Organic substances, their characteristics and classification. Organic compounds

Organic matter - These are compounds that contain a carbon atom. Even in the early stages of the development of chemistry, all substances were divided into two groups: mineral and organic. In those days, it was believed that in order to synthesize organic matter, it was necessary to have an unprecedented “vital force”, which is inherent only in living biological systems. Therefore, it is impossible to synthesize organic substances from mineral ones. And only at the beginning of the 19th century F. Weller refuted the existing opinion and synthesized urea from ammonium cyanate, that is, he obtained an organic substance from a mineral one. After which a number of scientists synthesized chloroform, aniline, acetate acid and many other chemical compounds.

Organic substances underlie the existence of living matter and are also the main food products for humans and animals. Most organic compounds are raw materials for various industries - food, chemical, light, pharmaceutical, etc.

Today, more than 30 million different organic compounds are known. Therefore, organic substances represent the most extensive class. The variety of organic compounds is associated with the unique properties and structure of Carbon. Neighboring carbon atoms are connected to each other by single or multiple (double, triple) bonds.

They are characterized by the presence of covalent bonds C-C, as well as polar covalent bonds C-N, C-O, C-Hal, C-metal, etc. Reactions involving organic substances have some features compared to mineral ones. Reactions of inorganic compounds usually involve ions. Often such reactions take place very quickly, sometimes instantly at the optimal temperature. Reactions with usually involve molecules. It should be said that in this case some covalent bonds are broken, while others are formed. As a rule, these reactions proceed much more slowly, and to speed them up it is necessary to increase the temperature or use a catalyst (acid or base).

How are organic substances formed in nature? Most organic compounds in nature are synthesized from carbon dioxide and water in the chlorophylls of green plants.

Classes of organic substances.

Based on the theory of O. Butlerov. Systematic classification is the foundation of scientific nomenclature, which makes it possible to name an organic substance based on the existing structural formula. The classification is based on two main features - the structure of the carbon skeleton, the number and placement of functional groups in the molecule.

The carbon skeleton is a part of an organic substance molecule that is stable in different ways. Depending on its structure, all organic substances are divided into groups.

Acyclic compounds include substances with a straight or branched carbon chain. Carbocyclic compounds include substances with cycles; they are divided into two subgroups - alicyclic and aromatic. Heterocyclic compounds are substances whose molecules are based on cycles, formed by carbon atoms and atoms of other chemical elements (Oxygen, Nitrogen, Sulfur), heteroatoms.

Organic substances are also classified according to the presence of functional groups that are part of the molecules. For example, classes of hydrocarbons (with the exception that there are no functional groups in their molecules), phenols, alcohols, ketones, aldehydes, amines, esters, carboxylic acids, etc. It should be remembered that each functional group (COOH, OH, NH2, SH, NH, NO) determines the physicochemical properties of a given compound.

There are many organic compounds, but among them there are compounds with common and similar properties. Therefore, they are all classified according to common characteristics and combined into separate classes and groups. The classification is based on hydrocarbons – compounds that consist only of carbon and hydrogen atoms. Other organic substances belong to "Other classes of organic compounds".

Hydrocarbons are divided into two large classes: acyclic and cyclic compounds.

Acyclic compounds (fatty or aliphatic) – compounds whose molecules contain an open (not closed in a ring) straight or branched carbon chain with single or multiple bonds. Acyclic compounds are divided into two main groups:

saturated (saturated) hydrocarbons (alkanes), in which all carbon atoms are connected to each other only by simple bonds;

unsaturated (unsaturated) hydrocarbons, in which between carbon atoms, in addition to single simple bonds, there are also double and triple bonds.

Unsaturated (unsaturated) hydrocarbons are divided into three groups: alkenes, alkynes and alkadienes.

Alkenes(olefins, ethylene hydrocarbons) – acyclic unsaturated hydrocarbons, which contain one double bond between carbon atoms, form a homologous series with the general formula CnH2n. The names of alkenes are formed from the names of the corresponding alkanes with the suffix “-ane” replaced by the suffix “-ene”. For example, propene, butene, isobutylene or methylpropene.

