In the past, scientists divided all substances in nature into conditionally inanimate and living ones, including the animal and plant kingdoms among the latter. Substances of the first group are called mineral. And those that entered the second, began to be called organic substances.

What is meant by this? The class of organic substances is the most extensive among all chemical compounds known to modern scientists. The question of which substances are organic can be answered as follows - these are chemical compounds that include carbon.

Please note that not all carbon-containing compounds are organic. For example, corbides and carbonates, carbonic acid and cyanides, carbon oxides are not among them.

Why are there so many organic substances?

The answer to this question lies in the properties of carbon. This element is curious in that it is able to form chains from its atoms. And at the same time, the carbon bond is very stable.

In addition, in organic compounds, it exhibits a high valence (IV), i.e. ability to form chemical bonds with other substances. And not only single, but also double and even triple (otherwise - multiples). As the bond multiplicity increases, the chain of atoms becomes shorter, and the bond stability increases.

And carbon is endowed with the ability to form linear, flat and three-dimensional structures.

That is why organic substances in nature are so diverse. You can easily check it yourself: stand in front of a mirror and carefully look at your reflection. Each of us is a walking guide to organic chemistry. Think about it: at least 30% of the mass of each of your cells is organic compounds. The proteins that built your body. Carbohydrates, which serve as "fuel" and a source of energy. Fats that store energy reserves. Hormones that control organ function and even your behavior. Enzymes that start chemical reactions within you. And even the "source code," the strands of DNA, are all carbon-based organic compounds.

Composition of organic substances

As we said at the very beginning, the main building material for organic matter is carbon. And practically any elements, combining with carbon, can form organic compounds.

In nature, most often in the composition of organic substances are hydrogen, oxygen, nitrogen, sulfur and phosphorus.

The structure of organic substances

The diversity of organic substances on the planet and the diversity of their structure can be explained characteristic features carbon atoms.

You remember that carbon atoms are able to form very strong bonds with each other, connecting in chains. The result is stable molecules. The way in which carbon atoms chain together (arrange in a zigzag pattern) is one of the key features her buildings. Carbon can combine both into open chains and into closed (cyclic) chains.

It is also important that the structure chemical substances directly affects their chemical properties. A significant role is also played by how atoms and groups of atoms in a molecule affect each other.

Due to the peculiarities of the structure, the number of carbon compounds of the same type goes to tens and hundreds. For an example, consider hydrogen compounds carbon: methane, ethane, propane, butane, etc.

For example, methane - CH 4. This combination of hydrogen and carbon normal conditions is in a gaseous state of aggregation. When oxygen appears in the composition, a liquid is formed - methyl alcohol CH 3 OH.

Not only substances with different qualitative composition (as in the example above) exhibit different properties, but substances of the same qualitative composition are also capable of this. An example is the different ability of methane CH 4 and ethylene C 2 H 4 to react with bromine and chlorine. Methane is capable of such reactions only when heated or under ultraviolet light. And ethylene reacts even without lighting and heating.

Consider this option: the qualitative composition of chemical compounds is the same, the quantitative is different. Then the chemical properties of the compounds are different. As in the case of acetylene C 2 H 2 and benzene C 6 H 6.

Not the last role in this variety is played by such properties of organic substances, "tied" to their structure, as isomerism and homology.

Imagine that you have two seemingly identical substances - the same composition and the same molecular formula to describe them. But the structure of these substances is fundamentally different, hence the difference in chemical and physical properties. For example, the molecular formula C 4 H 10 can be written for two different substances: butane and isobutane.

We are talking about isomers- compounds that have the same composition and molecular weight. But the atoms in their molecules are located in a different order (branched and unbranched structure).

Concerning homology- this is a characteristic of such a carbon chain in which each next member can be obtained by adding one CH 2 group to the previous one. Each homologous series can be expressed by one general formula. And knowing the formula, it is easy to determine the composition of any of the members of the series. For example, methane homologues are described by the formula C n H 2n+2 .

As the “homologous difference” CH 2 is added, the bond between the atoms of the substance is strengthened. Let's take the homologous series of methane: its first four members are gases (methane, ethane, propane, butane), the next six are liquids (pentane, hexane, heptane, octane, nonane, decane), and then substances in the solid state of aggregation follow (pentadecane, eicosan, etc.). And the stronger the bond between carbon atoms, the higher molecular weight, boiling and melting points of substances.

What classes of organic substances exist?

Organic substances of biological origin include:

• proteins;
• carbohydrates;
• nucleic acids;
• lipids.

The first three points can also be called biological polymers.

A more detailed classification of organic chemicals covers substances not only of biological origin.

The hydrocarbons are:

• acyclic compounds:
  • saturated hydrocarbons (alkanes);
  • unsaturated hydrocarbons:
    • alkenes;
    • alkynes;
    • alkadienes.
• cyclic compounds:
  • carbocyclic compounds:
    • alicyclic;
    • aromatic.
  • heterocyclic compounds.

There are also other classes of organic compounds in which carbon combines with substances other than hydrogen:

• alcohols and phenols;
• aldehydes and ketones;
• carboxylic acids;
• esters;
• lipids;
• carbohydrates:
  • monosaccharides;
  • oligosaccharides;
  • polysaccharides.
  • mucopolysaccharides.
• amines;
• amino acids;
• proteins;
• nucleic acids.

