Composition of an alcohol molecule. Monohydric alcohols, their physical and chemical properties

These are derivatives of hydrocarbons in which one hydrogen atom is replaced by a hydroxy group. The general formula of alcohols is CnH 2 n +1 OH.

Classification of monohydric alcohols.

Depending on the position where it is located HE-group, distinguish:

Primary alcohols:

Secondary alcohols:

Tertiary alcohols:

.

Isomerism of monohydric alcohols.

For monohydric alcohols characterized by isomerism of the carbon skeleton and isomerism of the position of the hydroxy group.

Physical properties of monohydric alcohols.

The reaction follows Markovnikov’s rule, so only song alcohol can be obtained from primary alkenes.

2. Hydrolysis of alkyl halides under the influence of aqueous solutions of alkalis:

If the heating is weak, then intramolecular dehydration occurs, resulting in the formation of ethers:

B) Alcohols can react with hydrogen halides, with tertiary alcohols reacting very quickly, while primary and secondary alcohols react slowly:

The use of monohydric alcohols.

Alcohols used primarily in industrial organic synthesis, in the food industry, medicine and pharmacy.

Hydrocarbon derivatives with one or more hydrogen atoms in the molecule replaced by an -OH group (hydroxyl group or hydroxy group) are alcohols. Chemical properties are determined by the hydrocarbon radical and hydroxyl group. Alcohols form a separate group in which each subsequent representative differs from the previous member by a homological difference corresponding to =CH2. All substances in this class can be represented by the formula: R-OH. For monoatomic saturated compounds, the general chemical formula is CnH2n+1OH. According to international nomenclature, names can be derived from hydrocarbons with the addition of the ending -ol (methanol, ethanol, propanol, and so on).

This is a very diverse and broad class of chemical compounds. Depending on the number of -OH groups in the molecule, it is divided into one-, two-, triatomic and so on - polyatomic compounds. The chemical properties of alcohols also depend on the content of hydroxy groups in the molecule. These substances are neutral and do not dissociate into ions in water, such as strong acids or strong bases. However, they can weakly exhibit both acidic (they decrease with increasing molecular weight and branching of the hydrocarbon chain in the series of alcohols) and basic (increasing with increasing molecular weight and branching of the molecule) properties.

The chemical properties of alcohols depend on the type and spatial arrangement of atoms: molecules come with chain isomerism and positional isomerism. Depending on the maximum number of single bonds of a carbon atom (linked to the hydroxy group) with other carbon atoms (with 1, 2 or 3), primary (normal), secondary or tertiary alcohols are distinguished. Primary alcohols have a hydroxyl group attached to the primary carbon atom. In secondary and tertiary - to secondary and tertiary, respectively. Starting with propanol, isomers appear that differ in the position of the hydroxyl group: propyl alcohol C3H7—OH and isopropyl alcohol CH3—(CHOH)—CH3.

It is necessary to name several main reactions that characterize the chemical properties of alcohols:

1. When reacting with or their hydroxides (deprotonation reaction), alcoholates are formed (the hydrogen atom is replaced by a metal atom), depending on the hydrocarbon radical, methylates, ethylates, propylates and so on are obtained, for example, sodium propoxide: 2CH3CH2OH + 2Na → 2CH3CH2ONa + H2.
2. When interacting with concentrated hydrohalic acids, HBr + CH3CH2OH ↔ CH3CH2Br + H2O are formed. This reaction is reversible. As a result, nucleophilic substitution of the hydroxyl group with a halogen ion occurs.
3. Alcohols can be oxidized to carbon dioxide, to aldehydes, or to ketones. Alcohols burn in the presence of oxygen: 3O2 + C2H5OH →2CO2 + 3H2O. Under the influence of a strong oxidizing agent (chromic acid, etc.), primary alcohols are converted into aldehydes: C2H5OH → CH3COH + H2O, and secondary alcohols are converted into ketones: CH3—(CHOH)—CH3 → CH3—(CHO)—CH3 + H2O.
4. The dehydration reaction occurs when heated in the presence of water-removing substances (sulfuric acid, etc.). As a result, alkenes are formed: C2H5OH → CH2=CH2 + H2O.
5. The esterification reaction also occurs when heated in the presence of water-subtracting compounds, but, unlike the previous reaction, at a lower temperature and with the formation of 2C2H5OH → C2H5-O-C2H5O. With sulfuric acid the reaction occurs in two stages. First, an ester of sulfuric acid is formed: C2H5OH + H2SO4 → C2H5O—SO2OH + H2O, then when heated to 140 ° C and in excess of alcohol, diethyl (often called sulfuric) ether is formed: C2H5OH + C2H5O—SO2OH → C2H5—O—C2H5O + H2SO4 .