Alkynes(acetylene hydrocarbons) – hydrocarbons that contain a triple bond between carbon atoms form a homologous series with the general formula CnH2n-2. The names of alkenes are formed from the names of the corresponding alkanes, replacing the suffix “-an” with the suffix “-in”. For example, ethine (acytelene), butine, peptin.

Alcadienes – organic compounds that contain two carbon-carbon double bonds. Depending on how the double bonds are positioned relative to each other, dienes are divided into three groups: conjugated dienes, allenes, and dienes with isolated double bonds. Typically, dienes include acyclic and cyclic 1,3-dienes, forming with the general formulas C n H 2n-2 and C n H 2n-4. Acyclic dienes are structural isomers of alkynes.

Cyclic compounds, in turn, are divided into two large groups:

1. carbocyclic compounds – compounds whose cycles consist only of carbon atoms; Carbocyclic compounds are divided into alicyclic – saturated (cycloparaffins) and aromatic;
2. heterocyclic compounds – compounds whose cycles consist not only of carbon atoms, but atoms of other elements: nitrogen, oxygen, sulfur, etc.

In molecules of both acyclic and cyclic compounds Hydrogen atoms can be replaced by other atoms or groups of atoms, thus, by introducing functional groups, hydrocarbon derivatives can be obtained. This property further expands the possibilities of obtaining various organic compounds and explains their diversity.

The presence of certain groups in the molecules of organic compounds determines the commonality of their properties. This is the basis for the classification of hydrocarbon derivatives.

"Other Classes of Organic Compounds" include the following:

Alcohols are obtained by replacing one or more hydrogen atoms with hydroxyl groups – OH. It is a compound with the general formula R – (OH)x, where x – number of hydroxyl groups.

Aldehydes contain an aldehyde group (C=O), which is always found at the end of the hydrocarbon chain.

Carboxylic acids contain one or more carboxyl groups – COOH.

Esters – derivatives of oxygen-containing acids, which are formally products of substitution of hydrogen atoms of hydroxides – OH acidic function on a hydrocarbon residue; are also considered as acyl derivatives of alcohols.

Fats (triglycerides) – natural organic compounds, full esters of glycerol and monocomponent fatty acids; belong to the class of lipids. Natural fats contain three acid radicals with an unbranched structure and, usually, an even number of carbon atoms.

Carbohydrates – organic substances that contain a straight chain of several carbon atoms, a carboxyl group and several hydroxyl groups.

Amines contain an amino group – NH 2

Amino acids– organic compounds whose molecule simultaneously contains carboxyl and amine groups.

Squirrels – high-molecular organic substances that consist of alpha amino acids connected in a chain by a peptide bond.

Nucleic acids – high molecular weight organic compounds, biopolymers formed by nucleotide residues.

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In the history of the development of organic chemistry, two periods are distinguished: empirical (from the mid-17th to the end of the 18th century), in which the knowledge of organic substances, methods of their isolation and processing occurred experimentally, and analytical (late 18th - mid-19th century), associated with the emergence of methods for establishing composition of organic substances. During the analytical period, it was found that all organic substances contain carbon. Among other elements that make up organic compounds, hydrogen, nitrogen, sulfur, oxygen and phosphorus were discovered.

Of great importance in the history of organic chemistry is the structural period (second half of the 19th - early 20th centuries), marked by the birth of the scientific theory of the structure of organic compounds, the founder of which was A.M. Butlerov.

Basic principles of the theory of the structure of organic compounds:

• atoms in molecules are connected to each other in a certain order by chemical bonds in accordance with their valency. Carbon in all organic compounds is tetravalent;
• the properties of substances depend not only on their qualitative and quantitative composition, but also on the order of connection of atoms;
• the atoms in a molecule mutually influence each other.

