Types of chemical bonds in organic compounds. Chemical bonds in organic compounds

Variety of inorganic and organic substances

Organic chemistry is chemistry carbon compounds... Inorganic carbon compounds include: carbon oxides, carbonic acid, carbonates and bicarbonates, carbides. Organic matter, other than carbon, contain hydrogen, oxygen, nitrogen, phosphorus, sulfur and other elements... Carbon atoms can form long unbranched and branched chains, rings, attach other elements, so the number of organic compounds is close to 20 million, while inorganic substances are just over 100 thousand.

The basis for the development of organic chemistry is AM Butlerov's theory of the structure of organic compounds. An important role in describing the structure of organic compounds belongs to the concept of valence, which characterizes the ability of atoms to form chemical bonds and determines their number. Carbon in organic compounds always tetravalent... The main postulate of A.M.Butlerov's theory is the provision on the chemical structure of matter, that is, the chemical bond. This order is displayed using structural formulas. Butlerov's theory asserts the idea that every substance has definite chemical structure and properties of substances depend on the structure.

A.M.Butlerov's theory of the chemical structure of organic compounds

Just as for inorganic chemistry the basis of development is the Periodic Law and the Periodic Table of Chemical Elements of D.I.Mendeleev, it became fundamental for organic chemistry.

A.M.Butlerov's theory of the chemical structure of organic compounds

The main postulate of Butlerov's theory is the position on the chemical structure of matter, which is understood as the order, the sequence of the mutual connection of atoms into molecules, i.e. chemical bond.

Chemical structure- the order of connection of atoms of chemical elements in a molecule according to their valence.

This order can be displayed using structural formulas, in which the valencies of atoms are indicated by dashes: one dash corresponds to the valence unit of an atom of a chemical element... For example, for organic matter methane, which has the molecular formula CH 4, the structural formula looks like this:

The main provisions of the theory of A.M.Butlerov:

The atoms in the molecules of organic substances are linked to each other according to their valence... Carbon in organic compounds is always tetravalent, and its atoms are able to combine with each other, forming various chains.

· The properties of substances are determined not only by their qualitative and quantitative composition, but also by the order of connection of atoms in a molecule, i.e. chemical structure of matter.

The properties of organic compounds depend not only on the composition of the substance and the order of the connection of atoms in its molecule, but also on mutual influence of atoms and groups of atoms on top of each other.

The theory of the structure of organic compounds is a dynamic and developing study. With the development of knowledge about the nature of chemical bonds, about the influence of the electronic structure of molecules of organic substances, they began to use, in addition to empirical and structural, electronic formulas. In such formulas, show the direction displacement of electron pairs in a molecule.

Quantum chemistry and chemistry of the structure of organic compounds confirmed the doctrine of the spatial direction of chemical bonds (cis- and trans isomerism), studied the energy characteristics of mutual transitions in isomers, made it possible to judge the mutual influence of atoms in molecules of various substances, created the prerequisites for predicting the types of isomerism and directions and mechanisms of chemical reactions.

Organic matter has a number of characteristics.

All organic substances contain carbon and hydrogen, therefore, when they burn, they form carbon dioxide and water.

Organic matter built difficult and can have a huge molecular weight (proteins, fats, carbohydrates).

Organic substances can be arranged in rows similar in composition, structure and properties homologues.

Organic substances are characterized by isomerism.

Isomerism and homology of organic substances

The properties of organic substances depend not only on their composition, but also on the order of the connection of atoms in a molecule.

Isomerism- this is the phenomenon of the existence of different substances - isomers with the same qualitative and quantitative composition, that is, with the same molecular formula.

There are two types of isomerism: structural and spatial(stereoisomerism). Structural isomers differ from each other in the order of bonding of atoms in a molecule; stereoisomers - the arrangement of atoms in space with the same order of bonds between them.

The main types of isomerism:

Structural isomerism - substances differ in the order of bonds of atoms in molecules:

1) isomerism of the carbon skeleton;

2) position isomerism:

multiple connections;
deputies;
functional groups;

3) isomerism of homologous series (interclass).

· Spatial isomerism - molecules of substances differ not in the order of bonding of atoms, but in their position in space: cis-, trans-isomerism (geometric).

Classification of organic substances

It is known 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. Organic substances are classified according to 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 in which carbon atoms are joined in this chain, substances are divided into acyclic that do not contain closed chains of carbon atoms in molecules, and carbocyclic containing such chains (cycles) in molecules.

In addition to carbon and hydrogen atoms, molecules of organic substances can contain atoms of other chemical elements. Substances in the molecules of which these so-called heteroatoms are included in a closed chain are referred to as heterocyclic compounds.

Heteroatoms(oxygen, nitrogen, etc.) can be part of molecules and acyclic compounds, forming functional groups in them, for example,

hydroxyl

carbonyl

carboxyl

amino group

Functional group- a group of atoms that determines the most characteristic chemical properties of a substance and its belonging to a certain class of compounds.

Nomenclature of organic compounds

At the beginning of the development of organic chemistry, the compounds being discovered were assigned trivial names, often associated with the history of their production: acetic acid (which is the basis of wine vinegar), butyric acid (formed in butter), glycol (that is, "sweet"), etc. As the number of new discovered substances increased, the need arose associate names with their structure. This is how rational names appeared: methylamine, diethylamine, ethyl alcohol, methyl ethyl ketone, which are based on the name of the simplest compound. For more complex connections, rational nomenclature is not suitable.

The theory of the structure of A.M. Butlerov provided the basis for the classification and nomenclature of organic compounds by structural elements and by the arrangement of carbon atoms in the molecule. Currently, the most used is the nomenclature developed by International Union of Pure and Applied Chemistry (IUPAC), which is called the nomenclature IUPAC... The IUPAC rules recommend several principles for the formation of names, one of them is the principle of substitution. On the basis of this, a substitutional nomenclature has been developed, which is the most universal. Here are a few basic rules of the substitution nomenclature and consider their application using the example of a heterofunctional compound containing two functional groups, the amino acid leucine:

1. The names of the compounds are based on the parent structure (the main chain of an acyclic molecule, a carbocyclic or heterocyclic system). The name of the parent structure forms the basis of the name, the root of the word.

In this case, the parent structure is a chain of five carbon atoms linked by single bonds. Thus, the root part of the name is pentane.

2. Characteristic groups and substituents (structural elements) are designated by prefixes and suffixes. Feature groups are categorized by seniority. Major group precedence order:

The senior characteristic group is identified, which is indicated in the suffix. All other substituents are named in the prefix alphabetically.

In this case, the highest characteristic group is carboxyl, that is, this compound belongs to the class of carboxylic acids, so we add -oic acid to the root part of the name. The second oldest group is the amino group, which is indicated by the prefix amino. In addition, the molecule contains a hydrocarbon substituent methyl-. Thus, the name is based on aminomethylpentanoic acid.

3. The name includes the designation of a double and triple bond, which comes immediately after the root.

The considered connection does not contain multiple links.

4. The atoms of the parent structure are numbered. The numbering starts from the end of the carbon chain to which the most significant characteristic group is located:

The chain numbering begins with the carbon atom that is part of the carboxyl group, it is assigned number 1. In this case, the amino group will be at carbon 2, and methyl - at carbon 4.

Thus, the natural amino acid leucine, according to the rules of the IUPAC nomenclature, is called 2-amino-4-methylpentanoic acid.

