Kazakh Humanitarian-Legal Innovative University

Department: Information Technology and Economics

On the topic: "Classification organic compounds. Communication types. Specific properties of organic compounds. Structural formulas. Isomerism.»

Completed by: Student of the 1st year, group E-124

Uvashov Azamat

Checked: Abylkasymova B. B

Semey 2010

1. Introduction

2. Classification of organic compounds

3. Types of communication

4. Structural formulas

5. Specific properties of organic compounds

6. Isomerism

Introduction

It is difficult to imagine progress in any field of the economy without chemistry - in particular, without organic chemistry. All spheres of the economy are connected with modern chemical science and technology.

Organic chemistry studies substances containing carbon in their composition, with the exception of carbon monoxide, carbon dioxide and carbonic acid salts (these compounds are closer in properties to inorganic compounds).

As a science, organic chemistry did not exist until the middle of the 18th century. By that time, three types of chemistry were distinguished: animal, plant and mineral chemistry. animal chemistry studied the substances that make up animal organisms; vegetable- substances that make up plants; mineral- substances included in the composition inanimate nature. This principle, however, did not allow one to separate organic substances from inorganic ones. For example, succinic acid belonged to the group of mineral substances, since it was obtained by distillation of fossil amber, potash was included in the group of plant substances, and calcium phosphate was in the group of animal substances, since they were obtained by calcining, respectively, plant (wood) and animal (bones) materials .

In the first half of the 19th century, it was proposed to separate carbon compounds into an independent chemical discipline - organic chemistry.

Among scientists at that time dominated vitalistic worldview, according to which organic compounds are formed only in a living organism under the influence of a special, supernatural "life force". This meant that it was impossible to obtain organic substances by synthesis from inorganic ones, that there was an unbridgeable gulf between organic and inorganic compounds. Vitalism became so entrenched in the minds of scientists that for a long time no attempts were made to synthesize organic substances. However, vitalism was refuted by practice, by chemical experiment.

The development of organic chemistry has now reached a level that makes it possible to begin solving such a fundamental problem of organic chemistry as the problem of the quantitative relationship between the structure of a substance and its properties, which can be any physical property, biological activity of any strictly specified type, the solution of problems of this type is carried out using mathematical methods.

Classification of organic compounds.

A huge number of organic compounds are classified taking into account the structure of the carbon chain (carbon skeleton) and the presence of functional groups in the molecule.

The diagram shows the classification of organic compounds depending on the structure of the carbon chain.

		organic compounds
Acyclic (aliphatic) (open circuit connections)				Cyclic (closed circuit connections)
Saturated (marginal)		Unsaturated (unsaturated)		Carbocyclic (the cycle consists of only carbon atoms)		Heterocyclic (the cycle consists of carbon atoms and other elements)
			Alicyclic (aliphatic cyclic)		aromatic

Hydrocarbons are taken as the basis for the classification, they are considered basic compounds in organic chemistry. All other organic compounds are considered as their derivatives.

When systematizing hydrocarbons, the structure of the carbon skeleton and the type of bonds connecting carbon atoms are taken into account.

I. ALIPHATIC (aleiphatos. Greek oil) hydrocarbons are linear or branched chains and do not contain cyclic fragments, they form two large groups.

1. Limit or saturated hydrocarbons (so named because they are not able to attach anything) are chains of carbon atoms connected by simple bonds and surrounded by hydrogen atoms. In the case when the chain has branches, a prefix is ​​added to the name iso. The simplest saturated hydrocarbon is methane, and a number of these compounds begin with it.

SATURATED HYDROCARBONS

VOLUME MODELS OF SATURATED HYDROCARBONS. The valencies of carbon are directed to the vertices of the mental tetrahedron, as a result, the chains of saturated hydrocarbons are not straight lines, but broken lines.

The main sources of saturated hydrocarbons are oil and natural gas. The reactivity of saturated hydrocarbons is very low, they can only react with the most aggressive substances, such as halogens or nitric acid. When saturated hydrocarbons are heated above 450 ° C without air, they break C-C connections and compounds with a shortened carbon chain are formed. High-temperature exposure in the presence of oxygen leads to their complete combustion to CO 2 and water, which allows them to be effectively used as a gaseous (methane - propane) or liquid motor fuel (octane).