The order of connection of atoms in a molecule is described by a structural formula in which chemical bonds are represented by dashes.

Characteristic properties of organic substances

There are several important properties that distinguish organic compounds into a separate, unique class of chemical compounds:

1. Organic compounds are usually gases, liquids, or low-melting solids, as opposed to inorganic compounds, which are mostly solids with a high melting point.
2. Organic compounds are mostly structured covalently, while inorganic compounds are structured ionicly.
3. The different topology of the formation of bonds between atoms forming organic compounds (primarily carbon atoms) leads to the appearance of isomers - compounds that have the same composition and molecular weight, but have different physicochemical properties. This phenomenon is called isomerism.
4. The phenomenon of homology is the existence of series of organic compounds in which the formula of any two neighbors of the series (homologs) differs by the same group - the homological difference CH 2. Organic matter burns.

Classification of organic substances

The classification is based on two important features - the structure of the carbon skeleton and the presence of functional groups in the molecule.

In molecules of organic substances, carbon atoms combine with each other, forming the so-called. carbon skeleton or chain. Chains can be open and closed (cyclic), open chains can be unbranched (normal) and branched:

Based on the structure of the carbon skeleton, they are divided into:

- alicyclic organic substances having an open carbon chain, both branched and unbranched. For example,

CH 3 -CH 2 -CH 2 -CH 3 (butane)

CH 3 -CH (CH 3) -CH 3 (isobutane)

- carbocyclic organic substances in which the carbon chain is closed in a cycle (ring). For example,

- heterocyclic organic compounds containing in the cycle not only carbon atoms, but also atoms of other elements, most often nitrogen, oxygen or sulfur:

A functional group is an atom or group of non-hydrocarbon atoms that determines whether a compound belongs to a particular class. The sign by which an organic substance is classified into one class or another is the nature of the functional group (Table 1).

Table 1. Functional groups and classes.

Compounds may contain more than one functional group. If these groups are the same, then the compounds are called polyfunctional, for example chloroform, glycerol. Compounds containing different functional groups are called heterofunctional; they can simultaneously be classified into several classes of compounds, for example, lactic acid can be considered both a carboxylic acid and an alcohol, and colamine can be considered an amine and an alcohol.

Rice. 5. Friedrich Wöhler
(1800–1882)

Rice. 6. Alexander
Mikhailovich Butlerov
(1828–1886)

The essence of the theory of chemical structure they created can be formulated in the form of three propositions.
1. Atoms in molecules are connected in a certain order according to their valence, and carbon in organic compounds is tetravalent.
2. The properties of substances are determined not only by the qualitative and quantitative elemental composition, but also by the order of connections of atoms in molecules, i.e. chemical structure.
3. Atoms in molecules have a mutual influence on each other, which affects the properties of substances.
* German chemist. Conducted research in the field of inorganic and organic chemistry. He established the existence of the phenomenon of isomerism and for the first time carried out the synthesis of an organic substance (urea) from an inorganic one. Received some metals (aluminum, beryllium, etc.).
** Outstanding Russian chemist, author of the theory of chemical
structure of organic substances. Based onconcepts of structure explained the phenomenon of isomerism, predicted the existence of isomers of a number of substances and synthesized them for the first time. He was the first to synthesize a sugary substance. Founder of the school of Russian chemistryIkov, which included V.V. Markovnikov, A.M. Zaitsev, E.E. Vagner, A.E. Favorsky and others.