Formulas of organic substances by classes

Examples of organic substances

As you remember, in the human body, various kinds of organic substances are the basis of the foundations. These are our tissues and fluids, hormones and pigments, enzymes and ATP, and much more.

In the bodies of humans and animals, proteins and fats are prioritized (half of the dry weight of an animal cell is protein). In plants (about 80% of the dry mass of the cell) - for carbohydrates, primarily complex - polysaccharides. Including for cellulose (without which there would be no paper), starch.

Let's talk about some of them in more detail.

For example, about carbohydrates. If it were possible to take and measure the masses of all organic substances on the planet, it would be carbohydrates that would win this competition.

They serve as a source of energy in the body, are building materials for cells, as well as carry out the supply of substances. Plants use starch for this purpose, and glycogen for animals.

In addition, carbohydrates are very diverse. For example, simple carbohydrates. The most common monosaccharides in nature are pentoses (including deoxyribose, which is part of DNA) and hexoses (glucose, which is well known to you).

Like bricks, at a large construction site of nature, polysaccharides are built from thousands and thousands of monosaccharides. Without them, more precisely, without cellulose, starch, there would be no plants. Yes, and animals without glycogen, lactose and chitin would have a hard time.

Let's look carefully at squirrels. Nature is the greatest master of mosaics and puzzles: from just 20 amino acids, 5 million types of proteins are formed in the human body. Proteins also have many vital functions. For example, construction, regulation of processes in the body, blood coagulation (there are separate proteins for this), movement, transport of certain substances in the body, they are also a source of energy, in the form of enzymes they act as a catalyst for reactions, provide protection. In protecting the body from negative external influences antibodies play an important role. And if a discord occurs in the fine tuning of the body, antibodies, instead of destroying external enemies, can act as aggressors to their own organs and tissues of the body.

Proteins are also divided into simple (proteins) and complex (proteins). And they have properties inherent only to them: denaturation (destruction, which you have noticed more than once when you boiled a hard-boiled egg) and renaturation (this property is widely used in the manufacture of antibiotics, food concentrates, etc.).

Let's not ignore and lipids(fats). In our body, they serve as a reserve source of energy. As solvents help the flow of bio chemical reactions. Participate in the construction of the body - for example, in the formation of cell membranes.

And a few more words about such curious organic compounds as hormones. They are involved in biochemical reactions and metabolism. These small hormones make men men (testosterone) and women women (estrogen). They make us happy or sad (thyroid hormones play an important role in mood swings, and endorphins give a feeling of happiness). And they even determine whether we are “owls” or “larks”. Are you ready to study late or do you prefer to get up early and do homework before school, decides not only your daily routine, but also some adrenal hormones.

Conclusion

The world of organic matter is truly amazing. It is enough to delve into its study just a little to take your breath away from the feeling of kinship with all life on Earth. Two legs, four or roots instead of legs - we are all united by the magic of mother nature's chemical laboratory. It causes carbon atoms to join in chains, react and create thousands of such diverse chemical compounds.

You now have a short guide to organic chemistry. Of course, not all possible information is presented here. Some points you may have to clarify on your own. But you can always use the route we have planned for your independent research.

You can also use the definition of organic matter given in the article, the classification and general formulas of organic compounds and general information about them to prepare for chemistry lessons at school.

Tell us in the comments which section of chemistry (organic or inorganic) you like best and why. Don't forget to share the article in social networks so your classmates can use it too.

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ORGANIC CHEMISTRY

Textbook for students of specialties 271200 "Technology of food products for special purposes and public catering", 351100 "Commodity science and examination of goods"

Introduction

Human use of organic substances and their isolation from natural sources has been dictated by practical needs since ancient times.

As a special branch of science, organic chemistry arose at the beginning of the 19th century and by now has reached enough high level development. Of the huge number of chemical compounds, most (over 5 million) contain carbon in their composition, and almost all of them are organic substances. Most organic compounds are substances obtained using new scientific methods. Natural compounds today are sufficiently studied substances and find new areas of application in human life support.

Currently, there is practically no industry National economy not related to organic chemistry: medicine, pharmacology, electronic technology, aviation and space, light and food industries, agriculture, etc.

A deep study of natural organic substances, such as fats, carbohydrates, proteins, vitamins, enzymes, and others, has opened up the possibility of interfering with metabolic processes, offering rational nutrition, and regulating physiological processes. Modern organic chemistry, thanks to the insight into the mechanisms of reactions occurring during the storage and processing of food products, made it possible to control them.

Organic substances have found application in the production of most consumer goods, in technology, in the production of dyes, cult goods, perfumes, the textile industry, etc.

Organic chemistry is an important theoretical base in the study of biochemistry, physiology, food production technology, commodity science, etc.