Hydrocarbons. Classification of hydrocarbons

Hydrocarbons are compounds consisting only of hydrogen and carbon atoms.

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

Cyclics are divided into two groups: carbocyclic compounds(the cycles are formed only by carbon atoms) and heterocyclic(the cycles also include other atoms, such as oxygen, nitrogen, sulfur).

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

Aromatic compounds are based on the structure of molecules planar carbon-containing cycles with a special closed system of p-electrons forming a common π-system (a single π-electron cloud). Aromaticity is also characteristic of many heterocyclic compounds.

All other carbocyclic compounds belong to the alicyclic series.

Both acyclic (aliphatic) and cyclic hydrocarbons can contain multiple (double or triple) bonds. Such hydrocarbons are called unsaturated(unsaturated), in contrast to the limiting (saturated), containing only single bonds.

Saturated 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 nowadays - paraffins:

Unsaturated aliphatic hydrocarbons containing one double bond are called alkenes... They have the general formula C n H 2n:

Unsaturated aliphatic hydrocarbons with two double bonds are called alkadienes... Their general formula is C n H 2n-2:

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

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

A special group of hydrocarbons, aromatic, or arenas(with a closed common n-electron system), is known from the example of hydrocarbons with the general formula C n H 2n - 6:

Thus, if one or more hydrogen atoms in their molecules 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.

Homologous series of hydrocarbons

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

Homological series refers to a number of compounds belonging to the same class (homologues), arranged in ascending order of their relative molecular weights, similar in structure and chemical properties, where each term differs from the previous one by the homologous difference CH 2. For example: CH 4 - methane, C 2 H 6 - ethane, C 3 H 8 - propane, C 4 H 10 - butane, etc. The similarity of the chemical properties of homologues greatly simplifies the study of organic compounds.

Isomers of hydrocarbons

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

Halogenated hydrocarbons can be considered as products of substitution in hydrocarbons of one or more hydrogen atoms by halogen atoms. In accordance with this, there can be limiting and unsaturated mono-, di-, tri- (in the general case, poly-) halogen derivatives.

The general formula of monohalogenated saturated hydrocarbons:

and the composition is expressed by the formula

where R is the residue from a saturated hydrocarbon (alkane), a hydrocarbon radical (this designation is used further when considering other classes of organic substances), G is a halogen atom (F, Cl, Br, I).

For example:

Here is one example of a dihalogenated derivative:

TO oxygenated organic substances include alcohols, phenols, aldehydes, ketones, carboxylic acids, ethers and esters. Alcohols are hydrocarbon derivatives 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.

General formula of limit monohydric alcohols:

and their composition is expressed by the general formula:

For example:

Known examples polyhydric alcohols, i.e., having several hydroxyl groups:

Phenols- derivatives of aromatic hydrocarbons (benzene series), in which one or more hydrogen atoms in the benzene ring are replaced by hydroxyl groups.

The simplest representative with the formula C 6 H 5 OH or

called phenol.

Aldehydes and ketones- derivatives of hydrocarbons containing a carbonyl group of atoms

(carbonyl).

In molecules aldehydes one bond of the carbonyl goes to a compound with a hydrogen atom, the other - with a hydrocarbon radical. General formula of aldehydes:

For example:

When ketones the carbonyl group is bonded to two (generally different) radicals, the general formula of ketones is:

For example:

The composition of saturated aldehydes and ketones is expressed by the formula C 2n H 2n O.

Carboxylic acids- derivatives of hydrocarbons containing carboxyl groups

(or -COOH).

If there is one carboxyl group in the acid molecule, then the carboxylic acid is monobasic. The general formula of saturated monobasic acids:

Their composition is expressed by the formula C n H 2n O 2.

For example:

Ethers are organic substances containing two hydrocarbon radicals connected by an oxygen atom: R-O-R or R 1 -O-R 2.

Radicals can be the same or different. The composition of ethers is expressed by the formula C n H 2n + 2 O.

For example:

Esters- compounds formed by replacing the hydrogen atom of the carboxyl group in carboxylic acids with a hydrocarbon radical.

General Esters Formula:

For example:

Nitro compounds- derivatives of hydrocarbons, in which one or more hydrogen atoms are replaced by a nitro group —NO 2.

The general formula for limiting mononitro compounds:

and the composition is expressed by the general formula C n H 2n + 1 NO 2.

For example:

Nitro derivatives of arenes:

Amines- compounds that are considered as derivatives of ammonia (NH 3), in which hydrogen atoms are replaced by hydrocarbon radicals. Depending on the nature of the radical, amines can be aliphatic, for example:

and aromatic, for example:

Depending on the number of hydrogen atoms replaced by radicals, the following are distinguished:

primary amines with the general formula:

secondary- with the general formula:

tertiary- with the general formula:

In a particular case, for secondary and tertiary amines, the radicals can be the same.

Primary amines can also be considered as derivatives of hydrocarbons (alkanes) in which one hydrogen atom is replaced by an amino group —NH 2. The composition of the saturated primary amines is expressed by the formula C n H 2n + 3 N.

For example:

Amino acids contain two functional groups connected to a hydrocarbon radical: an amino group —NH 2 and a carboxyl —COOH.

The general formula of α-amino acids (they are most important for building proteins that make up living organisms):

The composition of limiting amino acids containing one amino group and one carboxyl is expressed by the formula C n H 2n + 1 NO 2.

For example:

Other important organic compounds are known that have several different or identical functional groups, long linear chains linked to benzene rings. In such cases, a strict determination of the belonging of a substance to any particular class is impossible. These compounds are often isolated into specific groups of substances: carbohydrates, proteins, nucleic acids, antibiotics, alkaloids, etc.

At present, there are also many known compounds that can be classified as organic and inorganic. x are called organoelement compounds. Some of them can be considered as derivatives of hydrocarbons.

For example:

There are compounds that have the same molecular formula, which expresses the composition of substances.

The phenomenon of isomerism consists in the fact that there may be several substances with different properties, having the same composition of molecules, but different structures. These substances are called isomers.

In our case, these are interclass isomers: cycloalkanes and alkanes, alkadienes and alkynes, saturated monohydric alcohols and ethers, aldehydes and ketones, saturated monobasic carboxylic acids and esters.

Structural isomerism

There are the following varieties structural isomerism: isomerism of the carbon skeleton, isomerism of position, isomerism of various classes of organic compounds (interclass isomerism).

Isomerism of the carbon skeleton is due to different bond order between carbon atoms forming the skeleton of the molecule. As already shown, two hydrocarbons correspond to the molecular formula C 4 H 10: n-butane and isobutane. Three isomers are possible for the C 5 H 12 hydrocarbon: pentane, isopentane, and neopentane.

With an increase in the number of carbon atoms in a molecule, the number of isomers increases rapidly. For the C 10 H 22 hydrocarbon, there are already 75, and for the C 20 H 44 hydrocarbon - 366 319.

Position isomerism is due to the different position of the multiple bond, substituent, functional group with the same carbon skeleton of the molecule:

Isomerism of different classes of organic compounds (interclass isomerism) is due to different positions and combinations of atoms in molecules of substances that have the same molecular formula, but belong to different classes. So, the molecular formula C 6 H 12 corresponds to an unsaturated hydrocarbon hexene-1 and a cyclic hydrocarbon cyclohexane.

