have free valences after formation S-S connections and exhibiting weak properties of both acids and bases. Due to their physical and chemical properties, they are widely used in organic synthesis, in the production of solvents, fuel additives, as well as in the food industry, medicine, and cosmetology (ethanol).