When one or more hydrogen atoms are replaced by some functional (i.e., capable of subsequent transformations) group, the corresponding hydrocarbon derivatives are formed. Compounds containing the C-OH group are called alcohols, HC=O - aldehydes, COOH - carboxylic acids (the word "carboxylic" is added in order to distinguish them from ordinary mineral acids, for example, hydrochloric or sulfuric). A compound may simultaneously contain various functional groups, for example, COOH and NH 2, such compounds are called amino acids. The introduction of halogens or nitro groups into the composition of the hydrocarbon leads, respectively, to halogen or nitro derivatives.

UNSATURATED HYDROCARBONS in the form of volumetric models. The valencies of two carbon atoms connected by a double bond are located in the same plane, which can be observed at certain angles of rotation, at which point the rotation of the molecules stops.

The most typical for unsaturated hydrocarbons is the addition by a multiple bond, which makes it possible to synthesize various organic compounds on their basis.

ALICYCLIC HYDROCARBONS. Due to the specific direction of the bonds at the carbon atom, the cyclohexane molecule is not a flat, but a bent cycle - in the form of an armchair (/ - /), which is clearly visible at certain rotation angles (at this moment, the rotation of the molecules stops)

In addition to those shown above, there are other options for connecting cyclic fragments, for example, they can have one common atom (the so-called spirocyclic compounds), or they can be connected in such a way that two or more atoms are common to both cycles (bicyclic compounds), by combining three and more cycles, the formation of hydrocarbon skeletons is also possible.

HETEROCYCLIC COMPOUNDS. Their names have developed historically, for example, furan got its name from furan aldehyde - furfural, obtained from bran ( lat. furfur - bran). For all the compounds shown, the addition reactions are difficult, and the substitution reactions are quite easy. Thus, these are aromatic compounds of the non-benzene type.

The aromatic nature of these compounds is confirmed by the planar structure of the cycles, which is clearly visible at the moment when their rotation is suspended.

The diversity of compounds of this class is further increased due to the fact that the heterocycle can contain two or more heteroatoms in the cycle.

TYPES OF COMMUNICATION

chemical bond- this is the interaction of particles (atoms, ions), carried out by the exchange of electrons. There are several types of communication.
In answering this question, one should dwell in detail on the characteristics of covalent and ionic bonds.
A covalent bond is formed as a result of the socialization of electrons (with the formation of common electron pairs), which occurs during the overlap of electron clouds. Electron clouds of two atoms participate in the formation of a covalent bond.
There are two main types of covalent bonds:

a) non-polar and b) polar.

a) A covalent non-polar bond is formed between non-metal atoms of the same chemical element. Simple substances have such a bond, for example, O 2; N 2 ; C 12 . You can give a scheme for the formation of a hydrogen molecule: (electrons are indicated by dots in the diagram).
b) A covalent polar bond is formed between atoms of different non-metals.

Schematically, the formation of a covalent polar bond in the HC1 molecule can be depicted as follows:

The total electron density is shifted towards chlorine, as a result of which a partial negative charge arises on the chlorine atom, and a partial positive charge on the hydrogen atom. Thus, the molecule becomes polar:

An ionic bond is a bond between ions, that is, charged particles formed from an atom or a group of atoms as a result of the addition or release of electrons. Ionic bonding is characteristic of salts and alkalis.

The essence of the ionic bond is best considered using the example of the formation of sodium chloride. Sodium, as an alkali metal, tends to donate an electron located on the outer electron layer. Chlorine, on the contrary, tends to attach one electron to itself. As a result, sodium donates its electron to chlorine. As a result, oppositely charged particles are formed - Na + and Cl - ions, which are attracted to each other. When answering, you should pay attention to the fact that substances consisting of ions are formed by typical metals and non-metals. They are ionic crystalline substances, i.e., substances whose crystals are formed by ions, not molecules.

After considering each type of connection, one should proceed to their comparative characteristics.

For covalent non-polar, polar and ionic bonds, the common thing is the participation in the formation of bonds of external electrons, which are also called valence. The difference lies in the extent to which the electrons participating in the formation of the bond become common. If these electrons equally belong to both atoms, then the bond is covalent non-polar; if these electrons are more toward one atom than the other, then the bond is covalently polar. If the electrons involved in the formation of a bond belong to the same atom, then the bond is ionic.

Metal bond - bond between ion-atoms in crystal lattice metals and alloys, carried out due to the attraction of freely moving (along the crystal) electrons (Mg, Fe).

All of the above differences in the mechanism of bond formation explain the difference in the properties of substances with different types connections.

STRUCTURAL FORMULA

Structural formula- This is a kind of chemical formula that graphically describes the arrangement and bond order of atoms in a compound, expressed on a plane. Bonds in structural formulas are indicated by valence lines.