Classification of organic compounds

All organic compounds are divided according to the structure of the carbon skeleton:

1. Acyclic (aliphatic) compounds, having an open carbon chain, both straight and branched.

2-methylbutane

stearic acid

2. Carbocyclic compounds are compounds containing cycles of carbon atoms. They are divided into alicyclic and aromatic.

Alicyclic compounds are cyclic compounds that do not have aromatic properties.

cyclopentane

Aromatic substances include substances containing a benzene ring in the molecule, for example:
toluene

3. Heterocyclic compounds- substances containing cycles consisting of carbon atoms and heteroatoms, for example:

furan pyridine

The compounds of each section, in turn, are divided into classes that are derivatives of hydrocarbons, in their molecules hydrogen atoms are replaced by various functional groups:

halogen derivatives CH 3 -Cl; alcohols CH 3 -OH; nitro derivatives CH 3 -CH 2 -NO 2; amines CH 3 -CH 2 -NH 2; sulfonic acids CH 3 -CH 2 -SO 3 H; aldehydes CH 3 -HC \u003d O; carboxylic acids
and others.

Functional groups determine the chemical properties of organic compounds.

Depending on the number of hydrocarbon radicals associated with a particular carbon atom, the latter is called primary, secondary, tertiary and quaternary.

Classes of organic compounds

	homologous series	Functional group	Connection example	Name
	Limit hydrocarbons ( alkanes)
	Ethylene hydrocarbons ( alkenes)
	Acetylene hydrocarbons ( alkynes)
	Diene hydrocarbons ( alkadienes)			Butadiene-1,3
	aromatic hydrocarbons			Methylbenzene (toluene)
	Aldehydes			Propanal
				Propanone
End of table
	carboxylic acids			propanoic acid
	Esters			Ethyl acetate (acetic ethyl ester)
				ethylamine
	Amino acids			Aminoethanoic acid (glycine)
	Sulphonic acids			Benzenesulfonic acid

isomerism

isomerism- this is a phenomenon when substances, having the same quantitative and qualitative composition, differ in structure, physical and chemical properties.

Types of isomerism:

1. Structural isomerism:

a) Isomerism of the carbon skeleton.

2-methylpropane (isobutane)

b) Isomerism of the position of the double (triple) bond.

1-butene 2-butene

c) Isomerism of the position of the functional group.

1-propanol 2-propanol

2. Stereoisomerism (spatial):

a) Geometric: cis-, trans-isomerism. Due to the different spatial arrangement of substituents relative to the plane of the double bond; occurs due to the lack of rotation around the double bond.

cisbutene-2 ​​transbutene-2

b) Optical or mirror isomerism is a type of spatial isomerism (stereoisomerism) depending on the asymmetry of the molecule, i.e. from the spatial arrangement of four different atoms or groups of atoms around an asymmetric carbon atom. Optical isomers (stereoisomers) are related to each other like an object to its mirror image. Such optical isomers are called antipodes, and their mixtures in equal amounts of both are called racemic mixtures. In this case, they are optically inactive substances, since each of the isomers rotates the plane of polarization of light in the opposite direction. Lactic acid has 2 anitipods, the number of which is determined by the formula 2 n = number of isomers, where n is the number of asymmetric carbon atoms.

Many organic substances (hydroxy acids) are optically active substances. Each optically active substance has its own specific rotation of polarized light.

The fact of the optical activity of substances refers to all organic substances that have asymmetric carbon atoms in their composition (hydroxy acids, carbohydrates, amino acids, etc.).

All substances that contain a carbon atom, in addition to carbonates, carbides, cyanides, thiocyanates and carbonic acid, are organic compounds. This means that they are able to be created by living organisms from carbon atoms through enzymatic or other reactions. Today, many organic substances can be synthesized artificially, which allows the development of medicine and pharmacology, as well as the creation of high-strength polymer and composite materials.

Classification of organic compounds

Organic compounds are the most numerous class of substances. There are about 20 types of substances here. They are different in chemical properties, differ in physical qualities. Their melting point, mass, volatility and solubility, as well as state of aggregation under normal conditions are also different. Among them:

• hydrocarbons (alkanes, alkynes, alkenes, alkadienes, cycloalkanes, aromatic hydrocarbons);
• aldehydes;
• ketones;
• alcohols (dihydric, monohydric, polyhydric);
• ethers;
• esters;
• carboxylic acids;
• amines;
• amino acids;
• carbohydrates;
• fats;
• proteins;
• biopolymers and synthetic polymers.

This classification reflects the features of the chemical structure and the presence of specific atomic groups that determine the difference in the properties of a substance. IN general view the classification, which is based on the configuration of the carbon skeleton, which does not take into account the peculiarities of chemical interactions, looks different. According to its provisions, organic compounds are divided into:

• aliphatic compounds;
• aromatic substances;
• heterocyclic compounds.

These classes of organic compounds can have isomers in different groups of substances. The properties of the isomers are different, although their atomic composition may be the same. This follows from the provisions laid down by A. M. Butlerov. Also, the theory of the structure of organic compounds is the guiding basis for all research in organic chemistry. It is put on the same level with Mendeleev's Periodic Law.

The very concept of chemical structure was introduced by A. M. Butlerov. In the history of chemistry, it appeared on September 19, 1861. Previously, there were different opinions in science, and some scientists completely denied the existence of molecules and atoms. Therefore, in organic and inorganic chemistry there was no order. Moreover, there were no regularities by which it was possible to judge the properties of specific substances. At the same time, there were also compounds that, with the same composition, exhibited different properties.