Today it seems incredible that until the middle of the 19th century, during the period of great discoveries in natural science, scientists had little understanding of the internal structure of matter. It was Butlerov who introduced the term “chemical structure,” meaning by it a system of chemical bonds between atoms in a molecule and their relative arrangement in space. Thanks to this understanding of the structure of the molecule, it became possible to explain the phenomenon of isomerism, predict the existence of unknown isomers, and correlate the properties of substances with their chemical structure. To illustrate the phenomenon of isomerism, we present the formulas and properties of two substances - ethyl alcohol and dimethyl ether, which have the same elemental composition C2H6O, but different chemical structures (Table 2).
table 2

Illustration of the dependence of the properties of a substancefrom its structure

The phenomenon of isomerism, very widespread in organic chemistry, is one of the reasons for the diversity of organic substances. Another reason for the diversity of organic substances is the unique ability of the carbon atom to form chemical bonds with each other, resulting in carbon chains
of various lengths and structures: unbranched, branched, closed. For example, four carbon atoms can form chains like this:

If we take into account that between two carbon atoms there can exist not only simple (single) C–C bonds, but also double C=C and triple C≡C, then the number of variants of carbon chains and, consequently, various organic substances increases significantly.
The classification of organic substances is also based on Butlerov’s theory of chemical structure. Depending on the atoms of which chemical elements are included in the molecule, all organic groups: hydrocarbons, oxygen-containing, nitrogen-containing compounds.
Hydrocarbons are organic compounds consisting only of carbon and hydrogen atoms.
Based on the structure of the carbon chain and the presence or absence of multiple bonds in it, all hydrocarbons are divided into several classes. These classes are presented in Diagram 2.
If a hydrocarbon does not contain multiple bonds and the chain of carbon atoms is not closed, it belongs, as you know, to the class of saturated hydrocarbons, or alkanes. The root of this word is of Arabic origin, and the suffix -an is present in the names of all hydrocarbons of this class.
Scheme 2

Classification of hydrocarbons

The presence of one double bond in a hydrocarbon molecule allows it to be classified as an alkene, and its relationship to this group of substances is emphasized
suffix -en in the name. The simplest alkene is ethylene, which has the formula CH2=CH2. There can be two C=C double bonds in a molecule; in this case, the substance belongs to the class of alkadienes.
Try to explain the meaning of the suffixes -diene. For example, 1,3 butadiene has the structural formula: CH2=CH–CH=CH2.
Hydrocarbons with a carbon-carbon triple bond in the molecule are called alkynes. The suffix -in indicates that a substance belongs to this class. The ancestor of the class of alkynes is acetylene (ethyne), the molecular formula of which is C2H2, and the structural formula is HC≡CH. From compounds with a closed carbon chain
The most important atoms are arenes - a special class of hydrocarbons, the name of the first representative of which you have probably heard is benzene C6H6, the structural formula of which is also known to every cultural person:

As you already understood, in addition to carbon and hydrogen, organic substances can contain atoms of other elements, primarily oxygen and nitrogen. Most often, the atoms of these elements in various combinations form groups, which are called functional.
A functional group is a group of atoms that determines the most characteristic chemical properties of a substance and its belonging to a certain class of compounds.
The main classes of organic compounds containing functional groups are presented in Scheme 3.
Scheme 3
Main classes of organic substances containing functional groups

The functional group –OH is called hydroxyl and determines membership in one of the most important classes of organic substances – alcohols.
The names of alcohols are formed using the suffix -ol. For example, the most famous representative of alcohols is ethyl alcohol, or ethanol, C2H5OH.
An oxygen atom can be linked to a carbon atom by a chemical double bond. The >C=O group is called carbonyl. The carbonyl group is part of several
functional groups, including aldehyde and carboxyl. Organic substances containing these functional groups are called aldehydes and carboxylic acids, respectively. The most famous representatives of aldehydes are formaldehyde НСОН and acetaldehyde CH3СОН. Everyone is probably familiar with acetic acid CH3COOH, the solution of which is called table vinegar. A distinctive structural feature of nitrogen-containing organic compounds, and, first of all, amines and amino acids, is the presence of the amino group –NH2 in their molecules.
The above classification of organic substances is also very relative. Just as one molecule (for example, alkadienes) can contain two multiple bonds, a substance can have two or even more functional groups. Thus, the structural units of the main carriers of life on earth - protein molecules - are amino acids. The molecules of these substances necessarily contain at least two functional groups - a carboxyl and amino group. The simplest amino acid is called glycine and has the formula:

Like amphoteric hydroxides, amino acids combine the properties of acids (due to the carboxyl group) and bases (due to the presence of an amino group in the molecule).
For the organization of life on Earth, the amphoteric properties of amino acids are of particular importance - due to the interaction of amino groups and carboxyl groups of amino acids.
lots are connected into polymer chains of proteins.
? 1. What are the main provisions of the theory of chemical structure of A.M. Butlerov. What role did this theory play in the development of organic chemistry?
2. What classes of hydrocarbons do you know? On what basis is this classification made?
3. What is the functional group of an organic compound? What functional groups can you name? What classes of organic compounds contain the named functional groups? Write down the general formulas of classes of compounds and the formulas of their representatives.
4. Define isomerism, write down the formulas of possible isomers for compounds of the composition C4H10O. Using various sources of information, name each of them and prepare a report about one of the compounds.
5. Classify substances whose formulas are: C6H6, C2H6, C2H4, HCOOH, CH3OH, C6H12O6, to the corresponding classes of organic compounds. Using various sources of information, name each of them and prepare a report about one of the compounds.
6. Structural formula of glucose: Which class of organic compounds would you classify this substance as? Why is it called a dual function compound?
7. Compare organic and inorganic amphoteric compounds.
8. Why are amino acids classified as compounds with dual functions? What role does this structural feature of amino acids play in the organization of life on Earth?
9. Prepare a message on the topic “Amino acids - the “building blocks” of life” using the Internet.
10. Give examples of the relativity of dividing organic compounds into certain classes. Draw parallels to similar relativity for inorganic compounds.

Introduction

1. Saturated hydrocarbons

1.1. Saturated straight-chain compounds

1.1.1. Monovalent radicals

1.2. Saturated branched compounds with one substituent

1.3. Saturated branched compounds with several substituents

2. Unsaturated hydrocarbons

2.1. Unsaturated straight hydrocarbons with one double bond (alkenes)

2.2. Unsaturated straight hydrocarbons with one triple bond (alkynes)

2.3. Unsaturated branched hydrocarbons

3. Cyclic hydrocarbons

3.1. Aliphatic hydrocarbons

3.2. Aromatic hydrocarbons

3.3. Heterocyclic compounds

4. Hydrocarbons containing functional groups

4.1. Alcohols

4.2. Aldehydes and ketones 18

4.3. Carboxylic acids 20

4.4. Esters 22

4.4.1. Ethers 22

4.4.2. Esters 23

4.5. Amines 24

5. Organic compounds with several functional groups 25

Literature

Introduction

The scientific classification and nomenclature of organic compounds is based on the principles of the theory of the chemical structure of organic compounds by A.M. Butlerov.

All organic compounds are divided into the following main series:

Acyclic - they are also called aliphatic, or fatty compounds. These compounds have an open chain of carbon atoms.

These include:

1. Limit (saturated)
2. Unsaturated (unsaturated)

Cyclic - compounds with a chain of atoms closed in a ring. These include:

1. 1. Carbocyclic (isocyclic) - compounds whose ring system includes only carbon atoms:
   a) alicyclic (limited and unsaturated);
   b) aromatic.
2. Heterocyclic - compounds whose ring system, in addition to the carbon atom, includes atoms of other elements - heteroatoms (oxygen, nitrogen, sulfur, etc.)

Currently, three types of nomenclature are used to name organic compounds: trivial, rational and systematic nomenclature - IUPAC nomenclature (IUPAC) - International Union of Pure and Applied Chemistry (International Union of Pure and Applied Chemistry).

Trivial (historical) nomenclature is the first nomenclature that arose at the beginning of the development of organic chemistry, when there was no classification or theory of the structure of organic compounds. Organic compounds were given random names based on their source (oxalic acid, malic acid, vanillin), color or smell (aromatic compounds), and less often, based on their chemical properties (paraffins). Many such names are still often used today. For example: urea, toluene, xylene, indigo, acetic acid, butyric acid, valeric acid, glycol, alanine and many others.