Structural formulas are often used, where bonds with hydrogen atoms are not indicated by valence lines (type 2). In another type of structural formulas (skeletal) used for large molecules in organic chemistry, hydrogen atoms associated with carbon atoms are not indicated and carbon atoms are not indicated (type 3).

With the help of different types of symbols used in structural formulas, coordination bonds, hydrogen bonds, stereochemistry of molecules, delocalized bonds, charge localization, etc. are also indicated.

SPECIFIC PROPERTIES OF ORGANIC COMPOUNDS

The reactions of organic compounds have some specific features. Ions are usually involved in the reactions of inorganic compounds; These reactions proceed very quickly, sometimes instantaneously with normal temperature. Molecules usually participate in the reactions of organic compounds; in this case, some covalent bonds are broken, while others are formed. Such reactions proceed more slowly than ionic ones (for example, tens of hours), and in order to speed them up, it is often necessary to increase the temperature or add a catalyst. The most commonly used catalysts are acids and bases. Usually not one, but several reactions take place, so that the yield of the desired product is very often less than 50%. In this regard, in organic chemistry, not chemical equations are used, but reaction schemes without indicating stoichiometric ratios.

The reactions of organic compounds can proceed in a very complex way and it is not at all necessary to correspond to the simplest relative notation. Typically, a simple stoichiometric reaction actually occurs in several successive steps. As intermediate compounds (intermediates) in multistage processes, carbocations R+, carbanions R-, free radicals, carbenes: CX2, radical cations (for example, radical anions (for example, Ar) and other unstable particles that live for a fraction of a second) can appear. Detailed description of all changes that occur at the molecular level in the process of converting reactants into products is called the reaction mechanism.

The study of the influence of the structure of organic compounds on the mechanism of their reactions is studied by physical organic chemistry, the foundations of which were laid by K. Ingold, Robinson and L. Hammett (1930s).

The reactions of organic compounds can be classified depending on the method of breaking and forming bonds, the method of excitation of the reaction, its molecularity, etc.

isomerism

ISOMERIA (Greek isos - the same, meros - part) is one of the most important concepts in chemistry, mainly in organic. Substances can have the same composition and molecular weight, but different structures and compounds that contain the same elements in the same amount, but differ in the spatial arrangement of atoms or groups of atoms, are called isomers. Isomerism is one of the reasons why organic compounds are so numerous and varied.

Isomerism was first discovered by J. Liebig in 1823, who found that the silver salts of fulminant and isocyanic acids: Ag-O-N=C and Ag-N=C=O have the same composition, but different properties. The term "isomerism" was introduced in 1830 by I. Berzelius, who suggested that differences in the properties of compounds of the same composition arise due to the fact that the atoms in the molecule are arranged in an unequal order. Ideas about isomerism were finally formed after the creation of the theory of chemical structure by A.M. Butlerov (1860s). Based on this theory, he suggested that there must be four different butanols. By the time the theory was created, only one butanol (CH 3) 2CHCH 2 OH, obtained from plant materials, was known.

The subsequent synthesis of all isomers of butanol and the determination of their properties became a convincing confirmation of the theory.

According to the modern definition, two compounds of the same composition are considered isomers if their molecules cannot be combined in space so that they completely coincide. The combination, as a rule, is done mentally, in difficult cases use spatial models or calculation methods. There are several causes of isomerism.

Structural isomerism

It is caused, as a rule, by differences in the structure of the hydrocarbon skeleton or by an unequal arrangement of functional groups or multiple bonds.

Isomerism of the hydrocarbon skeleton. Saturated hydrocarbons containing from one to three carbon atoms (methane, ethane, propane) do not have isomers. For a compound with four carbon atoms C 4 H 10 (butane), two isomers are possible, for pentane C 5 H 12 - three isomers, for hexane C 6 H 14 - five

With an increase in the number of carbon atoms in a hydrocarbon molecule, the number of possible isomers increases dramatically. For heptane C 7 H 16, there are nine isomers, for hydrocarbon C 14 H 30 - 1885 isomers, for hydrocarbon C 20 H 42 - over 366,000.

In complex cases, the question of whether two compounds are isomers is decided by using various rotations around valence bonds (simple bonds allow this, which to a certain extent corresponds to their physical properties). After the individual fragments of the molecule are moved (without breaking bonds), one molecule is superimposed on another. If two molecules are exactly the same, then these are not isomers, but the same compound:

Isomers that differ in skeletal structure usually have different physical properties (melting point, boiling point, etc.), which makes it possible to separate one from the other. This type of isomerism also exists in aromatic hydrocarbons.