The statements of A. M. Butlerov in many ways directed the development of chemistry in the right direction and created a solid foundation for it. Through it, it was possible to systematize the accumulated facts, namely, chemical or physical properties certain substances, the patterns of their entry into reactions, and so on. Even the prediction of ways to obtain compounds and the presence of some common properties made possible by this theory. And most importantly, A. M. Butlerov showed that the structure of a substance molecule can be explained in terms of electrical interactions.

The logic of the theory of the structure of organic substances

Since, before 1861, many in chemistry rejected the existence of an atom or a molecule, the theory of organic compounds became a revolutionary proposal for the scientific world. And since A. M. Butlerov himself proceeds only from materialistic conclusions, he managed to refute the philosophical ideas about organic matter.

He managed to show that the molecular structure can be recognized empirically through chemical reactions. For example, the composition of any carbohydrate can be determined by burning a certain amount of it and counting the resulting water and carbon dioxide. The amount of nitrogen in the amine molecule is also calculated during combustion by measuring the volume of gases and releasing the chemical amount of molecular nitrogen.

If we consider Butlerov's judgments about the chemical structure, which depends on the structure, in the opposite direction, then a new conclusion suggests itself. Namely: knowing the chemical structure and composition of a substance, one can empirically assume its properties. But most importantly, Butlerov explained that in organic matter there is a huge number of substances that exhibit different properties, but have the same composition.

General provisions of the theory

Considering and investigating organic compounds, A. M. Butlerov deduced some of the most important patterns. He combined them into the provisions of the theory explaining the structure of chemicals of organic origin. The provisions of the theory are as follows:

• in the molecules of organic substances, atoms are interconnected in a strictly defined sequence, which depends on valency;
• chemical structure is the direct order according to which atoms are connected in organic molecules;
• the chemical structure determines the presence of the properties of an organic compound;
• depending on the structure of molecules with the same quantitative composition, different properties of the substance may appear;
• all atomic groups involved in the formation of a chemical compound have mutual influence Each other.

All classes of organic compounds are built according to the principles of this theory. Having laid the foundations, A. M. Butlerov was able to expand chemistry as a field of science. He explained that due to the fact that carbon exhibits a valence of four in organic substances, the variety of these compounds is determined. The presence of many active atomic groups determines whether a substance belongs to a certain class. And it is precisely due to the presence of specific atomic groups (radicals) that physical and chemical properties appear.

Hydrocarbons and their derivatives

These organic compounds of carbon and hydrogen are the simplest in composition among all the substances of the group. They are represented by a subclass of alkanes and cycloalkanes (saturated hydrocarbons), alkenes, alkadienes and alkatrienes, alkynes (unsaturated hydrocarbons), as well as a subclass of aromatic substances. In alkanes, all carbon atoms are connected only by a single C-C connection yu, because of which not a single H atom can be built into the composition of the hydrocarbon.

In unsaturated hydrocarbons, hydrogen can be incorporated at the site of the double C=C bond. Also, the C-C bond can be triple (alkynes). This allows these substances to enter into many reactions associated with the reduction or addition of radicals. All other substances, for the convenience of studying their ability to enter into reactions, are considered as derivatives of one of the classes of hydrocarbons.

Alcohols

Alcohols are called organic chemical compounds more complex than hydrocarbons. They are synthesized as a result of enzymatic reactions in living cells. The most typical example is the synthesis of ethanol from glucose as a result of fermentation.

In industry, alcohols are obtained from halogen derivatives of hydrocarbons. As a result of the substitution of a halogen atom for a hydroxyl group, alcohols are formed. Monohydric alcohols contain only one hydroxyl group, polyhydric - two or more. An example of a dihydric alcohol is ethylene glycol. The polyhydric alcohol is glycerol. The general formula of alcohols is R-OH (R is a carbon chain).

Aldehydes and ketones

After alcohols enter into reactions of organic compounds associated with the elimination of hydrogen from the alcohol (hydroxyl) group, a double bond between oxygen and carbon closes. If this reaction takes place at the alcohol group located at the terminal carbon atom, then as a result of it, an aldehyde is formed. If the carbon atom with alcohol is not located at the end of the carbon chain, then the result of the dehydration reaction is the production of a ketone. The general formula of ketones is R-CO-R, aldehydes R-COH (R is the hydrocarbon radical of the chain).

Esters (simple and complex)

The chemical structure of organic compounds of this class is complicated. Ethers are considered as reaction products between two alcohol molecules. When water is separated from them, a compound is formed sample R-O-R. Reaction mechanism: elimination of a hydrogen proton from one alcohol and a hydroxyl group from another alcohol.

Esters are reaction products between an alcohol and an organic carboxylic acid. Reaction mechanism: elimination of water from the alcohol and carbon groups of both molecules. Hydrogen is split off from the acid (along the hydroxyl group), and the OH group itself is separated from the alcohol. The resulting compound is depicted as R-CO-O-R, where the beech R denotes radicals - the rest of the carbon chain.

Carboxylic acids and amines

Carboxylic acids are called special substances that play an important role in the functioning of the cell. The chemical structure of organic compounds is as follows: a hydrocarbon radical (R) with a carboxyl group (-COOH) attached to it. The carboxyl group can only be located at the extreme carbon atom, because the valency C in the (-COOH) group is 4.