Isomers are the alkynes hydrocarbon - butyne-1 and a hydrocarbon with two double bonds in the butadiene-1,3 chain:

Diethyl ether and butyl alcohol have the same molecular formula C 4 H 10 O:

Structural isomers are aminoacetic acid and nitroethane corresponding to the molecular formula C 2 H 5 NO 2:

Isomers of this type contain different functional groups and belong to different classes of substances. Therefore, they differ in physical and chemical properties much more than isomers of the carbon skeleton or isomers of position.

Spatial isomerism

Spatial isomerism is subdivided into two types: geometric and optical.

Geometric isomerism is characteristic of compounds containing double bonds, and cyclic compounds... Since free rotation of atoms around the double bond or in the ring is impossible, the substituents can be located either on one side of the plane of the double bond or ring (cis-position), or on opposite sides (transposition). The designations cis and trans generally refer to a pair of identical substituents.

Geometric isomers differ in physical and chemical properties.

Optical isomerism occurs if the molecule is incompatible with its image in the mirror... This is possible when the carbon atom in the molecule has four different substituents. This atom is called asymmetric. An example of such a molecule is the α-aminopropionic acid (α-alanine) CH 3 CH (NH 2) OH molecule.

The α-alanine molecule cannot coincide with its mirror image under any displacement. Such spatial isomers are called mirror, optical antipodes, or enantiomers. All physical and practically all chemical properties of such isomers are identical.

The study of optical isomerism is necessary when considering many reactions occurring in the body. Most of these reactions take place under the action of enzymes - biological catalysts. The molecules of these substances must match the molecules of the compounds on which they act like a key to a lock, therefore, the spatial structure, the mutual arrangement of the molecular sites and other spatial factors are of great importance for the course of these reactions. Such reactions are called stereoselective.

Most natural compounds are individual enantiomers, and their biological action (from taste and smell to medicinal action) differs sharply from the properties of their optical antipodes obtained in the laboratory. Such a difference in biological activity is of great importance, since it underlies the most important property of all living organisms - metabolism.

Isomerism

The electronic structure of the carbon atom

Carbon, which is part of organic compounds, exhibits constant valence. The last energy level of the carbon atom contains 4 electrons, two of which occupy the 2s-orbital, which has a spherical shape, and two electrons occupy the 2p-orbitals, which have a dumbbell-like shape. Upon excitation, one electron from the 2s orbital can transfer to one of the vacant 2p orbitals. This transition requires some energy consumption (403 kJ / mol). As a result, an excited carbon atom has 4 unpaired electrons and its electronic configuration is expressed by the formula 2s 1 2p 3 .. Thus, in the case of the methane hydrocarbon (CH 4), the carbon atom forms 4 bonds with the s-electrons of hydrogen atoms. In this case, 1 bond of the s-s type (between the s-electron of the carbon atom and the s-electron of the hydrogen atom) and 3 p-s-bonds (between the 3 p-electrons of the carbon atom and 3 s-electrons of 3 hydrogen atoms) should be formed. This leads to the conclusion that the four covalent bonds formed by the carbon atom are not equal. However, practical experience in chemistry indicates that all 4 bonds in the methane molecule are absolutely equivalent, and the methane molecule has a tetrahedral structure with bond angles of 109.5 0, which could not be the case if the bonds were not equal. After all, only the orbitals of p-electrons are oriented in space along the mutually perpendicular axes x, y, z, and the orbital of the s-electron has a spherical shape, so the direction of formation of a bond with this electron would be arbitrary. The theory of hybridization was able to explain this contradiction. L. Polling suggested that in any molecules there are no bonds isolated from each other. When bonds are formed, the orbitals of all valence electrons overlap. Several types are known hybridization of electron orbitals... It is assumed that 4 electrons enter into hybridization in a molecule of methane and other alkanes.

Hybridization of carbon orbitals

Orbital hybridization- this is a change in the shape and energy of some electrons during the formation of a covalent bond, leading to a more efficient overlap of orbitals and an increase in the strength of bonds. Orbital hybridization always occurs when electrons belonging to different types of orbitals participate in the formation of bonds.

1. sp 3 -hybridization(the first valence state of carbon). During sp 3 -hybridization, the 3 p-orbitals and one s-orbital of the excited carbon atom interact in such a way that orbitals are obtained that are absolutely identical in energy and symmetrically located in space. This transformation can be written like this:

During hybridization, the total number of orbitals does not change, but only their energy and shape change. It is shown that the sp 3 -hybridization of the orbital resembles a three-dimensional figure, one of the blades of which is much larger than the other. Four hybrid orbitals are elongated from the center to the vertices of a regular tetrahedron at angles of 109.5 0. The bonds formed by hybrid electrons (eg, s-sp 3 bond) are stronger than bonds made by unhybridized p-electrons (eg, s-p bond). Since the hybrid sp 3 -orbital provides a larger area of overlapping electron orbitals than the unhybridized p-orbital. Molecules in which sp 3 hybridization is carried out have a tetrahedral structure. These, in addition to methane, include methane homologues, inorganic molecules such as ammonia. The figures show a hybridized orbital and a tetrahedral methane molecule.

The chemical bonds arising in methane between carbon and hydrogen atoms refer to the type of σ-bonds (sp 3 -s-bond). Generally speaking, any sigma bond is characterized by the fact that the electron density of two connected atoms overlaps along a line connecting the centers (nuclei) of the atoms. σ-bonds correspond to the maximum possible degree of overlapping of atomic orbitals, so they are strong enough.

2. sp 2 -hybridization(second valence state of carbon). It arises as a result of the overlap of one 2s and two 2p orbitals. The formed sp 2 -hybrid orbitals are located in one plane at an angle of 120 0 to each other, and the unhybridized p-orbital is perpendicular to it. The total number of orbitals does not change - there are four of them.

The sp 2 -hybridization state occurs in alkenes molecules, in carbonyl and carboxyl groups, i.e. for compounds containing a double bond. So, in the ethylene molecule, the hybridized electrons of the carbon atom form 3 σ-bonds (two bonds of the sp 2 -s type between the carbon atom and the hydrogen atoms and one bond of the sp 2 -sp 2 type between the carbon atoms). The remaining unhybridized p-electron of one carbon atom forms a π-bond with the unhybridized p-electron of the second carbon atom. A characteristic feature of the π-bond is that the overlap of the electron orbitals occurs outside the line connecting the two atoms. The orbital overlap occurs above and below the σ-bond connecting both carbon atoms. Thus, a double bond is a combination of σ- and π-bonds. The first two figures show that in the ethylene molecule the bond angles between the atoms forming the ethylene molecule are 120 0 (respectively, the orientation with space of three sp 2 -hybrid orbitals). The figures show the formation of a π-bond.

Since the overlapping area of unhybridized p-orbitals in π-bonds is less than the overlapping area of orbitals in σ-bonds, the π-bond is less strong than the σ-bond and breaks more easily in chemical reactions.

3. sp hybridization(the third valence state of carbon). In the state of sp-hybridization, a carbon atom has two sp-hybrid orbitals located linearly at an angle of 180 0 to each other and two unhybridized p-orbitals located in two mutually perpendicular planes. sp-hybridization is typical for alkynes and nitriles, i.e. for compounds containing a triple bond.