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 their 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 terms, the classification, which is based on the configuration of the carbon skeleton, which does not take into account the features 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 may have isomers in different groups 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, the chemical or physical properties of 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, depending 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, the atoms are interconnected in a strictly defined sequence, which depends on the 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 a mutual influence on 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 bond, which is why 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 cleaved from them, a compound of the R-O-R sample is formed. 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 are complex compounds that 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 a 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 most important role in the cell is structural and energetic. 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.

The simplest classification is that all known substances are divided into inorganic and organic. The organic substances are hydrocarbons and their derivatives. All other substances are inorganic.

inorganic substances divided by composition into simple and complex.

Simple substances consist of atoms of one chemical element and are divided into metals, non-metals, noble gases. Compounds are made up of atoms of different elements that are chemically bonded to each other.

Complex inorganic substances according to their composition and properties are divided into the following major classes: oxides, bases, acids, amphoteric hydroxides, salts.

• oxides- these are complex substances consisting of two chemical elements, one of which is oxygen with an oxidation state (-2). The general formula of oxides is: E m O n, where m is the number of atoms of the element E, and n is the number of oxygen atoms. Oxides, in turn, are classified into salt-forming and non-salt-forming. Salt-forming substances are divided into basic, amphoteric, acidic, which correspond to bases, amphoteric hydroxides, acids, respectively.
• Basic oxides are metal oxides in oxidation states +1 and +2. These include:
  • metal oxides of the main subgroup of the first group ( alkali metals) Li-Fr
  • metal oxides of the main subgroup of the second group ( Mg and alkaline earth metals) Mg-Ra
  • transition metal oxides in lower oxidation states
• Acid oxides- form non-metals with S.O. more than +2 and metals with S.O. from +5 to +7 (SO 2, SeO 2, P 2 O 5, As 2 O 3, CO 2, SiO 2, CrO 3 and Mn 2 O 7). Exception: for NO oxides 2 and ClO 2 there are no corresponding acid hydroxides, but they are considered acidic.
• Amphoteric oxides-formed by amphoteric metals with S.O. +2, +3, +4 (BeO, Cr 2 O 3 , ZnO, Al 2 O 3 , GeO 2 , SnO 2 and PbO).
• Non-salt-forming oxides- oxides of non-metals with С.О.+1, +2 (СО, NO, N 2 O, SiO).
• Foundations- these are complex substances consisting of metal atoms and one or more hydroxo groups (-OH). The general formula of the bases is: M (OH) y, where y is the number of hydroxo groups equal to the oxidation state of the metal M (usually +1 and +2). Bases are divided into soluble (alkali) and insoluble.
• acids- (acid hydroxides) are complex substances consisting of hydrogen atoms that can be replaced by metal atoms, and acid residues. The general formula of acids: H x Ac, where Ac is an acid residue (from the English "acid" - acid), x is the number of hydrogen atoms equal to the charge of the ion of the acid residue.
• Amphoteric hydroxides are complex substances that exhibit both the properties of acids and the properties of bases. Therefore, the formulas of amphoteric hydroxides can be written both in the form of acids and in the form of bases.
• salt- These are complex substances consisting of metal cations and anions of acid residues. This definition applies to medium salts.
• Medium salts- these are the products of the complete replacement of hydrogen atoms in the acid molecule by metal atoms or the complete replacement of hydroxo groups in the base molecule by acidic residues.
• Acid salts- hydrogen atoms in the acid are partially replaced by metal atoms. They are obtained by neutralizing a base with an excess of an acid. To properly name acid salt, it is necessary to add the prefix hydro- or dihydro- to the name of the normal salt, depending on the number of hydrogen atoms that make up the acid salt. For example, KHCO 3 is potassium bicarbonate, KH 2 PO 4 is potassium dihydroorthophosphate. It must be remembered that acid salts can only form two or more basic acids.
• Basic salts- hydroxo groups of the base (OH -) are partially replaced by acidic residues. To name basic salt, it is necessary to add the prefix hydroxo- or dihydroxo- to the name of the normal salt, depending on the number of OH groups that make up the salt. For example, (CuOH) 2 CO 3 is copper (II) hydroxocarbonate. It must be remembered that basic salts can only form bases containing two or more hydroxo groups.
• double salts- in their composition there are two different cations, they are obtained by crystallization from a mixed solution of salts with different cations, but the same anions. For example, KAl(SO 4) 2, KNaSO 4.
• mixed salts- in their composition there are two different anions. For example, Ca(OCl)Cl.
• Hydrate salts (crystal hydrates) - they include molecules of crystallization water. Example: Na 2 SO 4 10H 2 O.