Amines are simpler compounds that are derivatives of hydrocarbons. Here, any carbon atom has an amine radical (-NH2). There are primary amines in which the (-NH2) group is attached to one carbon (general formula R-NH2). In secondary amines, nitrogen combines with two carbon atoms (formula R-NH-R). Tertiary amines have nitrogen attached to three carbon atoms (R3N), where p is a radical, a carbon chain.

Amino acids

Amino acids - complex compounds, which exhibit the properties of both amines and acids of organic origin. There are several types of them, depending on the location of the amine group in relation to the carboxyl group. Alpha amino acids are the most important. Here the amine group is located at the carbon atom to which the carboxyl group is attached. This allows you to create peptide bond and synthesize proteins.

Carbohydrates and fats

Carbohydrates are aldehyde alcohols or keto alcohols. These are compounds with a linear or cyclic structure, as well as polymers (starch, cellulose, and others). Their essential role in the cell - structural and energy. Fats, or rather lipids, perform the same functions, only they participate in other biochemical processes. Chemically, fat is an ester of organic acids and glycerol.

Currently, more than 10 million organic compounds are known. Such a huge number of compounds requires a strict classification and uniform international nomenclature rules. This issue is given special attention in connection with the use of computer technology to create a variety of databases.

1.1. Classification

The structure of organic compounds is described using structural formulas.

A structural formula is an image of the sequence of binding atoms in a molecule using chemical symbols.

The concept of the sequence of connecting atoms in a molecule is directly related to the phenomenon isomerism, i.e., the existence of compounds of the same composition but different chemical structure, called structural isomers (isomers buildings). The most important characteristic of most inorganic compounds is compound, expressed by the molecular formula, e.g. hydrochloric acid HC1, sulfuric acid H 2 SO 4. For organic compounds, the composition and, accordingly, the molecular formula are not unambiguous characteristics, since many actually existing compounds can correspond to the same composition. For example, the structural isomers butane and isobutane, having the same molecular formula C 4 H 10, differ in the sequence of binding atoms and have different physicochemical characteristics.

The first classification criterion is the division of organic compounds into groups, taking into account the structure of the carbon skeleton (Scheme 1.1).

Scheme 1.1.Classification of organic compounds according to the structure of the carbon skeleton

Acyclic compounds are compounds with an open chain of carbon atoms.

Aliphatic (from the Greek.a leiphar- fat) hydrocarbons - the simplest representatives of acyclic compounds - contain only carbon and hydrogen atoms and can be rich(alkanes) and unsaturated(alkenes, alkadienes, alkynes). Their structural formulas often written in abbreviated (compressed) form, as shown in the example n-pentane and 2,3-dimethylbutane. In this case, the designation of single bonds is omitted, and identical groups are enclosed in brackets and the number of these groups is indicated.

The carbon chain can be unbranched(for example, in n-pentane) and branched(for example, in 2,3-dimethylbutane and isoprene).

Cyclic compounds are compounds with a closed chain of atoms.

Depending on the nature of the atoms that make up the cycle, carbocyclic and heterocyclic compounds are distinguished.

Carbocyclic compounds contain only carbon atoms in the cycle and are divided into aromatic And alicyclic(cyclic non-aromatic). The number of carbon atoms in the cycles can be different. Large cycles (macrocycles) are known, consisting of 30 carbon atoms or more.

For the image of cyclic structures are convenient skeletal formulas, in which the symbols of carbon and hydrogen atoms are omitted, but the symbols of the remaining elements (N, O, S, etc.) are indicated. Such

formulas, each corner of the polygon means a carbon atom with the required number of hydrogen atoms (taking into account the tetravalence of the carbon atom).

The ancestor of aromatic hydrocarbons (arenes) is benzene. Naphthalene, anthracene and phenanthrene are polycyclic arenes. They contain fused benzene rings.

Heterocyclic compounds contain in the cycle, in addition to carbon atoms, one or more atoms of other elements - heteroatoms (from the Greek. heteros- other, different): nitrogen, oxygen, sulfur, etc.

A wide variety of organic compounds can be considered as a whole as hydrocarbons or their derivatives obtained by introducing functional groups into the structure of hydrocarbons.

A functional group is a heteroatom or a group of non-hydrocarbon atoms that determines whether a compound belongs to a certain class and is responsible for its chemical properties.

The second, more significant classification criterion is the division of organic compounds into classes depending on the nature of the functional groups. General formulas and names of the most important classes are given in Table. 1.1.

Compounds with one functional group are called monofunctional (for example, ethanol), with several identical functional groups - polyfunctional (for example,

Table 1.1.The most important classes of organic compounds

* Double and triple bonds are sometimes referred to as functional groups.

** Occasionally used name thioethers should not be used because it

refers to sulfur-containing esters (see 6.4.2).

glycerol), with several different functional groups - heterofunctional (for example, colamine).

The compounds of each class are homologous series, i.e. a group of related compounds with the same type of structure, each subsequent member of which differs from the previous one by the homological difference CH 2 in the hydrocarbon radical. For example, the closest homologues are ethane С 2 H 6 and propane C s H 8, methanol

CH 3 OH and ethanol CH 3 CH 2 OH, propane CH 3 CH 2 COOH and butane CH 3 CH 2 CH 2 COOH acids. Homologues have close chemical properties and regularly changing physical properties.