The chemical properties of polyhydric alcohols, by analogy with their physical properties, depend on the type of hydrocarbon radical forming the molecule and, of course, the number of hydroxyl groups in it. For example, ethylene glycol CH3OH-CH3OH (boiling point 197 °C), which is a 2-atomic alcohol, is a colorless liquid (has a sweetish taste), which mixes with H2O, as well as lower alcohols in any ratio. Ethylene glycol, like its higher homologues, enter into all reactions characteristic of monohydric alcohols. Glycerol CH2OH—CHOH—CH2OH (boiling point 290 °C) is the simplest representative of 3-hydroxy alcohols. This is a thick, sweet-tasting liquid that cannot be mixed with it in any proportion. Dissolves in alcohol. Glycerol and its homologues are also characterized by all reactions of monohydric alcohols.

The chemical properties of alcohols determine the areas of their use. They are used as fuel (bioethanol or biobutanol and others), as solvents in various industries; as a raw material for the production of surfactants and detergents; for the synthesis of polymer materials. Some representatives of this class of organic compounds are widely used as lubricants or hydraulic fluids, as well as for the manufacture of medicines and biologically active substances.

Substances formed from saturated hydrocarbons and containing a hydroxyl group (-OH) are called saturated or saturated monohydric alcohols. The names of alcohols coincide with the names of alkanes in the homologous series with the suffix “-ol”.

Structure

The general formula of saturated monohydric alcohols is C n H 2n+1 -OH. Hydroxyl is a functional group and determines the physical and chemical properties of alcohols.

Main monohydric alcohols (homologous series of methanol):

• methanol or methyl alcohol - CH 3 OH;
• ethanol or ethyl alcohol - C 2 H 5 OH;
• propanol - C 3 H 7 OH;
• butanol - C 4 H 9 OH;
• pentanol - C 5 H 11 OH.

Rice. 1. Homologous series of monohydric alcohols.

Saturated alcohols are characterized by structural and interclass isomerism. Depending on the location of the hydroxyl group in the molecule, substances are distinguished:

• primary alcohols- hydroxyl is attached to the first carbon atom;
• secondary alcohols- hydroxyl is located at the second carbon atom;
• tertiary alcohols- hydroxyl is connected to the third carbon atom.

Starting with butanol, isomerism of the carbon skeleton is observed. In this case, the name of the alcohol is written with two numbers: the first indicates the position of the methyl group, the second - the hydroxyl.

Rice. 2. Isomerism of the carbon skeleton of saturated alcohols.

Monohydric alcohols form interclass isomers with ethers - ethyl alcohol (CH 3 CH 2 -OH), dimethyl ether (CH 3 -O-CH 3).

Despite the fact that propanol contains three carbon atoms, it can form only two isomers at the hydroxyl group - propanol-1 and propanol-2.

Properties

Depending on the number of carbon atoms, the state of aggregation of monohydric alcohols changes. If there are up to 15 carbon atoms in a molecule, then it is a liquid; more than 15 is a solid. The first two alcohols from the homologous series - methanol and ethanol, as well as the structural isomer propanol-2 - mix well with water. All alcohols melt and boil at high temperatures.

The activity of alcohols is explained by the presence of O-H and C-O bonds, which are easily broken. The main chemical properties of monohydric alcohols are given in the table.

Rice. 3. Qualitative reaction of monohydric alcohols.

Monohydric alcohols are widely used in industry. Ethanol is the most widely used. It is used to make perfumes, acetic acid, medicines, varnishes, dyes, solvents and other substances.

What have we learned?

From a chemistry lesson we learned that saturated or saturated monohydric alcohols are derivatives of saturated hydrocarbons with one hydroxyl group (hydroxyl). They are liquids or solids depending on the number of carbon atoms. Monohydric alcohols form isomers at the hydroxyl, methyl group and with ethers. Saturated monohydric alcohols react with alkali metals, acids, and oxides. Used to make medicines, solvents, acids.

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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 compounds are practically no different in appearance, only their chemical composition is different. 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:

1. 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.
2. XIV century (80s). An Italian merchant introduced the ethyl alcohol compound to the ancient Slavs, bringing this substance to Moscow.
3. 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.
4. 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-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 different modifications. Some types of alcohols come into close contact with food technologies, others are poisonous. To know their action and influence on the 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). Various types of grains are used as raw materials for its preparation. 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 compound is intended for use exclusively for 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.

During the technological process, this compound 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 the 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, which 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.