Classification of organic substances

Compounds containing only hydrogen and carbon atoms are called hydrocarbons. Before starting this section, remember, to simplify the record, chemists do not paint carbons and hydrogens in chains, but do not forget that carbon forms four bonds, and if in the figure carbon is bound by two bonds, then it is bound by two more bonds to hydrogens, although the last and not specified:

Depending on the structure of the carbon chain, organic compounds are divided into compounds with an open chain - acyclic(aliphatic) and cyclic- with a closed chain of atoms.

Cyclic are divided into two groups: carbocyclic connections and heterocyclic.

Carbocyclic compounds, in turn, include two series of compounds: alicyclic And aromatic.

aromatic compounds the structure of molecules is based on flat carbon-containing cycles with a special closed system of π-electrons. forming a common π-system (a single π-electron cloud).

Both acyclic (aliphatic) and cyclic hydrocarbons can contain multiple (double or triple) bonds. These hydrocarbons are called unlimited(unsaturated), as opposed to marginal(saturated) containing only single bonds.

Pi-bond (π-bond) - a covalent bond formed by the overlap of p-atomic orbitals. In contrast to the sigma bond, which occurs by overlapping s-atomic orbitals along the atomic bonding line, pi bonds occur when p-atomic orbitals overlap on either side of the atomic bonding line.

In the case of the formation of an aromatic system, for example, benzene C6H6, each of the six carbon atoms is in the state of sp2 - hybridization and forms three sigma bonds with bond angles of 120 °. The fourth p-electron of each carbon atom is oriented perpendicular to the plane of the benzene ring. In general, a single bond arises, extending to all carbon atoms of the benzene ring. Two regions of pi bonds of high electron density are formed on both sides of the plane of sigma bonds. With such a bond, all carbon atoms in the benzene molecule become equivalent and, therefore, such a system is more stable than a system with three localized double bonds.

Limit aliphatic hydrocarbons are called alkanes, they have the general formula C n H 2n + 2, where n is the number of carbon atoms. Their old name is often used today - paraffins:

Unsaturated aliphatic hydrocarbons with one triple bond are called alkynes. Their general formula C n H 2n - 2

Limit alicyclic hydrocarbons - cycloalkanes, their general formula is C n H 2n:

We have considered the classification of hydrocarbons. But if in these molecules one or more hydrogen atoms are replaced by other atoms or groups of atoms (halogens, hydroxyl groups, amino groups, etc.), hydrocarbon derivatives are formed: halogen derivatives, oxygen-containing, nitrogen-containing and other organic compounds.

The atoms or groups of atoms that determine the most characteristic properties of a given class of substances are called functional groups.

Hydrocarbons in their derivatives with the same functional group form homologous series.

A homologous series is a series of compounds belonging to the same class (homologs), differing from each other in composition by an integer number of -CH 2 - groups (homologous difference), having a similar structure and, therefore, similar chemical properties.

similarity chemical properties homologues greatly simplifies the study of organic compounds.

Substituted hydrocarbons

• Halogen derivatives of hydrocarbons can be considered as products of substitution in hydrocarbons of one or more hydrogen atoms by halogen atoms. In accordance with this, saturated and unsaturated mono-, li-, tri- (generally poly-) halogen derivatives can exist. , ethers and esters.
• Alcohols- derivatives of hydrocarbons in which one or more hydrogen atoms are replaced by hydroxyl groups. Alcohols are called monohydric if they have one hydroxyl group, and saturated if they are derivatives of alkanes. The general formula of saturated monohydric alcohols: R-OH.
• Phenols- derivatives of aromatic hydrocarbons (benzene series), in which one or more hydrogen atoms in the benzene ring are replaced by hydroxyl groups.
• Aldehydes and ketones- derivatives of hydrocarbons containing a carbonyl group of atoms (carbonyl). In aldehyde molecules, one carbonyl bond goes to the connection with a hydrogen atom, the other - with a hydrocarbon radical. In the case of ketones, the carbonyl group is bonded to two (generally different) radicals.
• Ethers are organic substances containing two hydrocarbon radicals connected by an oxygen atom: R=O-R or R-O-R 2 . The radicals can be the same or different. The composition of ethers is expressed by the formula C n H 2n +2O.
• Esters- compounds formed by replacing the hydrogen atom of the carboxyl group in carboxylic acids with a hydrocarbon radical.
• Nitro compounds- derivatives of hydrocarbons in which one or more hydrogen atoms are replaced by a nitro group -NO 2 .
• Amines- compounds that are considered as derivatives of ammonia, in which hydrogen atoms are replaced by hydrocarbon radicals. Depending on the nature of the radical, amines can be aliphatic. Depending on the number of hydrogen atoms replaced by radicals, primary, secondary, and tertiary amines are distinguished. In a particular case, secondary as well as tertiary amines may have the same radicals. Primary amines can also be considered as derivatives of hydrocarbons (alkanes) in which one hydrogen atom is replaced by an amino group. Amino acids contain two functional groups connected to a hydrocarbon radical - an amino group -NH 2 and a carboxyl -COOH.