1.2. Nomenclature

The nomenclature is a system of rules that allows you to give an unambiguous name to each individual compound. For medicine, knowledge of the general rules of nomenclature is especially great importance, since the names of numerous medicines are built in accordance with them.

Currently generally accepted IUPAC systematic nomenclature(IUPAC - International Union of Pure and Applied Chemistry)*.

However, they are still preserved and widely used (especially in medicine) trivial(ordinary) and semi-trivial names used even before the structure of matter became known. These names may reflect natural springs and methods of preparation, especially noticeable properties and applications. For example, lactose (milk sugar) is isolated from milk (from lat. lactum- milk), palmitic acid - from palm oil, pyruvic acid obtained by pyrolysis of tartaric acid, the name of glycerin reflects its sweet taste (from the Greek. glykys- sweet).

Trivial names especially often have natural compounds - amino acids, carbohydrates, alkaloids, steroids. The use of some established trivial and semi-trivial names is permitted by IUPAC rules. Such names include, for example, "glycerol" and the names of many well-known aromatic hydrocarbons and their derivatives.

* IUPAC Nomenclature Rules for Chemistry. T. 2. - Organic chemistry / per. from English. - M.: VINITI, 1979. - 896 p.; Khlebnikov A.F., Novikov M.S. Modern nomenclature of organic compounds, or How to correctly name organic substances. - St. Petersburg: NPO "Professional", 2004. - 431 p.

In the trivial names of disubstituted benzene derivatives, the mutual arrangement of substituents in the ring is indicated by prefixes ortho- (o-)- for nearby groups meta- (m-) through one carbon atom and para-(n-)- against. For example:

To use the IUPAC systematic nomenclature, you need to know the content of the following nomenclature terms:

organic radical;

ancestral structure;

Characteristic group;

Deputy;

Lokant.

Organic radical* - the rest of the molecule from which one or more hydrogen atoms are removed and one or more valences remain free.

Hydrocarbon radicals of the aliphatic series have common name - alkyls(in general formulas denoted by R), aromatic radicals - aryls(Ar). The first two representatives of alkanes - methane and ethane - form monovalent radicals methyl CH 3 - and ethyl CH 3 CH 2 -. The names of monovalent radicals are usually formed by replacing the suffix -en suffix -ill.

A carbon atom bonded to only one carbon atom (i.e. terminal) is called primary, with two - secondary, with three - tertiary with four - Quaternary.

* This term should not be confused with the term "free radical", which characterizes an atom or group of atoms with an unpaired electron.

Each subsequent homologue, due to the disequilibrium of carbon atoms, forms several radicals. When a hydrogen atom is removed from the terminal carbon atom of propane, a radical is obtained n-propyl (normal propyl), and from the secondary carbon atom - the isopropyl radical. Butane and isobutane each form two radicals. Letter n-(which is allowed to be omitted) before the name of the radical indicates that the free valency is at the end of the straight chain. Prefix second- (secondary) means that the free valency is at the secondary carbon atom, and the prefix tert- (tertiary) - in the tertiary.

ancestral structure - the chemical structure that forms the basis of the called compound. In acyclic compounds, the parent structure is considered main chain of carbon atoms, in carbocyclic and heterocyclic compounds - cycle.

characteristic group - a functional group associated with the parent structure or partly included in its composition.

Deputy- any atom or group of atoms that replaces a hydrogen atom in an organic compound.

Lokant(from lat. locus- place) a number or letter indicating the position of a substituent or multiple bond.

Two types of nomenclature are most widely used: substitutional and radical-functional.

1.2.1. Substitutive nomenclature

The general design of the name by substitutive nomenclature is shown in Scheme 1.2.

Scheme 1.2.General construction of the name of the compound according to the replacement nomenclature

The name of an organic compound is compound word, including the name of the parent structure (root) and the names of different types of substituents (in the form of prefixes and suffixes), reflecting their nature, location and number. Hence the name of this nomenclature - replacement.

Substituents are divided into two types:

Hydrocarbon radicals and characteristic groups, denoted only by prefixes (Table 1.2);

Characteristic groups, denoted by both prefixes and suffixes, depending on seniority (Table 1.3).

To compile the name of an organic compound according to substitutive nomenclature, the following sequence of rules is used.

Table 1.2.Some characteristic groups, denoted only by prefixes

Table 1.3.Prefixes and suffixes used to designate the most important characteristic groups

* The carbon atom marked in color is included in the parent structure.

** Most phenols have trivial names.

Rule 1 Choice of the senior characteristic group. All available substituents are identified. Among the characteristic groups, the senior group (if present) is determined using the seniority scale (see Table 1.3).

Rule 2 Determination of the ancestral structure. The main chain of carbon atoms is used as the parent structure in acyclic compounds, and the main cyclic structure in carbocyclic and heterocyclic compounds.

The main chain of carbon atoms in acyclic compounds is selected according to the criteria below, with each subsequent criterion being used if the previous one does not lead to an unambiguous result:

The maximum number of characteristic groups denoted by both prefixes and suffixes;

Maximum number of multiple bonds;

Maximum chain length of carbon atoms;

The maximum number of characteristic groups denoted by prefixes only.