So, in the acetylene molecule, the bond angles between the atoms are 180 o. Hybridized electrons of a carbon atom form 2 σ-bonds (one sp-s bond between a carbon atom and a hydrogen atom and another sp-sp bond between carbon atoms. Two unhybridized p-electrons of one carbon atom form two π-bonds with unhybridized p electrons of the second The overlapping of the orbitals of p-electrons occurs not only above and below the σ-bond, but also in front and behind, and the total cloud of p-electrons has a cylindrical shape.Thus, the triple bond is a combination of one σ-bond and two π-bonds. The presence of two less strong π-bonds in the acetylene molecule ensures the ability of this substance to enter into addition reactions with the breaking of the triple bond.

Reference material for passing the test:

Mendeleev table

Solubility table

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1. Hybridization of carbon atomic orbitals

Atomic orbital is a function that describes the density of the electron cloud at each point in space around the nucleus of an atom. An electron cloud is a region of space in which an electron can be found with a high probability.

To reconcile the electronic structure of the carbon atom and the valence of this element, the concepts of the excitation of the carbon atom are used. In the normal (unexcited) state, a carbon atom has two unpaired 2 R 2 -electron.

In an excited state (when energy is absorbed), one of 2 s 2 electrons can go to the free R-orbital. Then four unpaired electrons appear in the carbon atom. On the second energy level except 2 s-orbitals there are three 2 R-orbital. These 2 R-orbitals have an ellipsoidal shape, similar to dumbbells, and are oriented in space at an angle of 90 ° to each other. 2 R-Orbitals stand for 2 R NS, 2R y and 2 R z according to the axes along which these orbitals are located.

When chemical bonds are formed, the electron orbitals acquire the same shape.

So, in saturated hydrocarbons one s-orbital and three R-orbitals of a carbon atom with the formation of four identical (hybrid) sR 3-orbitals:

This is - sR 3-hybridization.

Hybridization- alignment (mixing) of atomic orbitals ( s and R) with the formation of new atomic orbitals, called hybrid orbitals.

TETRAHEDRON (angles = 109 ° 28?

sR 2 -Hybridization- mixing one s- and two R-orbitals. As a result, three hybrid sR 2 -orbitals.

These sR 2 -orbitals are located in the same plane (with the axes NS, at) and directed to the vertices of the triangle with an angle between the orbitals of 120 °.

Unhybridized R-orbital perpendicular to the plane of the three hybrid sR 2 -orbitals (oriented along the axis z).

Upper half R-orbital is above the plane, the lower half is below the plane.

A type sR 2-carbon hybridization occurs in compounds with a double bond:

C = C, C = O, C = N.

Moreover, only one of the bonds between two atoms (for example, C = C) can be a bond. (The other bonding orbitals of the atom point in opposite directions.)

The second bond is formed by overlapping non-hybrid R-orbitals on either side of the line connecting the atomic nuclei.

Covalent bond formed by lateral overlap R-orbitals of adjacent carbon atoms, called pi ( R) -connection .

sR-Hybridization s- and one R sR-orbitals. sR-Orbitals are located on one line (at an angle of 180 °) and are directed in opposite directions from the nucleus of the carbon atom. Two R at-connections. On the picture sR-orbitals are shown along the axis y, and unhybridized two R- orbitals - along the axes NS and z.

The triple carbon-carbon bond C? C consists of a y-bond arising from overlapping sp-hybrid orbitals, and two p-bonds.

2. Reactions of electrophilic substitution of hydrogen atoms in the benzene series

1. Halogenation reaction. The halogenation reaction of the benzene ring is carried out in the presence of catalysts (most often iron or aluminum halides). The role of the catalyst is to form a highly polarized complex with a halogen: FORMULA. The chlorine atom on the far left in the complex becomes electronically unsaturated as a result of the polarization of the Cl - Cl bond and is capable of interacting with nucleophilic reagents (in this case, benzene):

e - the complex cleaves off a proton and turns into a substitution product (chlorobenzene). The proton interacts with - with the regeneration of aluminum chloride, forming hydrogen chloride:

In the case of an excess of halogen, di- and polyhalogenated ones can be obtained, up to the complete replacement of all hydrogen atoms in benzene.

Direct iodination in the aromatic nucleus cannot be carried out due to the low reactivity of iodine. The direct fluorination of aromatic hydrocarbons proceeds so vigorously that a complex mixture of products is formed, in which the target fluorine derivatives are contained in small amounts. Depending on the conditions of the halogenation reaction of alkylbenzenes, halogen can replace hydrogen atoms in the benzene ring (cold in the presence of Lewis acids) or in the side chain (when heated or exposed to light). In the latter case, the reaction proceeds according to a free radical mechanism, similar to the mechanism of substitution in alkanes.

2. The nitration reaction. Benzene reacts slowly with concentrated nitric acid. The nitration rate increases significantly if the nitration reaction is carried out with a mixture of concentrated nitric and sulfuric acids (usually in a 1: 2 ratio); this mixture is called nitrating.

The process occurs due to the fact that sulfuric acid, as a stronger one, protonates nitric acid, and the resulting protonated particle decomposes into water and an active electrophilic reagent - nitronium cation (nitronium cation).

The benzene nitration reaction is an electrophilic substitution reaction and is ionic in nature. First, the formation of a p-complex occurs as a result of the interaction of electrons of the benzene ring with a positively charged particle of the nitronium cation.

Then the transition of the p-complex to the y-complex occurs. In this case, two p-electrons out of six go to the formation of the C-NO2 + covalent bond. The remaining four -electrons are distributed between the five carbon atoms of the benzene ring. A y-complex is formed in the form of an unstable carbocation.

The unstable y-complex under the influence of the HSO4- ion loses a proton with the formation of the aromatic structure of nitrobenzene.

3. Sulfonation reaction. To introduce a sulfo group into the benzene ring, fuming sulfuric acid is used, i.e., containing an excess of sulfuric anhydride (SO3). The electrophilic particle is SO3. The mechanism of sulfonation of aromatic compounds includes the following stages:

4. The reaction of alkylation according to Friedel-Crafts. The role of the catalyst (usually AlCl3) in this process is to enhance the polarization of the haloalkyl to form a positively charged particle that undergoes an electrophilic substitution reaction: FORMULA

3. Anthracene: structure and basic chemical properties

Anthracene - a compound, the molecule of which consists of three aromatic rings lying in the same plane. It is obtained from the anthracene fraction of coal tar boiling at 300 ... 350 ° C. In laboratory practice, anthracene can be obtained

a) according to the Friedel-Crafts reaction:

b) by Fittig reaction:

In the anthracene molecule, the ninth and tenth positions are most active, which are under the influence of the two extreme rings. Anthracene easily enters into addition reactions according to these provisions:

Anthracene easily forms anthraquinone under the action of oxidants, which is widely used for the synthesis of dyes:

4. Conjugated dienes and methods for their synthesis

Diene hydrocarbons (dienes) are called unsaturated hydrocarbons having two double bonds, of the general formula CnH2n-2.

Two double bonds in a hydrocarbon molecule can be located in different ways. If they are concentrated on one carbon atom, they are called cumulated: -C = C = C- If two double bonds are separated by one simple bond, they are called conjugated: -C = C - C = C- If the double bonds are separated by two or more simple bonds, then they are called isolated: -C = C- (CH2) n - C = C-

5. Orientation rules in the benzene ring

When studying substitution reactions in the benzene ring, it was found that if it already contains any substituent, then, depending on its nature, the second enters into a certain position. Thus, each substituent in the benzene ring exhibits a certain directing or orienting effect. The position of the newly introduced substituent is also influenced by the nature of the substituent itself, i.e., whether the active reagent is of an electrophilic or nucleophilic nature. All substitutes by the nature of their guiding action in are divided into two groups.