Other important organic compounds are known that have several different or identical functional groups, long linear chains associated with benzene rings. In such cases, a strict definition of whether a substance belongs to a particular class is impossible. These compounds are often isolated into specific groups of substances: carbohydrates, proteins, nucleic acids, antibiotics, alkaloids, etc. At present, many compounds are also known that can be classified as both organic and inorganic. They are called organoelement compounds. Some of them can be considered as derivatives of hydrocarbons.

Nomenclature

Two nomenclature is used to name organic compounds - rational and systematic (IUPAC) and trivial names.

Compilation of names according to the IUPAC nomenclature:

1) The basis of the name of the compound is the root of the word, denoting a saturated hydrocarbon with the same number of atoms as the main chain.

2) A suffix is ​​added to the root, characterizing the degree of saturation:

An (limiting, no multiple bonds);

Yong (in the presence of a double bond);

Ying (in the presence of a triple bond).

If there are several multiple bonds, then the number of such bonds (-diene, -triene, etc.) is indicated in the suffix, and after the suffix, the position of the multiple bond must be indicated in numbers, for example:

CH 3 -CH 2 -CH \u003d CH 2 CH 3 -CH \u003d CH -CH 3

butene-1 butene-2

CH 2 \u003d CH - CH \u003d CH 2

Groups such as nitro-, halogens, hydrocarbon radicals that are not included in the main chain are taken out to the prefix. They are listed in alphabetical order. The position of the substituent is indicated by a number before the prefix.

The title order is as follows:

1. Find the longest chain of C atoms.

2. Sequentially number the carbon atoms of the main chain, starting from the end closest to the branch.

3. The name of an alkane is made up of the names of side radicals, listed in alphabetical order, indicating the position in the main chain, and the name of the main chain.

Naming order

Chemical language, which includes chemical symbolism as one of the most specific parts (including chemical formulas), is an important active means of knowing chemistry and therefore requires a clear and conscious application.

Chemical formulas- this conditional images composition and structure of chemically individual substances through chemical symbols, indices and other signs. When studying the composition, chemical, electronic and spatial structure of substances, their physical and chemical properties, isomerism and other phenomena, chemical formulas of various types are used.

Especially many types of formulas (the simplest, molecular, structural, projection, conformational, etc.) are used in the study of substances of molecular structure - most organic substances and a relatively small part of inorganic substances under ordinary conditions. Significantly fewer types of formulas (the simplest ones) are used in the study of non-molecular compounds, the structure of which is more clearly reflected by ball-and-stick models and diagrams of crystal structures or their unit cells.

Drawing up full and short structural formulas of hydrocarbons

Example:

Make a complete and brief structural formula of propane C 3 H 8.

Solution:

1. Write 3 carbon atoms in a line, connect them with bonds:

S–S–S

2. Add dashes (bonds) so that 4 bonds extend from each carbon atom:

4. Write down a brief structural formula:

CH 3 -CH 2 -CH 3

Solubility table

Organic compounds are most often classified according to two criteria - by the structure of the carbon skeleton of the molecule or by the presence of a functional group in the molecule of the organic compound.

The classification of organic molecules according to the structure of the carbon skeleton can be represented as a diagram:

Acyclic compounds are compounds with an open carbon chain. They are based on aliphatic compounds (from the Greek aleiphatos – oil, fat, resin ) – hydrocarbons and their derivatives, the carbon atoms of which are interconnected in open unbranched or branched chains.

Cyclic compounds are compounds containing a closed circuit. Carbocyclic compounds in the ring contain only carbon atoms, heterocyclic compounds in the ring, in addition to carbon atoms, contain one or more heteroatoms (N, O, S atoms, etc.).