Rational nomenclature - According to this nomenclature, the name of the simplest (usually the first) member of a given homologous series is usually taken as the basis for the name of an organic compound. All other compounds are considered as derivatives of this compound, formed by replacing hydrogen atoms in it with hydrocarbon or other radicals (for example: trimethylacetic aldehyde, methylamine, chloroacetic acid, methyl alcohol). Currently, such nomenclature is used only in cases where it gives a particularly clear idea of ​​the connection.

Systematic nomenclature - IUPAC nomenclature - International Unified Chemical Nomenclature. Systematic nomenclature is based on the modern theory of the structure and classification of organic compounds and attempts to solve the main problem of nomenclature: the name of each organic compound must contain the correct names of the functions (substituents) and the main skeleton of the hydrocarbon and must be such that the name can be used to write the only correct structural formula.

The process of creating an international nomenclature began in 1892 ( Geneva nomenclature), continued in 1930 ( Liege nomenclature), since 1947, further development is associated with the activities of the IUPAC commission on the nomenclature of organic compounds. The IUPAC rules published over the years were collected in 1979 in “ blue book". The IUPAC Commission considers its task not to create a new, unified system of nomenclature, but to streamline, “codify” existing practice. The result of this is the coexistence in IUPAC rules of several nomenclature systems, and, consequently, several acceptable names for the same substance. IUPAC rules are based on the following systems: substitutive, radical-functional, additive (connective), replacement nomenclature, etc.

IN replacement nomenclature the name is based on one hydrocarbon fragment, and others are considered as hydrogen substituents (for example, (C 6 H 5) 3 CH - triphenylmethane).

IN radical functional nomenclature The name is based on the name of the characteristic functional group that determines the chemical class of the compound to which the name of the organic radical is attached, for example:

C 2 H 5 OH - ethyl alcohol;

C2H5Cl - ethyl chloride;

CH 3 –O–C 2 H 5 - methyl ethyl ether;

CH 3 –CO–CH = CH 2 - methylvinyl ketone.

IN connecting nomenclature the name is composed of several equal parts (for example, C 6 H 5 –C 6 H 5 biphenyl) or by adding the designations of attached atoms to the name of the main structure (for example, 1,2,3,4-tetrahydronaphthalene, hydrocinnamic acid, ethylene oxide, styrene dichloride).

Substitute nomenclature is used when there are non-carbon atoms (heteroatoms) in the molecular chain: the roots of the Latin names of these atoms ending in “a” (a-nomenclature) are attached to the names of the entire structure that would result if there were carbon instead of heteroatoms (for example, CH 3 –O–CH 2 –CH 2 –NH–CH 2 –CH 2 –S–CH 3 2-oxa-8-thia-5-azanonane).

The IUPAC system is generally recognized in the world, and is only adapted according to the grammar of the country's language. The full set of rules for applying the IUPAC system to many less common types of molecules is long and complex. Only the basic contents of the system are presented here, but this allows the naming of the connections for which the system is used.

1. SATURAL HYDROCARBONS

1.1. Saturated unbranched compounds

The names of the first four saturated hydrocarbons are trivial (historical names) - methane, ethane, propane, butane. Starting from the fifth, the names are formed by Greek numerals corresponding to the number of carbon atoms in the molecule, with the addition of the suffix " –AN", with the exception of the number "nine", when the root is the Latin numeral "nona".

Table 1. Names of saturated hydrocarbons

1.1.1. Monovalent radicals

Monovalent radicals formed from saturated unbranched saturated hydrocarbons by removing hydrogen from the terminal carbon atom are called replacing the suffix " –AN"in the name of the hydrocarbon with the suffix" –IL".