Substitutes of the first kind direct the introduced group to the ortho and pair - positions:

Substituents of this kind include the following groups, arranged in decreasing order of their orienting strength: N (CH3) 2, NH2, OH, CH3 and other alkyls, as well as Cl, Br, I.

Substitutes of the second kind in electrophilic substitution reactions direct the input groups to the meta position. The following groups belong to substituents of this kind: - NO2, - C N, - SO3H, - CHO, - COOH.

6. The nature of the double bond and the chemical properties of ethylene compounds

According to modern concepts, the two bonds connecting two unsaturated carbon atoms are not the same: one of them is a y-bond, and the other is a p-bond. The latter bond is less strong and “breaks” during addition reactions.

The inequality of the two bonds in unsaturated compounds is indicated, in particular, by a comparison of the formation energy of single and double bonds. The energy of formation of a single bond is 340 kJ / mol (approximately 82 kcal / mol), and a double bond is 615 kJ / mol (approximately 147 kcal / mol). Naturally, less energy is spent to break the p-bond than to break the y-bond. Thus, the fragility of the double bond is explained by the fact that one of the two bonds forming a double bond has a different electronic structure than the usual β-bonds, and has a lower strength.

Olefin names usually derived from the name of the corresponding saturated hydrocarbons, but the ending - an is replaced by the ending - ilen. According to the international nomenclature, instead of ending - ylen olefins are given a shorter ending - yen.

Isomerism olefins depends on the isomerism of the chain of carbon atoms, that is, on whether the chain is unbranched or branched, and on the position of the double bond in the chain. There is also a third reason for the isomerism of olefins: the different arrangement of atoms and atomic groups in space, i.e., stereoisomerism. Isomerism, which depends on the different arrangement of atoms and atomic groups in space, is calledspatial isomerism , orstereoisomerism .

Geometric , orcis- andtrans isomerism , is a kind of spatial isomerism, depending on the different location atoms with respect to the plane of the double bond.

To designate the place of the double bond (as well as branches in the chain), according to the international IUPAC nomenclature, the carbon atoms of the longest chain are numbered, starting from the end to which the double bond is closer. Thus, the two unbranched butylene isomers will be referred to as butene-1 and butene-2:

1. Hydrogenation reaction. Unsaturated hydrocarbons easily add hydrogen to the double bond in the presence of catalysts 67 (Pt, Pd, Ni). With a Pt or Pd catalyst, the reaction proceeds at 20 ... 100 ° C, with Ni - at higher temperatures:

2. Halogenation reaction. Alkenes under normal conditions add halogens, especially chlorine and bromine. As a result, dihalogenated alkane derivatives are formed containing halogens at adjacent carbon atoms, the so-called vicinal dihaloalkanes: CH

3CH = CH2 + Cl2> CH3CHClCH2Cl

3. Reaction of addition of hydrogen halides. Hydrohalogenation

4. Reaction of hydration of alkenes. Under normal conditions, alkenes do not react with water. But in the presence of catalysts under heating and pressure, they add water and form alcohols:

5. The reaction of addition of sulfuric acid. The interaction of alkenes with sulfuric acid proceeds similarly to the addition of hydrogen halides. As a result, acidic esters of sulfuric acid are formed:

6. Reaction of alkylation of alkenes. Possible catalytic addition to alkenes of alkanes with a tertiary carbon atom (catalysts - H2SO4, HF, AlCl3 and BF3):

7. The reaction of oxidation of alkenes... Alkenes are easily oxidized. Depending on the oxidation conditions, various products are formed. When burned in air, alkenes are converted to carbon dioxide and water: CH2 = CH2 + 3O2> 2CO2 + 2H2O.

When alkenes react with atmospheric oxygen in the presence of a silver catalyst, organic oxides are formed:

Acyl hydroperoxides act similarly on ethylene (Prilezhaev's reaction):

One of the most characteristic oxidation reactions is the interaction of alkenes with a weakly alkaline solution of potassium permanganate KMnO4 with the formation of dihydric alcohols - glycols (Wagner reaction). The reaction proceeds in the cold as follows:

Concentrated solutions of oxidizing agents (potassium permanganate in an acidic medium, chromic acid, nitric acid) break the alkene molecule at a double bond to form ketones and acids:

8. Alkenes ozonation reaction. It is also widely used to establish the structure of alkenes:

9. Substitution reactions. Alkenes are also capable of substitution reactions under certain conditions. Thus, during high-temperature (500 ... 550 ° C) chlorination of alkenes, hydrogen is replaced in the allyl position:

10. Reaction of polymerization of alkenes

CH2 = CH2> (-CH2 - CH2 -) n polyethylene is obtained

11. Isomerization reaction. At high temperatures or in the presence of catalysts, alkenes can be isomerized, with either a change in the structure of the carbon skeleton or a movement of the double bond:

7. Naphthalene and its structure. Hückel's rule

Naphthalene hydrocarbons are the main aromatic hydrocarbon in coal tar. There are a large number of polycyclic aromatic compounds in which the benzene rings share ortho-positioned carbon atoms. The most important of these are naphthalene, anthracene and phenanthrene. In anthracene, the rings are connected linearly, while in phenanthrene, at an angle, unlike the benzene molecule, not all bonds in the naphthalene core have the same length:

Hückel's rule : aromatic is a planar monocyclic conjugated system containing (4n + 2) p-electrons (where n = 0,1,2 ...).

Thus, planar cyclic conjugated systems containing 2, 6,10, 14, etc. will be aromatic. p-electrons.

8. Alkyne and sp-hybridization of the carbon atom. Methods for obtaining alkynes

Hydrocarbons of the acetylene series have the general formula

WITH n H2 n-2

The first simplest hydrocarbon in this series is acetylene C2H2. The structural formula of acetylene, like other hydrocarbons of this series, contains a triple bond:

NS? C - N.

sR-Hybridization is mixing (alignment in shape and energy) of one s- and one R-orbitals with the formation of two hybrid sR-orbitals. sR-Orbitals are located on one line (at an angle of 180 °) and are directed in opposite directions from the nucleus of the carbon atom.

Two R-orbitals remain unhybridized. They are placed mutually perpendicular to the directions at-connections.

On the picture sR-orbitals are shown along the axis y, and unhybridized two R- orbitals - along the axes NS and z.

The triple carbon-carbon bond C? C consists of a y-bond, which appears when sp-hybrid orbitals overlap, and two p-bonds.

Calcium carbide is produced on an industrial scale by heating coal in electric furnaces with quicklime at a temperature of about 2500 ° C according to the reaction

CaO + 3C> CaC2 + CO.

If you act on calcium carbide with water, then it rapidly decomposes with the release of gas - acetylene:

A newer industrial method for producing acetylene is pyrolysis of hydrocarbons, in particular methane, which at 1400 ° C gives a mixture of acetylene with hydrogen:

2CH4> H-C = C-H + 3H2.

1. Dehydrohalogenation of vicinal dihaloalkanes

2. Reaction of sodium acetylenides with primary alkyl halides:

3. Dehalogenation of vicinal tetrahaloalkanes:

9. Production methods and chemicalproperties of alcohols

Alcohols are hydrocarbon derivatives in which one or more hydrogen atoms are replaced by the corresponding number of hydroxyl groups (-OH).