Depending on the nature of the functional group, hydrocarbon derivatives are divided into classes of organic compounds. Functional group is an atom or group of atoms, usually of a non-hydrocarbon character, which determines the typical chemical properties of a compound and its belonging to a certain class of organic compounds. Double or triple bonds act as a functional group in unsaturated molecules.

Name of the functional group	Connection class name	General class formula
Carboxyl -COOH	carboxylic acids
Sulfonic -SO 3 H	Sulphonic acids
Oxo group (carbonyl)	Aldehydes
Oxo group (carbonyl)
Hydroxyl -OH
Thiol (mercapto) -SH	Thiols (mercaptans)
F, -Cl, -Br, -I	Halogen derivatives
Alkoxy - OR	Ethers
Alkylthiol -SR	Thioethers
	Nitro compounds
Alkoxycarbonyl	Esters
Amino-NH 2		RNH 2 ,R 1 NHR 2, R 1 R 2 R 3 N
carboxamide

2.2 Principles of chemical nomenclature - systematic nomenclature iupak. Substitutive and radical-functional nomenclature

Nomenclature is a system of rules that allows you to give a unique name to a compound. At the core replacement nomenclature lies the choice of the parent structure. The name is constructed as a compound word consisting of a root (the name of the parent structure), suffixes reflecting the degree of unsaturation, prefixes and endings indicating the nature, number and position of substituents.

The parent structure (generic hydride) is an unbranched acyclic or cyclic compound in the structure of which only hydrogen atoms are attached to carbon atoms or other elements.

A substituent is a functional (characteristic) group or hydrocarbon radical associated with the parent structure.

A characteristic group is a functional group associated with the parent structure or part of it.

Main group- a characteristic group introduced when forming names in the form of an ending at the end of the name when forming names using functional groups.

Substituents associated with the parent structure are divided into two types. Substituents of the 1st type- hydrocarbon radicals and non-hydrocarbon characteristic groups indicated in the name only in prefixes.

Substituents of the 2nd type- characteristic groups indicated in the title, depending on the seniority, either in the prefix or in the ending. In the table below, the seniority of the substituents decreases from top to bottom.

	Functional group		Ending
carboxylic acid		carboxy	carboxylic acid
			oic acid
Sulfonic acids			sulfonic acid
			carbonitrile
Aldehydes			carbaldehyde
		Hydroxy
		Mercapto

*- The carbon atom of the functional group is part of the parent structure.

The compilation of the name of an organic compound is carried out in a certain sequence.

Determine the main characteristic group, if present. Main group is entered as an ending to the connection name.

The parent structure of the compound is determined. As a parent structure, as a rule, the cycle in carbocyclic and heterocyclic compounds or the main carbon chain in acyclic compounds is taken. The main carbon chain is chosen taking into account the following criteria: 1) the maximum number of characteristic groups of the 2nd type, denoted by both prefixes and suffixes; 2) the maximum number of multiple bonds; 3) maximum chain length; 4) the maximum number of characteristic groups of the 1st type, denoted only by prefixes. Each subsequent criterion is used if the previous criterion does not lead to an unambiguous choice of the parent structure.

The numbering of the parent structure is carried out in such a way that the highest characteristic group receives the smallest number. In the presence of several identical senior functional groups, the parent structure is numbered in such a way that the substituents receive the smallest numbers.

The ancestral structure is called, in the name of which the senior characteristic group is reflected by the ending. Saturation or unsaturation of the ancestral structure is reflected by suffixes - an,-en,-in, which are indicated before the ending, which gives the highest characteristic group.

Names are given to substituents, which are reflected in the name of the compound in the form of prefixes and are listed in a single alphabetical order. Multiple prefixes in the same alphabetical order are not taken into account. 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, the lower carbon atom number is indicated). Numbers are placed before prefixes and after suffixes or endings. The number of identical substituents is reflected in the name using multiplier prefixes di, three, tetra, penta and etc.

The name of the connection is formed according to the scheme:

Examples of names according to the replacement IUPAC nomenclature:

Radical-functional nomenclature has limited use. It is mainly used when naming simple mono- and bifunctional compounds.

If the molecule contains one functional group, then the name of the compound is formed from the names of the hydrocarbon radical and the characteristic group:

In the case of more complex compounds, a parent structure with a trivial name is chosen. The location of substituents, which are indicated in prefixes, is made using numbers, Greek letters or prefixes ortho-, meta-, para-.