Rule 3 The numbering of the parent structure. The parent structure is numbered so that the highest characteristic group gets the smallest locant. If the choice of numbering is ambiguous, then the rule of least locants is applied, i.e., they are numbered so that the substituents receive the smallest numbers.

Rule 4 The name of the parental structure block with the senior characteristic group. In the name of the ancestral structure, the degree of saturation is reflected by suffixes: -en in the case of a saturated carbon skeleton, -en - in the presence of double and -in - triple bond. A suffix is ​​attached to the name of the ancestral structure, denoting the senior characteristic group.

Rule 5 Names of substituents (except for the senior characteristic group). Name the substituents, denoted by prefixes in alphabetical order. The position of each substituent and each multiple bond is indicated by the numbers corresponding to the number of the carbon atom to which the substituent is bound (for a multiple bond, only the smallest number is indicated).

In Russian terminology, numbers are placed before prefixes and after suffixes, for example, 2-aminoethanol H 2 NCH 2 CH 2 OH, butadiene-1,3

CH 2 \u003d CH-CH \u003d CH 2, propanol-1 CH 3 CH 2 CH 2 OH.

To illustrate these rules, examples of the construction of the names of a number of compounds in accordance with the general scheme 1.2 are given below. In each case, the features of the structure and the way they are reflected in the name are noted.

Scheme 1.3.Construction of a systematic name for halothane

2-bromo-1,1,1-trifluoro-2-chloroethane (an agent for inhalation anesthesia)

If the compound has several identical substituents at the same carbon atom, the locant is repeated as many times as there are substituents, with the addition of the appropriate multiplying prefix (Scheme 1.3). Substituents are listed alphabetically, with the multiplying prefix (in this example - three-) are not taken into account in alphabetical order. Scheme 1.4. Building a systematic name for the citral

after suffix -al, as for the combination -oic acid, you can not indicate the position of the characteristic groups, since they are always at the beginning of the chain (Scheme 1.4). Double bonds reflect suffix -diene with the corresponding locants in the name of the parent structure.

The suffix denotes the highest of the three characteristic groups (Scheme 1.5); other substituents, including non-senior characteristic groups, are listed alphabetically as prefixes.

Scheme 1.5.Construction of a systematic name for penicillamine

Scheme 1.6.Construction of a systematic name for oxaloacetic acid

oxobutanedioic acid (product of carbohydrate metabolism)

Multiply prefix di- before combination -oic acid indicates the presence of two senior characteristic groups (Scheme 1.6). Lokant before oxo- omitted because a different position of the oxo group corresponds to the same structure.

Scheme 1.7.Building a systematic name for menthol

The numbering in the cycle is from the carbon atom to which the highest characteristic group (OH) is associated (Scheme 1.7), despite the fact that the smallest set of locants of all substituents in the ring can be 1,2,4-, and not 1,2,5 - (as in the example under consideration).

Scheme 1.8.Construction of a systematic name for pyridoxal

ISubstituents: HYDROXYMETHYL, HYDROXY, METHYL I

An aldehyde group whose carbon atom is not included in the parent structure (Scheme 1.8) is denoted by the suffix -carbal dehyde (see Table 1.3). Group -CH 2 OH is considered as a composite substituent and is called "hydroxymethyl", that is, methyl, in which the hydrogen atom is in turn replaced by a hydroxyl group. Other examples of compound substituents: dimethylamino- (CH 3) 2 N-, ethoxy- (short for ethyloxy) C 2 H 5 O-.

1.2.2. Radical-functional nomenclature

Radical-functional nomenclature is used less frequently than substitutional nomenclature. It is mainly used for such classes of organic compounds as alcohols, amines, ethers, sulfides, and some others.

For compounds with one functional group, the common name includes the name of the hydrocarbon radical, and the presence of a functional group is reflected indirectly through the name of the corresponding class of compounds adopted in this type of nomenclature (Table 1.4).

Table 1.4.Names of compound classes used in radical functional nomenclature*

1.2.3. Building a structure by systematic name

Depicting a structure from a systematic name is usually an easier task. First, the parent structure is written down - an open chain or a cycle, then carbon atoms are numbered and substituents are arranged. In conclusion, hydrogen atoms are added with the condition that each carbon atom is tetravalent.

As an example, the construction of the structures of the drug PAS (short for para-aminosalicylic acid, systematic name - 4-amino-2-hydroxybenzoic acid) and citric (2-hydroxypropane-1,2,3-tricarboxylic) acid is given.

4-Amino-2-hydroxybenzoic acid

Parental structure - the trivial name of the cycle with the highest characteristic

group (COOH):

The arrangement of substituents is a group at the C-4 atom and an OH group at the C-2 atom:

2-Hydroxypropane-1,2,3-tricarboxylic acid

Main carbon chain and numbering:

The arrangement of substituents is three COOH groups (-tricarboxylic acid) and an OH group at the C-2 atom:

Addition of hydrogen atoms:

It should be noted that in the systematic name of citric acid, propane, not a longer chain - pentane, since it is impossible to include carbon atoms of all carboxyl groups in a five-carbon chain.