General formula of alcohols

where R is an alkyl or substituted alkyl group.

The nature of the radical R, to which the hydroxyl group is bound, determines the limit or unsaturation of alcohols, and the number of hydroxyl groups determines its atomicity: alcohols are monoatomic, diatomic, triatomic and polyatomic.

Obtaining: 1. Hydration of alkenes

2. Enzymatic hydrolysis of carbohydrates... Enzymatic hydrolysis of sugars by yeast - the most ancient synthetic chemical process - is still of great importance for the production of ethyl alcohol.

When starch is used as a starting material, in addition to ethyl alcohol, fusel oil is also formed (in smaller amounts), which is a mixture of primary alcohols, mainly isopentyl, isopropyl and isobutyl alcohols.

3. Synthesis of methyl alcohol:

4. Reaction of hydroboration-oxidation of alkenes:

5. Synthesis of alcohols using the Grignard reagent:

Properties: The chemical properties of alcohols are determined by both the structure of the alkyl radical and the reactive hydroxyl group. Reactions involving the hydroxyl group can proceed either with the cleavage of the C-OH bond (360 kJ / mol), or with the cleavage of the O-H bond (429 kJ / mol) A. Cleavage of the C-OH bond

1. Reaction with hydrogen halides:

ROH + HX> RX + H2O.

Reactivity decreases in the order: HI> HBr> HCl

2. Reaction with phosphorus trihalides:

3. Dehydration of alcohols in the presence of dehydrating agents:

B. Disconnection HE

4. Reaction of alcohols with metals(Na, K, Mg, Al)

5. Formation of ethers:

Esterification reaction

6. Oxidation reactions When alcohols are oxidized with a chromium mixture or KMnO4 in a sulfuric acid solution, the composition of the products depends on the nature of the carbon atom (primary, secondary, or tertiary) to which the hydroxyl group is associated: primary alcohols form aldehydes, secondary alcohols - ketones.

9. Alkadienes and methods for their preparation

Diene hydrocarbons (dienes) are called unsaturated hydrocarbons having two double bonds, of the general formula

Two double bonds in a hydrocarbon molecule can be located in different ways.

If they are concentrated on one carbon atom, they are called cumulated:

If two double bonds are separated by one single bond, they are called conjugated:

If double bonds are separated by two or more simple bonds, then they are called isolated: -C = C- (CH2) n - C = C-

Dienes are usually prepared by the same methods as simple alkenes. For example, the most important diene, 1,3-butadiene (used to make synthetic rubber), is produced in the United States from the dehydrogenation of butane:

In the USSR, industrial synthesis of butadiene-1,3 was used according to the method of S.V. Lebedev (1933) from ethyl alcohol at 400 ... 500 ° C over MgO-ZnO catalyst:

The reaction includes the following stages: dehydrogenation of alcohol to aldehyde, aldol condensation of acetaldehyde, reduction of aldol to butanediol-1,3 and finally dehydration of alcohol:

10. Electronegativity of elements and types of chemical bonds

Elektronegativeness (h) (relative electronegativity) is a fundamental chemical property of an atom, a quantitative characteristic of the ability of an atom in a molecule to displace common electron pairs towards itself, that is, the ability of atoms to attract electrons of other atoms to themselves.

The highest degree of electronegativity is in halogens and strong oxidants (p-elements of group VII, O, Kr, Xe), and the lowest is in active metals (s-elements of group I).

Ionic. The electronic configuration of an inert gas for any atom can be formed due to the transfer of electrons: the atoms of one of the elements donate electrons, which are transferred to the atoms of the other element.

In this case, a so-called ionic (electrovalent, heteropolar) bond is formed between these atoms.

This type of bond occurs between the atoms of elements with significantly different electronegativity (for example, between a typical metal and a typical non-metal).

Covalent bond. In the interaction of atoms equal (atoms of the same element) or close in electronegativity, the transfer of electrons does not occur. The electronic configuration of an inert gas for such atoms is formed due to the generalization of two, four, or six electrons by interacting atoms. Each of the shared pairs of electrons forms one covalent (homeopolar) bond:

A covalent bond is the most common type of bond in organic chemistry. It is strong enough.

A covalent bond and, accordingly, a molecule can be non-polar when both bonded atoms have the same electron affinity (for example, H: H). It can be polar, when the electron pair, due to the greater electron affinity of one of the atoms, is pulled in its direction:

With this method, the designations + and - mean that on the atom with the sign there is an excess electron density, and on the atom with the sign +, the electron density is somewhat reduced compared to isolated atoms.

Donor-acceptor bond. When atoms that have lone electron pairs interact with a proton or another atom that lacks two electrons before the formation of an octet (doublet), the lone electron pair becomes common and forms a new covalent bond between these atoms.

In this case, the atom that donates electrons is called a donor, and the atom that accepts electrons is called an acceptor:

chemical covalent benzene naphthalene

In the emerging ammonium ion, the formed covalent bond differs from the bonds that existed in the ammonia molecule, only by the method of formation, in terms of physical and chemical properties, all four N-H bonds are absolutely identical.

Semipolar connection. This type of donor-acceptor bond is often found in molecules of organic compounds (for example, in nitro compounds, in sulfoxides, etc.).

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The valence states of the carbon atom

Shaft. comp.	Interacting orbitals	Space page	Communication type	Shaft. injection
		tetrahedral.

		linear

With a change in the type of hybridization of a carbon atom, its properties also change. When passing from sp 3 to sp-, the fraction of the s-orbital in the hybridized cloud increases, which entails a change in its shape. The boundaries of the electron cloud approach the core in the case of sp 2 and sp orbitals, as compared to the sp 3 cloud. This is reflected in an increase in the electronegativity of the carbon atom in the series: sp 3< sp 2 < sp. В связи с этим, уменьшается ковалентный радиус, увеличивается полярность связи.

Types of chemical bonds

Ionic bond

It arises in the case of a complete donation of electrons by some atoms and their acquisition by others. In this case, the atoms are converted into ions.

Covalent bond

Formed by the socialization of electrons. The binding of atoms in a molecule is carried out by an electron pair belonging simultaneously to two atoms. Communityization of electrons is possible in two ways:

1) colligation (exchange mechanism);

2) coordination (donor-acceptor mechanism).

There are two types of covalent bonds: σ (sigma) - and π (pi) - bonds.

A σ-bond is a single covalent bond formed when atomic orbitals overlap along a straight line (axis) connecting the nuclei of two bound atoms with the maximum overlap on this straight line.

π-bond is the bond formed by lateral overlap of unhybridized p z-atomic orbitals with a maximum overlap on either side of the straight line connecting the atomic nuclei.

Quantitative characteristics of the covalent bond

1. Bond energy is the energy released during the formation of a bond or necessary to break it.

2. The bond length is the distance between the centers of the bonded atoms.

3. The polarity of the bond is the uneven distribution of the electron density.

4. Bond polarizability - displacement of bond electrons under the influence of an external electric field, including another reacting particle.

Intermolecular interactions

Types of isomerism in organic compounds

Isomerism is a phenomenon of the existence of isomers. Isomer is a thing having the same composition of atoms, but different in structure.

BUT) Structural isomer-i 1) Isomerism of the carbon skeleton.

Distinguishing in the mutual arrangement of C.

2) Isomerism by the position of the multiple bond

(double).