2.3 Conformations of open chain compounds

Compounds that have the same qualitative and quantitative composition, the same chemical structure, but differ in the arrangement of atoms and groups of atoms in space, are called stereoisomers. A conformation is the spatial arrangement of atoms in a molecule as a result of the rotation of atoms or groups of atoms around one or more single bonds. Stereoisomers that turn into each other as a result of rotation around a single bond are called conformational isomers. For their representation on a plane, stereochemical formulas or Newman projection formulas are most often used.

In stereochemical formulas, the bonds lying in the plane of the paper are represented by a dash; connections directed to the observer are indicated by a bold wedge; bonds located behind the plane (leaving from the observer) are indicated by a hatched wedge. The stereochemical formulas of methane and ethane can be represented as follows:

To obtain Newman projection formulas in a molecule, a C-C bond is chosen, the carbon atom farthest from the observer is indicated by a circle, the carbon atom closest to the observer and the C-C bond is indicated by a dot. Three other bonds of carbon atoms on the plane are displayed at an angle of 120 relative to each other. The stereochemical formulas of ethane can be represented as Newman projection formulas as follows:

Rotation relative to ordinary bonds in the methane molecule does not lead to a change in the spatial position of the atoms in the molecule. But in the ethane molecule, as a result of rotation around the ordinary C-C bond, the arrangement of atoms in space changes, i.e. conformational isomers arise. The minimum angle of rotation (torsion angle) is considered to be an angle of 60. For ethane, thus, two conformations appear, which pass into each other during successive rotations of 60. These conformations differ in energy. The conformation in which the atoms (substituents) are in the closest position, since the bonds obscure each other, is called obscured. The conformation in which the atoms (substituents) are as far apart as possible is called inhibited (anti-conformation). For ethane, the difference in the energies of conformations is small and equals 11.7 kJ/mol, which is comparable to the energy of thermal motion of ethane molecules. Such a small difference in the energies of the conformational isomers of ethane does not allow them to be isolated and identified at ordinary temperature. The eclipsed conformation has a higher energy, which is due to the appearance torsion stresses (Pitzer stresses) - in interactions caused by the repulsion of opposing bonds. In the hindered conformation, the bonds are as far away as possible and the interactions between them are minimal, which determines the minimum energy of the conformation.

In butane, when rotated relative to the bond between the second and third carbon atoms, an additional beveled conformation ( gosh-conformation). In addition, the eclipsed conformations of butane differ energetically.

The veiled (initial) conformation of butane is characterized by maximum energy, which is due to the presence torsion And van der Waals stresses. Van der Waals stresses in this conformation arise due to the mutual repulsion of the bulky (compared to the H atom) methyl groups, which turned out to be close. This interaction increases the energy of the conformation, making it energetically unfavorable. When rotated by 60, there is beveled a conformation in which there are no torsional stresses (bonds do not obscure each other), and van der Waals stresses are significantly reduced due to the distance of methyl groups from each other, so the energy of the gauche conformation is 22 kJ/mol less than the energy of the obscured conformation. At the next rotation by 60°, a eclipsed conformation appears, in which, however, only torsional stresses take place. Van der Waals stresses do not arise between the H atom and the CH 3 group due to the small size of the H atom. The energy of this conformation is less than the energy of the initial eclipsed conformation by 7.5 kJ/mol. Another rotation by 60° leads to the appearance of a hindered conformation, in which there are no torsional and van der Waals stresses, since the bonds do not obscure each other, and the bulky methyl groups are maximally removed from each other. The energy of the hindered conformation is minimal, less than the energy of the initial eclipsed conformation by 25.5 kJ/mol, and compared to the energy of the skew conformation it is less by 3.5 kJ/mol. Subsequent rotations give rise to eclipsed, skewed, and original eclipsed conformations. Under normal conditions, most butane molecules are in the form of a mixture of gauche and anti-conformers.

>> Chemistry: Classification of organic compounds

You already know that the properties of organic substances are determined by their composition and chemical structure. Therefore, it is not surprising that the classification of organic compounds is based on the theory of structure - the theory of A. M. Butlerov. Classify organic substances by the presence and order of connection of atoms in their molecules. The most durable and least changeable part of the molecule of organic matter is its skeleton - a chain of carbon atoms. Depending on the order of connection of carbon atoms in this chain, substances are divided into acyclic, which do not contain closed chains of carbon atoms in molecules, and carbocyclic, containing such chains (cycles) in molecules.

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