With the development of chemical science and the advent of a large number new chemical compounds, the need to develop and adopt a naming system understandable to scientists all over the world, i.e. . Next, we give an overview of the main nomenclatures of organic compounds.

Trivial nomenclature

In the origins of the development of organic chemistry, new compounds were attributed trivial names, i.e. names that have developed historically and are often associated with the way they were obtained, appearance and even taste, etc. Such a nomenclature of organic compounds is called trivial. The table below shows some of the compounds that have retained their names to this day.

Rational nomenclature

With the expansion of the list of organic compounds, it became necessary to associate their name with the Base of Rational Nomenclature of Organic Compounds is the name of the simplest organic compound. For example:

However, more complex organic compounds cannot be assigned names in this way. In this case, the compounds should be named according to the rules of IUPAC systematic nomenclature.

IUPAC systematic nomenclature

IUPAC (IUPAC) - International Union of Pure and Applied Chemistry (International Union of Pure and Applied Chemistry).

In this case, when naming compounds, one should take into account the location of carbon atoms in the molecule and structural elements. The most commonly used is the substitutional nomenclature of organic compounds, i.e. stands out basic foundation a molecule in which hydrogen atoms are replaced by some structural units or atoms.

Before you start building the names of compounds, we advise you to learn the names numeric prefixes, roots and suffixes used in IUPAC nomenclature.

As well as the names of functional groups:

Numerals are used to indicate the number of multiple bonds and functional groups:

Limit hydrocarbon radicals:

Unsaturated hydrocarbon radicals:

Aromatic hydrocarbon radicals:

Rules for constructing the name of an organic compound according to the IUPAC nomenclature:

1. Select the main chain of the molecule

Determine all functional groups present and their precedence

Determine the presence of multiple bonds

1. Number the main chain, and the numbering should start from the end of the chain closest to the senior group. If there are several such possibilities, the chain is numbered so that either the multiple bond or another substituent present in the molecule receives the minimum number.

Carbocyclic compounds are numbered starting from the carbon atom associated with the highest characteristic group. If there are two or more substituents, they try to number the chain so that the substituents have the minimum numbers.

1. Create a connection name:

- Determine the basis of the name of the compound that makes up the root of the word that denotes saturated hydrocarbon with the same number of atoms as the main chain.

- After the stem of the name, a suffix follows, showing the degree of saturation and the number of multiple bonds. For example, - tetraene, diene. In the absence of multiple bonds, use the suffix - sk.

- Then, also the name of the senior functional group.

— This is followed by a listing of the alternates in alphabetical order, indicating their location in Arabic numerals. For example, - 5-isobutyl, - 3-fluorine. In the presence of several identical substituents, their number and position are indicated, for example, 2,5 - dibromo-, 1,4,8-trimethy-.

It should be noted that numbers are separated from words by a hyphen, and between themselves by commas.

As example Let's name the following connection:

1. Choose main circuit, which must include senior group - COOH.

Define others functional groups: - OH, - Cl, - SH, - NH 2.

Multiple bonds No.

2. We number the main chain starting with the older group.

3. The number of atoms in the main chain is 12. Name basis

10-amino-6-hydroxy-7-chloro-9-sulfanyl-methyl ester of dodecanoic acid.

10-amino-6-hydroxy-7-chloro-9-sulfanyl-methyldodecanoate

Nomenclature of optical isomers

1. In some classes of compounds, such as aldehydes, hydroxy and amino acids, the mutual arrangement of substituents is indicated by D, L- nomenclature. letter D denote the configuration of the dextrorotatory isomer, L- left-handed.

At the core D,L-the nomenclature of organic compounds are Fischer projections:

• α-amino acids and α-hydroxy acids isolate the "oxy-acid key", i.e. upper parts of their projection formulas. If the hydroxyl (amino-) group is located on the right, then this D-isomer, left L-isomer.

For example, the tartaric acid shown below has D- configuration by oxy-acid key:

• to determine isomer configurations sugars isolate the "glycerin key", i.e. compare the lower parts (lower asymmetric carbon atom) of the sugar projection formula with the lower part of the projection formula glyceraldehyde.

The designation of the sugar configuration and the direction of rotation is similar to the configuration of glyceraldehyde, i.e. D– the configuration corresponds to the location of the hydroxyl group is located on the right, L configurations on the left.

For example, below is D-glucose.

2) R-, S-nomenclature (Kahn, Ingold and Prelog nomenclature)

In this case, the substituents at the asymmetric carbon atom are arranged in order of precedence. Optical isomers are designated R And S, and the racemate RS.

To describe the connection configuration according to R,S-nomenclature proceed as follows:

1. All substituents on the asymmetric carbon atom are determined.
2. The seniority of the deputies is determined, i.e. compare them atomic masses. The rules for determining the seniority series are the same as when using the E/Z nomenclature of geometric isomers.
3. The substituents are oriented in space so that the junior substituent (usually hydrogen) is in the corner furthest from the observer.
4. The configuration is determined by the location of the remaining substituents. If the movement from the senior to the middle and then to the junior deputy (i.e., in order of decreasing seniority) is carried out clockwise, then this is the R configuration, counterclockwise - the S-configuration.

The table below lists the deputies in ascending order of precedence:

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