3) From the position of the functional group Differences in the position of the functional group relative to the carbon skeleton.

IN) Spatial isomer-i

Associated with different positions of atoms or groups of atoms relative to the double bond. (Cis- (bath) and trans-isomer (chair), mirror isoieria)

Saturated hydrocarbons, their chemical properties.

Alkanes (paraffins) are saturated (saturated) hydrocarbons with an open chain. They have the general formula СnН2n + 2. In alkanes, carbon atoms are linked to each other only by simple (single) bonds, and the rest of the valences are carbon saturated with hydrogen atoms. The characteristic suffix for saturated hydrocarbons is an.,

CH4 - methane; C2H6 - ethane; С3Н8 - propane

С4Н10 - butane (2 isomers)

С5Н12 - pentane (3 isomers)

С6Н14 - hexane, С7Н16 - heptane

Chemical properties:

1) Substitution: CH4 + Cl2 → CH3Cl + HCl (methyl chloride)

CH3Cl + HCl → CH2Cl2 + HCl (methylene chloride) CH2Cl2 + Cl2 → CHCl3 + HCl (chloroform)

3) Nitration: typical for those having a secondary or tertiary carbon atom.

R-I KONOVALOVA

4) At a temperature of 100-500 ° C and access to oxygen, fatty acids are formed, and at a temperature of 500-600 ° C, a cracking process is observed

P-th combustion CH4 + 2O2 → CO2 + H20 (complete), 2СН4 + О2а2СО + 4Н2 (incomplete)

Catalytic oxidation 2СН3-СН2-СН2-СН3 + 5О2 → 4СН3СООН (acetic acid),

Chipping reaction: (cracking)

Isomerization

Getting alkanes.

Methane production

in industry:

1. Fractionation of natural gas and distillation of oil.

2. Synthesis from elements at high temperature (voltaic arc),

C + 2H2 → CH4

Chemical methods of obtaining: 1) From salts of organic acids. Fusion of sodium acetate with alkali: СН3СOONa + NaOH → CH4 + Na2CO3

2) Würz synthesis: CH3Cl + 2Na + ClCH2-CH3 → 2NaCl + C3H8

3) From magnesium organic compounds: CH3Br + Mg → CH3MgBr
CH3MgBr + H2O → CH4 + Mg (OH) Br

4) Berthelot synthesis: C2H5I + HI → C2H6 + I2

5) From alkenes

6) Reduction of halogenated alkanes. CH3Cl + H2 → (p, pt) → CH4 + HCl

Orientation rules

1. The substituents present in the benzene nucleus direct the newly entering group to certain positions, i. E. have an orienting effect.

2. According to their guiding action, all substituents are divided into two groups: orientants of the first kind and orientants of the second kind.
Orientants of the 1st kind (ortho-pair-orientators) direct the subsequent substitution mainly to ortho- and pair-position.
These include electron donor groups (electronic effects of groups are indicated in brackets):

R ( + I); -OH (+ M, -I); -OR (+ M, -I); -NH 2 (+ M, -I); -NR 2 (+ M, -I)
The + M-effect in these groups is stronger than the -I-effect.

Orientants of the 1st kind increase the electron density in the benzene ring, especially on carbon atoms in ortho- and pair-positions, which favors the interaction with electrophilic reagents of precisely these atoms.
Example:

Orientants of the first kind, increasing the electron density in the benzene ring, increase its activity in electrophilic substitution reactions in comparison with unsubstituted benzene.

A special place among orientants of the 1st kind is occupied by halogens, which exhibit electron-withdrawing properties:- F (+ M<–I ), -Cl (+ M<–I ), -Br (+ M<–I ).
Being ortho-pair-orientants, they slow down electrophilic substitution. The reason is strong –I-effect of electronegative halogen atoms, which lowers the electron density in the ring.

Orientants of the 2nd kind ( meta-orients) direct the subsequent replacement mainly to meta-position.
These include electron-withdrawing groups:

-NO 2 (–M, –I); -COOH (–M, –I); -CH = O (–M, –I); -SO 3 H (–I); -NH 3 + (–I); -CCl 3 (–I).

Type 2 orientants reduce the electron density in the benzene ring, especially in ortho- and pair-provisions. Therefore, the electrophile attacks carbon atoms not in these positions, but in meta- the position where the electron density is slightly higher.
Example:

All orientants of the second kind, decreasing in general the electron density in the benzene ring, reduce its activity in electrophilic substitution reactions.

Thus, the ease of electrophilic substitution for compounds (given as examples) decreases in the order:

toluene C 6 H 5 CH 3> benzene C 6 H 6> nitrobenzene C 6 H 5 NO 2.

Chem. Holy Island.

ADDITIONAL REACTIONS

1. Hydrogenation of carbonyl compounds, like alkenes, occurs in the presence of cata-

lysers (Ni, Pt, Pd). Primary alcohols are formed from aldehydes during reduction.

you, H-COH + H2 → CH3OH;

2. Connection of Н2О

R-COH + H2O = R-CH (OH) 2 (dihydric alcohol) 3. Reaction with senilic acid R-COH + H-CN = R-CH (OH) (CN) (oxynitrile)

4. Interaction with alcohols R-COH + R1-OH = R-CH (OR1) (OH) (hemiacetal) R-COH + R1-OH = (t * HCl) = R-CH (OR1) (OR1) (acetal )

CARBONYL GROUP SUBSTITUTION REACTIONS

CH3-COH + PCl5 → CH3-CHCl2 + POCl3

REACTIONS CAUSED BY SUBSTITUTION IN THE RADICAL

CH3-COH + Br2 = Br-CH2-COH + HBr (bromoacetic aldehyde)

R. OXIDATION

CH3-COH + Ag2O → CH3COOH + 2Ag

R. ALDOLNOY CONCENTRATION

CH3COH + CH3COH → CH3-CH (CH3) -CH2-COH → CH3-CH = CH-COH + H2O

Getting aldehydes.

Aldehydes include organic compounds containing a carbonyl group C = O, linked in aldehydes with one hydrocarbon radical

1 oxidation of methanol on a copper catalyst at 300О

CH3OH + O2 → 2H-COH (formaldehyde, formic aldehyde) + 2H2O;

2. Dehydrogenation of methanol in the gas phase on a catalyst (Сu, Ni). СН3OH → H-COH + H2

С2H2 + H2O CH2 = CH-OH CH3-COH (acetic anhedra

3 ALKALINE HYDROLYSIS OF DIGALOGENE DERIVATIVES

CH3-CHCl2 + 2NaOH → CH3-C (OH) 3 + 2NaCl → CH3COH + H2O + 2NaCl

4.R.KUCHEROVA CH≡CH + H2O → CH3COH

Dicarboxylic acids.