1. 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.
2. Using potatoes. Pour alcohol over a piece of raw potato 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.
3. 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.
4. Measuring the boiling point. You should use a regular thermometer to measure the boiling point of alcohols. Please note that methanol boils at +64⁰С, and ethanol – at +78⁰С.
5. Using 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.
6. 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 industrial 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, exactly the same symptoms can be encountered in the case of ordinary alcohol intoxication. Therefore, you should pay attention to the amount of alcohol consumed. 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 an 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.

Alcohols are complex organic compounds, hydrocarbons, necessarily containing one or more hydroxyls (OH- groups) associated with a hydrocarbon radical.

History of discovery

According to historians, already 8 centuries BC, people were drinking drinks containing ethyl alcohol. They were obtained by fermenting fruit or honey. In its pure form, ethanol was isolated from wine by the Arabs around the 6th-7th centuries, and by Europeans five centuries later. In the 17th century, methanol was obtained by distilling wood, and in the 19th century, chemists discovered that alcohols are a whole category of organic substances.

Classification

— Based on the number of hydroxyls, alcohols are divided into one-, two-, three-, and polyhydric. For example, monohydric ethanol; trihydric glycerol.
- Based on the number of radicals associated with the carbon atom connected to the OH- group, alcohols are divided into primary, secondary, and tertiary.
- Based on the nature of the radical bonds, alcohols are saturated, unsaturated, or aromatic. In aromatic alcohols, the hydroxyl is not connected directly to the benzene ring, but through other radical(s).
— Compounds in which OH— is directly linked to the benzene ring are considered a separate class of phenols.

Properties

Depending on how many hydrocarbon radicals are in the molecule, alcohols can be liquid, viscous, or solid. Water solubility decreases with increasing number of radicals.

The simplest alcohols are mixed with water in any proportions. If the molecule contains more than 9 radicals, then they do not dissolve in water at all. All alcohols dissolve well in organic solvents.
— Alcohols burn, releasing a large amount of energy.
- They react with metals, resulting in the formation of salts - alcoholates.
— Interact with bases, exhibiting the properties of weak acids.
— React with acids and anhydrides, exhibiting basic properties. The reactions result in esters.
— Exposure to strong oxidizing agents leads to the formation of aldehydes or ketones (depending on the type of alcohol).
— Under certain conditions, ethers, alkenes (compounds with a double bond), halohydrocarbons, amines (hydrocarbons derived from ammonia) are obtained from alcohols.

Alcohols are toxic to the human body, some are poisonous (methylene, ethylene glycol). Ethylene has a narcotic effect. Alcohol vapors are also dangerous, so work with alcohol-based solvents must be carried out in compliance with safety precautions.

However, alcohols participate in the natural metabolism of plants, animals and humans. The category of alcohols includes such vital substances as vitamins A and D, steroid hormones estradiol and cortisol. More than half of the lipids that supply energy to our body are based on glycerol.

Application

— In organic synthesis.
— Biofuels, fuel additives, brake fluid ingredient, hydraulic fluids.
- Solvents.
— Raw materials for the production of surfactants, polymers, pesticides, antifreeze, explosives and toxic substances, household chemicals.
— Fragrant substances for perfumery. Included in cosmetic and medical products.
— Base of alcoholic beverages, solvent for essences; sweetener (mannitol, etc.); coloring (lutein), flavoring (menthol).

In our store you can buy different types of alcohols.

Butyl alcohol

Monohydric alcohol. Used as a solvent; plasticizer at production of polymers; formaldehyde resin modifier; raw materials for organic synthesis and production of fragrant substances for perfumery; fuel additives.

Furfuryl alcohol

Monohydric alcohol. In demand for the polymerization of resins and plastics, as a solvent and film former in paint and varnish products; raw materials for organic synthesis; binding and compacting agent in the production of polymer concrete.

Isopropyl alcohol (2-propanol)

Secondary monohydric alcohol. It is actively used in medicine, metallurgy, and the chemical industry. A substitute for ethanol in perfumes, cosmetics, disinfectants, household chemicals, antifreeze, and cleaners.

Ethylene glycol

Dihydric alcohol. Used in the production of polymers; paints for printing houses and textile production; It is part of antifreeze, brake fluids, and coolants. Used for drying gases; as a raw material for organic synthesis; solvent; a means for cryogenic “freezing” of living organisms.

Glycerol

Trihydric alcohol. In demand in cosmetology, food industry, medicine, as a raw material in org. synthesis; for the manufacture of nitroglycerin explosive. It is used in agriculture, electrical engineering, textile, paper, leather, tobacco, paint and varnish industries, in the production of plastics and household chemicals.

Mannitol

Hexahydric (polyhydric) alcohol. Used as a food additive; raw materials for the manufacture of varnishes, paints, drying oils, resins; is part of surfactants and perfume products.