Does the carbon atom with free valence get a number? These radicals are called normal or unbranched alkyls:

CH 3 – - methyl;

CH 3 –CH 2 –CH 2 –CH 2 – - butyl;

CH 3 –CH 2 –CH 2 –CH 2 –CH 2 –CH 2 – - hexyl.

Table 2. Names of hydrocarbon radicals

1.2. Saturated branched compounds with one substituent

The IUPAC nomenclature for alkanes in individual names retains the principle of Geneva nomenclature. When naming an alkane, one starts from the name of the hydrocarbon corresponding to the longest carbon chain in a given compound (the main chain), and then indicates the radicals adjacent to this main chain.

The main carbon chain, firstly, must be the longest, and secondly, if there are two or more chains of equal length, then the most branched one is selected.

*To name saturated branched compounds, choose the longest chain of carbon atoms:

* The selected chain is numbered from one end to the other with Arabic numerals, and the numbering begins from the end to which the substituent is closest:

*Indicate the position of the substituent (number of the carbon atom at which the alkyl radical is located):

*Alkyl radical is named according to its position in the chain:

*Called the main (longest carbon chain):

If the substituent is a halogen (fluorine, chlorine, bromine, iodine), then all nomenclature rules remain the same:

Trivial names are retained only for the following hydrocarbons:

If there are several identical substituents in the hydrocarbon chain, then the prefix “di”, “tri”, “tetra”, “penta”, “hexa”, etc. is placed in front of their names, indicating the number of groups present:

1.3. Saturated branched compounds with several substituents

If there are two or more different side chains, they can be listed: a) in alphabetical order or b) in order of increasing complexity.

a) When listing the different side chains in alphabetical order multiplying prefixes are not taken into account. First, the names of atoms and groups are arranged in alphabetical order, and then multiplying prefixes and location numbers (locants) are inserted:

2-methyl-5-propyl-3,4-diethyloctane

b) When listing side chains in order of increasing complexity, proceed from the following principles:

A less complex chain is one that has fewer total carbon atoms, for example:

less complex than

If the total number of carbon atoms in a branched radical is the same, then the side chain with the longest main chain of the radical will be less complex, for example:

less complex than

If two or more side chains are in equivalent position, then the lower number is given to the chain that is listed first in the name, regardless of whether the order is of increasing complexity or alphabetical:

a) alphabetical order:

b) order of difficulty:

If there are several hydrocarbon radicals in the hydrocarbon chain and they are different in complexity, and when numbering different rows of several numbers are obtained, they are compared by arranging the numbers in the rows in ascending order. “Smallest” are considered the digits of the series in which the first different digit is smaller (for example: 2, 3, 5 less than 2, 4, 5 or 2, 7, 8 less than 3, 4, 9). This principle is observed regardless of the nature of the substituents.

In some reference books, the sum of digits is used to determine the choice of numbering; numbering begins on the side where the sum of digits indicating the position of the substituents is the smallest:

2, 3 , 5, 6, 7, 9 - the series of numbers is the smallest

2, 4 , 5, 6, 8, 9

2+3+5+6+7+9 = 32 - the sum of the substituent numbers is the smallest

2+4+5+6+8+9 = 34

therefore, the hydrocarbon chain is numbered from left to right, then the name of the hydrocarbon will be:

(2, 6, 9-trimethyl-5,7-dipropyl-3,6-diethyldecane)

(2,2,4-trimethylpentane, but not 2,4,4-trimethylpentane)

If the hydrocarbon chain contains several different substituents (for example, hydrocarbon radicals and halogens), then the substituents are listed either in alphabetical order or in order of increasing complexity (fluorine, chlorine, bromine, iodine):

a) alphabetical order 3-bromo-1-iodo-2-methyl-5-chloropentane;

b) order of increasing complexity: 5-chloro-3-bromo-1-iodo-2-methylpentane.

Literature

1. IUPAC rules of nomenclature for chemistry. M., 1979, vol. 2, half volumes 1,2
2. Chemist's Handbook. L., 1968
3. Banks J. Names of organic compounds. M., 1980