Carboxylic acids are hydrocarbon derivatives containing

one or more carboxyl groups. The general formula for carboxylic acids is R-COOH. The carboxyl group, in turn, consists of

carbonyl (> C = O) and hydroxyl (-OH) groups Depending on the number of carboxyl groups, carboxylic acids are divided into

monobasic (monocarboxylic), dibasic (dicarboxylic) and polybasic acids. These are organic compounds containing two carboxyl groups. Dibasic acids

NOOS-COOH oxalic (ethanedioic)

HOOS-CH2-COOH malonic propanedioic

HOOS-CH2-CH2-COOH amber (butanediic)

HOOS-CH2-CH2-CH2-COOH pentanediate, glutaric

HOOC-CH2-CH2-COOH succinic = (- H2O) = succinic acid anhydride

OBTAINING:

1) oxidation of 2 -atomic alcohols CH2 (OH) - CH2 (OH) → [O], - H2O → COH-COH → [O] → COOH-COOH

2) from dihalogen derivatives Cl-CH2-CH2-Cl → (2KCl) → N≡C-CH2-CH2-C≡N → (+ 6H2O, -2NH3) → HOOC-CH2-CH2-COOH + 2H2O

CHEMICAL ST-VA

1) substitution reactions

COOH-COOH → (+ NaOH, -H2O) → COONa-COOH → (+ NaOH, -H2O) → COONa-COONa

2) release of CO2 during heating

COOH-COOH → CO2 + HCOOH

COOH-CH2-COOH → CO2 + CH3COOH

3) release of H2O on heating

COOH-CH2-CH2-COOH → (t, -H2O) → (-CH2-COOOC-CH2-) CYCLE

4) COOH-COOH → [O] → CO2 + CO + H2O

5) COOH-CH2-COOH + 2C2H5O → CO (O-C2H5) -CH2-CO (O-C2H5) + H2O

6) COOH-CH2-CH2-COOH + 2NH4OH → COONH4-CH2-CH2-COONH4 → (-H2O) → СОNH2-CH2-CH2-CONH2 → (-NH3) → (-CH2-C (O) -NH-C (O) -CH2-) → (-CH = CH-NH-CH = CH-)

Chem sv-va

1) Harns all reactions to the carboxyl group-oxidation

Ether formation

Formation of two types of esters

Heat decomposition

Water release when heated (alpha acid)

Beta acid

Gama acid

Optical isomerism.

Colamin

Serine

Lecetin

Di - and tripeptides.

– these are organic substances, the molecules of which are built of amino acids linked by a peptide bond. Depending on the number of amino acids included in the molecule, dipeptides, tripeptides, etc., as well as polypeptides are distinguished. As a rule, peptide molecules are linear, with one end of the chain ending in a carboxyl group ( -Un), and the other is an amino group ( -NH 2). But the chain can be closed in a cyclic structure. The addition occurs due to the release of water from the carbonyl group of one a / c and the amino group of the other. Since proteins are synthesized in the form of polypeptide chains, the boundary between a polypeptide and a simple protein is arbitrary. Peptides are many substances important for organisms - some hormones, antibiotics, toxins.

Nucleosides and Nucleotides.

Nucleic acids are made up of mononucleotides. Nucleotide consists of three components: 1 . nitrogenous base (purine or permedine), 2 . sugar: ribose (C 5 H 10 O 5) or deoxyribose C 5 H 10 O 4., phosphoric acid. Purine bases. The founder - PURIN:

Pyrimidine bases. PYRIMIDINE:

Nitrogenous bases: AMP-adenosine monophosphate (adenyl acid):

ATP adenosine triphosphate:

Nucleosides Are nucleotides without phosphoric acid. Adenosine:

The attachment of phosphoric to - you is possible at three positions of the hydroxo groups of ribose: 2, 3, 5. Adenine, guanine and cytosine are included in both DNA and RNA. Thymine - only in DNA, uracil - only in RNA.

Diagram of the structure of RNA and DNA.

DNA structure: DNA strand is a carbohydrate phosphate sequence to which nitrogenous bases are linked. Phosphoric acid molecules combine oxyribose molecules, OH 3 and 5 carbon groups. A DNA molecule has 2 chains of nucleotides located in parallel to each other. These two chains are held together by hydrogen bonds. Complementarity ensures the same distance between nitrogenous bases. The sequence of the nitrogenous bases of one chain strictly corresponds to the sequence of the bases of the other chain.

RNA structure. RNA strand - it is a sequence of ribonucleotides linked in one strand. (linear structure) . The connection of ribonucleotides with each other is carried out by an ether bond between the 3rd -HE ribose of one nucleotide and the 5th -HE ribose of the next nucleotide. The nitrogenous bases of RNA are A and G (purine) and C and U (pyrimidine). A and D join pentose through N 9th position. C and Y - through the N atom in the 1st position. A distinctive feature of DNA from RNA is that it is not characterized by a stable helical structure. It is linear. RNA)

Dialysis. Electrophoresis.

Dialysis is a method of purifying protein solutions from low molecular weight impurities. For dialysis, a cylinder is needed, in which, instead of a day, a PPM, the pores of which allow small molecules to pass through, but do not allow protein molecules to pass through. A cylinder with a protein solution with impurities is immersed in a container with distilled water. Small molecules of impurities freely pass through the pores of the membrane, being evenly distributed between the areas inside and outside the cylinder. For complete cleaning, the cylinder must be immersed in running water. With the help of dialysis, protein solutions of the pharmaceutical industry are purified. This method is at the heart of the "artificial kidney".

Electropharesis is a method of separating proteins into individual fractions. The operation of the apparatus eff is based on the ability of charged protein molecules to move in an electric field to an oppositely charged electrode. Different molecules - different speed, depending on molecular weight, total charge, shape. The apparatus for the eff consists of a horizontally located carrier (helium) and electrodes that create an electric field. A solution with electrolytes is applied to the carrier. The test solution is applied to the start zone and voltage is applied. After a certain period of time, proteins with different molecular weights are distributed over the zones. From each zone, proteins can be extracted and quantified.

Catalysis. Types of catalysis.

Catalysis is a chemical phenomenon, the essence of which is the change in the rates of chemical reactions under the action of certain substances (they are called catalysts).

Homogeneous catalysis - catalyst and reagents are in the same phase.

Heterogeneous catalysis - the catalyst is usually solid, and the reaction takes place on its surface.

Adsorption, essence, meaning.

Adsorption - the settling of particles on the surface of the adsorbent. Activated carbon in gas masks protects against the effects of poisonous gases.

67) Chromatography:

Chromatography is a method of separating and analyzing mixtures of substances and studying the physicochemical properties of substances, based on the distribution of components between two phases: mobile and stationary. A solid substance (sorbent) or a film of a liquid applied to a solid substance serves as an immobile substance. Mobile is a liquid or gas flowing through a stationary phase. You can clean the substance from impurities.

The phenomenon of diffusion.

Diffusion is a one-sided transition of a soluble substance from a higher concentration to a lower one.

Types of chemical bonds in organic compounds

A covalent bond is an intramolecular chemical bond carried out due to one or more electron pairs strongly interacting with the nuclei of both connected atoms.

Sigma bond is a bond formed as a result of overlapping electron clouds and located on a straight line connecting the centers of atomic nuclei.

Pi - bond - a bond formed as a result of overlapping electron clouds and located outside the straight line connecting the centers of the nuclei of atoms.

Parameter name	Meaning
Topic of the article:	Chemical bonds in organic compounds
Rubric (thematic category)	Education

Types of chemical bonds in organic compounds. Chemical bonds in organic compounds

Variety of inorganic and organic substances

A.M.Butlerov's theory of the chemical structure of organic compounds

Isomerism and homology of organic substances

Classification of organic substances

Nomenclature of organic compounds

Hydrocarbons. Classification of hydrocarbons

Homologous series of hydrocarbons

Isomers of hydrocarbons

Structural isomerism

Spatial isomerism

The electronic structure of the carbon atom

Hybridization of carbon orbitals

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